青藏高原不同下垫面地气之间能水循环研究

The land surface - atmosphere interaction on the Tibetan Plateau has a significant effect on China, Asia and even global climate change. Therefore, it is an important requirement to forecast weather and climate change by understanding energy and water exchanges between land surface and atmosphere. Water and energy cycle are organic connection together. Energy cycle process is mainly achieved by water cycle. Soil freezing and thawing processes play decisive role in the regional energy and water cycle process. The high frequency of freeze/thaw cycles at the ground surface significantly influences water and energy exchanges between ground and atmosphere. In the project, based on the field observation data, data analysis, and numerical simulations (Simultaneous Heat and Water (SHAW) model, Community Land Model (CLM), and Regional Climate Model (RegCM4)), the soil freezing and thawing processes, temporal and spatial distributions of water and heat, and land - atmosphere interaction process on different land surfaces (i.e. permafrost, seasonal frozen ground, alpine grassland, desertification grassland et al.) will be investigated in detail, so as to quantitatively recognize energy and water cycle between land surface and atmosphere under different undersurfaces. Based on the understanding of the energy and water recycles in observational sites, expanding the observation analysis and simulation along the Qinghai-Xizang (Tibet) highway, besides using the regional climate model (RegCM4) to simulate the energy and water cycles between land surface and atmosphere on different land surface type. From these, the energy and water cycle processes between land surface and atmosphere on the Tibetan Plateau will be further clarified.

青藏高原上的地气相互作用对我国、亚洲乃至全球的气候变化均有重大影响，理解地气之间的能水交换是预报天气气候变化的重要条件。能量和水分循环是有机联系在一起的，能量循环过程主要通过水循环来实现。土壤冻融在区域的能水循环过程中扮演着举足轻重的角色，土壤冻融状态的频繁变化，极大地影响着陆面和大气之间水分和能量的交换过程。本项目拟通过野外观测和资料分析以及数值模拟（陆面过程模式SHAW和CLM与区域气候模式RegCM4），来详细研究青藏高原不同下垫面（多年冻土、季节冻土、高寒草甸、荒漠草原等）土壤冻融过程、水热时空分布特征、地气相互作用及能量水分循环过程，通过对单点（观测点）的地气之间能水循环过程的认识，将其扩展到对青藏公路沿线站点的观测分析和模拟，并利用区域气候模式模拟研究青藏高原不同下垫面地气之间的能水循环过程。从而对青藏高原区域尺度上的地气相互作用及能量和水分循环过程有更清楚的认识。

青藏高原土壤冻融过程在地气能水循环过程中扮演着举足轻重的角色。土壤冻融状态的频繁变化，极大地影响着陆面和大气之间水分和能量的交换过程。本项目通过野外观测和资料分析以及数值模拟详细研究了青藏高原中部土壤冻融过程、水热时空分布特征、地气相互作用及能量水分循环过程。将单点的地气之间能水循环过程扩展到对青藏公路沿线站点的观测分析和模拟，并利用区域气候模式模拟研究青藏高原不同下垫面地气之间的能水循环过程。区域气候模式RegCM4能再现青藏高原平均气温和夏季降水的主要分布特征，较好地模拟出青藏铁路沿线地区气温的年变化和年际变化，但是对降水的模拟效果相对较差。通过观测和模型模拟研究对青藏高原区域尺度上的地气相互作用及能量和水分循环过程有了更深刻系统的的认识。青藏高原是全球变化研究关键地区之一，具有全球变化研究的独特性和优越性。目前，观测资料的缺乏是青藏高原地气之间能水循环面临的重大挑战。因此，综合使用可靠的原位观测、遥感测量及改进的数值模式对于未来的研究至关重要。本项目执行期内培养博士后1名，博士研究生1名，硕士研究生2名，在读博士研究生1名。发表论文12篇，其中SCI论文10篇。