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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]

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]

The extratropical meridional energy transport in the atmosphere is fundamentally intermittent in nature, having extremes large enough to affect the net seasonal transport. Here, we investigate how these extreme transports are associated with the dynamics of the atmosphere at multiple spatial scales, from planetary to synoptic. We use the ERA5 reanalysis data to perform a wavenumber decomposition of meridional energy transport in the Northern Hemisphere mid-latitudes during winter and summer. We then relate extreme transport events to atmospheric circulation anomalies and dominant weather regimes, identified by clustering 500 hPa geopotential height fields. In general, planetary-scale waves determine the strength and meridional position of the synoptic-scale baroclinic activity with their phase and amplitude, but important differences emerge between seasons. During winter, large wavenumbers (k = 2–3) are key drivers of the meridional-energy-transport extremes, and planetary- and synoptic-scale transport extremes virtually never co-occur. In summer, extremes are associated with higher wavenumbers (k = 4–6), identified as synoptic-scale motions. We link these waves and the transport extremes to recent results on exceptionally strong and persistent co-occurring summertime heat waves across the Northern Hemisphere mid-latitudes. We show that the weather regime structures associated with these heat wave events are typical for extremely large poleward-energy-transport events. [ABSTRACT FROM AUTHOR]

A new global high-resolution coupled climate model, EC-Earth3P-HR has been developed by the EC-Earth consortium, with a resolution of approximately 40 km for the atmosphere and 0.25 degree for the ocean, alongside with a standard resolution version of the model, EC-Earth3P (80 km atmosphere, 1.0 degree ocean). The model forcing and simulations follow the HighResMIP protocol. According to this protocol all simulations are made with both high and standard resolutions. The model has been optimized with respect to scalability, performance, data-storage and post-processing. In accordance with the HighResMIP protocol no specific tuning for the high resolution version has been applied. Increasing horizontal resolution does not result in a general reduction of biases and overall improvement of the variability, and deteriorating impacts can be detected for specific regions and phenomena such as some Euro-Atlantic weather regimes, whereas others such as El Niño-Southern Oscillation show a clear improvement in their spatial structure. The omission of specific tuning might be responsible for this. The shortness of the spin-up, as prescribed by the HighResMIP protocol, prevented the model to reach equilibrium. The trend in the control and historical simulations, however, appeared to be similar, resulting in a warming trend, obtained by subtracting the control from the historical simulation, close to the observational one. [ABSTRACT FROM AUTHOR]