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Polar winter descent of reactive nitrogen (NOy) produced by energetic particle precipitation (EPP) in the mesosphere and lower thermosphere affects polar stratospheric ozone by catalytic reactions. This, in turn, may have implications for regional climate via radiative and dynamical feedbacks. NOy observations taken by the MIPAS/Envisat instrument during 2002--2012 have provided observational constraints on the solar-activity modulated variability of stratospheric EPP-NOy amounts. These constraints have allowed to formulate a chemical upper boundary condition for climate models in the context of solar forcing recommendations for CMIP6. Recently, a reprocessed MIPAS version 8 dataset has been released. Compared to the previous version, we assess what impact the changes in this new data version have on the EPP-NOy quantification, and on the formulation of chemical upper boundary conditions for climate models.The Earth Explorer 11 candidate Changing Atmosphere Infra-Red Tomography (CAIRT) will observe the altitude region from about 5 km to 115 km with an across-track resolution of 30 to 50 km within a 500 km wide field of view. This instrument will provide NOy and dynamical tracer observations from the upper troposphere to the lower thermosphere with unprecedented spatial resolution. Given that neither MIPAS nor any of the current instruments observes the lower thermosphere at this spatial resolution, we will assess the potential of this mission to advance our understanding of the EPP-climate link in the future., The 28th IUGG General Assembly (IUGG2023) (Berlin 2023)

The final level-1b version of MIPAS spectral data, version 8, is the basis of the improved level-2 IMK/IAA research data product that covers all observations modes (NOM, UTLS, MA, UA and NLC) and consists of: temperature, O3, H2O, CH4, N2O, CO, HNO3, NO2, NO, HNO4, BrONO2, N2O5, PAN, ClONO2, ClO, HOCl, CCl4, CH3Cl, COCl2, COF2, COClF, CFC-11, CFC-12, HCFC-22, CFC-113, CF4, C2H6, C2H2, HCN, HCOOH, H2CO, CH3OH, CH3COOH, acetone, HDO, H2O2, O3P, heavy ozone isotopologues, 15N isotopologues of HNO3, N2O, and NO2, SO2, OCS, SF6, NH3, sulphate aerosol, ammonium nitrate aerosol, PSCs, PMCs, and CO2 (above 65 km).Improvements with respect to previous versions will be discussed. The data come on a constant fine vertical altitude grid and contain pressure, temperature, trace gas volume mixing ratios, vertical resolution and the diagonal of the averaging kernel matrix. An elaborate error estimation for each single profile, compliant with the SPARC TUNER initiative and described in von Clarmann et al. (2022, doi: 10.5194/amt-15-6991-2022), is provided. In addition, as an easy-to-use data product, the abundances of most of the retrieved trace gases are also provided on a coarser vertical grid (constant over location and time for an individual trace gas) for which the averaging kernel matrix transforms to a unity matrix. This presentation allows for a fast and direct comparison to model simulations. We present examples for temperature and several trace species, demonstrate the improvements against earlier data versions, and discuss a number of use cases., The 28th IUGG General Assembly (IUGG2023) (Berlin 2023)

It has been suggested that dust storms efficiently transport water vapor from the near-surface to the middle atmosphere on Mars. Knowledge of the water vapor vertical profile during dust storms is important to understand water escape. During Martian Year 34, two dust storms occurred on Mars: a global dust storm (June to mid-September 2018) and a regional storm (January 2019). Here we present water vapor vertical profiles in the periods of the two dust storms (Ls = 162–260° and Ls = 298–345°) from the solar occultation measurements by Nadir and Occultation for Mars Discovery (NOMAD) onboard ExoMars Trace Gas Orbiter (TGO). We show a significant increase of water vapor abundance in the middle atmosphere (40–100 km) during the global dust storm. The water enhancement rapidly occurs following the onset of the storm (Ls~190°) and has a peak at the most active period (Ls~200°). Water vapor reaches very high altitudes (up to 100 km) with a volume mixing ratio of ~50 ppm. The water vapor abundance in the middle atmosphere shows high values consistently at 60°S-60°N at the growth phase of the dust storm (Ls = 195°–220°), and peaks at latitudes greater than 60°S at the decay phase (Ls = 220°–260°). This is explained by the seasonal change of meridional circulation: from equinoctial Hadley circulation (two cells) to the solstitial one (a single pole-to-pole cell). We also find a conspicuous increase of water vapor density in the middle atmosphere at the period of the regional dust storm (Ls = 322–327°), in particular at latitudes greater than 60°S. ©2019. American Geophysical Union. All Rights Reserved., S. A. is >Charge de Recherches> of the F.R.S.-FNRS. ExoMars is a space mission of the European Space Agency and Roscosmos. The NOMAD experiment is led by the Royal Belgian Institute for Space Aeronomy (IASBBIRA), assisted by Co-PI teams from Spain (IAA-CSIC), Italy (INAF-IAPS), and the United Kingdom (Open University). This project acknowledges funding by the Belgian Science Policy Office, with the financial and contractual coordination by the European Space Agency Prodex Office (PEA 4000103401 and 4000121493), by the Spanish MICINN through its Plan Nacional and by European funds under grants PGC2018-101836-B-I00 and ESP2017-87143-R (MINECO/FEDER), as well as by UK Space Agency through grants ST/R005761/1, ST/P001262/1, ST/R001405/1, and ST/S00145X/1 and Italian Space Agency through grant 2018-2-HH.0. The IAA/CSIC team acknowledges financial support from the State Agency for Research of the Spanish MCIU through the >Center of Excellence Severo Ochoa> award for the Instituto de Astrofisica de Andalucia (SEV-2017-0709). This work was supported by the Belgian Fonds de la Recherche Scientifique-FNRS under grant numbers 30442502 (ET_HOME) and T.0171.16 (CRAMIC) and Belgian Science Policy Office BrainBe SCOOP Project. U.S. investigators were supported by the National Aeronautics and Space Administration. Canadian investigators were supported by the Canadian Space Agency. The results retrieved from the NOMAD measurements used in this article are available on the BIRA-IASB data repository: http://repository.aeronomie.be/?doi= 10.18758/71021054 (Aoki et al., 2019).

NOMAD (Nadir and Occultation for MArs Discovery) is one of the four instruments on board the ExoMars Trace Gas Orbiter, scheduled for launch in March 2016. It consists of a suite of three high-resolution spectrometers - SO (Solar Occultation), LNO (Limb, Nadir and Occultation) and UVIS (Ultraviolet and Visible Spectrometer). Based upon the characteristics of the channels and the values of Signal-to-Noise Ratio obtained from radiometric models discussed in (Vandaele et al., 2015a, 2015b; Thomas et al., 2016), the expected performances of the instrument in terms of sensitivity to detection have been investigated. The analysis led to the determination of detection limits for 18 molecules, namely CO, HO, HDO, CH, CH, CH, HCO, CH, SO, HS, HCl, HCN, HO, NH, NO, NO, OCS, O. NOMAD should have the ability to measure methane concentrations, NOMAD has been made possible thanks to funding by the Belgian Science Policy Office (BELSPO) and financial and contractual coordination by the ESA Prodex Office (PlanetADAM no 4000107727). The research was performed as part of the >Inter-university Attraction Poles> programme financed by the Belgian Government (Planet TOPERS no P7-15) and a BRAIN Research Grant BR/143/A2/SCOOP. The research leading to these results has received funding from the European Community's Seventh Framework Programme (FP7/2007-2013) under Grant Agreement no. 607177 CrossDrive. UK funding is acknowledged under the UK Space Agency Grant ST/I003061/1.

The NOMAD instrument has been designed to best fulfil the science objectives of the ExoMars Trace Gas Orbiter mission that will be launched in 2016. The instrument is a combination of three channels that cover the UV, visible and IR spectral ranges and can perform solar occultation, nadir and limb observations. In this series of two papers, we present the optical models representing the three channels of the instrument and use them to determine signal to noise levels for different observation modes and Martian conditions. In this first part, we focus on the UVIS channel, which will sound the Martian atmosphere using nadir and solar occultation viewing modes, covering the 200-650nm spectral range. High SNR levels (, NOMAD has been made possible thanks to funding by the Belgian Science Policy Office (BELSPO) and financial and contractual coordination by the ESA Prodex Office (contracts no 4000107727 and 4000103401). The research was performed as part of the >Interuniversity Attraction Poles> programme financed by the Belgian government (Planet TOPERS, contract PAI no P7/15). UK funding is acknowledged under the UK Space Agency grant ST/I003061/1.

International audience; Airglow observations with a Spectral Airglow Temperature Imager (SATI), installed at the Sierra Nevada Observatory (37.06° N, 3.38° W) at 2900-m height, have been used to investigate the presence of tidal variations at mid-latitudes in the mesosphere/lower thermosphere region. Diurnal variations of the column emission rate and vertically averaged temperature of the O2 Atmospheric (0-1) band and of the OH Meinel (6-2) band from 5 years (1998-2003) of observations have been analysed. From these observations a clear tidal variation of both emission rates and rotational temperatures is inferred. It is found that the amplitude of the daily variation for both emission rates and temperatures is greater from late autumn to spring than during summer. The amplitude decreases by more than a factor of two during summer and early autumn with respect to the amplitude in the winter-spring months. Although the tidal modulations are preferentially semidiurnal in both rotational temperatures and emission rates during the whole year, during early spring the tidal modulations seem to be more consistent with a diurnal modulation in both rotational temperatures and emission rates. Moreover, the OH emission rate from late autumn to early winter has a pattern suggesting both diurnal and semidiurnal tidal modulations.

International audience

The surname of author Cathy Quantin-Nataf was misspelled 'Quantin-Nata' , authors Ehouarn Millour and Roland Young were missing from the ACS Science Team list, and minor changes have been made to the author and affiliation lists; see accompanying Amendment. These errors have been corrected online.