COMS-Based Retrieval of Daily Actual Evapotranspiration over Korea

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 polarorbiting satellite data (Système Pour l'Observation 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.

Impact of Aerosols From Urban and Shipping Emission Sources on Terrestrial Carbon Uptake and Evapotranspiration: A Case Study in East Asia

“…The carbon and water fluxes based on NUWRF-Chem simulations and independent data products (i.e., the daily SMAP L4C product and COMS ET) all show increasing spatial gradients from China to the Korean Peninsula. Discrepancies between these flux estimates are nonnegligible but within those among various model-or/and observation-based flux estimates reported previously (e.g., Anav et al, 2015;Norton et al, 2019;Park et al, 2017;Tramontana et al, 2016;Yue & Unger, 2017). SMAP L4C GPP shows smoother spatial gradients than the modeled in certain highly productive regions.…”

“…With a longer SMAP observation record and continuing calibration refinements, more recent versions of this product are expected to have better quality, and (2) the daily ET product based on Korea's geostationary Communication, Ocean, and Metrological Satellites (COMS). Compared with ET measurements in 2012 at flux towers located in a mixed forest and a rice paddy in Korea, the COMS ET product has been found to have ~1 mm day -1 biases (Park et al, ).…”