A New Look at the Daily Cycle of Trade Wind Cumuli

• Published in: Journal of Advances in Modeling Earth Systems
• Main Authors: Vial, Jessica, Vogel, Raphaela, Bony, Sandrine, Stevens, Bjorn, Winker, David, M., Cai, Xia, Hohenegger, Cathy, Naumann, Ann, Kristin, Brogniez, Hélène
• Other Authors: Max-Planck-Institut für Meteorologie (MPI-M), Max-Planck-Gesellschaft, Laboratoire de Météorologie Dynamique (UMR 8539) (LMD), Institut national des sciences de l'Univers (INSU - CNRS)-École polytechnique (X), Institut Polytechnique de Paris (IP Paris)-Institut Polytechnique de Paris (IP Paris)-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), NASA Langley Research Center Hampton (LaRC), Science Systems and Applications, Inc. Hampton (SSAI), Max Planck Institute for Meteorology (MPI-M), 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)
• Format: Article in Journal/Newspaper
• Language: English
• Published: HAL CCSD 2019
• Subjects: [SDU.STU.ME]Sciences of the Universe [physics]/Earth Sciences/Meteorology; North Atlantic
• Online Access: https://hal.sorbonne-universite.fr/hal-02344773; https://hal.sorbonne-universite.fr/hal-02344773v1/document; https://hal.sorbonne-universite.fr/hal-02344773v1/file/Vial_et_al-2019-Journal_of_Advances_in_Modeling_Earth_Systems.pdf; https://doi.org/10.1029/2019MS001746

International audience A description of the daily cycle of oceanic shallow cumulus for undisturbed boreal winter conditions in the North Atlantic trades is presented. Modern investigation tools are used, including storm-resolving and large-eddy simulations, runover large domains in realistic configurations, and observations from in situ measurements and satellite-based retrievals. Models and observations clearly show pronounced diurnal variations in cloudiness, both near cloud base and below the trade inversion. The daily cycle reflects the evolution of two cloud populations: (i) a population of nonprecipitating small cumuli with weak vertical extent, which grows during the day and maximizes around sunset, and (ii) a population o deeper precipitating clouds with a stratiform cloud layer below the trade inversion, which grows during the night and maximizes just before sunrise. Previous studies have reported that cloudiness near cloud base undergoes weak variations on time scales longer than a day. However, here we find that it can vary strongly at the diurnal time scale. This daily cycle could serve as a critical test of the models' representation of the physical processes controlling cloudiness near cloud base, which is thought to be key for the determination of the Earth's climate response to warming.