Estimation of maximum air temperature using COMS data in Northeast Asia

摘要

Air temperature (Ta) plays important role for the circulation of energy and water between the surface and atmosphere. Ta was accurately measured from ground observation stations. However, the number of ground observation stations is limited, and Ta is influenced from temporal and spatial change. In this study, Ta was estimated using satellite data from April 2011 to March 2012 in the Northeast Asia where consist of the various ecosystem. States of surface and atmosphere were considered through Normalized Difference Water Index (NDWI) and the differences of brightness temperature values of 11μm (TBB1) and 12μm (TBB2). Dataset was divided into nine cases that had seasonal characteristics according surface states (NDWI) and atmosphere states (TBB1-TBB2). Ta was acquired from 174 ground observation stations, and multiple regression equation of each case was consisted of LST, NDVI, TBB1-TBB2. The weighting region was set to be within 8.33% of total density from boundary area of cases in order to reduce the errors that can occur due to the small value. The weighting was applied as distance from the nearest four points. The spatial representativeness of estimated Ta was determined as 9 by 9 window size. R-squared of estimated Ta from satellite was 0.94, RMSE was 2.98 K, Bias was 0.56 K.