藏北高原地面热源长期变化及其对高原季风系统的热力影响研究

Five sites of surface heat source (SHS) which are the parts of atmospheric boundary level (ABL) observation net of Nagqu Station of Plateau Climate and Environment (NPCE, CAS) in northern Tibetan Plateau are involved to this proposal project. The positive algorithm and inverse algorithm independent each other will be used to calculate and establish a long term SHS data series. The temporal and spatial characteristics of SHS intensity and its composition (SHS formation) and configuration (SHS discharge) will be analyzed. Based on potential height in pressure level of ERA40 reanalysis data, the activity of pressure system of low level atmosphere in the Tibetan Plateau will be analyzed also. And the dynamic plateau monsoon index (DPMI) time series will be calculate and establish also. The correlation of SHS intensity and its composition and configuration with low level pressure system activity will be established and analyzed. It is expect to have a quantitative understanding of thermal effect and its mechanism of SHS long term changes on the formation and evolution of plateau monsoon system based on above analysis. It is also expected to provide a scientific support for influence mechanism of air-land coupling processes to the monsoon system and its energy and water cycle in the Tibetan Plateau and provide a theoretical basis for the weather forecast and climate prediction in China.

利用那曲高寒气候环境观测研究站藏北高原大气边界层观测网络的5个地面热源观测点所获得的长期观测资料，采用相互独立的正算法和反算法计算并建立统一的地面热源及其组分序列。分析藏北高原地面热源强度及其组分构成（热源形成）和配置（热源分配）的长期变化规律和空间分布特征。利用ERA40再分析资料的等压面位势高度场数据，分析高原近地层气压系统活动规律，计算并建立动态高原季风指数序列。分析地面热源强度及其组分构成和配置与高原近地层气压系统活动和高原季风系统演变之间的关联，研究藏北高原地面热源长期变化在高原季风形成和演化过程中的热力作用及其机理。探讨高原地–气耦合过程影响季风与能量和水分循环的机制，为深入认识青藏高原地—气耦合过程做出贡献，为我国天气预报和气候预测提供理论依据。

利用那曲高寒气候环境观测研究站藏北高原大气边界层观测网络的5个地面热源观测点所获得的长期观测资料，通过正算法和反算法计算了地面热源强度及其组分构成，并分析了地表能量闭合度；利用ERA40再分析资料和地面观测数据，计算了动态高原季风指数和地面加热场指数，探讨了高原热力作用强度对高原季风爆发的指示意义以及高原季风与东亚季风的关系；升尺度分析了藏北地区空气动力学粗糙度，研究了藏北地区空间尺度对地表通量可能的影响，探讨了局地和像元/网格尺度空气动力学粗糙度和感热通量的差异及可能机制；优化了多年冻土区土壤热传导率参数化方案和冻融参数化方案，改进了风吹雪模型并将其耦合到陆面过程模型中，提高了现有陆面模型对冻融过程和积雪过程的模拟能力；对四种地表通量计算方法在藏北高寒草地下垫面的适用性、稳定性以及差异性进行了对比分析，重新估算了藏北高原几类典型面上的热量和水汽总体输送系数，规范和统一了地表通量计算方法，据此给出了高寒草地下垫面地面热源变化的长时间序列。