A study on the performance of a triple nested mesoscale model over tropical Indian Ocean during INDOEX

Abstract

A triple nested version of the fifth generation PSU- NCAR Mesoscale Model (MM5) was used over the INDOEX domain. A 3-dimensional model study over the tropical Indian Ocean was performed. The domain extended from 40.12°N-32.04°S; 32.10°E-117.90°E for the outermost grid (horizontal resolution of 180 km), while the inner most grid (20 km horizontal resolution) extended from 19.81°N-13.92S; 56.20°E-91.64°E, with 17 vertical σ levels. The model was integrated for 48 h starting from 00 UTC 5 March 1999. The model results were validated against analysis for large-scale characteristics (circulation pattern, ITCZ location and rainfall). MM5 was able to realistically simulate these large-scale features. In addition to this validation, objective evaluation of the model performance was undertaken by comparing GPS sonde vertical soundings obtained from RV Ronald H. Brown for the times of model integration. MM5 results were in good agreement with both dynamical (wind components) and thermodynamical (temperature and humidity) fields over the INDOEX domain.