Assessing cloud representation of two global atmospheric models using multiple overpasses of CloudSat-CALIPSO over the same Arctic cyclone
- 1Laboratoire de Météorologie Dynamique, Institut Pierre Simon Laplace, ENS, Université PSL, École Polytechnique, Institut Polytechnique de Paris, Sorbonne Université, CNRS, Paris, France
- 2Centre National d'Etudes Spatiales, Paris, France
- 3LATMOS, Institut Pierre Simon Laplace, Université Versailles Saint-Quentin, Université Paris-Saclay, Sorbonne Université, CNRS, Guyancourt, France
- 4Institut für Physik der Atmosphäre, Deutsches Zentrum für Luft- und Raumfahrt DLR, Oberpfaffenhofen, Germany
- 5Centre National de Recherches Météorologiques, University of Toulouse, Météo-France, CNRS, Toulouse, France
- 6Commissariat à l'Energie Atomique et aux énergies renouvelables, Université Grenoble Alpes, DES, Institut de technico-économie des systèmes énergétiques, Grenoble, France
Mixed-phase clouds are common in Arctic cyclones, but their representation in global atmospheric models is still challenging. The aim of the study is to evaluate and improve the ratio of ice and liquid water within mixed-phase clouds simulated by two general circulation models (GCM): ARPEGE (operational at Météo-France) and LMDZ (the atmospheric component of the IPSL-CM Earth System Model). For that evaluation, we consider ERA5 reanalysis for the overall dynamics, and for the cloud representation, DARDAR satellite products which provide the ice water content (IWC) as well as categorization masks along CloudSat-CALIPSO tracks. This work focuses on an Arctic cyclone that occurred in May 2019 near Svalbard and has been sampled several times by the two satellites CloudSat and CALIPSO.
Compared to satellite observations, LMDZ simulations provide quite realistic IWC while ARPEGE underestimates this quantity. However, by comparing liquid and ice occurrences between models and observations, both GCMs clearly miss occurrences of liquid phase at temperature lower than -30°C but they all overestimate the liquid occurrence in the whole negative temperature range between 0°C and -30°C.
In order to improve such liquid and ice occurrences, different liquid/ice partition functions are tested in the two models. In particular, different shapes and extensions to lower temperatures are considered. This helps to improve the occurrence of liquid water at the lowest temperatures but does not correct the overestimated occurrences between 0°C and -30°C. As temperature does not discriminate liquid-ice partition properly, different other predictors are tested and distance from the cloud top appears to be the most relevant.
How to cite: Wimmer, M., Aubry, C., Rivière, G., Delanoë, J., Bazile, E., Vignon, E., and Hofmann, L.: Assessing cloud representation of two global atmospheric models using multiple overpasses of CloudSat-CALIPSO over the same Arctic cyclone, EMS Annual Meeting 2023, Bratislava, Slovakia, 4–8 Sep 2023, EMS2023-300, https://doi.org/10.5194/ems2023-300, 2023.
