The evolution of AMULSE (Atmospheric Measurements by Ultra-Light Spectrometer) and its interest in atmospheric applications. Results of the Atmospheric Profiles Of GreenhousE gasEs (APOGEE) weather balloon release campaign for satellite retrieval validation

Abstract. We report in this paper the development of an embedded ultralight spectrometer (< 3 kg) based on tuneable diode laser absorption spectroscopy (with a sampling rate of 24 Hz) in the mid-infrared spectral region. This instrument is dedicated to in-situ measurements of the vertical profile concentrations of three main greenhouse gases: carbon dioxide (CO2), methane (CH4) and water vapour (H2O) under weather and tethered balloons. The plug and play instrument is compact, robust and cost-effective, autonomous, having a low power consumption, a non-intrusive probe. It was first calibrated during an in situ campaign on an ICOS (Integrated Carbon Observation System) site for several days, then used in a tethered balloon campaign and for a balloon campaign several balloon flights up to 30 km altitude in the Reims-France in 2017–2018 in collaboration with Météo-France/CNRM. This paper shows the valuable interest of the data measured by AMULSE instrument during the APOGEE measurement campaign, specifically for the vertical profiles of CO2 and CH4, which remain very sparse. We have carried out several experiments showing that the measured profiles have several applications: for the validation of simulations of infrared satellite observations, for evaluating the quality of chemical profiles from Chemistry Transport Models (CTM) and for evaluating the quality of retrieved chemical profiles from the assimilation of infrared satellite observations. The results show that the simulations of infrared satellite observations from IASI and CrIS instruments performed in operational mode for NWP by the Radiative Transfer Model (RTM) RTTOV are of good quality. We also show that the MOCAGE and CAMS CTMs modeled ozone profiles fairly accurately and that the CAMS CTM represents the methane in the troposphere well compared to MOCAGE. Finally, the measured in situ ozone profiles allowed us to show the good quality of the retrieved ozone profiles by assimilating ozone-sensitive infrared spectral radiances from IASI and CrIS.