面向计算区域高分辨率光合与呼吸分量通量的碳同化技术研究

观测精度优于1%的GOSAT、OCO-2和TANSAT二氧化碳卫星为高分辨率区域碳同化系统的发展提供了契机。本项目拟选取以山东禹城生态试验站为中心的800km×800km的区域为研究区，首先，针对高分辨率区域同化系统巨大维数的特点，研发能够同时具有集合方法与变分方法优势的EnKF-4Dvar同化新算法；其次，基于WRF-VPRM区域大气模式和EnKF-4Dvar同化算法，构建依托地基二氧化碳浓度和卫星二氧化碳柱浓度的高分辨率区域碳同化系统。该同化系统由该项目申请人之前研发的中国碳同化反演系统（CT-China，CAS）提供1×1°的边界场，计算高分辨率（5km）陆-气碳交换的光合和呼吸分量通量。依托禹城生态试验站及其周围区域长期积累的观测数据和项目申请人发展的基于遥感和footprint模型的尺度转换方法，进行自上而下和自下而上估算的光合和呼吸分量通量互为校验分析。

GOSAT, OCO - 2 and TANSAT carbon dioxide（CO2）satellites, which have the observation accuracy better than 1%, bring bright prospects for developing the high-resolution regional carbon assimilation system. The proposed project plans to select an 800 km × 800 km region as the research area that centering on the yucheng ecological experimental station located in Shandong Province. In view of the characteristics of huge dimensions in regional high-resolution carbon assimilation system, we will first develop and improve a new assimilation algorithm (EnKF-4Dvar) integrated with ensemble and variational method advantages. Secondly, based on a variety of ground and satellite CO2 concentration, high resolution regional carbon assimilation system will be built by using EnKF-4Dvar and regional atmospheric model (WRF-VPRM). This carbon assimilation system will be applied to quantitatively estimate high resolution (5km) photosynthetic and respiratory fluxes of surface-atmosphere carbon flux exchange with the boundary field (1°×1°) generated from CT-China developed by the applicant before. Finally, photosynthetic and respiratory fluxes estimated from the “top-down” and “bottom-up” approaches will validate and analysis each other, based on the long period accumulated observations of yucheng ecological experimental station and the surrounding areas, by using scale conversion methods developed from remote sensing and footprint model finished by the surface project of the applicant in 2016.