A200-11
Large-eddy Simulations of Marine Boundary-layer Clouds during the ACTIVATE Campaign: Sensitivities to Large-scale Forcings

Tuesday, 15 December 2020: 12:00
Virtual
Xiangyu Li1, Hailong Wang1, Andrew S Ackerman2, Brian Cairns2, Seethala Chellappan3, Gao Chen4, Jingyi Chen1, Ewan Crosbie5, Richard Anthony Ferrare6, Geet George7, Johnathan W Hair6, Simon Kirschler8, Mary M Kleb6, Richard Moore6, David Painemal9, Amy Jo Scarino6, Michael Shook6, Taylor J Shingler10, Armin Sorooshian11, Kenneth Lee Thornhill II6, Florian Tornow2,12, Christiane Voigt8, Xubin Zeng13, Luke D Ziemba6 and Paquita Zuidema14, (1)Pacific Northwest National Laboratory, Richland, WA, United States, (2)NASA Goddard Institute for Space Studies, New York, NY, United States, (3)University of Miami, Miami, United States, (4)NASA Langley Research Ctr, Hampton, VA, United States, (5)University of Arizona, Tucson, AZ, United States, (6)NASA Langley Research Center, Hampton, VA, United States, (7)Max Planck Institute for Meteorology, Hamburg, Germany, (8)German Aerospace Center DLR Oberpfaffenhofen, Institute of Atmospheric Physics, Oberpfaffenhofen, Germany, (9)Science Systems and Applications, Inc. Hampton, Hampton, VA, United States, (10)Science Systems and Applications, Inc., Hampton, VA, United States, (11)University of Arizona, Department of Chemical and Environmental Engineering, Tucson, AZ, United States, (12)Columbia University, New York, United States, (13)University of Arizona, Department of Hydrology and Atmospheric Sciences, Tucson, AZ, United States, (14)University of Miami, Miami, FL, United States
Abstract:
Clouds pose the largest uncertainty in modelling the climate system. Large-eddy simulation (LES) is able to capture key boundary-layer (BL) turbulence and cloud processes. Yet, large-scale divergence and surface turbulent fluxes of sensible and latent heat, which are important in affecting the BL water and heat budget and driving the evolution of BL vertical structures, are often poorly constrained for LES simulations. It’s even more challenging over the Western North Atlantic during winter when weather systems (e.g., cold air outbreak) pass through the warm underlying surface. As a first step to investigating cloud-aerosol-meteorology interactions in this region using LES, we derive the large-scale divergence and surface heat/moisture fluxes from measurements (e.g., dropsonde and IR camera) obtained during the Aerosol Cloud meTeorology Interactions oVer the western ATlantic Experiment (ACTIVATE) field campaign Phase I (February-March 2020). ERA5 reanalysis dataset shows that large-scale divergence and surface turbulence fluxes have large spatiotemporal variations during two process-study cases on February 28th and March 1st, respectively. We perform LES simulations using the Weather Research and Forecasting (WRF) model to test the sensitivity of BL clouds to these derived large-scale forcings from ACTIVATE measurements and ERA5 reanalysis. Cloud properties obtained from remote-sensing and in-situ instruments (onboard stacked two-aircraft flights) are used to evaluate our WRF-LES sensitivity experiments. The WRF-LES sensitivity to the observed large-scale forcings and comparison to ERA5 reanalysis and ACTIVATE measurements for the two process-study cases will be presented and discussed.
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