Comparison of Three Evapotranspiration Datasets Over The Indian Region

Abstract:

Evapotranspiration (ET) plays crucial role in water and energy budget of a region. For the Indian region where major agricultural practices and diverse climatic regimes exist, spatially distributed observations of ET are essential for improving our understanding of the water cycle. Lack of ET field data at regional scales make various applications in water and agriculture sectors challenging. Unlike for precipitation only a few datasets are available for ET at global or national scales. Therefore, in the present study we have analysed spatio-temporal variations in ET across the Indian region using three gridded ET datasets during 2001-2014. We compare AMBHAS (Assimilation of Multi satellite data at Berambadi watershed for Hydrology And land Surface experiment), MODIS global ET and GLEAMS (The Global Land Evaporation: Amsterdam Model) datasets over India. The first dataset is a regional dataset and the other two are global datasets and these datasets are all based on different parameterization. We find that the annual mean ET across the Indian region during the study period estimated using these datasets varies between 639-818 ± 17-53% mm/year. ET estimates in the global datasets are lower compared to regional dataset. However, ET estimates in the three datasets are similar in the monsoon months. The spatial pattern of ET correlates well with precipitation across India in global datasets but not in AMBHAS. Our results indicate that the ET estimates are subject to large uncertainties across the study region. Our analysis is likely to help to close the water budget over the Indian region.