Spatio-temporal dynamics of evapotranspiration on the Tibetan Plateau from 2000 to 2010

Abstract

Evapotranspiration (ET) is a key process of the climate system because it links water, energy and carbon cycles. In this study we modified a Penman–Monteith based algorithm to estimate ET on the Tibetan Plateau at a 1 km spatial resolution for the period 2000–2010 using meteorological and satellite remote sensing data. The results showed that the average annual ET on the Tibetan Plateau was 350.3 mm year–1 and decreased from the southeast toward the northwest. The highest ET value was found in open water bodies (680.9 mm year–1) and the lowest ET value was found in open shrubland (254.0 mm year–1). Overall, the inter-annual ET decreased from 2000 to 2010 and there was significant negative ET trend over 42% of the region, primarily in the northwest of the Tibetan Plateau. Relative humidity was the dominant factor in controlling long-term variations of ET in the arid northwest plateau. But under moist conditions, leaf area index or temperature drove ET. In addition, <em>P</em>-ET on the Tibetan Plateau significantly increased and about 37% of the region showed strong positive <em>P</em>-ET trend primarily in the central of the Tibetan Plateau. In conclusion, the positive <em>P</em>-ET trend in four seasons suggested that the Tibetan Plateau might have become wetter during the past decade.