基于多源陆面通量数据相融合的新资料及其在中国夏季风影响过渡区的应用

New Dataset Based on Multi-Source Land Surface Flux Data and Its Application in the East Asian Summer Monsoon Boundary Area

夏季风影响过渡区是陆面能量交换与区域气候相互作用显著的热点区域。然而,目前缺乏适用于该区域的高精度长期通量数据集,这限制了陆面水热交换与气候相互作用的研究。如何融合目前已有的多源通量资料进行重构建以及应用显得十分必要。本研究综合包括中国北方协同观测试验和中国通量网的多种下垫面通量观测以及多种格点资料,试图重构中国夏季风影响过渡区的陆面能量通量数据集。在筛选具有优良下垫面代表性站点并考察模拟和观测散点分布规律的基础上,利用多元回归模型构建了一套适用于夏季风影响过渡区并且受观测资料约束的月平均感热、潜热和净辐射数据集。交叉验证结果表明构建的数据集相对于几种原始格点数据集精度有一定提高,最大程度上消除了原始格点资料的系统偏差。进一步分析表明在地表能量平衡分量中,陆面湍流通量对夏季风的响应更为显著,并且夏季风影响过渡区陆面湍流热通量对夏季风持续时间呈现对数分布的年际变化规律;当夏季风处于低持续影响状态时陆面湍流热通量年际变化更为显著,偏弱的夏季风系统可能导致陆面过程对气候变化更强的影响。本文基于多源通量数据融合构建的新数据集可以为气候变化研究提供数据支撑,同时增加了对陆面过程与季风系统相互作用的认识。

The EASM(East Asian summer monsoon)boundary area is active with intense interaction between the land surface process and the regional climate.However,the lack of high-quality long-term flux datasets for this region limits the study of the interaction among the land surface water,heat exchange,and climate.It is necessary to reconstruct a new dataset based on the currently available multiple flux data and then apply it in climate research.In this study,the datasets of land surface energy fluxes in the EASM boundary area in China were reconstructed by integrating the field observations conducted over northern China and several gridded datasets.Based on the selection of sites with good underlying representative surface and the investigation of the scattering distribution of simulations and observations,a set of monthly average sensible heat,latent heat,and net radiation datasets was generated using a multiple regression model.The cross-validation results showed that the accuracy of the constructed dataset was improved compared with several original gridded datasets,and the systematic deviation of the original lattice data was maximally eliminated.Further analysis suggests that among the surface energy balance components,the response of land surface turbulent flux to summer monsoon was more significant,and the interannual variation of the land surface turbulent heat flux with the summer monsoon duration in the EASM boundary area showed logarithmic distribution.The turbulent heat fluxes presented more significant interannual variations,as the summer monsoon was in a low persistent state.A weaker summer monsoon system may lead to a stronger impact of land surface processes on climate change.The new dataset based on multi-source flux data fusion can support climate change research and further clarify the interaction between land surface processes and monsoon climate.