Characterizing evapotranspiration over a meadow ecosystem on the Qinghai‐Tibetan Plateau

Abstract

[1] To characterize evapotranspiration (ET) over grasslands on the Qinghai-Tibetan Plateau, we examined ET and its relevant environmental variables in a Kobresia meadow from 2002 to 2004 using the eddy covariance method. The annual precipitation changed greatly, with 554, 706, and 666 mm a À1 for the three consecutive calendar years. The annual ET varied correspondingly to the annual precipitation with 341, 407, and 426 mm a À1 . The annual ET was, however, constant at about 60% of the annual precipitation. About 85% annual ET occurred during the growing season from May to September, and the averaged ET for this period was 1.90, 2.23, and 2.22 mm/d, respectively for the three consecutive years. The averaged ET was, however, very low (<0.40 mm/d) during the nongrowing season from October to April. The annual canopy conductance (g c ) and the Priestley-Taylor coefficient (a) showed the lowest values in the year with the lowest precipitation. This study first demonstrates that the alpine meadow ecosystem is characterized by a low ratio of annual ET to precipitation and that the interannual variation of ET is determined by annual precipitation.

Spatial-Temporal Patterns and Controls of Evapotranspiration across the Tibetan Plateau (2000–2012)

“…The Tibetan Plateau, located in southwest China, features several climate types. It not only has the characteristics of the hot and rainy equatorial region and the north with a cold and dry climate but also has a number of microclimates and the plateau alpine zone with its obvious vertical distribution of climate [47,48]. The unique atmospheric conditions, topography (such as high elevation), and weather systems result in all sorts of chaos and strange plateau climate zones that are fragile and vulnerable to the effects of global climate change [42,48].…”

“…It not only has the characteristics of the hot and rainy equatorial region and the north with a cold and dry climate but also has a number of microclimates and the plateau alpine zone with its obvious vertical distribution of climate [47,48]. The unique atmospheric conditions, topography (such as high elevation), and weather systems result in all sorts of chaos and strange plateau climate zones that are fragile and vulnerable to the effects of global climate change [42,48]. Alpine steppes and alpine meadows cover most of the study area, with forests occurring mainly in the south and southeast of the plateau and large tracts of bare land such as desert steppes occurring in the northwest (Figure 1).…”

Trends and Changes in Recent and Future Penman-Monteith Potential Evapotranspiration in Benin (West Africa)

“…Understanding the mechanism of evapotranspiration is vital in hydrological and agricultural studies at the global, regional and local scales [1][2][3][4][5]. Evapotranspiration estimates are a required input for hydrological modeling, alongside rainfall.…”

Water and carbon dioxide fluxes over an alpine meadow in southwest China and the impact of a spring drought event

“…The range of daily mean vapor pressure deficit (VPD) (Fig. 2d, 0 to 1.07 kPa) recorded at this site was much lower compared with Haibei alpine meadow (0.02 to 1.7 kPa) (Gu et al 2008) and two semiarid grasslands (2 to 5 kPa) (Wever et al 2002;Hunt et al 2002). The prevailing wind direction in the dry season was mainly northwest, while that in the wet season was south to southwest (Fig.…”

“…Compared with the northern temperate zone of the Tibetan Plateau (Gu et al 2008), Lijiang is located in a subtropical zone while it is much warmer with more annual precipitation. The precipitation mainly occurs from June to October.…”