Abstract
This study examines the dynamics and robustness of large-scale evapotranspiration products in water-limited environments. Four types of ET products are tested against rainfall in two large semi-arid to arid Australian basins from 2003 to 2010: two energy balance ET methods which are forced by optical satellite retrievals from MODIS; a newly developed land surface model (AWRA); and one approach based on observations from the Gravity Recovery and Climate Experiment (GRACE) and rainfall data. The two basins are quasi (Murray-Darling Basin: 1.06 million km2) and completely (Lake Eyre Basin: 1.14 million km2) endorheic. During the study period, two extreme climatic events—the Millennium drought and the strongest La Niña event—were recorded in the basins and are used in our assessment. The two remotely-sensed ET products constrained by the energy balance tended to overestimate ET flux over water-stressed regions. They had low sensitivity to climatic extremes and poor capability to close the water balance. However, these two remotely-sensed and energy balance products demonstrated their superiority in capturing spatial features including over small-scale and complicated landscapes. AWRA and GRACE formulated in the water balance framework were more sensitive to rainfall variability and yielded more realistic ET estimates during climate extremes. GRACE demonstrated its ability to account for seasonal and inter-annual change in water storage for ET evaluation.
Highlights
Evapotranspiration (ET) governs water and energy exchange between the atmosphere and theEarth’s surface [1]
The northern parts of Murray-Darling Basin (MDB) and Lake Eyre Basin (LEB) present a high ET rate of 400–600 mm/year, which is attributed to the strong ET fluxes caused by tropical rainstorms during the summer
Four ET datasets derived from PT-CMRS, PM-Mu, a newly developed land surface model (AWRA), and Gravity Recovery and Climate Experiment (GRACE) were compared in the Murray-Daring and Lake Eyre Basins, against rainfall variations and during climate extremes
Summary
Evapotranspiration (ET) governs water and energy exchange between the atmosphere and theEarth’s surface [1]. More than half of the solar energy absorbed by the land surface is used for evaporation and transpiration [2]. Water 2017, 9, 614 land returns to the atmosphere via the ET process [3]. This percentage could even reach more than. Accurate ET quantification, especially at a catchment or basin scale, is necessary for water resources allocation and irrigation schedule design [6,7]. It is beneficial for understanding regional climate change and hydrological interactions [8,9]
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