Spatio-temporal variability of temperature and potential evapotranspiration over India

Worldwide, major changes in the climate are expected due to global warming, which leads to temperature variations. To assess the climate change impact on the hydrological cycle, a spatio-temporal change detection study of potential evapotranspiration (PET) along with maximum and minimum temperatures (T_max and T_min) over India have been performed for the second half of the 20th century (1950–2005) both at monthly and seasonal scale. From the observed monthly climatology of PET over India, high values of PET are envisioned during the months of March, April, May and June. Temperature is one of the significant factors in explaining changes in PET. Hence seasonal correlations of PET with T_max and T_min were analyzed using Spearman rank correlation. Correlation of PET with T_max was found to be higher compared to that with T_min. Seasonal variability of trend at each grid point over India was studied for T_max, T_min and PET separately. Trend Free Pre-Whitening and Modified Mann Kendall approaches, which consider the effect of serial correlation, were employed for the trend detection analysis. A significant trend was observed in T_min compared to T_max and PET. Significant upward trends in T_max, T_min and PET were observed over most of the grid points in the interior peninsular region.