Investigating the Sensitivity of a Land Surface Scheme's Simulation of Soil Wetness and Evaporation to Spatial and Temporal Leaf Area Index Variability within the Global Soil Wetness Project

[摘要] A suite of sensitivity experiments focusing on leaf area index (LAI) was conducted within the GSWP framework using one land surface scheme. First, the LAI was changed from the original 1°×1° resolution provided by GSWP so that it was determined by vegetation type. This was then varied by plus and minus one standard deviation. Additional experiments explored sensitivity to the global use of a single LAI value, to aggregation of LAI to coarser resolution, and to changes in the seasonal variation in LAI. Results showed a sensitivity to LAI such that changes in total evaporation of 30W m-2 (July average) were common. Changes in soil wetness occurred which commonly exceeded 5%, and sometimes exceeded 10%, of the soil moisture at saturation. These changes in soil wetness are large enough to suggest that LAI needs to be provided with care within GSWP, and that any soil wetness product requires LAI to be provided with reasonable accuracy (perhaps within±1 and certainly within±2). Any problems in the LAI data (particularly in the magnitude rather than the precise seasonal variation) will lead to errors in the simulation of a soil wetness product.

[学科分类] 大气科学