COMS-Based Retrieval of Daily Actual Evapotranspiration over Korea

Na-Yeon Park,Mi-Lim Ou,Kyung-Soo Han,Youngmi Kim,Jun-Dong Park,Jae-Dong Jang,Kyeong-Sang Lee,Eun-Ha Sohn,Minji Seo

doi:10.1155/2017/2151809

Abstract

Evapotranspiration (ET) from the land surface is an important hydrometeorological factor in the exchange of energy between the atmosphere and land surface. The accurate quantification for management of water resources and understanding of climate change are crucial, requiring continuous temporal and spatial monitoring. The objective of this study is to apply and estimate daily actual ET using semiempirical method, B-method, which is based on surface energy balance over heterogeneous area, Korea. To estimate daily ET, we used geostationary meteorological satellite data (Communication, Ocean and Meteorological Satellite, COMS) and polar-orbiting satellite data (Système Pour ľObservation de la Terre, SPOT). Estimated daily ET using only satellite data was relatively accurate and reflects land surface characteristics. It had high periodicity and spatial resolution over a wide area on clear-sky days. The daily ET was overestimated by about 1 mm/day at the two flux tower measurements sites, but the simulated seasonal variation and pattern were in good agreement with flux tower measurements. In the mixed forest, the root-mean-square error (RMSE) was 0.94 mm/day and the bias was 1.05 mm/day, while, in the rice paddy, RMSE was 1.12 mm/day and bias was 1.21 mm/day.

Highlights

Evapotranspiration (ET) from land surfaces, which drives latent heat flux, is the sum of water loss from plant transpiration and water evaporation from land surfaces
The combination of geostationary (COMS) daily ET was higher than the flux tower ET measurements by about 1 mm/day in spring (March–May) when vegetation was growing and in winter (December and January) when vegetation was inactive after harvest
Freshwater cultivation was mainly conducted in rice paddies from April to September; the ET tended to decrease after harvest time in September

Summary

Introduction

Evapotranspiration (ET) from land surfaces, which drives latent heat flux (expressed in mm/day), is the sum of water loss from plant transpiration and water evaporation from land surfaces. An ET of 1 mm/day is equivalent to a loss of 10,000 liters per hectare per day [1]. It is a phenomenon in which liquid water changes to vapor, resulting in the transfer of water and energy between land surfaces and the atmosphere. As such, it is one of the most important components in the water cycle, representing total water consumed by plants and evaporated from water bodies and nonvegetated surfaces. ET is an essential variable for understanding surface energy balance (SEB), the global water cycle, and water and vegetation dynamics in terrestrial ecosystems [3,4,5,6,7,8]

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Conclusion