Correlation between heat flux, moisture and wind pattern over the Indian Ocean and Southwest monsoon intensity in Thailand by using MM 5 numerical model

Abstract

The NCAR’s Mesoscale Model MM5 was used to compute the heat flux, moisture and wind pattern over the Indian Ocean from Latitude 30 degree S to 300 degree N and longitude 40 degree E to 120 degree E for 5 years. The data are used only during the southwest monsoon season from May to October in 1996 to 2000, which covered El Nino year (1997) and La Nina year (1998). The correlation of these parameters was relatively high with R [superscript 2] = 0.723 in normal year to the rainfall pattern at the 13 synoptic weather stations in Thailand. In normal year, when the heat flux over the southeast Indian Ocean near the west coast of Australia was increased and persist for approximately 5 days before the average onset date of wet monsoon season (on 15 May) for 11 days, this caused the onset of southwest monsoon at 9 stations in Thailand to start around the average of the southwest monsoon date In El Nino year, the onset of southwest monsoon at most stations was delayed than the average date for 50 days with lesser intensity than normal year. In La Nina year, the onset of the southwest monsoon at most stations were sooner than the averages date for 5 days with stronger intensity than normal. The result of this study will be used by Thai Meteorological Department to predict the onset of southwest monsoon for agricultural activities more accurately than the present method.