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The radiative infrared cooling of CO 2 in the middle atmosphere, where it emits under non-local thermodynamic equilibrium (non-LTE) conditions, is a crucial contribution to the energy balance of this region and hence to establishing its thermal structure. The non-LTE computation is too CPU time-consuming to be fully incorporated into climate models, and hence it is parameterized. The most used parameterization of the CO 2 15 µm cooling for Earth's middle and upper atmosphere was developed by. The valid range of this parameterization with respect to CO 2 volume mixing ratios (VMRs) is, however, exceeded by the CO 2 of several scenarios considered in the Coupled Climate Model Intercomparison Projects, in particular the abrupt-4 × CO 2 experiment. Therefore, an extension, as well as an update, of that parameterization is both needed and timely. In this work, we present an update of that parameterization that now covers CO 2 volume mixing ratios in the lower atmosphere from ∼0.5 to over 10 times the CO 2 pre-industrial value of 284 ppmv (i.e. 150 to 3000 ppmv). Furthermore, it is improved by using a more contemporary CO 2 line list and the collisional rates that affect the CO 2 cooling rates. Overall, its accuracy is improved when tested for the reference temperature profiles as well as for measured temperature fields covering all expected conditions (latitude and season) of the middle atmosphere. The errors obtained for the reference temperature profiles are below 0.5 K d -1 for the present-day and lower CO 2 VMRs. Those errors increase to ∼1 –2K d -1 at altitudes between 110 and 120 km for CO 2 concentrations of 2 to 3 times the pre-industrial values. For very high CO 2 concentrations (4 to 10 times the pre-industrial abundances), those errors are below ∼1 K d -1 for most regions and conditions, except at 107–135 km, where the parameterization overestimates them by ∼1.2 %. These errors are comparable to the deviation of the non-LTE cooling rates with respect to LTE at about 70 km and below, but they are negligible (several times smaller) above that altitude. When applied to a large dataset of global (pole to pole and four seasons) temperature profiles measured by MIPAS (Michelson Interferometer for Passive Atmospheric Spectroscopy) (middle- and upper-atmosphere mode), the errors of the parameterization for the mean cooling rate (bias) are generally below 0.5 K d -1 , except between 5×10-3 and 3×10-4 hPa (∼85 –98 km), where they can reach biases of 1–2 K d -1. For single-temperature profiles, the cooling rate error (estimated by the root mean square – rms – of a statistically significant sample) is about 1–2 K d -1 below 5×10-3 hPa (∼85 km) and above 2×10-4 hPa (∼102 km). In the intermediate region, however, it is between 2 and 7 K d -1. For elevated stratopause events, the parameterization underestimates the mean cooling rates by 3–7 K d -1 (∼ 10 %) at altitudes of 85–95 km and the individual cooling rates show a significant rms (5–15 K d -1). Further, we have also tested the parameterization for the temperature obtained by a high-resolution version of the Whole Atmosphere Community Climate Model (WACCM-X), which shows a large temperature variability and wave structure in the middle atmosphere. In this case, the mean (bias) error of the parameterization is very small, smaller than 0.5 K d -1 for most atmospheric layers, reaching only maximum values of 2 K d -1 near 5×10-4 hPa (∼ 96 km). The rms has values of 1–2 K d -1 (∼20 %) below ∼2×10-2 hPa (∼80 km) and values smaller than 4 K d -1 (∼2 %) above 10 -4 hPa (∼105 km). In the intermediate region between ∼5×10-3 and ∼2×10-4 hPa (85–102 km), the rms is in the range of 5–12 K d -1. While these values are significant in percentage at ∼5×10-3 – 5×10-4 hPa, they are very small above ∼5×10-4 hPa (96 km). The routine is very fast, taking (1.5–7.5) ×10-5 s, depending on the extension of the atmospheric profile, the processor and the Fortran compiler. [ABSTRACT FROM AUTHOR]

We present a new version of O3 data retrieved from the three Michelson Interferometer for Passive Atmospheric Sounding (MIPAS) observation modes that we refer to for simplicity as the modes of the middle atmosphere (middle atmosphere, MA; upper atmosphere, UA; and noctilucent cloud, NLC). The O3 profiles cover altitudes from 20 up to 100 km for the daytime and up to 105 km at nighttime, for all latitudes, and the period 2005 until 2012. The data have been obtained with the IMK–IAA (Institute of Meteorology and Climate Research and Instituto de Astrofísica de Andalucía) MIPAS level-2 data processor and are based on ESA version-8 re-calibrated radiance spectra with improved temporal stability. The processing included several improvements with respect to the previous version, such as the consistency of the microwindows and spectroscopic data with those used in the nominal-mode V8R data, the O3 a priori profiles, and updates of the non-local thermodynamic equilibrium (non-LTE) parameters and the nighttime atomic oxygen. In particular, the collisional relaxation of O3 (v1 , v3) by the atomic oxygen was reduced by a factor of 2 in order to obtain a better agreement of nighttime mesospheric O3 with "non-LTE-free" measurements. Random errors are dominated by the measurement noise with 1 σ values for single profiles for the daytime of < 5 % below ∼ 60 km , 5 %–10 % between 60 and 70 km , 10 %–20 % at 70–90 km , and about 30 % at 95 km. For nighttime, they are very similar below 70 km but smaller above (10 %–20 % at 75–95 km , 20 %–30 % at 95–100 km and larger than 30 % above 100 km). The systematic error is ∼ 6 % below ∼ 60 km (dominated by uncertainties in spectroscopic data) and 8 %–12 % above ∼ 60 km , mainly caused by non-LTE uncertainties. The systematic errors in the 80–100 km range are significantly smaller than in the previous version. The major differences with respect to the previous version are as follows: (1) the new retrievals provide O3 abundances in the 20–50 km altitude range that are larger by about 2 %–5 % (0.2–0.5 ppmv); (2) O3 abundances were reduced by ∼ 2 %–4 % between 50 and 60 km in the tropics and mid-latitudes; (3) O3 abundances in the nighttime O3 minimum just below 80 km were reduced, leading to a more realistic diurnal variation; (4) daytime O3 concentrations in the secondary maximum at the tropical and middle latitudes (∼ 40 %, 0.2–0.3 ppmv) were larger; and (5) nighttime O3 abundances in the secondary maximum were reduced by 10 %–30 %. The O3 profiles retrieved from the nominal mode (NOM) and the middle-atmosphere modes are fully consistent in their common altitude range (20–70 km). Only at 60–70 km does daytime O3 of NOM seem to be larger than that of MA/UA by 2 %–10 %. Compared to other satellite instruments, MIPAS seems to have a positive bias of 5 %–8 % below 70 km. Noticeably, the new version of MIPAS data agrees much better than before with all instruments in the upper mesosphere–lower thermosphere, reducing the differences from ∼± 20 % to ∼± 10 %. Further, the diurnal variation in O3 in the upper mesosphere (near 80 km) has been significantly improved. [ABSTRACT FROM AUTHOR]

Abstract. The radiative infrared cooling of CO2 in the middle atmosphere, where it emits under non-Local Thermodynamic Equilibrium (non-LTE) conditions, is a crucial contribution to the energy balance of this region and hence to establishing its thermal structure. The non-LTE computation is too CPU time-consuming to be fully incorporated in climate models and hence it is parameterized. The most used parameterization of the CO2 15 µm cooling for the Earth's middle and upper atmosphere was developed by Fomichev et al. (1998). The valid range of this parameterization with respect to CO2 volume mixing ratios (VMR) is, however, exceeded by the CO2 of several scenarios considered in the Coupled Climate Model Intercomparison Projects; in particular, the abrupt-4xCO2 experiment. Therefore, an extension, as well as an update, of that parameterization is both needed and timely. In this work, we present an update of the parameterization developed by Fomichev et al. (1998), which now covers CO2 volume mixing ratios in the lower atmosphere from -0.5 to over 10 times the CO2 pre-industrial value of 284 ppmv (i.e., 150 ppmv to 3000 ppmv). Furthermore, it is improved by using a more contemporary CO2 line list and collisional rates that affect the CO2 cooling rates. Overall, accuracy is improved when tested against reference lineby- line calculations and by using measured global temperature profiles of the middle atmosphere. On average the errors are below 0.5Kday-1 for the present-day and lower CO2 VMRs. The errors increase to -1-2 Kday1 at altitudes between 100- 120 km for CO2 concentrations of two to three times the preindustrial values. For very high CO2 concentrations (four to ten times the pre-industrial abundances) the errors are below -1Kday-1 for most regions and conditions, except at 110-120 km where the parameterization overestimates them by -1.5%. When applied to a large dataset of global (pole-to-pole and four seasons) measured temperature profiles, the errors of the parameterization are generally below 0.5Kday-1, except between 5x10-3 hPa and 3x10-4 hPa (-85-95 km), where they can reach biases of 1-2Kday-1. However, for elevated stratopause events, it underestimates the cooling rates by 3-7Kday-1 (10%) at altitudes of 80--100 km and the parameterized cooling rates show a large spread when compared to reference calculations. [ABSTRACT FROM AUTHOR]

We present a new version of O3 data retrieved from the three MIPAS observations modes of the middle atmosphere (MA, UA and NLC). The O3 profiles cover altitudes from 20 up to 100 km altitudes for daytime and up to 105 km at nighttime, for all latitudes, and the period 2005 until 2012. The data has been obtained with the IMK-IAA MIPAS level 2 data processor and are based on ESA version 8 re-calibrated radiance spectra with improved temporal stability. The processing included several improvements with respect to the previous version, such as the consistency of the microwindows and spectroscopic data with those used in the nominal mode V8 data, the O3 a priori profiles, and updates of the non-LTE parameters and of the nighttime atomic oxygen. Random errors are dominated by the measurement noise with 1s values for single profiles for daytime of <5% below ~60 km, 5-10% between 60 and 70 km, 10-20% at 70-90 km and about 30% at 95 km. For nighttime, they are very similar below 70 km but smaller above (10-20% at 75-95 km, 20-30% at 95-100 km and larger than 30% above 100 km). The systematic error is ~6% below ~60 km (dominated by uncertainties in spectroscopic data), and 8-12% above ~60 km, mainly caused by non-LTE uncertainties. The systematic errors in the 80-100 km range are significantly smaller than in the previous version. The major differences with respect to the previous version are: 1) The new retrievals provide O3 abundances in the 20 - 50 km altitude range larger by about 2-5% (0.2-0.5 ppmv); 2) O3 abundances reduced by ~2-4% between 50 and 60 km in the tropics and mid-latitudes; 3) reduced O3 abundances in the nighttime O3 minimum just below 80 km, leading to a more realistic diurnal variation; 4) larger daytime O3 concentrations in the secondary maximum at the tropical and mid-latitudes (~40%, 0.2-0.3 ppmv); and 5) nighttime O3 abundances in the secondary maximum reduced by 10-30%. The O3 profiles retrieved from the nominal mode (NOM) and the middle atmosphere modes are fully consistent in their common altitude range (20-70 km). Only at 60-70 km daytime O3 of NOM seems to be larger than that of MA/UA by 2-10%. Compared to other satellite instruments, MIPAS seems to have a positive bias of 5-8% below 70 km. Noticeably, the new version of MIPAS agrees much better than before with all instruments in the upper mesosphere/lower thermosphere, reducing the differences from ~ ±20% to ~ ±10%. Further, the diurnal variation of O3 in the upper mesosphere (near 80 km) has been significantly improved. [ABSTRACT FROM AUTHOR]

Motivated by an improved European Space Agency (ESA) version of calibrated Michelson Interferometer for Passive Atmospheric Sounding (MIPAS) spectra (version 8.03), we have released version 8 of MIPAS temperatures and pointing information retrieved from 2005–2012 MIPAS measurements at 12–15 µ m in the Middle Atmosphere (MA), Upper Atmosphere (UA) and Noctilucent Cloud (NLC) measurement modes. The Institute of Meteorology and Climate Research–Instituto de Astrofisica de Andalucia (IMK–IAA) retrieval processor in use considers non-local thermodynamic equilibrium (non-LTE) emission explicitly for each limb scan. This non-LTE treatment is essential to obtain accurate temperatures above the mid-mesosphere because at the altitudes covered, up to 115 km, the simplified climatology-based non-LTE treatment employed for the Nominal (NOM) measurements is insufficient. Other updates in MA/UA/NLC version 8 non-LTE temperature retrievals from previous data releases include more realistic atomic oxygen and carbon dioxide abundances, an updated set of spectroscopic data, an improved spectral shift retrieval, a continuum retrieval extended to altitudes up to 58 km, consideration of an altitude-dependent radiance offset retrieval, the use of wider microwindows above 85 km to capture the offset, an improved accuracy in forward model calculations, new a priori temperature information, improved temperature horizontal gradient retrievals and the use of MIPAS version 5 interfering species where available. The resulting MIPAS MA/UA/NLC IMK–IAA temperature dataset is reliable for scientific analysis in the full measurement vertical range for the MA (18–102 km) and the NLC (39–102 km) observations and from 42 to 115 km for the UA observations. The random temperature errors, dominated by the instrumental noise, are typically less than 1 K below 60 km, 1–3 K at 60–70 km, 3–5 K at 70–90 km, 6–8 K at 90–100 km, 8–12 K at 100–105 km and 12–20 K at 105–115 km. Random pointing correction errors, also mainly arising from instrumental noise, are on average 50 m for tangent altitudes up to 60 km and decrease linearly to values smaller than 20 m for altitudes above 95 km. The vertical resolution is 3 km at altitudes below 50 km, 3–5 km at 50–70 km, 4–6 km at 70–90 km, 6–10 km at 90–100 km and 8–11 km at 100–115 km. The systematic errors in retrieved temperatures below 75 km are driven by uncertainties in the CO 2 spectroscopic data and, above 80 km, by uncertainties in the non-LTE model parameters (including collisional rates and atomic oxygen abundance) and the CO 2 abundance. These lead to systematic temperature errors of less than 0.7 K below 55 km, 1 K at 60–80 km, 1–2 K at 80–90 km, 3 K at 95 km, 6–8 K at 100 km, 10–20 K at 105 km and 20–30 K at 115 km. Systematic errors in the tangent altitude correction, mainly arising from CO 2 spectroscopic uncertainties, are 250 m at 20 km, 200 m at 40–60 km, 100 m at 80 km and smaller than 50 m above 90 km. The consistency between the MA/UA/NLC and the NOM IMK–IAA datasets is excellent below 70 km (typical 0.5–1 K differences). The comparison of this temperature dataset with co-located Sounding of the Atmosphere using Broadband Emission Radiometry (SABER) temperature measurements shows excellent agreement, with differences typically within 1.5 K below 90 km, 1–3 K at 90–95 km, 1–5 K at 95–100 km, 1–8 K at 100–105 km and 1–10 K above. The agreement with SABER improves with respect to previous MIPAS IMK–IAA data versions. [ABSTRACT FROM AUTHOR]

In this paper we describe the stratospheric and mesospheric ozone (version V5r_O3_m22) distributions retrieved from MIPAS observations in the three middle atmosphere modes (MA, NLC, and UA) taken with an unapodized spectral resolution of 0.0625cm-1 from 2005 until April 2012. O3 is retrieved from microwindows in the 14.8 and 10µm spectral regions and requires non-local thermodynamic equilibrium (non-LTE) modelling of the O3 v1 and v3 vibrational levels. Ozone is reliably retrieved from 20km in the MA mode (40km for UA and NLC) up to ~105km during dark conditions and up to ~95km during illuminated conditions. Daytime MIPAS O3 has an average vertical resolution of 3-4km below 70km, 6-8km at 70-80km, 8-10km at 80-90, and 5-7km at the secondary maximum (90-100km). For nighttime conditions, the vertical resolution is similar below 70km and better in the upper mesosphere and lower thermosphere: 4-6km at 70-100km, 4-5km at the secondary maximum, and 6-8km at 100-105km. The noise error for daytime conditions is typically smaller than 2% below 50km, 2-10% between 50 and 70km, 10-20% at 70-90km, and ~30% above 95km. For nighttime, the noise errors are very similar below around 70km but significantly smaller above, being 10-20% at 75-95km, 20-30% at 95-100km, and larger than 30% above 100km. The additional major O3 errors are the spectroscopic data uncertainties below 50km (10-12%) and the non-LTE and temperature errors above 70km. The validation performed suggests that the spectroscopic errors below 50km, mainly caused by the O3 air-broadened half-widths of the v2 band, are overestimated. The non-LTE error (including the uncertainty of atomic oxygen in nighttime) is relevant only above ~85km with values of 15-20%. The temperature error varies from ~3% up to 80km to 15-20% near 100km. Between 50 and 70km, the pointing and spectroscopic errors are the dominant uncertainties. The validation performed in comparisons with SABER, GOMOS, MLS, SMILES, and ACE-FTS shows that MIPAS O3 has an accuracy better than 5% at and below 50km, with a positive bias of a few percent. In the 50-75km region, MIPAS O3 has a positive bias of 10%, which is possibly caused in part by O3 spectroscopic errors in the 10µm region. Between 75 and 90km, MIPAS nighttime O3 is in agreement with other instruments by 10%, but for daytime the agreement is slightly larger, ~10-20%. Above 90km, MIPAS daytime O3 is in agreement with other instruments by 10%. At night, however, it shows a positive bias increasing from 10% at 90km to 20% at 95-100km, the latter of which is attributed to the large atomic oxygen abundance used. We also present MIPAS O3 distributions as function of altitude, latitude, and time, showing the major O3 features in the middle and upper mesosphere. In addition to the rapid diurnal variation due to photochemistry, the data also show apparent signatures of the diurnal migrating tide during both day- and nighttime, as well as the effects of the semi-annual oscillation above ~70km in the tropics and mid-latitudes. The tropical daytime O3 at 90km shows a solar signature in phase with the solar cycle. [ABSTRACT FROM AUTHOR]

In this paper we describe the stratospheric and mesospheric ozone (version V5r_O3_m22) distributions retrieved from MIPAS observations in the three middle atmosphere modes (MA, NLC and UA) taken with an unapodized spectral resolution of 0.0625 cm-1 from 2005 until April 2012. O3 is retrieved from microwindows in the 14.8 µm and 10 µm spectral regions and requires non-LTE modelling of the O3 v1 and v3 vibrational levels. Ozone is reliably retrieved from 20 km in the MA mode (40 km for UA and NLC) up to ~ 105 km during dark conditions and up to ~ 95 km during illuminated conditions. Daytime MIPAS O3 has an average vertical resolution of 3-4 km below 70 km, 6-8 km at 70-80 km, 8-10 km at 80-90 km and 5-7 km at the secondary maximum (90-100 km). For nighttime conditions the vertical resolution is similar below 70 km, and better in the upper mesosphere and lower thermosphere: 4-6 km at 70-100 km, 4-5 km at the secondary maximum, and 6-8 km at 100-105 km. The noise error for daytime conditions is typically smaller than 2 % below 50 km, 2-10 % between 50 and 70 km, 10-20 % at 70-90 km and ~ 30 % above 95 km. For nighttime, the noise errors are very similar below around 70 km but significantly smaller above, being 10-20 % at 75-95 km, 20-30 % at 95-100 km and larger than 30 % above 100 km. The additional major O3 errors are the spectroscopic data uncertainties below 50 km (10-12 %), and the non-LTE and temperature errors above 70 km. The validation performed suggests that the spectroscopic errors below 50 km, mainly caused by the O3 air-broadened half-widths of the v2 band, are overestimated. The non-LTE error (including the uncertainty of atomic oxygen at nighttime) is relevant only above ~ 85 km with values of 15-20 %. The temperature error varies from ~ 3 % up to 80 km to 15-20 % near 100 km. Between 50 and 70 km, the pointing and spectroscopic errors are the dominant uncertainties. The validation performed in comparisons with SABER, GOMOS, MLS, SMILES and ACE-FTS shows that MIPAS O3 has an accuracy better than 5 % at and below 50 km, with a positive bias of a few percent. In the 50-75 km region, MIPAS O3 has a positive bias of ~ 10 %, which is possibly caused in part by O3 spectroscopic errors in the 10 µm region. Between 75 and 90 km, MIPAS nighttime O3 is in agreement with other instruments by 10 %, but for daytime the agreement is slightly larger, ~ 10-20 %. Above 90 km, MIPAS daytime O3 is in agreement with other instruments by 10 %. At nighttime, however, it shows a positive bias increasing from 10 % at 90 km to 20 % at 95-100 km, the latter of which is attributed to the large atomic oxygen abundance used. We also present MIPAS O3 distributions as function of altitude, latitude and time, showing the major O3 features in the middle and upper mesosphere. In addition to the rapid diurnal variation due to photochemistry, the data also show apparent signatures of the diurnal migrating tide, both during day and nighttime, as well as the effects of the semi-annual oscillation above ~ 70 km in the tropics and mid-latitudes. The tropical daytime O3 at 90 km shows a solar signature in phase with the solar cycle. [ABSTRACT FROM AUTHOR]

Global distributions of the CO2 vmr (volume mixing ratio) in the mesosphere and lower thermosphere (from 70 up to ~140 km) have been derived from high-resolution limb emission daytime MIPAS (Michelson Interferometer for Passive Atmospheric Sounding) spectra in the 4.3 µm region. This is the first time that the CO2 vmr has been retrieved in the 120-140 km range. The data set spans from January 2005 to March 2012. The retrieval of CO2 has been performed jointly with the elevation pointing of the line of sight (LOS) by using a non-local thermodynamic equilibrium (non-LTE) retrieval scheme. The non-LTE model incorporates the new vibrational-vibrational and vibrational-translational collisional rates recently derived from the MIPAS spectra by Jurado-Navarro et al. (2015). It also takes advantage of simultaneous MIPAS measurements of other atmospheric parameters (retrieved in previous steps), such as the kinetic temperature (derived up to ~100 km from the CO2 15 µm region of MIPAS spectra and from 100 up to 170 km from the NO 5.3 µm emission of the same MIPAS spectra) and the O3 measurements (up to ~100 km). The latter is very important for calculations of the non-LTE populations because it strongly constrains the O(³P) and O(¹D) concentrations below ~100 km. The estimated precision of the retrieved CO2 vmr profiles varies with altitude ranging from ~1% below 90 km to 5% around 120 km and larger than 10% above 130 km. There are some latitudinal and seasonal variations of the precision, which are mainly driven by the solar illumination conditions. The retrieved CO2 profiles have a vertical resolution of about 5-7 km below 120 km and between 10 and 20 km at 120-140 km. We have shown that the inclusion of the LOS as joint fit parameter improves the retrieval of CO2, allowing for a clear discrimination between the information on CO2 concentration and the LOS and also leading to significantly smaller systematic errors. The retrieved CO2 has an improved accuracy because of the new rate coefficients recently derived from MIPAS and the simultaneous MIPAS measurements of other key atmospheric parameters (retrieved in previous steps) needed for non-LTE modelling like kinetic temperature and O3 concentration. The major systematic error source is the uncertainty of the pressure/temperature profiles, inducing errors at midlatitude conditions of up to 15% above 100 km (20% for polar summer) and of ~5% around 80 km. The errors due to uncertainties in the O(¹D) and O(³P) profiles are within 3-4% in the 100-120 km region, and those due to uncertainties in the gain calibration and in the near-infrared solar flux are within ~2% at all altitudes. The retrieved CO2 shows the major features expected and predicted by general circulation models. In particular, its abrupt decline above 80-90 km and the seasonal change of the latitudinal distribution, with higher CO2 abundances in polar summer from 70 up to ~95 km and lower CO2 vmr in the polar winter. Above ~95 km, CO2 is more abundant in the polar winter than at the midlatitudes and polar summer regions, caused by the reversal of the mean circulation in that altitude region. Also, the solstice seasonal distribution, with a significant pole-to-pole CO2 gradient, lasts about 2.5 months in each hemisphere, while the seasonal transition occurs quickly. [ABSTRACT FROM AUTHOR]

Motivated by an improved ESA version of MIPAS calibrated spectra (version 8.03), we have released version 8 of MIPAS temperatures and pointing information retrieved from 2005-2012 MIPAS measurements at 12-15 µm in the Middle Atmosphere (MA), Upper Atmosphere (UA) and Noctilucent Cloud (NLC) measurement modes. The IMK/IAA retrieval processor in use considers non-local thermodynamic equilibrium (non-LTE) emission explicitly for each limb scan. This non-LTE treatment is essential to obtain accurate temperatures above the mid-mesosphere, because at the altitudes covered, up to 115 km, the simplified climatology-based non-LTE treatment employed for the nominal (NOM) measurements is insufficient. Other updates in MA/UA/NLC V8 non-LTE temperature retrievals from previous data releases include: more realistic atomic oxygen and carbon dioxide abundances; an updated set of spectroscopic data; an improved spectral shift retrieval; a continuum retrieval extended to altitudes up to 58 km; consideration of an altitude-dependent radiance offset retrieval; the use of wider microwindows above 85 km to capture the offset; an improved accuracy in forward model calculations; new temperature a priori information; improved temperature horizontal gradient retrievals; and, the use of MIPAS version 5 interfering species, where available. The resulting MIPAS MA/UA/NLC IMK/IAA temperature dataset is reliable for scientific analysis in the full measurement vertical range for the MA (18-102 km) and the NLC (39-102 km) observations, and from 42 to 115 km for the UA observations. The random temperature errors, dominated by the instrumental noise, are typically less than 1K below 60 km, 1-3K at 60-70 km, 3-5K at 70-90 km, 6-8K at 90-100 km, 8-12K at 100-105 km and 12-20K at 105-115 km. Pointing correction random errors, also mainly arising from instrumental noise, are on average 50m for tangent altitudes up to 60 km and decrease linearly to values smaller than 20m for altitudes above 95 km. The vertical resolution is 3 km at altitudes below 50 km, 3-5 km at 50-70 km, 4-6 km at 70-90 km, 6-10 km at 90-100 km and 8-11 km at 100-115 km. The systematic errors of retrieved temperatures below 75 km are driven by uncertainties in the CO2 spectroscopic data and, above 80 km, by uncertainties in the non-LTE model parameters (including collisional rates and atomic oxygen abundance) and the CO2 abundance. These lead to systematic temperature errors of less than 0.7K below 55 km, 1K at 60-80 km, 1-2K at 80-90 km, 3K at 95 km, 6-8K at 100 km, 10-20K at 105 km and 20-30K at 115 km. Systematic errors in the tangent altitude correction, mainly arising from CO2 spectroscopic uncertainties, are 250m at 20 km and 200m at 40-60 km, 100m at 80 km and smaller than 50m above 90 km. The consistency between the MA/UA/NLC and the NOM IMK/IAA datasets is excellent below 70 km (typical 0.5-1K differences). The comparison of this V8 temperature dataset with co-located SABER temperature measurements shows an excellent agreement, even better than in previous MIPAS IMK/IAA versions. [ABSTRACT FROM AUTHOR]

Abstract: After molecular nitrogen, methane is the most abundant species in Titan’s atmosphere and plays a major role in its energy budget and its chemistry. Methane has strong bands at 3.3μm emitting mainly at daytime after absorption of solar radiation. This emission is strongly affected by non-local thermodynamic equilibrium (non-LTE) in Titan’s upper atmosphere and, hence, an accurate modeling of the non-LTE populations of the emitting vibrational levels is necessary for its analysis. We present a sophisticated and extensive non-LTE model which considers 22 CH4 levels and takes into account all known excitation mechanisms in which they take part. Solar absorption is the major excitation process controlling the population of the v 3-quanta levels above 1000km whereas the distribution of the vibrational energy within levels of similar energy through collisions with N2 is also of importance below that altitude. CH4–CH4 vibrational exchange of v 4-quanta affects their population below 500km. We found that the ν 3 →ground band dominates Titan’s 3.3μmdaytime limb radiance above 750km whereas the ν 3 + ν 4 → ν 4 band does below that altitude and down to 300km. The ν 3 + ν 2 → ν 2, the 2ν 3 → ν 3, and the 13CH4 ν 3 →ground bands each contribute from 5% to 8% at regions below 800km. The ν 3 +2ν 4 →2ν 4and ν 2 + ν 3 + ν 4 → ν 2 + ν 4 bands each contribute from 2% to 5% below 650km. Contributions from other CH4 bands are negligible. We have used the non-LTE model to retrieve the CH4 abundance from 500 to 1100km in the southern hemisphere from Cassini–VIMS daytime measurements near 3.3μm. Our retrievals show good agreement with previous measurements and model results, supporting a weak deviation from well mixed values from the lower atmosphere up to 1000km. [Copyright &y& Elsevier]

Abstract: In this article we report the most recent advances of our knowledge of non-LTE atmospheric emissions gained from the MIPAS spectra on the Envisat satellite. These include improvements in our knowledge: of the collisional processes between the CO2 (1001), (0221), and (0201) vibrational levels; of the nascent distribution and collisional relaxation of the O3 vibrational states; and of the vibrational–vibrational energy transfer rates between H2O(020) and O2. In addition we report: the first evidence of mesospheric CH4 7.6-μm emission; much lower non-LTE populations of the in the daytime stratosphere than previously thought; the first experimental confirmation of the non-LTE excitation of NO(1) in the daytime stratosphere; and the first detection of the CO first hot band non-LTE emission near 4.7 μm. To cite this article: M. López-Puertas et al., C. R. Physique 6 (2005). [Copyright &y& Elsevier]

Vertical profiles of nitric oxide (NO) concentration are derived between 120 and 250 km using updated NO emission rates measured by Sounding of the Atmosphere using Broadband Emission Radiometry (SABER) instrument on the NASA Thermosphere Ionosphere Mesosphere Energetics and Dynamics satellite. The Naval Research Laboratory Mass Spectrometer Incoherent Scatter Radar (MSIS) 2.1 model is used to provide the required parameters of temperature, atomic oxygen number density, and molecule oxygen number density needed to derive the NO concentrations using a non‐local thermodynamic equilibrium (non‐LTE) model. The SABER NO concentration shows a significant correlation with solar activity with larger peak NO concentrations and higher altitude extent during solar maximum years compared to those during the solar minimum years. The SABER NO agrees well with the MSIS 2.1 NO at altitudes above 120 km for all latitudes, while the pronounced SABER‐MSIS NO discrepancy below 120 km is likely due to the temperature underestimation by MSIS 2.1. A detailed error analysis is presented and considers systematic and random errors in all the terms in the non‐LTE model used to derive the NO concentration. Random error in MSIS 2.1 temperature and atomic oxygen dominates the uncertainty in single NO profiles above 120 km. We estimated a systematic error up to ∼36% between 120 and 250 km during solar maximum years. Plain Language Summary: Nitric oxide (NO) is a minor constituent of the Earth's thermosphere and regulates the energy budget by emitting infrared radiation that cools the region. Understanding the distribution of the NO concentration is important in understanding the energy redistribution in the Earth's upper atmosphere. In this paper, a new NO concentration data set between 120 and 250 km from January 2002 to the present day is derived from the latest Sounding of the Atmosphere using Broadband Emission Radiometry (SABER) NO emission measurements and Mass Spectrometer Incoherent Scatter Radar (MSIS) 2.1 empirical model of temperature and O, and O2 number density. The derived SABER NO concentration varies with solar activity. The SABER NO agrees well with the empirical MSIS 2.1 NO between 120 and 250 km. Below 120 km, the temperature may be warmer than predicted by MSIS 2.1, leading to a substantial difference between SABER NO and MSIS 2.1 NO. A comprehensive error analysis considering systematic and random errors in all the terms in the model used to derive the NO concentration from SABER data shows that the systematic uncertainty of the SABER NO density is up to 36% above 120 km. Key Points: The nitric oxide (NO) 5.3 μm infrared emission rates derived from Sounding of the Atmosphere using Broadband Emission Radiometry (SABER) measurements have been updatedVertical profiles of NO concentration, spanning 20+ years, are derived from the SABER NO emission rates, and Mass Spectrometer Incoherent Scatter Radar (MSIS) 2.1 T, n(O), and n(O2)The SABER NO concentrations exhibit good agreement (±30%) with those in the MSIS 2.1 empirical model between 120 and 250 km [ABSTRACT FROM AUTHOR]

Using the IMK–IAA data processor, methane and nitrous oxide distributions were retrieved from version-8 limb emission spectra recorded with the Michelson Interferometer for Passive Atmospheric Sounding (MIPAS). The dataset includes measurements from the nominal, upper troposphere–lower stratosphere, middle-atmosphere, upper-atmosphere and noctilucent-cloud observation modes. The processing differs from the previous version-5 data with respect to the atmospheric state variables that are jointly retrieved along with the target gases CH 4 and N 2 O, the treatment of the radiance offset, the selection of microwindows, the regularization, the spectroscopic data used and the treatment of horizontal variability of the atmospheric state. Besides the regular data product, a coarse-grid representation of the profiles with unity averaging kernels is available, as well as a specific research product for middle-atmosphere measurements resulting from a slightly different retrieval approach. The CH 4 errors are dominated by the large spectroscopic uncertainty for line intensities, which probably is too pessimistic, and estimated to be 21 %–34 % in the altitude range 6–68 km for northern midlatitude summer day conditions. The N 2 O errors are 7 %–17 % below 45 km. At higher altitudes they increase strongly due to nearly vanishing N 2 O amounts. Analysis of the horizontal averaging kernels reveals that for both gases the horizontal resolution is sampling-limited; i.e., information is not smeared over consecutive limb scans. Zonal-mean seasonal composites of both CH 4 and N 2 O exhibit the typical distribution of source gases with strong upwelling in the tropics and subsidence above the winter poles. Comparison with the previous data version shows several improvements: first, the vertical resolution of the retrieved CH 4 (N 2 O) profiles has generally been significantly enhanced and varies between 2.5 (2.5) and 4 (5) km at altitudes between 10 and 60 km, with the best resolution around 30 km for both species. Secondly, the number of non-converged retrievals has been clearly reduced, and thirdly, formerly strongly oscillating profiles are now considerably smoother. [ABSTRACT FROM AUTHOR]

The gravity wave drag parametrization of the Whole Atmosphere Community Climate Model (WACCM) has been modified to include the wave‐driven atmospheric vertical mixing caused by propagating, non‐breaking, gravity waves. The strength of this atmospheric mixing is represented in the model via the "effective wave diffusivity" coefficient (Kwave). Using Kwave, a new total dynamical diffusivity (KDyn) is defined. KDyn represents the vertical mixing of the atmosphere by both breaking (dissipating) and vertically propagating (non‐dissipating) gravity waves. Here we show that, when the new diffusivity is used, the downward fluxes of Fe and Na between 80 and 100 km largely increase. Larger meteoric ablation injection rates of these metals (within a factor 2 of measurements) can now be used in WACCM, which produce Na and Fe layers in good agreement with lidar observations. Mesospheric CO2 is also significantly impacted, with the largest CO2 concentration increase occurring between 80 and 90 km, where model‐observations agreement improves. However, in regions where the model overestimates CO2 concentration, the new parametrization exacerbates the model bias. The mesospheric cooling simulated by the new parametrization, while needed, is currently too strong almost everywhere. The summer mesopause in both hemispheres becomes too cold by about 30 K compared to observations, but it shifts upward, partially correcting the WACCM low summer mesopause. Our results highlight the far‐reaching implications and the necessity of representing vertically propagating non‐breaking gravity waves in climate models. This novel method of modeling gravity waves contributes to growing evidence that it is time to move away from dissipative‐only gravity wave parametrizations. Plain Language Summary: Atmospheric gravity waves are generated in the lowest layers (∼bottom 10 km) of the atmosphere by processes such as weather systems and air masses interacting with the topography, and can propagate upward to ∼120 km. In this work, the representation of atmospheric gravity waves in a state‐of‐the‐art chemistry climate model, the Whole Atmosphere Community Climate Model (WACCM), has been updated. In the new model version, the mixing of the atmosphere caused by gravity waves that propagate upwards above 80 km and do not break is part of the total mixing of the atmosphere, which hitherto was considered to be caused by the turbulence created by gravity wave breaking. We show here that when this additional source of atmospheric mixing is taken into account, the WACCM model is better able to simulate the sodium and iron atom densities in the upper layers of the atmosphere (between ∼80 and 100 km), created by the ablation of cosmic dust. Additionally, gravity waves significantly affect the representation of CO2 mixing ratios and air temperature within the model. Our work is important because it shows that propagating gravity waves have non‐negligible impacts on basic properties of the Earth's atmosphere such as temperature, winds, and chemical species like CO2, and that the lack of their representation in current climate models needs to be addressed. Key Points: A parametrization representing vertical mixing by non‐breaking gravity waves has been implemented in a chemistry‐climate modelMesospheric CO2 and temperature are significantly impacted by the additional source of vertical mixingWave‐induced constituent transport largely reconciles the modeled mesospheric Na and Fe layers with the estimated meteoric injection rates [ABSTRACT FROM AUTHOR]

The Michelson Interferometer for Passive Atmospheric Sounding (MIPAS) on Envisat provided infrared limb emission spectra, which were used to infer global distributions of CFC-11, CFC-12, and HCFC-22. Spectra were analysed using constrained non-linear least-squares fitting. Changes with respect to earlier data versions refer to the use of version 8 spectra, the altitude range where the background continuum is considered, details of the regularization and microwindow selection, and the occasional joint fitting of interfering species, the use of new spectroscopic data, the joint fit of a tangent-height-dependent spectral offset, and the use of 2D temperature fields. In the lower stratosphere the error budget is dominated by uncertainties in spectroscopic data, while above this measurement noise is the leading error source. The vertical resolution of CFC-11 and CFC-12 is 2–3 km near the tropopause, about 4 km at 30 km altitude, and 6–10 km at 50 km. The vertical resolution of HCFC-22 is somewhat coarser, 3–4 km at the tropopause and 10–12 km at 35 km altitude. In the altitude range of interest, the horizontal resolution is typically limited by the horizontal sampling of the measurements, not by the smearing of the retrievals. Horizontal information displacement does not exceed 150 km , which can become an issue only for comparisons with model simulations with high horizontal resolution or localized in situ observations. Along with the regular data product, an alternative representation of the data on a coarser vertical grid is offered. These data can be used without consideration of the averaging kernels. The new data version provides improvement with respect to reduction of biases and improved consistency between the full- and reduced-resolution mission period of MIPAS. [ABSTRACT FROM AUTHOR]

Elevated stratopauses are typically associated with prolonged disturbed conditions in the Northern Hemisphere polar winter. The Michelson Interferometer for Passive Atmospheric Sounding (MIPAS) and the Microwave Limb Sounder (MLS) observed a short‐lived and highly zonally asymmetric stratopause at mesospheric altitudes in November 2009, the earliest in the season reported so far. The Arctic climatological winter stratopause vanished, and MIPAS and MLS measured temperatures of 260 K at 82 km and 250 K at 75 km, respectively, in a region smaller than in typical midwinter elevated stratopause events. Planetary wave activity was initially high. Zonal mean zonal winds and the poleward temperature gradient northward of 70°N stayed reversed during 7 days, but the mesosphere did not cool. Wave activity dropped until the eastward stratospheric winds resumed and a strong vortex restored in the mesosphere. The stratopause emerged at high altitudes, staying there for 2–5 days. It was accompanied by enhanced downward transport. It took the stratopause 9 days to move down to its typical winter altitudes. Key Points: MIPAS and MLS observed a highly zonally asymmetric Arctic stratopause at high altitudes in November 2009 accompanied by a strong descentThe event has similarities with typical elevated stratopause events, but it is of smaller scale in terms of duration and extentThis is the first time a high‐altitude stratopause observed from space this early in the winter season is reported [ABSTRACT FROM AUTHOR]

Elevated stratopauses are typically associated with prolonged disturbed conditions in the Northern Hemisphere polar winter. The Michelson Interferometer for Passive Atmospheric Sounding (MIPAS) and the Microwave Limb Sounder (MLS) observed a short‐lived and highly zonally asymmetric stratopause at mesospheric altitudes in November 2009, the earliest in the season reported so far. The Arctic climatological winter stratopause vanished, and MIPAS and MLS measured temperatures of 260 K at 82 km and 250 K at 75 km, respectively, in a region smaller than in typical midwinter elevated stratopause events. Planetary wave activity was initially high. Zonal mean zonal winds and the poleward temperature gradient northward of 70°N stayed reversed during 7 days, but the mesosphere did not cool. Wave activity dropped until the eastward stratospheric winds resumed and a strong vortex restored in the mesosphere. The stratopause emerged at high altitudes, staying there for 2–5 days. It was accompanied by enhanced downward transport. It took the stratopause 9 days to move down to its typical winter altitudes. Key Points: MIPAS and MLS observed a highly zonally asymmetric Arctic stratopause at high altitudes in November 2009 accompanied by a strong descentThe event has similarities with typical elevated stratopause events, but it is of smaller scale in terms of duration and extentThis is the first time a high‐altitude stratopause observed from space this early in the winter season is reported [ABSTRACT FROM AUTHOR]

The Michelson Interferometer for Passive Atmospheric Sounding (MIPAS) on Envisat provided infrared limb emission spectra, which were used to infer global distributions of CFC-11, CFC-12, and HCFC-22. Spectra were analyzed using constrained non-linear least squares fitting. Changes with respect to earlier data versions refer to the use of version 8 spectra, the altitude range where the background continuum is considered, details of the regularization and microwindow selection, and the occasional joint-fitting of interfering species, new spectroscopic data, the joint-fit of a tangent-height dependent spectral offset, and the use of 2D temperature fields. In the lower stratosphere the error budget is dominated by uncertainties in spectroscopic data, while above measurement noise is the leading error source. The vertical resolution of CFC-11 and CFC-12 is 2-3 km near the tropopause, about 4 km at 30 km altitude and 6-10 km at 50 km. The vertical resolution of HCFC-22 is somewhat coarser, 3-4 km at the tropopause and 10-12 km at 35 km altitude. In the altitude range of interest, the horizontal resolution is typically limited by the horizontal sampling of the measurements, not by the smearing of the retrieval. Horizontal information displacement does not exceed 150 km, which can become an issue only for comparisons with model simulations with high horizontal resolution or localized in-situ observations. Along with the regular data product, an alternative representation of the data on a coarser vertical grid is offered. These data can be used without consideration of the averaging kernels. The new data version provides improvement with respect to reduction of biases and improved consistency between the full and reduced resolution mission period of MIPAS. [ABSTRACT FROM AUTHOR]

New global nitric oxide (NO) volume mixing ratio and lower-thermospheric temperature data products, retrieved from Michelson Interferometer for Passive Atmospheric Sounding (MIPAS) spectra with the Institute of Meteorology and Climate Research and Instituto de Astrofísica de Andalucía (IMK-IAA) MIPAS data processor, have been released. The dataset covers the entire Envisat mission lifetime and includes retrieval results from all MIPAS observation modes. The data are based on European Space Agency (ESA) version 8 calibration and were processed using an improved retrieval approach compared to previous versions, specifically regarding the choice and construction of the a priori and atmospheric parameter profiles, the treatment of horizontal inhomogeneities, the treatment of the radiance offset correction, and the selection of optimized numerical settings. NO retrieval errors in individual observations are dominated by measurement noise and range from 5 % to 50 % in the stratosphere and thermosphere and reach 40 % to 90 % in the mesosphere. Systematic errors are typically within 10 %–30 %. Lower-thermospheric temperature errors are 5 to 50 K with a systematic component of around 20 K, the latter being dominated by non-thermodynamic equilibrium (non-LTE)-related uncertainties. NO data from different observation modes are consistent within 5 %–10 %. MIPAS version 8 temperatures have a better representation of the diurnal tide in the lower thermosphere compared to previous data versions. The new MIPAS temperatures are systematically warmer than results from the empirical US Naval Research Laboratory Mass Spectrometer Incoherent Scatter Radar (NRLMSIS) version 2.0 model by 30 to 80 K in the 100–120 km region and are colder above. [ABSTRACT FROM AUTHOR]

A new global O 3 data product retrieved from the Michelson Interferometer for Passive Atmospheric Sounding (MIPAS) spectra with the IMK–IAA MIPAS data processor has been released. These data are based on ESA version 8 recalibrated radiance spectra with improved temporal stability. Changes in the level-2 processing with respect to previous data versions include the following: (1) the retrievals use improved temperature data and thus suffer less from the propagation of related errors. (2) The background continuum is now considered up to 58 km. (3) A priori information is now used to constrain the retrieval of the radiance offset. (4) Water vapour is fitted jointly with ozone to minimize the impact of interfering water lines. (5) A more adequate regularization has been chosen. (6) Ozone absorption lines in the MIPAS A band (685–980 cm -1) are used almost exclusively because of inconsistencies in spectroscopic data in the MIPAS AB band (1010–1180 cm -1). Only at altitudes above 50 km, where A-band ozone lines do not provide sufficient information, are ozone lines in the MIPAS AB band used. (7) Temperature-adjusted climatologies of vibrational temperatures of O 3 and CO 2 are considered to account for non-local thermodynamic equilibrium radiation. Ozone errors are estimated to be less than 10 % in the altitude range 20–50 km. The error budget is dominated by the spectroscopic errors, followed by the uncertainty of the instrumental line shape function, the gain calibration error, and the spectral noise. The error contribution of interfering gases is almost negligible. The vertical resolution depends on altitude and atmospheric conditions. In 2002–2004 it varies between 2.5 km at the lowest altitudes and 6 km at 70 km, while in 2005–2012 it covers 2 to 5.5 km in the same altitude range. The horizontal smearing in terms of the full width at half maximum of the horizontal component of the two-dimensional averaging kernel matrix is smaller than, or approximately equal to, the distance between two subsequent limb scans at all altitudes. This implies that the horizontal resolution is sampling-limited or optimal, respectively. An additional data version is made available that is free of the formal a priori information and thus more user-friendly for certain applications. Version 8 ozone results show a better consistency between the two MIPAS measurement periods. They seem to be more realistic than preceding data versions in terms of long-term stability, as at least a part of the drift is corrected. Further, the representation of elevated stratopause situations is improved. [ABSTRACT FROM AUTHOR]

New global nitric oxide (NO) volume mixing ratio and lower thermospheric temperature data products, retrieved from Michelson Interferometer for Passive Atmospheric Sounding (MIPAS) spectra with the IMK-IAA MIPAS data processor, have been released. The dataset covers the entire Envisat mission lifetime and includes retrieval results from all MIPAS observation modes. The data are based on ESA version 8 calibration and were processed using an improved retrieval approach compared to previous versions, specifically regarding the choice and construction of the a priori and atmospheric parameter profiles, the treatment of horizontal inhomogeneities, the treatment of the radiance offset correction, and the selection of optimized numerical settings. NO retrieval errors of individual observations are dominated by measurement noise and range from 5% to 50% in the stratosphere and thermosphere, and reach 40% to 90% in the mesosphere. Systematic errors are typically within 10-30%. Lower thermospheric temperature errors are 5K to 50K with a systematic component of around 10 K, the latter being dominated by non-LTE related uncertainties. NO data from different observation modes are consistent within 5-10%. MIPAS version 8 temperatures have a better representation of the diurnal tide in the lower thermosphere compared to previous data versions. The new MIPAS temperatures are systematically warmer than results from the empirical NLRMSIS2.0 model by 30K to 80K in the 100-120 km region, and are colder above. [ABSTRACT FROM AUTHOR]

A new global O3 data product retrieved from Michelson Interferometer for Passive Atmospheric Sounding (MIPAS) spectra with the IMK/IAA MIPAS data processor has been released. These data are based on ESA version 8 recalibration of radiance spectra which takes detector aging into consideration to minimize drifts. The new ozone retrievals use improved temperatures and thus suffer less from the propagation of related errors. Changes in the level-2 processing with respect to previous data versions and relevant to ozone include: (1) The background continuum is now considered up to 58, km. (2) A priori information is now used to constrain the retrieval of the radiance offset. (3)Water vapour is jointly retrieved along with ozone mixing ratios. 4) A more adequate regularization has been chosen. (5) Ozone lines in the MIPAS A band (685-980 cm-1) are used almost exclusively because of inconsistencies in spectroscopic data of the MIPAS AB band (1010-1180 cm-1). Only at altitudes above 50 km, where A band ozone lines do not provide sufficient information, ozone lines in the MIPAS AB band are used. 6) Temperature-adjusted climatologies of vibrational temperatures of O3 and CO2 are considered to account for non-local thermodynamic equilibrium radiation. Ozone errors are estimated to be less than 10% in the altitude range 20-50 km. The error budget is dominated by the spectroscopic errors of ozone and carbon dioxide. The latter error contribution is propagated from the results of temperature and line-of-sight retrievals. Further notable contributions are the uncertainty of the instrumental line shape function, the gain calibration error, and the spectral noise, directly in the ozone lines and propagated via the previously retrieved temperature and line-of-sight. The error contribution of interfering gases is almost negligible. The vertical resolution in terms of the full width at half maximum of the averaging kernel rows depends on altitude and atmospheric conditions. For the measurement period 2002-2004 it varies between 2.5 km at the lowest altitudes and 6 km at 70 km, while in 2005-2012 covers 2 to 5.5 km in the same altitude range. The horizontal smearing in terms of the full width at half maximum of the horizontal component of the 2-dimensional averaging kernel matrix is smaller than, or approximately equal to, the distance between two subsequent limb scans, at all altitudes. This implies that the horizontal resolution is sampling-limited or optimal, respectively. Along with the regular representation of the data, that have non-unity averaging kernels, a resampled data version is made available that is free of formal a priori information and thus more user-friendly for certain applications. Version 8 ozone results show a better consistency between the two MIPAS measurement periods. They seem to be more realistic than preceding data versions in terms of long-term stability, as at least a part of the drift is corrected. Further, the representation of elevated stratopause situations is improved, but there is still some indication of a positive bias in the upper stratosphere. [ABSTRACT FROM AUTHOR]

High quality long-term data sets of altitude-resolved measurements of the atmospheric composition are important because they can be used both to study the evolution of the atmosphere and as a benchmark for future missions. For the final ESA reprocessing of MIPAS (Michelson Interferometer for Passive Atmospheric Sounding) on ENVISAT (ENViromental SATellite) data, numerous improvements were implemented in the Level 2 (L2) processor Optimised Retrieval Model (ORM) version 8.22 (V8) and its auxiliary data. The implemented changes involve all aspects of the processing chain, from the modelling of the measurements with the handling of the horizontal inhomogeneities along the line of sight to the use of the optimal estimation technique to retrieve the minor species, from a more sensitive approach to detecting the spectra affected by clouds to a refined method for identifying low quality products. Improvements in the modelling of the measurements were also obtained with an update of the used spectroscopic data and of the databases providing the a priori knowledge of the atmosphere. The HITRAN_mipas_pf4.45 spectroscopic database was finalised with new spectroscopic data verified with MIPAS measurements themselves, while recently measured cross-sections were used for the heavy molecules. The Level 2 Initial Guess (IG2) data set, containing the climatology used by the MIPAS L2 processor to generate the initial guess and interfering species profiles when the retrieved profiles from previous scans are not available, was improved taking into account the diurnal variation of the profiles defined using climatologies from both measurements and models. Horizontal gradients were generated using the ECMWF ERA-Interim data closest in time and space to the MIPAS data. Further improvements in the L2 V8 products derived from the use of the L1b V8 products, which were upgraded to reduce the instrumental temporal drift and to handle the abrupt changes in the calibration gain. The improvements introduced into the ORM V8 L2 processor and its upgraded auxiliary data, together with the use of the L1b V8 products, lead to the generation of the MIPAS L2 V8 products, which are characterised by an increased accuracy, better temporal stability and a greater number of retrieved species. [ABSTRACT FROM AUTHOR]

The observations acquired during the full mission of the Michelson Interferometer for Passive Atmospheric Sounding (MIPAS) instrument, aboard the European Space Agency Environmental Satellite (Envisat), have been analysed with version 8.22 of the Optimised Retrieval Model (ORM), originally developed as the scientific prototype of the ESA level-2 processor for MIPAS observations. The results of the analyses have been included into the MIPAS level-2 version 8 (level2-v8) database containing atmospheric fields of pressure, temperature, and volume mixing ratio (VMR) of MIPAS main targets H2O , O3 , HNO3 , CH4 , N2O , and NO2 , along with the minor gases CFC -11, ClONO2 , N2O5 , CFC -12, COF2 , CCl4 , CF4 , HCFC -22, C2H2 , CH3Cl , COCl2 , C2H6 , OCS , and HDO. The database covers all the measurements acquired by MIPAS in the nominal measurement mode of the full resolution (FR) part of the mission (from July 2002 to March 2004) and all the observation modes of the optimised resolution (OR) part (from January 2005 to April 2012). The number of species included in the MIPAS level2-v8 dataset makes it of particular importance for the studies of stratospheric chemistry. The database is considered by ESA the final release of the MIPAS level-2 products. The ORM algorithm is operated at the vertical grid coincident to the tangent altitudes of the observations or to a subset of them, spanning (in the nominal mode) the altitude range from 6 to 68 km in the FR phase and from 6 to 70 km in the OR period. In the latitude domain, FR profiles are spaced by about 4.7 ∘ , while the OR profiles are spaced by about 3.7 ∘. For each retrieved species, the auxiliary data and the retrieval choices are described. Each product is characterised in terms of the retrieval error, spatial resolution, and "useful" vertical range in both phases of the MIPAS mission. These depend on the characteristics of the measurements (spectral and vertical resolution of the measurements), the retrieval choices (number of spectral points included in the analyses, number of altitudes included in the vertical retrieval grid), and the information content of the measurements for each trace species. For temperature, water vapour, ozone, and nitric acid, the number of degrees of freedom is significantly larger in the OR phase than in the FR one, mainly due to the finer vertical measurement grid. In the FR phase, some trace species are characterised by a smaller retrieval error with respect to the OR phase, mainly due to the larger number of spectral points used in the analyses, along with the reduced vertical resolution. The way of handling possible caveats (negative VMR, vertical grid representation) is discussed. The quality of the retrieved profiles is assessed through four criteria, two providing information on the successful convergence of the retrieval iterations, one on the capability of the retrieval to reproduce the measurements, and one on the presence of outliers. An easy way to identify and filter the problematic profiles with the information contained in the output files is provided. MIPAS level2-v8 data are available to the scientific community through the ESA portal (10.5270/EN1-c8hgqx4). [ABSTRACT FROM AUTHOR]

The observations acquired during the full mission of the Michelson Interferometer for Passive Atmospheric Sounding (MIPAS) instrument, on board the European Space Agency ENVISAT satellite, have been analysed with version 8.22 of the Optimised Retrieval Model (ORM), originally developed as the scientific prototype of the ESA level 2 processor for MIPAS observations. The results of the analyses have been included into the MIPAS level 2 version 8 (level2-v8) database containing atmospheric fields of pressure, temperature and volume mixing ratio of MIPAS main targets H2O, O3, HNO3, CH4, N2O, and NO2, along with the minor gases CFC-11, ClONO2, N2O5, CFC-12, COF2, CCl4, CF4, HCFC-22, C2H2, CH3Cl, COCl2, C2H6, OCS, HDO. The database covers all the measurements acquired by MIPAS in the nominal measurement mode of the Full Resolution (FR) part of the mission (from July 2002 to March 2004) and all the observation modes of the Optimised Resolution (OR) part (from January 2005 to April 2012). The number of species included in the MIPAS level2-v8 data-set makes it of particular importance for the studies of stratospheric chemistry. The database is considered by ESA the final release of the MIPAS level 2 products. The ORM algorithm is operated at the vertical grid coincident to the tangent altitudes of the observations or to a subset of them, spanning (in the nominal mode) the altitude range from 6 to 68km in the FR phase and from 6 to 70km in the OR period. In the latitude domain, FR profiles are spaced by about 4.7 degrees while the OR profiles are spaced by about 3.7 degrees. For each retrieved species the auxiliary data and the retrieval choices are described. Each product is characterised in terms of the retrieval error, spatial resolution, and 'useful' vertical range in both phases of the MIPAS mission. These depend on the characteristics of the measurements (spectral and vertical resolution of the measurements), on the retrieval choices (number of spectral points included in the analyses, number of altitudes included in the vertical retrieval grid), and on the information content of the measurements for each trace species. For temperature, water vapour, ozone and nitric acid the number of degrees of freedom is significantly larger in the OR phase than in the FR one, mainly due to the finer vertical measurement grid. In the FR phase some trace species are characterised by a smaller retrieval error with respect to the OR phase, mainly due to the larger number of spectral points used in the analyses, along with the reduced vertical resolution. The way of handling possible caveats (negative VMR, vertical grid representation) is discussed. The quality of the retrieved profiles is assessed through four criteria, two providing information on the successful convergence of the retrieval iterations, one on the capability of the retrieval to reproduce the measurements, and one on the presence of outliers. An easy way to identify and filter the problematic profiles with the information contained in the output files is provided. MIPAS level2-v8 data are available to the scientific community through the ESA portal https://earth.esa.int/eogateway/. [ABSTRACT FROM AUTHOR]

High quality long-term data sets of altitude-resolved measurements of the atmospheric composition are important because they can be used both to study the evolution of the atmosphere and as a benchmark for future missions. For the final ESA reprocessing of MIPAS (Michelson Interferometer for Passive Atmospheric Sounding) on ENVISAT (ENViromental SATellite) data, numerous improvements were implemented in the level 2 (L2) processor Optimised Retrieval Model (ORM) version 8.22 (V8) and its auxiliary data. The implemented changes involve all aspects of the processing chain, from the modelling of the measurements with the handling of the horizontal inhomogeneities along the line of sight to the use of the Optimal Estimation for retrieving the minor species, from a more sensitive approach to detect the spectra affected by clouds to a refined method for identifying low quality products. Improvements in the modelling of the measurements were obtained also with an update of the used spectroscopic data and of the databases providing the a priori knowledge of the atmosphere. The HITRAN_mipas_pf4.45 spectroscopic database was finalised with new spectroscopic data verified with MIPAS measurements themselves, while recently measured cross-sections were used for the heavy molecules. The so-called IG2 data set, containing the climatology used by MIPAS L2 processor to generate the initial guess and interfering species profiles when the retrieved profiles from previous scans are not available, was improved taking into account the diurnal variation of the profiles defined using climatologies from both measurements and models. Horizontal gradients were generated using ECMWF ERA-Interim data closest in time and space to the MIPAS data. Further improvements in the L2 V8 products derived from the use of the L1b V8 products, which were upgraded to reduce the instrumental temporal drift and to handle the abrupt changes in the calibration gain. The improvements introduced into the ORM V8 L2 processor and its upgraded auxiliary data, together with the use of the L1b V8 products, lead to the generation of the MIPAS L2 V8 products that are characterised by an increased accuracy, better temporal stability, and a greater number of retrieved species. [ABSTRACT FROM AUTHOR]

High-resolution precision spectroscopy provides a multitude of robust techniques for probing exoplanetary atmospheres. We present multiple VLT/ESPRESSO transit observations of the hot-Jupiter exoplanet WASP-19b with previously published but disputed atmospheric features from low resolution studies. Through spectral synthesis and modelling of the Rossiter–McLaughlin (RM) effect we calculate stellar, orbital and physical parameters for the system. From narrow-band spectroscopy we do not detect any of H  i , Fe  i , Mg  i , Ca  i , Na  i , and K  i neutral species, placing upper limits on their line contrasts. Through cross-correlation analyses with atmospheric models, we do not detect Fe  i and place a 3σ upper limit of |$\log \, (X_{\textrm {Fe}}/X_\odot) \approx -1.83\, \pm \, 0.11$| on its mass fraction, from injection and retrieval. We show the inability to detect the presence of H2O for known abundances, owing to lack of strong absorption bands, as well as relatively low S/N ratio. We detect a barely significant peak (3.02 ± 0.15 σ) in the cross-correlation map for TiO, consistent with the sub-solar abundance previously reported. This is merely a hint for the presence of TiO and does not constitute a confirmation. However, we do confirm the presence of previously observed enhanced scattering towards blue wavelengths, through chromatic RM measurements, pointing to a hazy atmosphere. We finally present a reanalysis of low-resolution transmission spectra of this exoplanet, concluding that unocculted starspots alone cannot explain previously detected features. Our reanalysis of the FORS2 spectra of WASP-19b finds a ∼100× sub-solar TiO abundance, precisely constrained to |$\log \, X_{\textrm {TiO}} \approx -7.52 \pm 0.38$|⁠ , consistent with the TiO hint from ESPRESSO. We present plausible paths to reconciliation with other seemingly contradicting results. [ABSTRACT FROM AUTHOR]

High-resolution precision spectroscopy provides a multitude of robust techniques for probing exoplanetary atmospheres. We present multiple VLT/ESPRESSO transit observations of the hot-Jupiter exoplanet WASP-19b with previously published but disputed atmospheric features from low resolution studies. Through spectral synthesis and modelling of the Rossiter–McLaughlin (RM) effect we calculate stellar, orbital and physical parameters for the system. From narrow-band spectroscopy we do not detect any of H  i , Fe  i , Mg  i , Ca  i , Na  i , and K  i neutral species, placing upper limits on their line contrasts. Through cross-correlation analyses with atmospheric models, we do not detect Fe  i and place a 3σ upper limit of |$\log \, (X_{\textrm {Fe}}/X_\odot) \approx -1.83\, \pm \, 0.11$| on its mass fraction, from injection and retrieval. We show the inability to detect the presence of H2O for known abundances, owing to lack of strong absorption bands, as well as relatively low S/N ratio. We detect a barely significant peak (3.02 ± 0.15 σ) in the cross-correlation map for TiO, consistent with the sub-solar abundance previously reported. This is merely a hint for the presence of TiO and does not constitute a confirmation. However, we do confirm the presence of previously observed enhanced scattering towards blue wavelengths, through chromatic RM measurements, pointing to a hazy atmosphere. We finally present a reanalysis of low-resolution transmission spectra of this exoplanet, concluding that unocculted starspots alone cannot explain previously detected features. Our reanalysis of the FORS2 spectra of WASP-19b finds a ∼100× sub-solar TiO abundance, precisely constrained to |$\log \, X_{\textrm {TiO}} \approx -7.52 \pm 0.38$|⁠ , consistent with the TiO hint from ESPRESSO. We present plausible paths to reconciliation with other seemingly contradicting results. [ABSTRACT FROM AUTHOR]

A new global set of atmospheric temperature profiles is retrieved from recalibrated radiance spectra recorded with the Michelson Interferometer for Passive Atmospheric Sounding (MIPAS). Changes with respect to previous data versions include a new radiometric calibration considering the time dependency of the detector nonlinearity and a more robust frequency calibration scheme. Temperature is retrieved using a smoothing constraint, while tangent altitude pointing information is constrained using optimal estimation. ECMWF ERA-Interim is used as a priori temperature below 43 km. Above, a priori data are based on data from the Whole Atmosphere Community Climate Model Version 4 (WACCM4). Bias-corrected fields from specified dynamics runs, sampled at the MIPAS times and locations, are used, blended with ERA-Interim between 43 and 53 km. Horizontal variability of temperature is considered by scaling an a priori 3D temperature field in the orbit plane in a way that the horizontal structure is provided by the a priori while the vertical structure comes from the measurements. Additional microwindows with better sensitivity at higher altitudes are used. The background continuum is jointly fitted with the target parameters up to 58 km altitude. The radiance offset correction is strongly regularized towards an empirically determined vertical offset profile. In order to avoid the propagation of uncertainties of O 3 and H 2 O a priori assumptions, the abundances of these species are retrieved jointly with temperature. The retrieval is based on HITRAN 2016 spectroscopic data, with a few amendments. Temperature-adjusted climatologies of vibrational populations of CO 2 states emitting in the 15 µ m region are used in the radiative transfer modeling in order to account for non-local thermodynamic equilibrium. Numerical integration in the radiative transfer model is now performed at higher accuracy. The random component of the temperature uncertainty typically varies between 0.4 and 1 K, with occasional excursions up to 1.3 K above 60 km altitude. The leading sources of the random component of the temperature error are measurement noise, gain calibration uncertainty, spectral shift, and uncertain CO 2 mixing ratios. The systematic error is caused by uncertainties in spectroscopic data and line shape uncertainties. It ranges from 0.2 K at 20 km altitude for northern midlatitude summer conditions to 2.3 K at 12 km for tropical conditions. The estimated total uncertainty amounts to values between 0.6 K at 20 km for midlatitude summer conditions to 2.5 K at 12–15 km for tropical conditions. The vertical resolution varies around 3 km for altitudes below 50 km. The long-term drift encountered in the previous temperature product has been largely reduced. The consistency between high spectral resolution results from 2002 to 2004 and the reduced spectral resolution results from 2005 to 2012 has been largely improved. As expected, most pronounced temperature differences between version 8 and previous data versions are found in elevated stratopause situations. The fact that the phase of temperature waves seen by MIPAS is not locked to the wave phase found in ECMWF analyses demonstrates that our retrieval provides independent information and does not merely reproduce the prior information. [ABSTRACT FROM AUTHOR]

A new global set of atmospheric temperature profiles is retrieved from recalibrated radiance spectra recorded with the Michelson Interferometer for Passive Atmospheric Sounding (MIPAS). Changes with respect to previous data versions include a new radiometric calibration considering the time-dependency of the detector non-linearity, and a more robust frequency calibration scheme. Temperature is retrieved using a smoothing constraint, while tangent altitude pointing information is constrained using optimal estimation. ECMWF ERA-Interim is used as temperature a priori below 43 km. Above, a priori data is based on data from the Whole Atmosphere Community Climate Model Version 4 (WACCM4). Bias-corrected fields from specified dynamics runs, sampled at the MIPAS times and locations, are used, blended with ERA-Interim between 43 and 53 km. Horizontal variability of temperature is considered by scaling an a priori 3D temperature field in the orbit plane in a way that the horizontal structure is provided by the a priori while the vertical structure comes from the measurements. Additional microwindows with better sensitivity at higher altitudes are used. The background continuum is jointly fitted with the target parameters up to 58 km altitude. The radiance offset correction is strongly regularized towards an empirically determined vertical offset profile. In order to avoid the propagation of uncertainties of O3 and H2O a priori assumptions, the abundances of these species are retrieved jointly with temperature. The retrieval is based on HITRAN 2016 spectroscopic data, with a few amendments. Temperature-adjusted climatologies of vibrational populations of CO2 states emitting in the 15 micron region are used in the radiative transfer modelling in order to account for non-local thermodynamic equilibrium. Numerical integration in the radiative transfer model is now performed at higher accuracy. The random component of the temperature uncertainty typically varies between 0.4 and 0.8 K, with occasional excursions up to 1.3 K above 60 km altitude. The leading sources of the random component of the temperature error are measurement noise, gain calibration uncertainty, spectral shift, and uncertain CO2 mixing ratios. The systematic error is caused by uncertainties in spectroscopic data and line shape uncertainties. It ranges from 0.2 K at 24 km altitude for northern midlatitude nighttime conditions to 2.3 K at 12 km for tropical nighttime conditions. The estimated total uncertainty amounts to values between 0.5 K at 24 km and northern polar winter conditions to 2.3 K at 12 km and northern midlatitude day conditions. The vertical resolution varies around 3 km for altitudes below 50 km. The long-term drift encountered in the previous temperature product has been largely reduced. The consistency between high spectral resolution results from 2002-2004 and the reduced spectral resolution results from 2005-2012 has been largely improved. As expected, most pronounced temperature differences between version 8 and previous data versions are found in elevated stratopause situations. The fact that the phase of temperature waves seen by MIPAS is not locked to the wave phase found in ECMWF analyses demonstrates that our retrieval provides independent information and does not merely reproduce the prior information. [ABSTRACT FROM AUTHOR]

Hot gas giant exoplanets can lose part of their atmosphere due to strong stellar irradiation, and these losses can affect their physical and chemical evolution. Studies of atmospheric escape from exoplanets have mostly relied on space-based observations of the hydrogen Lyman-a line in the far ultraviolet region, which is strongly affected by interstellar absorption. Using ground-based high-resolution spectroscopy, we detected excess absorption in the helium triplet at 1083 nanometers during the transit of the Saturn-mass exoplanet WASP-69b, at a signal-to-noise ratio of 18. We measured line blueshifts of several kilometers per second and posttransit absorption, which we interpret as the escape of part of the atmosphere trailing behind the planet in comet-like form. [ABSTRACT FROM AUTHOR]

The Michelson Interferometer for Passive Atmospheric Sounding (MIPAS) was an infrared limb emission spectrometer on the Envisat platform. From 2002 to 2012, it performed pole-to-pole measurements during day and night, producing more than 1000 profiles per day. The European Space Agency (ESA) recently released the new version 7 of Level 1B MIPAS spectra, in which a new set of timedependent correction coefficients for the nonlinearity in the detector response functions was implemented. This change is expected to reduce the long-term drift of the MIPAS Level 2 data. We evaluate the long-term stability of ozone Level 2 data retrieved from MIPAS v7 Level 1B spectra with the IMK/IAA scientific level 2 processor. For this, we compare MIPAS data with ozone measurements from the Microwave Limb Sounder (MLS) instrument on NASA's Aura satellite, ozonesondes and ground-based lidar instruments. The ozonesondes and lidars alone do not allow us to conclude with enough significance that the new version is more stable than the previous one, but a clear improvement in long-term stability is observed in the satellite-data-based drift analysis. The results of ozonesondes, lidars and satellite drift analysis are consistent: all indicate that the drifts of the new version are less negative/more positive nearly everywhere above 15 km. The 10-year MIPAS ozone trends calculated from the old and the new data versions are compared. The new trends are closer to old drift-corrected trends than the old uncorrected trends were. From this, we conclude that the nonlinearity correction performed on Level 1B data is an improvement. These results indicate that MIPAS data are now even more suited for trend studies, alone or as part of a merged data record. [ABSTRACT FROM AUTHOR]

Abstract: Thermospheric infrared radiance at 4.3μm is susceptible to the influence of solar-geomagnetic disturbances. Ionization processes followed by ion-neutral chemical reactions lead to vibrationally excited NO+ (i.e., NO+(v)) and subsequent 4.3μm emission in the ionospheric E-region. Large enhancements of nighttime 4.3μm emission were observed by the TIMED/SABER instrument during the April 2002 and October–November 2003 solar storms. Global measurements of infrared 4.3μm emission provide an excellent proxy to observe the nighttime E-region response to auroral dosing and to conduct a detailed study of E-region ion-neutral chemistry and energy transfer mechanisms. Furthermore, we find that photoionization processes followed by ion-neutral reactions during quiescent, daytime conditions increase the NO+ concentration enough to introduce biases in the TIMED/SABER operational processing of kinetic temperature and CO2 data, with the largest effect at summer solstice. In this paper, we discuss solar storm enhancements of 4.3μm emission observed from SABER and assess the impact of NO+(v) 4.3μm emission on quiescent, daytime retrievals of Tk/CO2 from the SABER instrument. [Copyright &y& Elsevier]

Abstract: The Sounding of the Atmosphere using Broadband Emission Radiometry (SABER) experiment is one of four instruments on NASA’s Thermosphere–Ionosphere–Energetics and Dynamics (TIMED) satellite. SABER measures broadband infrared limb emission and derives vertical profiles of kinetic temperature (Tk) from the lower stratosphere to approximately 120km, and vertical profiles of carbon dioxide (CO2) volume mixing ratio (vmr) from approximately 70km to 120km. In this paper we report on SABER Tk/CO2 data in the mesosphere and lower thermosphere (MLT) region from the version 1.06 dataset. The continuous SABER measurements provide an excellent dataset to understand the evolution and mechanisms responsible for the global two-level structure of the mesopause altitude. SABER MLT Tk comparisons with ground-based sodium lidar and rocket falling sphere Tk measurements are generally in good agreement. However, SABER CO2 data differs significantly from TIME-GCM model simulations. Indirect CO2 validation through SABER-lidar MLT Tk comparisons and SABER-radiation transfer comparisons of nighttime 4.3μm limb emission suggest the SABER-derived CO2 data is a better representation of the true atmospheric MLT CO2 abundance compared to model simulations of CO2 vmr. [Copyright &y& Elsevier]

We present a non-local thermodynamic equilibrium retrieval scheme for atmospheric composition and its application to Mars CO 2 infrared limb emissions as measured by the OMEGA instrument on board Mars Express (MEx). These emissions are caused by CO 2 fluorescence of solar radiation, and thus the retrieval scheme accounts for non-LTE processes. We analyzed the dayside limb observations from a selection of three OMEGA orbits or data qubes. Before the retrieval was applied, we performed a radiometric calibration, cleaned the spectra (including clustering techniques) and generated radiance vertical profiles for each dataset. We also present information on the inversion set up, results on the retrieved CO 2 density profiles, as well as the temperature profiles derived from the CO 2 densities by assuming hydrostatic equilibrium. An extensive sensitivity study of the retrieval scheme was carried out, including its application to the OMEGA spectra taken at different MEx orbital configurations, to conclude on its performance and to offer recommendations for its systematic use with MEx datasets. The uncertainty due to the instrumental Gain calibration and that caused by the retrieval noise error itself are of large importance for the inversion, but a comparable component of the total error comes from the uncertainties of the temperature provided by the GCM. We demonstrated that, between 120 and 160 km, CO 2 profiles can be derived with a precision around 30% and a vertical resolution of about 15 km. • OMEGA limb observations with high spatial resolution • Non-LTE model for CO 2 limb observations in the Mars thermosphere • Retrieval scheme applied to three interesting OMEGA data qubes • CO 2 profiles can be derived with a precision of around 20% between 120 and 160 km. • A vertical resolution of around 15 km is possible with the OMEGA spatial resolution. [ABSTRACT FROM AUTHOR]