Quantify the Evapotranspiration and Evaporation Amounts over Different
Landscapes On The Tibetan Plateau
Abstract
Land evapotranspiration (ET) and lake evaporation are important water
budget components, representing the main processes of energy and water
exchange between the earth and the atmosphere, and thus can influence
the regional-scale hydrological cycles. Based on several long-term and
comprehensive land-atmosphere interaction measurements over the Tibetan
Plateau, the total amounts of land ET and lake evaporation are estimated
by a combination of satellite products and meteorological data, the
results show that: (1) the total ET amount has an average annual value
of 1.238±0.058×103 km3. The trends
of annual ET amount show high variable in spatial distributions, with an
increasing trend in the east plateau and a decreasing trend in the west
plateau. (2) As for the lake surface, lake ice phenology are clearly
presented by MODIS 8-day snow cover products, and they show large
spatial variability in the duration of ice-free season. The estimated
Bowen ratio and evaporation amounts show acceptable accuracies, and
display opposite spatial distributions, with the latter being higher in
the southern part than in the northern part. On the TP, a lake with a
higher elevation, a smaller area and a larger latitude mostly
corresponds to a shorter ice-free season (a lower total net radiation),
a larger Bowen ratio and finally a lower evaporation amount. The
multi-year average evaporation amounts are listed, with the total water
evaporated from lake surface being approximately 29.4±1.2
km3 year-1 for the studied 75 lakes
and 51.7±2.1 km3 year-1 for all
Plateau lakes included. (3) To further explore the land/lake-atmosphere
interaction processes in detail over data-limited regions of the TP and
supported by the “Third Pole Environment (TPE) program, 16
comprehensive observation and research stations have been constructed
over all kinds of landscapes and in different regions of the TP in 2021.
These data have provided significance for future research on plateau-
and regional-scale water budget, hydrological cycle and water resources
management.