Representation by two climate models of the dynamical and diabatic processes involved in the development of an explosively deepening cyclone during NAWDEX

• Published in: Weather and Climate Dynamics
• Main Authors: Flack, David L. A., Rivière, Gwendal, Musat, Ionela, Roehrig, Romain, Bony, Sandrine, Delanoë, Julien, Cazenave, Quitterie, Pelon, Jacques
• Other Authors: Laboratoire de Météorologie Dynamique (UMR 8539) (LMD), Institut national des sciences de l'Univers (INSU - CNRS)-École polytechnique (X)-École des Ponts ParisTech (ENPC)-Sorbonne Université (SU)-Centre National de la Recherche Scientifique (CNRS)-Département des Géosciences - ENS Paris, École normale supérieure - Paris (ENS-PSL), Université Paris sciences et lettres (PSL)-Université Paris sciences et lettres (PSL)-École normale supérieure - Paris (ENS-PSL), Université Paris sciences et lettres (PSL)-Université Paris sciences et lettres (PSL), Met Office Hadley Centre for Climate Change (MOHC), United Kingdom Met Office Exeter, Centre national de recherches météorologiques (CNRM), Institut national des sciences de l'Univers (INSU - CNRS)-Observatoire Midi-Pyrénées (OMP), Institut de Recherche pour le Développement (IRD)-Université Toulouse III - Paul Sabatier (UT3), Université de Toulouse (UT)-Université de Toulouse (UT)-Institut national des sciences de l'Univers (INSU - CNRS)-Centre National d'Études Spatiales Toulouse (CNES)-Centre National de la Recherche Scientifique (CNRS)-Météo-France -Institut de Recherche pour le Développement (IRD)-Université Toulouse III - Paul Sabatier (UT3), Université de Toulouse (UT)-Université de Toulouse (UT)-Institut national des sciences de l'Univers (INSU - CNRS)-Centre National d'Études Spatiales Toulouse (CNES)-Centre National de la Recherche Scientifique (CNRS)-Météo-France -Centre National de la Recherche Scientifique (CNRS), SPACE - LATMOS, Laboratoire Atmosphères, Milieux, Observations Spatiales (LATMOS), Université de Versailles Saint-Quentin-en-Yvelines (UVSQ)-Institut national des sciences de l'Univers (INSU - CNRS)-Sorbonne Université (SU)-Centre National de la Recherche Scientifique (CNRS)-Université de Versailles Saint-Quentin-en-Yvelines (UVSQ)-Institut national des sciences de l'Univers (INSU - CNRS)-Sorbonne Université (SU)-Centre National de la Recherche Scientifique (CNRS), TROPO - LATMOS
• Format: Article in Journal/Newspaper
• Language: English
• Published: HAL CCSD 2021
• Subjects: [PHYS.PHYS.PHYS-AO-PH]Physics [physics]/Physics [physics]/Atmospheric and Oceanic Physics [physics.ao-ph]; [SDU.STU.ME]Sciences of the Universe [physics]/Earth Sciences/Meteorology; North Atlantic
• Online Access: https://hal-insu.archives-ouvertes.fr/insu-03183467; https://hal-insu.archives-ouvertes.fr/insu-03183467/document; https://hal-insu.archives-ouvertes.fr/insu-03183467/file/wcd-2-233-2021.pdf; https://doi.org/10.5194/wcd-2-233-2021

International audience The dynamical and microphysical properties of a well-observed cyclone from the North Atlantic Waveguide and Downstream Impact Experiment (NAWDEX), called the Stalactite cyclone and corresponding to intensive observa- tion period 6, is examined using two atmospheric compo- nents (ARPEGE-Climat 6.3 and LMDZ6A) of the global cli- mate models CNRM-CM6-1 and IPSL-CM6A, respectively. The hindcasts are performed in “weather forecast mode”, run at approximately 150–200 km (low resolution, LR) and ap- proximately 50 km (high resolution, HR) grid spacings, and initialised during the initiation stage of the cyclone. Cyclo- genesis results from the merging of two relative vorticity maxima at low levels: one associated with a diabatic Rossby vortex (DRV) and the other initiated by baroclinic interac- tion with a pre-existing upper-level potential vorticity (PV) cut-off. All hindcasts produce (to some extent) a DRV. How- ever, the second vorticity maximum is almost absent in LR hindcasts because of an underestimated upper-level PV cut- off. The evolution of the cyclone is examined via the quasi- geostrophic ω equation which separates the diabatic heat- ing component from the dynamical one. In contrast to some previous studies, there is no change in the relative impor- tance of diabatic heating with increased resolution. The anal- ysis shows that LMDZ6A produces stronger diabatic heat- ing compared to ARPEGE-Climat 6.3. Hindcasts initialised during the mature stage of the cyclone are compared withairborne remote-sensing measurements. There is an under- estimation of the ice water content in the model compared to the one retrieved from radar-lidar measurements. Consis- tent with the increased heating rate in LMDZ6A compared to ARPEGE-Climat 6.3, the sum of liquid and ice water con- tents is higher in LMDZ6A than ARPEGE-Climat 6.3 and, in that sense, LMDZ6A is closer to the observations. How- ever, LMDZ6A strongly overestimates the fraction of super- cooled liquid compared to the observations by a factor ...