[A-CG36] 衛星による地球環境観測

[ACG36-17] Ecohydrological Land Reanalysis: A semi-global vegetation water content and soil moisture dataset by land data assimilation

*澤田 洋平¹、藤井 秀幸^2,3、筒井 浩行⁴、小池 俊雄⁴、会田 健太郎²、島田 利元²、可知 美佐子² (1.東京大学、2.宇宙航空研究開発機構、3.リモートセンシング技術センター、4.土木研究所水災害・リスクマネジメント国際センター)

キーワード：マイクロ波リモートセンシング、データ同化、水循環、陸域生態系

The accurate estimation of terrestrial water and vegetation is a grand challenge in hydrometeorology. Many previous studies developed land data assimilation systems (LDASs) and provided global-scale land surface datasets by integrating numerical simulation and satellite data. However, vegetation dynamics has not been explicitly solved in these land reanalysis datasets. Here we present the newly developed land reanalysis dataset, ECoHydrological Land reAnalysis (ECHLA). ECHLA is generated by sequentially assimilating C- and X- band microwave brightness temperature satellite observations into a land surface model which can explicitly simulate the dynamic evolution of vegetation biomass. The ECHLA dataset provides semi-global soil moisture from surface to 1.95m depth, Leaf Area Index (LAI), and vegetation water content and is available from 2002 to 2020. We assess the performance of ECHLA to estimate soil moisture and vegetation dynamics by comparing the ECHLA dataset with independent satellite and in-situ observation data. We found that our sequential update by data assimilation substantially improves the skill to reproduce the seasonal cycle of vegetation. Data assimilation also contributes to improving the skill to simulate soil moisture mainly in the shallow soil layers (0-0.15m depth). The ECHLA dataset will be publicly available and expected to contribute to understanding terrestrial ecohydrological cycles and water-related natural disasters such as drought.