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Séminaire

Developing A Satellite-Based Dataset of Convective Mass Flux: Validations and Applications to Convective Dynamics Studies and Evaluation of GCM

Zhengzhao Johnny Luo (City University of New York, City College) 

Most current GCM cumulus parameterization schemes are based on the concept of convective mass flux. Yet, no global observations of this critical parameter exist at this time. To fill the vacuum, we developed a novel, satellite-based method to retrieve convective mass flux.

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Date début 16/09/2021 11:00
Date fin 16/09/2021
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Description

The method is a hybrid approach that blends multiple information including satellite observations of convective cloud properties, ambient sounding, and plume model simulations, and then combines them in a Bayesian manner to retrieve vertical profiles of convective vertical velocity (wc) and convective mass flux (Mc).

Two validation studies have been conducted to assess the mass flux retrieval method. First, the satellite-retrievals are compared with collocated ground-based radar wind profiler (RWP) observations collected by the DOE ARM during the GoAmazon 2014/15 field campaign. Then, Observing System Simulation Experiments (OSSEs) were conducted using Goddard Cumulus Ensemble (GCE) model in 3D Large-Eddy Simulation (LES) setting. Both validation studies show that the satellite-based method performs reasonably well in retrieving wc.

Discrepancies will be discussed. The satellite-based estimates of wc and Mc open up new opportunities for studying convective cloud dynamics globally. We will show two examples: one concerns the global patterns of wc; the other investigates the temporal variation of Mc following convective lifecycle. Finally, we will show some preliminary results from an evaluation of the GISS GCM simulations using the new convective mass flux dataset.

Zhengzhao Johnny Luo, Professeur au City University of New York, City College est en séjour au LMD jusqu’en novembre 2021 (projet IPSL).

Informations supplémentaires

La conférence aura lieu en ligne le jeudi 16 septembre à 11h.

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