Global variation of transpiration and soil evaporation and the role of their major climate drivers

Abstract

Although global variation in actual evapotranspiration has been widely investigated, it remains unclear how its two major components, transpiration and soil evaporation, are driven by climate drivers across global land surface. This paper uses a well‐validated, process‐based model that estimates transpiration and soil evaporation, and for the first time investigates and quantifies how the main global drivers, associated to vegetation process and the water and energy cycle, drive the spatiotemporal variation of the two components. The results show that transpiration and soil evaporation dominate the variance of actual evapotranspiration in wet and dry regions, respectively. Dry southern hemisphere from 13°S to 27°S is highlighted since it contributes to 21% global soil evaporation variance, with only 11% global land area. In wet regions, particularly in the humid tropics, there are strong correlations between transpiration, actual evapotranspiration, and potential evapotranspiration, with precipitation playing a relatively minor role, and available radiative energy is the major contributor to the interannual variability in transpiration and actual evapotranspiration in Amazonia. Conversely in dry regions, there are strong correlations between soil evaporation, actual evapotranspiration, and precipitation. Our findings highlight that ecohydrological links are highly related to climate regimes, and the small region such as Australia has important contribution to interannual variation in global soil evaporation and evapotranspiration, and anthropogenic activities strongly influence the variances in irrigation regions.

Impact of amplified evaporation due to lake expansion on the water budget across the inner Tibetan Plateau

“…The CSIRO ET was derived from the Penman-Monteith-Leuning (PML) model and has been comprehensively assessed from point to global scales using catchment precipitation/streamflow data, eddycovariance flux tower data, satellite-derived soil moisture and field measurements etc. Zhang et al, 2017b). Table 1 shows basic properties of these used evaporation data sets.…”

Use of satellite leaf area index estimating evapotranspiration and gross assimilation for Australian ecosystems

“…The two main components of terrestrial ET are transpiration from vegetation canopy (E t ) and evaporation from soil surface (E s ). Among the satellite‐based ET models (Cleugh et al, ; Leuning et al, ; Mu et al, , ), the Penman–Monteith–Leuning (PML) model (Leuning et al, ) has routinely been used to estimate terrestrial ET and its components as a process‐based approach (Zhang et al, , ; Zhou, Zhang, Vaze, Lane, & Xu, ). Hence, the PML model is used in this study as the prototype to develop a coupled water and carbon model.…”

“…Numerous models have been developed to estimate ET (Bastiaanssen, Menenti, et al, 1998;Bastiaanssen, Pelgrum, et al, 1998;Cleugh, Leuning, Mu, & Running, 2007;Guerschman et al, 2009;Leuning, Zhang, Rajaud, Cleugh, & Tu, 2008;Long & Singh, 2012;McVicar & Jupp, 2002;Mu, Heinsch, Zhao, & Running, 2007;Norman, Kustas, & Humes, 1995;Yang, Long, & Shang, 2013;Zhang, Chiew, Zhang, & Li, 2009) and GPP (Hu et al, 2017;Ma et al, 2014;Running et al, 2004;Yang, Donohue, McVicar, & Roderick, 2015;Yebra et al, 2015) from stand to regional and global scale during the past few decades. On the one hand, the Penman-Monteith (PM) equation (Monteith, 1965)-based ET models have been proven as biophysically solid, which is often applied in combination with land surface information (e.g., radiation and vegetation) derived from remotely sensed imageries (Cleugh et al, 2007;Leuning et al, 2008;Mallick et al, 2015;Morillas et al, 2013;Mu, Zhao, & Running, 2011;Zhang et al, 2017;Zhang et al, 2016). However, carbon flux and the corresponding stomatal response are usually neglected in these models, which could induce uncertainties regardless of structure and conductance formulation (Liu, Wu, & Wang, 2017).…”

Estimation of Soil Evaporation and Vegetation Transpiration Using Two Trapezoidal Models From MODIS Data

“…Compared to the total ET, soil evaporation (ET s ) may have more significant effects on crop/vegetation water use by decreasing the air vapor pressure deficit and reducing the overall evaporative demand, and vegetation transpiration (ET v ) is more critical in agricultural applications for better allocating water resources and improving water use efficiency (Crow et al, 2008;Good et al, 2017;Song et al, 2015;. Remote sensing-based models play a dominant role in ET research and global implications (Fisher et al, 2017;Tang, Shao, et al, 2015;Zhang et al, 2017), and the spatially distributed land surface temperature (LST) estimated from thermal infrared remote sensing data is widely used in the study of ET (Anderson et al, 2012;Wang et al, 2006). LST/fraction vegetation cover (FVC) feature model is one of widely used ET estimation models, which is based on the interpretation of the contextual relationship between remotely sensed LST and FVC (Carlson, 2007;Jiang & Islam, 2003;Zhang et al, 2016).…”