Change Point Analysis of Air Temperature in India

Abstract

Change point analysis was performed on air temperature at different pressure levels in the Indian subcontinent to identify the time at which a major change in trend, if any, has occurred. Pettit test, a nonparametric test to identify change point in a time series was used for this purpose. It tests the null hypothesis that the variable follows one or more distributions that have the same location parameter against the 9lternate hypothesis that a change point exists. The significance of the change point is detennine'q. d~4, if it is greater than the considered level of 90% confidence, then, the change point is considered to be significant. T,he test was performed on the suiface temperature data of the Indian subcontinent for the period 1949- 2014, obtained from the NCEPINCAR reanalysis data set at a resolution of 2.5°. The results of the test for the dry period indicate that the southern, northern and north eastern parts of India exhibited a significant change point in the nineteen seventies. During the wet season and the south west monsoon season, a significant change was observed in the southern, central and eas_ tern parts of lndia in the last decade. Analysis of the annual mean temperature revealed that a significant change point occurred in South India in the last decade.