The study on the climatological numerical simulations with actual or potential distributions of vegetation

Abstract

Two climatological AGCM (Atmospheric General Circulation Model) simulations are performed using with actual vegetation distribution (AVD) or potential vegetation distribution (PVD) as boundary conditions. The AVD data are obtained by the NOAA-AVHRR NDVI (Normalized Difference Vegetation Index) datasets (Kajiwara, et.al.). And the PVD data are obtained with natural vegetation models and climatological atmospheric datasets (Box, et.al.). It is found that the moisture amount in the atmosphere simulated with PVD increases compared with the moisture amount simulated with the AVD. The soil wetness simulated with the PVD, which indicates the desert, is more moist than the soil wetness with AVD, which indicates the grassland, at the rim of the Sahara Desert region. On the other hand it is occurred as a problem that the moisture condition with PVD, which indicates the desert, near the surface becomes dry against the conditionwith AVD, which indicates the grassland at the Central Asia. They suggest following 2 possibilities. 1) The model resolution may not be enough to represent correct water transport by subgrid-scale baroclinic turbulence. 2) It seems necessary to include an interaction among the vegetation, atmosphere and ocean.