Abstract:
A Regional Climate Model (RegCM) developed by ICTP, Triesty, Italy ISemployed for the
study of some meteorological parnmeters in and around Bangladesh. Companson between
model and observational data has been made at a large spatial domain (over the entire
Bangladesh) and a few temporal scales (daily, monthly, and seasonal). It is essential to do
some validation of the RegCM model outputs WIththe ground based data say rain-gauge and
surface airtemperature to adopt the RegCM for this region. In this connection, the daily raingauge
data and surface air temperature of 19 stations throughout the country colle~1edby the
BangladeshMetcorological Department (BMD) arc processed to calibrate model output.
RegCM is run at 0.54" " 0,54° horizontal grid resolution in two parameterizations: Grell
scheme wnh Arakawa-Schubert (GAS) and Fritch-Chappell (GFC) assumptions. GAS run
used Lateral BoundaIy Conditions (LBCs) data for 1995-2000 whereas GFC run used LBC
data for 1991, 1994, 19% and 1999.
A validation study on daily scale rainfall has been conducted over Bangladesh using RegCM
model data with conventional rain-gauge observational data for the Pre-monsoon (March-
May), Monsoon (June-September) and Post-monsoon (October-November) periods, for the
calculation of daily temperature data of the entire year is used.
It is found that model overestimates in calculating rainfall in Pre-monsoon and
underestimates in Monsoon periods. For the entire rainy seasOn (March-November), model
calculates about 101.39% of the surface min for GFC assumption i. e. model overestimated
about 1,4 % in rainy-season scale. In GAS assumption, model can simulate the temperature
about 94 % in annual scale.
Finally, OFC option is better for the calculation of rainfall whereas GAS is better for the
calculation of temperature,
