BESS를 이용한 한반도 광합성과 증발산의 시공간 패턴 분석

학위논문 (석사)-- 서울대학교 환경대학원 : 환경계획학과, 2013. 2. 이도원.Analysis on spatial and temporal patterns of gross primary productivity (GPP) and evapotranspiration (ET) is critical in understanding and predicting terrestrial carbon and water cycles. However, there have been a few studies which provide spatially and temporally continuous estimates of GPP and ET in the Korean Peninsula. In this study, spatial and temporal patterns of GPP and ET in the Korean Peninsula were studied by using a bio-physical model, Breathing Earth System Simulator (BESS). GPP and ET from BESS are sensitive to Leaf Area Index (LAI) which is one of important input variables of BESS. LAI refinement was conducted by using re-modified temporal and spatial filter (rTSF) and LAI refinement improved accuracy compared to LAI from BESS and raw MODIS. The simulations of 11-year (2001-2011) GPP and ET in the Korean Peninsula were performed by using refined LAI. BESS derived GPP and ET were verified with eddy covariance measurements at 4 sites and 5 sites, respectively. Also, BESS derived basin ET was evaluated against water balance derived ET at a basin scale. Both GPP and ET from BESS show high positive bias at GDK and GCK sites while BESS derived GPP and ET were comparable to eddy covariance measurement at other sites and water balance derived ET. The mean annual land GPP and ET over the eleven years (2001-2011) were 1,183 gC m-2 year-1and 491 mm year-1. Land cover change was one of major causes for interannual variation of GPP and ET. In dry year, ET at highland became more sensitive to canopy conductance than that in normal year. Spring and autumn droughts caused spring and autumn ET to become most sensitive to canopy conductance. The sensitivity of ET to available energy increased in summer due to clouds during the summer monsoon.I. Introduction 1 II. Methods 8 1. Site description 8 2. Description of BESS 10 3. Improvement of BESS 11 1) Reprocessing MODIS LAI data 11 2) Change in Land cover type 24 4. Evaluation 26 1) Evaluation method 26 2) Evaluation data 27 III. Results 29 1. Evaluation 29 1) Reprocessing MODIS LAI product 29 2) BESS derived GPP and ET 34 2. Analysis on Spatial and Temporal patterns 42 IV. Discussion 52 1. Evaluation of BESS. 52 2. Spatial and Temporal Patterns of GPP and ET 52 3. What controls evapotranspiration in Korea? 54 4. How do the contributions of sunlit and shaded leaves to GPP change in different season? 55 V. Conclusion 57 Reference 58 Acknowledgements 68Maste