Evaluating ICON-ART-LAM vertical profiles and columns of CH4 for May-June 2018 over Europe

A greenhouse gas satellite data assimilation system is currently being developed for the ICOsahedral Nonhydrostatic (ICON) - Aerosols and Reactive Trace gases (ART) - Limited Area Mode (LAM) model at the German Weather Service. This work is part of the modelling module of the Integrated Greenhouse Gas Monitoring System project (ITMS-M). A first step towards the satellite data assimilation system is the derivation of vertical columns of methane from ICON-ART-LAM simulations that can be compared to column retrievals of CH₄ from satellite sensors such as the TROPOspheric Monitoring Instrument (TROPOMI) on board of the Copernicus Sentinel-5 Precursor satellite. As the ICON-ART-LAM simulations are limited to about 20 km altitude, vertical columns cannot directly be derived from the model output alone.

In this presentation, the potential of adding CH₄ concentrations from the Copernicus Atmosphere Monitoring Service (CAMS) egg4 greenhouse gas reanalysis and CAMS inversion optimized products above the ICON-ART-LAM upper boundary is evaluated for the time period May-June 2018 and a domain covering Europe (6.5 x 6.5 km² horizontal grid spacing). The vertical profiles of ICON-ART-LAM are investigated for consistency with the CAMS simulations and ICON-ART-LAM vertical columns derived from the model output will be compared against CH₄ vertical columns from TROPOMI. For the latter, the satellite orbit and the sensitivity of the satellite sensor towards retrieving CH₄ in different layers of the atmosphere are considered.