基于多套再分析资料和CLM4.5模式研究北半球多年冻土年代际变化及其成因

大范围和长期持续的多年冻土消融对水文水资源、生态系统、人类工程设施以及气候变化均有重大影响。那么在近几十年全球气候显著变暖的背景下，北半球多年冻土消融的实际程度如何？多年冻土面积、活动层厚度及近地表土壤冻融循环如何变化？在区域和年代际尺度上充分地澄清这些问题不仅具有指导冻土工程设施建设和维护的现实意义，而且在理解北半球生态环境和气候变化方面具有重要的科学意义。但是目前还没有在区域和年代际尺度上对这些问题进行充分地评估和量化。因此，本项目计划在校正四套再分析资料中降水的基础上，利用这些资料结合最新版本通用陆面模式和土壤温度观测资料，在区域尺度上对近几十年北半球多年冻土的年代际变化，近地表土壤冻融循环的年代际变化及其成因，以及多年冻土对气温、降水等气象要素变化的敏感性展开系统地模拟研究，为研究多年冻土对气候变化的响应规律以及冻土工程稳定性提供依据。

Severe permafrost thawing can significantly affect hydrology and water resources, ecosystems, human engineering facilities, and climate change. In this case, what is the degree of thaw in permafrost in the Northern Hemisphere during the recent decades? What are the changes in permafrost area, active layer thickness and the near-surface soil freeze/thaw cycle? To answer these questions is of great importance in understanding ecological environment change as well as guiding the construction and maintenance of frozen ground engineering infrastructures in the Northern Hemisphere. But these questions have not been fully assessed and quantified on the regional and interdecadal scale. Therefore, this project will first correct the precipitation in four reanalysis data, and then use these data, combined with the Community Land Model version 4.5 and soil temperature observations, explore interdecadal change and its cause in permafrost and the near-surface soil freeze/thaw cycle, as well as sensitivity of permafrost to meteorological elements (e.g., air temperature and precipitation) in the Northern Hemisphere, on the regional scale. These works will be useful for studying the laws governing the response of permafrost to climate change and frozen ground engineering stabilization in the Northern Hemisphere.