Effects of a modified BATS on simulation of the diurnal cycle within a regional climate model

The Enhanced Biosphere-Atmosphere Transfer Scheme (en-BATS), described by White (1996; 2000), has been developed for application within the Florida State University Nested Regional Spectral Model (FSUNRSM) (Cocke 1998; Cocke and LaRow 1999). In seasonal integrations over the southeastern United States, White (1999) was able to show improvements in simulations of important near-surface meteorological fields related to the use of en-BATS. The use of vegetation index and other gridded surface data in the determination of parameters for en-BATS allows the model to be applied less arbitrarily over transitional landscapes and through seasonal variations. The required datasets have thus far been prepared for most of the United States and southeastern Canada at the nominal 40 km resolution of the regional model for use (White and Cocke 1997).

Since en-BATS was developed by enhancement of certain aspects of BATS Version 1E (Dicksinson et al. 1993), examples of the effects of specific facets of en-BATS on simulation of the diurnal cycle at the surface will be presented in comparison to BATS. These will include effects of reformulated vegetative shading effects, seasonal variation of vegetation morphology, and evaluation of the relationship between leaf temperature and evapotranspiration. Results will be shown from both stand-alone and coupled integrations, and from a variety of surface environments.