Effects of topography on the spatial distribution of evapotranspiration over a complex terrain using two‐source energy balance model with ASTER data

Abstract

Abstract:Spatial distribution of evapotranspiration (ET) over a complex terrain is estimated using a new approach of the conventional two-source energy balance (TSEB) model by considering the effect of topography (difference in slope and aspect). We name this approach topography considered two-source energy balance (T 2 SEB) model. The novelty of this model is the estimation of incoming shortwave solar radiation considering slope, aspect, altitude, latitude, longitude, and the day of calculation in the TSEB model, so that the new model should have wider applicability than existing models over topographically complex areas. In this study, high spatial resolution Advanced Spaceborne Thermal Emission and Reflection Radiometer (ASTER) data and meteorological data are used. ET over a complex terrain of Nagoya, Japan, on three different dates, 4 November 2005, 25 May 2004 and 30 October 2003, is estimated using both TSEB and T 2 SEB models. To validate both models, estimated results are compared with ground observation data at the flux tower site. Moreover, estimated results from TSEB and T 2 SEB models are compared in five different locations of different topography within the study area. Variation of net radiation absorbed by the surface (R n ) with topographical variables is also studied with the help of scatter plots. Estimated results for all three dates agreed within š75 W m 2 with calculated values from both models at the flux tower site. TSEB underestimated/overestimated ET in sunlit/shaded areas in hilly areas. The T 2 SEB model estimated ET in hilly areas better than the TSEB model.

Incorporation of Net Radiation Model Considering Complex Terrain in Evapotranspiration Determination with Sentinel-2 Data

“…Then, the daily net radiation calculation results were incorporated into a remote sensing based ETWatch model with a high spatial resolution under complex topographic conditions. The model performance was satisfactory, and a similar accuracy was achieved to that reported in previous studies [6,[92][93][94].…”

“…Factors such as meteorological, vegetation, and radiation conditions and soil moisture influence the ET process [4,5]. In mountainous areas with a complex topography, topographic factors require greater consideration to obtain better ET estimates [6,7].…”

High Spatial and Temporal Resolution Energy Flux Mapping of Different Land Covers Using an Off-the-Shelf Unmanned Aerial System

“…While the UAS method is not restricted in range by the necessity for homogeneous land cover, the range of the survey area is limited by battery life, local airspace restrictions and air laws, and operations are limited to a narrow window of meteorological conditions (e.g., winds below 9 m s −1 ). Some platforms have, however, surveyed very large areas in a single flight [27,28]. Typically the reported accuracy of TIR cameras is low, meaning additional control and evaluation steps are often taken to reduce errors caused by internal calibration processes, variability in surface emissivity and atmospheric conditions [18,29,30].…”

ECOSTRESS Reveals the Importance of Topography and Forest Structure for Evapotranspiration from a Tropical Forest Region of the Andes

“…Therein, dayto-day variations in ET at a given site are often explained by fluctuations in microclimatic variables such as air humidity, wind speed, and solar irradiance [26,27], while seasonal ET variations in the (sub)tropics are often related to water availability [28]. Previous studies have related spatial variability in ET to topographic variables such as elevation, slope, or aspect [29,30], as well as to variables related to ecosystem structure [31]. In contrast to topographic characteristics, ecosystem structure variables are highly variable across time, often because of human intervention.…”