NORTHEAST MONSOON RAINFALL BEHAVIOUR OVER WESTERN PART OF TAMIL NADU

摘要

The hehavior of rainfall and characteristics of rainfall over the land and hilly terrain areas of western (Tasini) Nadu (Coimbatore, Erode & Nilgiris districts) are considered for rainfall analysis and pattern over small region, (T monthly) rainfall data for Coimbatore, Erode and Nilgiris districts of Tamil Nadu are collected for 57 years from 1951 to 2007 to findout the relation between monsoon rainfall and annual rainfall and spatial distribution of rainfall in these three districts. In every district five to fifteen rain gauge stations data are taken tor large sampling. The rainfall parameters of Southwest monsoon rainfall, Northeast monsoon rainfall, monsoon rainfall (rfm) and annual rainfall (rfa) are calculated. Regression analysis has been made to understand the dependence of annual rainfall over the monsoon rainfall. To test the data quality, a two variable t-test is performed to estimate the level of significance. The trends of rainfall anomalies over these areas are observed. It is observed thal the rainfall trends in these three districts are not varying in nature during Northeast monsoon season. It is also observed that the trend of rainfall is partially maximum at Coimbatore district compared to Erode and Nilgiris district and minimum of trend of rainfall is observed at Nilgiris district.