Global Satellite Retrievals of the Near-Surface Atmospheric Vapor Pressure Deficit from AMSR-E and AMSR2

[摘要] The near-surface atmospheric Vapor Pressure Deficit (VPD) is a key environmental variable affecting vegetation water stress, evapotranspiration and atmospheric moisture demand. VPD is readily derived from in situ standard weather station measurements, but more spatially continuous global observations and capabilities for regional monitoring of VPD are lacking. Here, we document a new method to estimate daily (AM and PM) land surface VPD globally at 25-km resolution using a satellite passive microwave remotely sensed Land Parameter Data Record (LPDR) derived from the Advanced Microwave Scanning Radiometer (AMSR) sensors. The AMSR derived VPD record shows strong correspondence (R >= 0.80, p-value < 0.001) and favorable performance (0.48kPa <= RMSE <= 0.69kPa) against independent VPD observations from global weather stations and model reanalysis (MERRA-2) data. The estimated AMSR VPD retrieval uncertainties vary with land cover type, satellite observation time, and underlying LPDR data quality. These results provide new satellite capabilities for global mapping and monitoring of land surface VPD dynamics from ongoing AMSR2 operations, while favorable accuracy and similar observations from both AMSR2 and AMSR-E allow for the development of climate data records documenting recent (from 2002) VPD trends and potential impacts on vegetation, land surface evaporation and energy budgets.

[发布日期] 2018-07-25

[学科分类] 大气科学

[关键词] VAPOR PRESSURE;EVAPOTRANSPIRATION;ATMOSPHERIC MOISTURE;MICROWAVE RADIOMETERS;MERRA