SIMULATION OF BLOCKING SYSTEM BY LIMITED AREA MODEL

Abstract

The present thesis investigates the simulation of blocking systems by limited area model, Regional Climatic Model, (RegCM3). 6-hour datasets of geopotential height, synoptic charts and NCEP/NECAR reanalyzed at surface and 500 hpa levels through the period of 1 December 1994 - 31 December 2005 had been used in the present work. In addition to that the input data required for limited area model (RegCM3) has been used through that period.

Comparative studies usmg of different mm1mum duration criteria of blocking systems and limited area model (RegCM3) outputs with three different horizontal resolutions (100 Km, 90 Km and 60 Km) had been done. However, the area concerned of the present study is (10° S - 72° N) latitude and (55° W- 95° E) longitude. From the characteristics of blocking persistence it is liable to divide the area concerned to three distinct zones. First one from 55° W to Greenwich 0° longitude. Second zone from Greenwich 0° to 50° E longitude and the third one from 50° E to 95° E longitude.

A seasonal classification of the blocking systems for four seasons (winter, spring, summer and autumn) that existed through the period of study (1994-2005) has been made. The results revealed that the simulation ofblocking systems of limited area model (RegCM3) within (90 Km) horizontal resolution give high accuracy in simulation rather than that with (100 Km) and (60 Km) horizontal resolution for all seasons over the study area. Whereas, accuracy simulation of blocking systems reached to (80 %) within (90 Km) horizontal resolution of the limited area :rriodel (RegCM3).