Direct radiative effects of tropospheric aerosols on changes of global surface soil moisture
A coupled modeling framework including a terrestrial ecosystem model and an atmospheric radiative transfer model is used to evaluate the aerosols’ direct radiative effects on the surface soil moisture in global terrestrial ecosystems during 2003–2010. We conduct two sets of model runs with and without aerosols in a hindcast mode. Comparison analysis indicates that the simulated soil moisture is comparable with other existing products and satellite retrievals. Simulations with aerosol loadings show an increase in the surface soil moisture by 3.8 ± 0.4 % and 4.1 ± 0.5 % during growing seasons (June to September) in temperate and boreal Northern Hemisphere (>10 °N) and the whole year in tropical regions (−10°S~10°N). This positive effect is as large as 30 % in dense-vegetated ecosystems, such as tropical forests and temperate broadleaf evergreen forests. The effect of aerosols on soil moisture varies with local leaf area index and climate, and exhibits seasonal variations. Surface soil moisture is persistently affected by high aerosols loadings in Amazonian tropical forests during drought seasons of 2005 and 2010. This study highlights the importance to consider the aerosols’ effects in impacting the soil moisture dynamics of the global terrestrial ecosystems.
KeywordsSoil Moisture Latent Heat Flux Diffuse Radiation Surface Soil Moisture Aerosol Loading
We acknowledge that the model forcing data for this study are provided by Land Surface Hydrology Research Group at Princeton University. This research is funded to Q.Z. by the NASA Land Use and Land Cover Change program (NASA-NNX09A126G), the Department of Energy (DE-FG02-08ER64599), the National Science Foundation (NSF-102891 and NSF-0919331), NSF Carbon and Water in the Earth Program (NSF-0630319) and the NSF CDI Type II project (IIS-1028291)
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