UM-41 : Biosphere atmosphere transfer scheme

Abstract

The land surface parameterization, scheme biosphere, Atmosphere Transfer scheme(BATS) developed at National Centre for Atmospheric Research has been studied to under stand the physical processes involved -in Land surface atmosphere interactions. Attempts have been made to describe all the processes taken into account in BATS in a more simplified way. Wherever needed, processes are explained with the help of sketches. This user's manual provides in detail the features and structure of the model; the computer requirement to run the model; the program description - main drive program and subroutines used; input data description and output description.

The model calculates the transfers of momentum, heat and moisture between earth’s surface and the atmosphere; determines the value of wind, moisture and temperature in the atmosphere, within vegetation canopies and at the level of surface ,observations and; determines (over land sea ice) value of temperature and moisture (moisture content of the soil, the excess rainfall that goes into runoff etc.) quantities at the of surface. This land surface parameterization scheme accounts for vegetative and soil control on evapotranspiration and runoff efficiencies and for effects of seasonally varying canopy cover. The modification of BATS at Colorado State University to allow for variability in precipitation within the sub grid has also been focused upon.