Retrieving the global distribution of the threshold of wind erosion from satellite data and implementing it into the Geophysical Fluid Dynamics Laboratory land–atmosphere model (GFDL AM4.0/LM4.0)

Bing Pu , Paul Ginoux (1) , Huan Guo , N Christina Hsu , John Kimball (2) , Béatrice Marticorena (3) , Sergey Malyshev (4) , Vaishali Naik (5) , Norman T O'Neill , Carlos Pérez García-Pando , Juliette Paireau , Joseph M Prospero , Elena Shevliakova , Ming Zhao

1 GFDL - NOAA Geophysical Fluid Dynamics Laboratory
2 Flathead Lake Biological Station
3 LISA (UMR_7583) - Laboratoire Interuniversitaire des Systèmes Atmosphériques
4 CICS - Cooperative Institute for Climate Studies
5 NOAA - National Oceanic and Atmospheric Administration

Dust emission is initiated when surface wind velocities exceed the threshold of wind erosion. Many dust models used constant threshold values globally. Here we use satellite products to characterize the frequency of dust events and land surface properties. By matching this frequency derived from Moderate Resolution Imaging Spectroradiometer (MODIS) Deep Blue aerosol products with surface winds, we are able to retrieve a climatological monthly global distribution of the wind erosion threshold (V threshold) over dry and sparsely vegetated surfaces. This monthly two-dimensional threshold velocity is then implemented into the Geophysical Fluid Dynamics Laboratory coupled land-atmosphere model (AM4.0/LM4.0). It is found that the climatology of dust optical depth (DOD) and total aerosol optical depth, surface PM 10 dust concentrations, and the seasonal cycle of DOD are better captured over the "dust belt" (i.e., northern Africa and the Middle East) by simulations with the new wind erosion threshold than those using the default globally constant threshold. The most significant improvement is the frequency distribution of dust events, which is generally ignored in model evaluation. By using monthly rather than annual mean V threshold , all comparisons with observations are further improved. The monthly global threshold of wind erosion can be retrieved under different spatial resolutions to match the resolution of dust models and thus can help improve the simulations of dust climatology and seasonal cycles as well as dust forecasting.

Domaines: Sciences de l'environnement

Bing Pu, Paul Ginoux, Huan Guo, N Christina Hsu, John Kimball, et al.. Retrieving the global distribution of the threshold of wind erosion from satellite data and implementing it into the Geophysical Fluid Dynamics Laboratory land–atmosphere model (GFDL AM4.0/LM4.0). Atmospheric Chemistry and Physics, 2020, 20, pp.55 - 81. ⟨10.5194/acp-20-55-2020⟩. ⟨hal-03000915⟩