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Global emissions of the ozone depleting gas 1,1-dichloro-1-fluoroethane (HCFC-141b, CH3CCl2F), derived from measurements of atmospheric mole fractions, have been rising between 2017–2021 despite a fall in reported production and consumption for dispersive uses. This study evaluates the possible drivers behind this renewed rise in emissions. HCFC-141b is a controlled substance under the Montreal Protocol, and its phase-out is currently underway, after a peak in reported consumption and production in developing countries (Article 5) in 2013. If reported production and consumption are correct, it suggests that the 2017–2021 rise is due to an increase in emissions from the bank when HCFC-141b containing appliances reach the end of their life, or from production of HCFC-141b not reported for dispersive uses. Regional emissions have been estimated between 2017–2020 for all regions where measurements have sufficient sensitivity to emissions. This includes the regions of northwestern Europe, east Asia, the USA and Australia, where emissions decreased by a total of 1.6 ± 3.9 Gg yr−1, compared to a mean global increase of 3.0 ± 1.2 Gg yr−1 over the same period. Collectively these regions only account for around a third of global emissions in 2020. Therefore we are not able to pinpoint the source regions or specific activities responsible for the recent global emission rise.

Organic, inorganic and total bromine (Brtot) around the upper troposphere and lower stratosphere (UTLS) were measured over southern Argentina and the surrounding regions extending down to the Antarctic Peninsula in September and November of 2019. These observations were recorded from the German High Altitude and LOng range research aircraft (HALO) as part of the Transport and Composition of the Southern Hemisphere UTLS (SouthTRAC) research campaign. Total bromine (Brtot) is inferred from measured total organic bromine (Brorg) added to inorganic bromine (Bryinorg). Brorg is comprised of the bromine summed from CH3Br, the halons, and the major very short-lived brominated species measured onboard HALO by the University of Frankfurt, while the Bryinorg is evaluated from limb measured BrO and CLaMS photochemical transport modelling (FZ Jülich) accounting for the BrO/Bryinorg ratio. Air mass transport pathways into the UTLS and the likely origins of bromine-rich air masses reaching the Southern Hemisphere (SH) lower stratosphere are identified through distributions of in situ measured transport (CO and N­­2O) and air mass lag-time (SF6) tracers as well as Lagrangian transport modelling. Additionally, Brtot measured in the SH is compared with previous measurements observed in the Northern Hemisphere as part of the Wave-driven ISentropic Exchange (WISE) research campaign in fall 2017, as well as the long term trend in stratospheric bromine.

Inverse modeling is a widely used top-down method to infer greenhouse gas (GHG) emissions and their spatial distribution based on atmospheric observations. The errors associated with inverse modeling have multiple sources, such as observations and a-priori emission estimates, but they are often dominated by the transport model error. Here, we utilize the Lagrangian Particle Dispersion Model (LPDM) FLEXPART, driven by the meteorological fields of the regional numerical weather prediction model COSMO. The main source of errors in LPDMs is the turbulence diffusion parameterization and the meteorological fields. The latter are outputs of an Eulerian model. Recently, we introduced an improved parameterization scheme of the turbulence diffusion in FLEXPART, which significantly improves FLEXPART-COSMO simulations at 1 km resolution. We exploit F-gases measurements from two extended field campaigns on the Swiss Plateau (in Beromünster and Sottens) and we conduct both high- (1 km) and low-resolution (7 km) FLEXPART transport simulations that are then used in a Bayesian analytical inversion to estimate spatial emission distributions. Our results for four F-gases (HFC-134a, HFC-125, HFC-32, SF6) indicate that both high-resolution inversions and a dense measurement network significantly improve the ability to estimate the spatial distribution of emissions. Furthermore, the total emission estimates from the high-resolution inversions (351±44 Mg yr−1 for HFC-134a, 101±21 Mg yr−1 for HFC-125, 50±8 Mg yr−1 for HFC-32, 9.0±1.1 Mg yr−1 for SF6) are significantly higher compared to the low-resolution inversions (20–40 % increase) and result in total a-posteriori emission estimates that are closer to national inventory values as reported to the UNFCCC (10–20 % difference between high-resolution inversion estimates and inventory values compared to 30–40 % difference between the low-resolution inversion estimates and inventory values). Specifically, we attribute these improvements to a better representation of the atmospheric flow in complex terrain in the high-resolution model, partly induced by the more realistic topography. We further conduct numerous sensitivity inversions, varying different parameters and variables of our Bayesian inversion framework to explore the whole range of uncertainty in the inversion errors (e.g., inversion grid, spatial distribution of a-priori emissions, covariance parameters like baseline uncertainty and spatial correlation length, temporal resolution of the assimilated observations, observation network, seasonality of emissions). From the above-mentioned parameters, we find that the uncertainty of the mole fraction baseline and the spatial distribution of the a-priori emissions have the largest impact on the a-posteriori total emission estimates and their spatial distribution. This study is a step towards mitigating the errors associated with the transport models and better characterizing the uncertainty inherent in the inversion error. Improvements in the latter will facilitate the validation and standardization of the national GHG emission inventories and support policymakers.

The TWIN - Hemera stratospheric balloon flight took place on 12 - 13-Aug-2021 from the Esrange Space Center near Kiruna, Sweden (67°N).The project was supported by Hemera (www.hemera-h2020.eu) via the first call of proposals, and the flight was managed by the CNES (Centre national d'Etudes Spatiales) and SSC (Swedish Space Corporation). The scientific payload was developed in collaboration by several institutions from the Netherlands, Germany and France.The main objectives were: (1) to characterize the vertical structure of COS mole fraction and isotopic composition; (2) to characterize the CFCs, other ozone depleting substances and climate relevant trace gases in the present atmosphere, linked to their change over the past decade; and (3) to compare and evaluate several instruments and sampling techniques.The payload included several AirCores (U. Frankfurt, CIO and FZJ), two Pico-SDLA mid-infrared in-situ diode laser spectrometers (GSMA/DT-INSU), and devices for taking large whole air samples of stratospheric air for subsequent laboratory measurements: the BONBON whole-air cryosampler (U. Frankfurt) and LISA (CIO). IMAU is involved for the analysis of isotopic composition and mole fractions of samplers from the cryo-sampler. This approach allows obtaining a comprehensive dataset covering a range of spatial resolutions: from the multitude of gas species to be measured in the high-volume samples, to the subset of gases at higher vertical resolution from AirCores, and finally to the continuous in-situ CO2 and CH4 data from tunable diode laser spectroscopy. We expect this dataset to lead to novel and important knowledge on the trace gases in the stratosphere.In this presentation we will describe the overall setup of the scientific payload, the flight characteristics, and we will give an overview of the already performed and planned measurements.

Inorganic chlorine (Cly) is the sum of the degradation products of long-lived chlorinated source gases. These include the reservoir species (HCl and ClONO2) and active chlorine species (i.e. ClOx). The active chlorine species drive catalytic cycles that deplete ozone in the polar winter stratosphere. This work presents calculations of inorganic chlorine (Cly) derived from chlorinated source gas measurements on board the High Altitude and Long Range Research Aircraft (HALO) during the Southern hemisphere Transport, Dynamic and Chemistry (SouthTRAC) campaign in late winter and early spring 2019. Results are compared to Cly of the Northern Hemisphere derived from measurements of the POLSTRACC-GW-LCYCLE-SALSA (PGS) campaign in the Arctic winter of 2015/2016. A scaled correlation was used for PGS data, since not all source gases were measured. Cly from a scaled correlation was compared to directly determined Cly and agreed well. An air mass classification based on in situ N2O measurements allocates the measurements to the vortex, the vortex boundary region, and mid-latitudes. Although the Antarctic vortex was weakened in 2019 compared to previous years, Cly reached 1687 ± 20 ppt at 385 K, therefore up to around 50 % of total chlorine could be found in inorganic form inside the Antarctic vortex, whereas only 15 % of total chlorine could be found in inorganic form in the southern mid-latitudes. In contrast, only 40 % of total chlorine could be found in inorganic form in the Arctic vortex during PGS and roughly 20 % in the northern mid-latitudes. Differences inside the respective vortex reaches up to 565 ppt more Cly in the Antarctic vortex 2019 than in the Arctic vortex 2016 (at comparable distance to the local tropopause). As far as is known, this is the first comparison of inorganic chlorine within the respective polar vortex. Based on the results of these two campaigns, the difference of Cly inside the respective vortex is significant and larger than reported inter annual variations.

The mean age of air is a powerful diagnostic tool to investigate stratospheric transport processes. It can be derived from suitable trace gas measurements and from model calculations. In contrast to the Northern Hemisphere (NH), data coverage of in situ measurements of such trace gases in the Southern Hemisphere (SH) is sparse. Due to its tropospheric trend and its very long atmospheric lifetime, SF6 is such a suitable trace gas. SF6 mixing ratios were measured with an airborne in situ GC-ECD system during several HALO aircraft campaigns, including locations in the SH polar vortex.Here we present the mean age derived from in situ SF6 measurements during the POLSTRACC campaign (Polar Stratosphere in a Changing Climate) in NH winter/spring 2015/2016 and during the SouthTRAC campaign (Transport and Composition of the Southern Hemisphere UTLS) in SH winter/spring 2019. Mean age values over 4 years were observed in both polar vortices. On average, higher mean age values were observed at lower levels of potential temperature during SouthTRAC 2019 than during POLSTRACC 2015/2016. The findings will be discussed in context of the Brewer-Dobson circulation.

We report on measurements of total bromine (Brtot) in the upper troposphere and lower stratosphere (UTLS) taken from the German High Altitude and LOng range research aircraft (HALO) over the North Atlantic, Norwegian Sea and north-western Europe in September/ October 2017 during the WISE (Wave-driven ISentropic Exchange) research campaign. Brtot is calculated from measured total organic bromine (Brorg) (i.e., the sum of bromine contained in CH3Br, the halons and the major very short-lived brominated substances) added to inorganic bromine (Bryinorg), evaluated from measured BrO and photochemical modelling. Combining these data, the weighted mean [Brtot] is 19.2 ± 1.2 ppt in the extratropical lower stratosphere (Ex-LS) of the northern hemisphere. The inferred average Brtot for the Ex-LS is slightly smaller than expected for the middle stratosphere in 2016 (~19.6 ppt (ranging from 19-20 ppt) as reported by the WMO/UNEP Assessment (2018)). However, it reflects the expected variability in Brtot in the Ex-LS due to influxes of shorter lived brominated source and product gases from different regions of entry. A closer look into Brorg and Bryinorg as well as simultaneously measured transport tracers (CO, N2O, ...) and an air mass lag-time tracer (SF6), suggests that a filament of air with elevated Brtot protruded into the extratropical lowermost stratosphere (Ex-LMS) from 350-385 K and between equivalent latitudes of 55-80˚N (high bromine filament – HBrF). Lagrangian transport modelling shows the multi-pathway contributions to Ex-LMS bromine. According to CLaMS air mass origin simulations, contributions to the HBrF consist of predominantly isentropic transport from the tropical troposphere (also with elevated [Brtot] = 21.6 ± 0.7 ppt) as well as a smaller contribution from an exchange across the extratropical tropopause which are mixed into the stratospheric background air. In contrast, the surrounding LS above and below the HBrF has less tropical tropospheric air, but instead additional stratospheric background air. Of the tropical tropospheric air in the HBrF, the majority is from the outflow of the Asian monsoon anticyclone and the adjacent tropical regions, which greatly influences concentrations of trace gases transported into the Ex-LMS in boreal summer and fall. The resulting increase of Brtot in the Ex-LMS and its consequences for ozone is investigated through the TOMCAT/SLIMCAT model simulations. However, more extensive monitoring of total stratospheric bromine in more aged air (i.e., in the middle stratosphere) as well as globally and seasonally is required in addition to model simulations to fully understand its impact on Ex-LMS ozone and the radiative forcing of climate.

Verification of the nationally reported greenhouse gas (GHG) inventories using inverse modelling and atmospheric observations is considered to be best practice by the United Nations Framework Convention on Climate Change (UNFCCC). It allows for an independent assessment of the nationally reported GHG emissions using a comprehensively different approach to the inventory methods. Significant differences in the emissions estimated using the two approaches are a means of identifying areas worthy of further investigation. An inversion methodology called Inversion Technique for Emission Modelling (InTEM) has been developed that uses a non-negative least squares minimisation technique to determine the emission magnitude and distribution that most accurately reproduces the observations. By estimating the underlying baseline time series, atmospheric concentrations where the short-term impact of regional pollution has been removed, and by modelling where the air has passed over on route to the observation stations on a regional scale, estimates of UK emissions are made. In this study we use an extensive network of observations with six stations across the UK and six more in neighbouring countries. InTEM uses information from a Lagrangian dispersion model NAME (Numerical Atmospheric dispersion Modelling Environment), driven by three-dimensional, modelled meteorology, to understand how the air mixes during transport from the emission sources to observation points. The InTEM inversion results are submitted annually by the UK as part of their National Inventory Report to the UNFCCC. They are used within the UK inventory team to highlight areas for investigation and have led to significant improvements to the submitted UK inventory. The latest UK comparisons will be shown along with examples of how the inversion results have informed the inventory.

Synthetic halocarbons are used for a wide range of applications, for example air conditioning or foam blowing. Many of them are long-lived greenhouse gases contributing to climate change and, in addition, may contribute to stratospheric ozone depletion if containing chlorine or bromine. Therefore, their production and use are regulated by the Montreal Protocol and its amendments. These long-lived halocarbons are increasingly replaced by a fourth generation of unsaturated short-lived halocarbons, the hydrochlorofluoroolefines (HCFOs) and hydrofluoroolefines (HFOs). The main removal process of these compounds in the atmosphere is reaction with OH radicals, and their average lifetimes are of the order of up to a few tens of days.As part of the IAGOS-CARIBIC instrument package we operate an automated air sample collection system during regular flights in the upper troposphere and lowermost stratosphere. At altitudes around 10-12 km, samples are collected in stainless steel and glass flasks at predefined times. Post-flight laboratory analyses include gas chromatography - mass spectrometry measurements of a wide range of halocarbons. The short-lived compounds HFO-1234ze(E) and HCFO-1233zd(E) were detected in a small number of samples, indicating that these compounds are sufficiently long lived for transport into the upper troposphere. There were not found in stratospheric samples.At this altitude, low abundance of OH and low temperatures may slow down chemical decay, and tracer lifetimes may increase significantly. Based on average temperatures and OH abundance, we estimate local lifetimes of HFO-1234ze(E) and HCFO-1233zd(E) in the mid-latitudes of up to 75 days and 200 days, respectively. Short-lived H(C)FOs reaching the upper troposphere could thus be transported over large distances and their degradation products may be deposited far from their emission sources.

Production and use of many synthetic halogenated trace gases are regulated internationally because of their contribution to stratospheric ozone depletion or to climate change. In many applications they have been replaced by shorter-lived compounds which have become measurable in the atmosphere as emissions increased. Non-target monitoring of trace gases rather than targeted measurements of well-known substances is needed to keep up with such changes in the atmospheric composition. We regularly deploy gas chromatography (GC) coupled to time-of-flight mass spectrometry (TOF-MS) for analysis of flask air samples and in situ measurements at the Taunus Observatory, a site in central Germany. TOF-MS record data over a continuous mass range enable a retrospective analysis of the data set, which can thus be considered a type of digital air archive. This archive can be made use of if new substances come into use and their mass spectrometric fingerprint is identified. However, quantifying new replacement halocarbons can be challenging, as mole fractions are generally low, requiring high measurement precision and low detection limits. In addition, calibration can be demanding, as calibration gases may not contain sufficiently high amounts of newly used substances or the amounts in the calibration gas have not been quantified. This paper presents an indirect data evaluation approach for TOF-MS data, where the calibration is linked to another compound which could be quantified in the calibration gas. We also present an approach to evaluate the quality of the indirect calibration method and to select periods of stable instrument performance and well suited reference compounds. The method is applied to three short-lived synthetic halocarbons: HFO-1234-yf, HFO-1234ze(E), and HCFO-1233zd(E). They represent replacements for longer-lived HFCs and exhibit increasing mole fractions in the atmosphere. The indirectly calibrated results are compared to directly calibrated measurements using data from TOF-MS canister sample analysis and TOF-MS in situ measurements, which are available for some periods of our data set. The application of the indirect calibration method on several test cases can result into accuracies around 13 % to 20 %. For H(C)FOs accuracies up to 25 % are achieved. The indirectly calculated mole fractions of the investigated H(C)FOs at Taunus Observatory range between measured mole fractions at urban Dübendorf and Jungfraujoch stations in Switzerland.

Bromine greatly influences the UT/LS ozone concentrations, however the transport of bromine across the tropical tropopause layer and in particular across the extratropical tropopause is not well quantified. Air-borne measurements of atmospheric trace gases such as organic and inorganic bromine along the tropopause are studied during the WISE (Wave-driven ISentropic Exchange) research campaign over the northern Atlantic and western Europe from September 13 - October 21, 2017. The remote sensing instrument mini-DOAS (Differential Optical Absorption Spectroscopy) is mounted on the HALO (High Altitude and LOng range) aircraft and measures BrO (O3, NO2 among other trace gases). The novel scaling method is applied to infer the target gas BrO mixing ratios from slant column densities using in-situ O3 measurements from the FAIRO instrument (operated by KIT) as the scaling gas. For each flight, the inferred mixing ratios are directly compared with CLaMS (Chemical Lagrangian Model of the Stratosphere) simulated curtains of the trace gases along the flight path. The partitioning coefficient of inorganic bromine from CLaMS and all relevant organic halogen species and air mass ages (SF6, CO2) from the GhOST-MS instrument (operated by UFra) are used to determine the total bromine budget along the UT/LS. A climatology of organic, inorganic and total bromine is constructed with respect to the extratropical tropopause as well as the air mass ages. This indicates the interplay of bromine transport across the extratropical tropopause and of the transport of air via the lower branch from the tropics as well as potential losses of inorganic bromine by uptake onto and sedimentation of ice particles.

A laser spectrometer for automated monthly measurements of methane (CH4) mixing ratios aboard the CARIBIC passenger aircraft is presented. The instrument is based on a commercial Fast Greenhouse Gas Analyser (FGGA, Los Gatos Res.), which was adapted to meet the requirements imposed by unattended airborne operation. It was characterised in the laboratory with respect to instrument stability, precision, cross sensitivity to H2O, and accuracy. For airborne operation, a calibration strategy is described that utilises CH4 measurements obtained from flask samples taken during the same flights. The precision of airborne measurements is 2 ppb for 10 s averages. The accuracy at aircraft cruising altitude is 3.85 ppb. During aircraft ascent and descent, where no flask samples were obtained, instrumental drifts can be less accurately determined and the uncertainty is estimated to be 12.4 ppb. A linear humidity bias correction was applied to the CH4 measurements, which was most important in the lower troposphere. On average, the correction bias was around 6.5 ppb at an altitude of 2 km, and negligible at cruising flight level. Observations from 103 long-distance flights are presented that span a large part of the northern hemispheric upper troposphere and lowermost stratosphere (UT/LMS), with occasional crossing of the tropics on flights to southern Africa. These accurate data mark the largest UT/LMS in-situ CH4 dataset worldwide. An example of a tracer-tracer correlation study with ozone is given, highlighting the possibility for accurate cross-tropopause transport analyses.

Jeder der schon einmal ein spannendes Kanurennsport‐Ereignis verfolgt hat, ist fasziniert von den extremen Leistungen der Athleten. Dabei ist es egal, ob es sich um den Einer oder die Mannschaftsboote handelt. Kaum vorstellbar, dass hinter den perfekt ablaufenden Bewegungen, die oftmals nur wenige Sekunden oder Minuten dauern, jahrelanges hartes Training, vor allem im Winter, mit zahlreichen Hohen und Tiefen stecken. Oftmals entscheiden nur Kleinigkeiten uber Sieg oder Niederlage. So kann eine kleine Unachtsamkeit zu einer Verletzung fuhren und die letzten Jahre der harten Schinderei umsonst erscheinen lassen. Auch Missverstandnisse zwischen Trainern und Sportlern oder der Sieg des inneren Schweinehundes in schwachen Momenten konnen im entscheidenden Moment die Ursache fur eine Niederlage beim Wettkampf sein. Auch in Unternehmen konnen Kleinigkeiten, Missverstandnisse, zu ungenaue Ziele oder die eigene Tragheit den wirtschaftlichen Erfolg verhindern. So kann die Gesundheitswirtschaft vom Kanurennsport lernen, wie sie vom Start bis zum Ziel erfolgreich ist, Konflikte sportlich nimmt und den inneren Schweinehund besiegt.

[1] Estimates of surface fluxes of carbon monoxide (CO) inferred from remote sensing observations or free tropospheric trace gas measurements using global chemical transport models can have significant uncertainties because of discrepancies in the vertical transport in the models, which make it challenging to unequivocally relate the observations back to the surface fluxes in the models. The new Measurement of Pollution in the Troposphere (MOPITT) version 5 retrievals provide greater sensitivity to lower tropospheric CO over land relative to the previous versions and are, therefore, useful for evaluating vertical transport in models. We have assimilated the new MOPITT CO retrievals, using the Goddard Earth Observing System (GEOS)-Chem model, to study the influence of vertical transport errors on inferred CO sources. We compared the source estimates obtained by assimilating the CO profiles, the column amounts, and the surface level retrievals for June–August 2006. The three different inversions produced large differences in the source estimates in regions of convection and strong CO emissions. The inversion using the CO profiles suggested an 85% increase in emissions in India/Southeast Asia, which exacerbated the model bias in the lower and middle troposphere, whereas using the surface level retrievals produced a 37% decrease in Indian/Southeast Asian emissions, which exacerbated the underestimate of CO in the upper troposphere. Globally, the inversion with the surface retrievals suggested a 22% reduction in emissions from the a priori estimate of 161 Tg CO/month (from combustion and the oxidation of biogenic volatile organic compounds), averaged in June–August 2006. The analysis results were validated with independent surface CO measurements from NOAA Global Monitoring Division (GMD) network and upper troposphere CO measurements from the Civil Aircraft for the Regular Investigation of the Atmosphere Based on an Instrumented Container (CARIBIC). We found that the inversion with the surface retrievals agreed best with surface CO data but produced the largest discrepancy with the CARIBIC aircraft data in the upper troposphere, suggesting the influence of vertical transport errors in the model. Our results show that the comparison of the a posteriori CO distributions obtained from the inversions using the surface and profile retrievals provides a means of characterizing the potential impact of the vertical transport biases on the source estimates and the CO distribution.

Long term measurements in background air (Cape Grim, Tasmania) and firn air (NEEM, Greenland) of the potent long-lived greenhouse gas SF5CF3 show that emissions declined after the late 1990s, having grown since the 1950s, and became indistinguishable from zero after 2003. The timing of this decline suggests that emissions of this gas may have been related to the production of certain fluorochemicals; production of which have been recently phased out. An earlier observation of closely correlated atmospheric abundances of SF5CF3 and SF6 are shown here to have likely been purely coincidental, as their respective trends diverged after 2002. Due to its long lifetime (ca. 900 yr), atmospheric concentrations of SF5CF3 have not declined, and it is now well mixed between hemispheres, as is also shown here from interhemispheric aircraft measurements. Total cumulative emissions of SF5CF3 amount to around 5 kT.

This paper investigates the acetone variability in the upper troposphere (UT) as sampled during the CARIBIC airborne experiment and simulated by the LMDz-INCA global chemistry climate model. The aim is to (1) describe spatial distribution and temporal variability of acetone; (2) propose benchmarks deduced from the observed data set; and (3) investigate the representativeness of the observational data set. According to the model results, South Asia (including part of the Indian Ocean, all of India, China, and the Indochinese peninsula) and Europe (including Mediterranean Sea) are net source regions of acetone, where nearly 25 % of North Hemispheric (NH) primary emissions and nearly 40 % of the NH chemical production of acetone take place. The impact of these net source regions on continental upper tropospheric acetone is studied by analysing CARIBIC observations of 2006 and 2007 when most flight routes stretched between Frankfurt (Germany) and Manila (Philippines), and by focussing over 3 sub-regions where acetone variability is strong: Europe-Mediterranean, Central South China and South China Sea. Important spatial variability was observed over different scales: (1) east-west positive gradient of annually averaged acetone vmr in UT over the Eurasian continent, namely a factor two increase from east to west; (2) ocean/continent contrast with 50 % enhancement over the continents; (3) the acetone volume mixing ration (vmr) may vary in summer by more than 1000 pptv within only 5 latitude-longitude degrees; (4) the standard deviation for measurements acquired during a short flight sequence over a sub-region may reach 40 %. Temporal variability is also important: (1) the acetone volume mixing ratio (vmr) in the UT varies with the season, increasing from winter to summer by a factor 2 to 4; (2) a difference as large as 200 pptv may be observed between successive inbound and outbound flights over the same sub-region due to different flight specifications (trajectory in relation to the plume, time of day). A satisfactory agreement for the abundance of acetone is found between model results and observations, with e.g. only 30 % overestimation of the annual average over Central-South China and the South China Sea (between 450 and 600 pptv), and an underestimation by less than 20 % over Europe-Mediterranean (around 800 pptv). Consequently, annual budget terms could be computed with LMDz-INCA, yielding a global atmospheric burden of 7.2 Tg acetone, a 127 Tg yr−1 global source/sink strength, and a 21-day mean residence time. Moreover the study shows that LMDz-INCA can reproduce the impact of summer convection over China when boundary layer compounds are lifted to cruise altitude of 10–11 km and higher. The consequent enhancement of acetone vmr during summer is reproduced by LMDz-INCA, to reach agreement on an observed maximum of 970 ± 400 pptv (average during each flight sequence over the defined zone ± standard deviation). The summer enhancement of acetone is characterized by a high spatial and temporal heterogeneity, showing the necessity to increase the airborne measurement frequency over Central-South China and the South China Sea in August and September, when the annual maximum is expected (daily average model values reaching potentially 3000 pptv). In contrast, the annual cycle in the UT over Europe-Mediterranean is not reproduced by LMDz-INCA, in particular the observed summer enhancement of acetone to 1400 ± 400 pptv after long-range transport of free tropospheric air masses over North Atlantic Ocean is not reproduced. In view of the agreement on the acetone annual cycle at surface level, this disagreement in UT over Europe indicates misrepresentation of simulated transport of primary acetone or biased spatial distribution of acetone chemical sinks and secondary sources. The sink and source budget in long-range transported free tropospheric air masses may be studied by analysing atmospheric chemical composition observed by CARIBIC in summer flights between North America and Europe.

We infer CO2 surface fluxes using satellite observations of mid-tropospheric CO2 from the Tropospheric Emission Spectrometer (TES) and measurements of CO2 from surface flasks in a time-independent inversion analysis based on the GEOS-Chem model. Using TES CO2 observations over oceans, spanning 40° S–40° N, we find that the horizontal and vertical coverage of the TES and flask data are complementary. This complementarity is demonstrated by combining the datasets in a joint inversion, which provides better constraints than from either dataset alone, when a posteriori CO2 distributions are evaluated against independent ship and aircraft CO2 data. In particular, the joint inversion offers improved constraints in the tropics where surface measurements are sparse, such as the tropical forests of South America. Aggregating the annual surface-to-atmosphere fluxes from the joint inversion for the year 2006 yields −1.13±0.21 Pg C for the global ocean, −2.77±0.20 Pg C for the global land biosphere and −3.90±0.29 Pg C for the total global natural flux (defined as the sum of all biospheric, oceanic, and biomass burning contributions but excluding CO2 emissions from fossil fuel combustion). These global ocean and global land fluxes are shown to be near the median of the broad range of values from other inversion results for 2006. To achieve these results, a bias in TES CO2 in the Southern Hemisphere was assessed and corrected using aircraft flask data, and we demonstrate that our results have low sensitivity to variations in the bias correction approach. Overall, this analysis suggests that future carbon data assimilation systems can benefit by integrating in situ and satellite observations of CO2 and that the vertical information provided by satellite observations of mid-tropospheric CO2 combined with measurements of surface CO2, provides an important additional constraint for flux inversions.

Quantifying the fluxes of carbon dioxide (CO 2 ) between the atmosphere and terrestrial ecosystems in all their diversity, across the continents, is important and urgent for implementing effective mitigating policies. Whereas much is known for Europe and North America for instance, in comparison, South Asia, with 1.6 billion inhabitants and considerable CO 2 fluxes, remained terra incognita in this respect. We use regional measurements of atmospheric CO 2 aboard a Lufthansa passenger aircraft between Frankfurt (Germany) and Chennai (India) at cruise altitude, in addition to the existing network sites for 2008, to estimate monthly fluxes for 64-regions using Bayesian inversion and transport model simulations. The applicability of the model's transport parameterization is confirmed using SF 6 , CH 4 and N 2 O simulations for the CARIBIC datasets. The annual amplitude of carbon flux obtained by including the aircraft data is twice as large as the fluxes simulated by a terrestrial ecosystem model that was applied to prescribe the fluxes used in the inversions. It is shown that South Asia sequestered carbon at a rate of 0.37 ± 0.20 Pg C yr −1 (1 Pg C = 10 15 g of carbon in CO 2 ) for the years 2007 and 2008. The seasonality and the strength of the calculated monthly fluxes are successfully validated using independent measurements of vertical CO 2 profiles over Delhi and spatial variations at cruising altitude over Asia aboard Japan Airlines passenger aircraft.

Heavy duty EURO 4 diesel engine exhaust particle and ion size distributions were measured at the tailpipe using dynamometer testing. Measurements of particle volatility and electrical charge were undertaken to clarify diesel exhaust nucleation mode characteristics with different exhaust after-treatment systems. Nucleation mode particle volatility and charging probability were dependent on exhaust after-treatment: particles were volatile and uncharged when the engine was equipped with diesel particulate filter and partly volatile and partly charged in exhaust without any after-treatment or with an oxidation catalyst only. The absence of charged particles in the nucleation mode of diesel particulate filtered exhaust excludes the ion mediated process as a nucleation particle formation mechanism.

Gaseous sulfuric acid (GSA) is thought to represent an important if not the most important nucleating gas present in modern diesel automobile exhaust. It triggers the formation of new aerosol particles, which grow by condensation and coagulation. Here we report on the first measurements of GSA in automobile exhaust. The experiment was made using a modern passenger diesel car equipped with an exhaust after-treatment system composed of an oxidation catalyst and a diesel-particle filter. The diesel fuel used had an ultra-low sulfur mass fraction of only 5×10 −6 . Measured GSA number concentrations reached up to 1×10 9 cm −3 . Freshly nucleated particles with diameters larger than 3 nm were also measured. The concentrations reached up to 1×10 5 cm −3 and were positively correlated with GSA for GSA exceeding a threshold value in the range of 5×10 7 –2×10 8 cm −3 . This suggests that GSA was involved in the formation of new volatile particles.

Excitation functions for quasi-elastic scattering have been measured at backward angles for the systems 32,34S+197Au and 32,34S+208Pb for energies spanning the Coulomb barrier. Representative distributions, sensitive to the low energy part of the fusion barrier distribution, have been extracted from the data. For the fusion reactions of 32,34S with 197Au couplings related to the nuclear structure of 197Au appear to be dominant in shaping the low energy part of the barrier distibution. For the system 32S+208Pb the barrier distribution is broader and extends further to lower energies, than in the case of 34S+208Pb. This is consistent with the interpretation that the neutron pick-up channels are energetically more favoured in the 32S induced reaction and therefore couple more strongly to the relative motion. It may also be due to the increased collectivity of 32S, when compared with 34S., 11 pages, 5 figures

A unique set of gaseous mercury measurements in the upper troposphere and lower stratosphere (UT/LS) has been obtained during the monthly CARIBIC (www.caribic-atmospheric.com) flights since May 2005. The passenger Airbus 340-600 of Lufthansa covered routes to the Far East, North America, India, and the southern hemisphere. The accompanying measurements of CO, O3, NOy, H2O, aerosols, halocarbons, hydrocarbons, greenhouse gases, and several other parameters as well as backward trajectories enable a detailed analysis of these measurements. Speciation tests have shown that the CARIBIC measurements represent a good approximation of total gaseous mercury (TGM) concentrations. Above the tropopause TGM always decrease with increasing potential vorticity (PV) and O3 which implies its conversion to particle bound mercury. The observation of the lowest TGM concentrations at the highest particle concentrations in the stratosphere provides further evidence for such conversion. We will show how a seasonally dependent conversion rate could be derived using concomitantly measured SF6 mixing ratios as a timer. Tropospheric mercury data suggest the existence of a decreasing trend in the northern hemisphere whose size is comparable with the trend derived from long-term measurements by ship cruises, at Cape Point (South Africa) and Mace Head (Ireland).

Received 29 May 2012; revised 8 August 2012; accepted 16 August 2012; published 4 October 2012. [1] We investigate the upper tropospheric distribution of methane (CH4) at low latitudes based on the analysis of air samples collected from aboard passenger aircraft. The distribution of CH4 exhibits spatial and seasonal differences, such as the pronounced seasonal cycles over tropical Asia and elevated mixing ratios over central Africa. Over Africa, the correlations of methane, ethane, and acetylene with carbon monoxide indicate that these high mixing ratios originate from biomass burning as well as from biogenic sources. Upper tropospheric mixing ratios of CH4were modeled using a chemistry transport model. The simulation captures the large-scale features of the distributions along different flight routes, but discrepancies occur in some regions. Over Africa, where emissions are not well constrained, the model predicts a too steep interhemispheric gradient. During summer, efficient convective vertical transport and enhanced emissions give rise to a large-scale CH4 maximum in the upper troposphere over subtropical Asia. This seasonal (monsoonal) cycle is analyzed with a tagged tracer simulation. The model confirms that in this region convection links upper tropospheric mixing ratios to regional sources on the Indian subcontinent, subtropical East Asia, and Southeast Asia. This type of aircraft data can therefore provide information about surface fluxes.

[1] During the summer monsoon the upper troposphere over South Asia is characterized by the monsoon anticyclone centered above the Tibetan Plateau. Surface air that has been rapidly transported upwards through deep convection becomes trapped within the strong anticyclonic circulation. Observations of trace gases within this anticyclone by the CARIBIC flying observatory revealed large enhancements in the greenhouse gas methane (CH4), which increased over the course of the monsoon. Meteorological analysis indicated that these air masses originated primarily in India, for which relatively little is known about CH4 emissions. Using correlations between concentrations of CH4 and carbon monoxide (CO) we estimated total emissions of 30.8 Tg CH4during the 2008 monsoon season (June–September), 19.7 Tg of which were identified as additional, monsoon-related biogenic methane using the relationship of CH4 to ethane (C2H6). After accounting for the ∼3.9 Tg attributed to rice agriculture in the current inventories, ∼15.8 Tg of additional CH4 remain. Underestimated rice emissions provide a partial explanation, with the remainder most likely attributable to microbial production in waterlogged areas such as landfills, polluted waterways and wetlands.

Carbon monoxide (CO) and other atmospheric trace constituents were measured from onboard an Airbus 340�600 passenger aircraft in the upper troposphere (UT) between south China and the Philippines during Civil Aircraft for the Regular Investigation of the Atmosphere Based on an Instrument Container (CARIBIC) flights from May 2005 until March 2008. A total of 132 events having CO enhancements were observed in the UT over the region during the 81 CARIBIC flights from Frankfurt, Germany, to Manila, Philippines, with a stopover in Guangzhou, China. Among these, 51 high�CO events with enhancements more than 50 ppb above background were observed. For these events enhancements ranged from 52.7 to 221.3 ppb and persisted for 3 to 78 min (�40 to 1200 km), indicating an influence of strong pollution from biomass/biofuel/fossil fuel burning on the trace gas composition of the UT. Back trajectory analysis shows that south China, the Indochinese Peninsula, and the Philippines/Indonesia are the main source regions of the high�CO events. The composition of air parcels originating from south China was found to be primarily influenced by anthropogenic urban/industrial emissions, while emissions from biomass/biofuel burning contributed substantially to CO enhancements from the Indochinese Peninsula. During the Philippines/Indonesia events, air parcel composition suggests contributions from both biomass/biofuel burning and urban/industrial sources. Long�range transport of air parcels from northeast Asia and India also contributed to CO enhancements in the UT over the region. The general features of regional influence, typical cases, and the contributions of biomass/biofuel burning and anthropogenic emissions are presented and discussed to characterize the air parcels during the observed high�CO events.

As part of the effort to understand volcanic plume composition and chemistry during the eruption of the Icelandic volcano Eyjafjallajkull, the CARIBIC atmospheric observatory was deployed for three special science flights aboard a Lufthansa passenger aircraft. Measurements made during these flights included the collection of whole air samples, which were analyzed for non-methane hydrocarbons (NMHCs). Hydrocarbon concentrations in plume samples were found to be reduced to levels below background, with relative depletions characteristic of reaction with chlorine radicals (Cl). Recent observations of halogen oxides in volcanic plumes provide evidence for halogen radical chemistry, but quantitative data for free halogen radical concentrations in volcanic plumes were absent. Here we present the first observation-based calculations of Cl radical concentrations in volcanic plumes, estimated from observed NMHC depletions. Inferred Cl concentrations were between 1.3 × 10 and 6.6 × 10 Cl cm. The relationship between NMHC variability and local lifetimes was used to investigate the ratio between OH and Cl within the plume, with [OH]/[Cl] estimated to be ∼37. Copyright 2011 by the American Geophysical Union.

Analysis of individual particles by analytical electron microscopy as well as quantitative analysis using particle-induced X-ray emission (PIXE) and particle elastic scattering analysis (PESA) were carried out on samples collected from a flight at 10 km altitude between 50 degrees N and 30 degrees S as part of the Civil Aircraft for Regular Investigation of the atmosphere Based on an Instrument Container (CARIBIC) project (http://www.caribic-atmospheric.com). Particle morphology showed large variability with sampling latitude. Complicated branched structures dominated the large particles of the extratropical northern and southern hemisphere and the northern tropics. Particles in the tropics of the southern hemisphere were small in size and large in number concentration, whereas particles in or close to the intertropical convergence zone were few and small in size. Particles in the lowermost stratosphere were found to have similar structures but more branched than the ones found in the upper troposphere of the extratropics. Quantitative analysis revealed that the sulfur concentration varied by a factor of 50 in the nine samples analyzed in this study. The carbon-to-sulfur mass concentration ratio was lowest in the lowermost stratosphere (0.5) and highest in the tropics of the southern hemisphere (3.5). The elemental distribution of carbon and sulfur in individual particles was mapped by energy-filtered transmission electron microscopy (EFTEM). Almost all particles analyzed contained a mixture of carbonaceous and sulfurous matter. Particles with satellites were found by EFTEM to contain both carbon and sulfur in the central particle, whereas in the satellite particles only carbonaceous material was detected. (Less)

This paper summarizes the yields and the emission patterns of ${K}^{+}$ and of ${K}^{\ensuremath{-}}$ mesons measured in inclusive C+C, Ni+Ni, and Au+Au collisions at incident energies from $0.6A$ to $2.0A$ GeV using the Kaon Spectrometer KaoS at GSI. For Ni+Ni collisions at $1.5A$ and at $1.93A$ GeV as well as for Au+Au at $1.5A$ GeV, detailed results are presented of the multiplicities, of the inverse slope parameters, and of the anisotropies in the angular emission patterns as a function of the collision centrality. When comparing transport-model calculations to the measured ${K}^{+}$ production yields, an agreement is only obtained for a soft nuclear equation of state (compression modulus ${K}_{\mathrm{N}}\ensuremath{\approx}200$ MeV). The production of ${K}^{\ensuremath{-}}$ mesons at energies around $1A$ to $2A$ GeV is dominated by the strangeness-exchange reaction ${K}^{\ensuremath{-}}N\ensuremath{\rightleftharpoons}\ensuremath{\pi}Y$ ($Y=\ensuremath{\Lambda},\ensuremath{\Sigma}$) which leads to a coupling between the ${K}^{\ensuremath{-}}$ and ${K}^{+}$ yields. However, both particle species show distinct differences in their emission patterns suggesting different freeze-out conditions for ${K}^{+}$ and ${K}^{\ensuremath{-}}$ mesons.

The emission of K{sup +} and {pi}{sup {+-}} mesons has been studied in the asymmetric collision system Au+C and in the inverse reaction C+Au at 1.0A GeV (and at 1.8A GeV for C+Au only) in order to extract the effective source rapidities based on their distribution in the p{sub t}-y plane. The extracted source rapidity of K{sup +} mesons is about y{sub s}/y{sub beam}=0.25 at both incident energies [y(Au)=0,y(C)=y{sub beam}]. This corresponds to a reaction volume consisting of the C nucleus and a tube cut out of the Au nucleus. In clear contrast, the source rapidities of {pi}{sup {+-}} mesons vary from y{sub s}/y{sub beam}=0.5 in peripheral collisions (corresponding to NN interactions) to about y{sub s}/y{sub beam}