喜马拉雅山区地面大气与对流层大气交换研究

青藏高原 大型山地 局地环流 地气交换
邹捍 2006-01 项目
【英文摘要】Surface-atmosphere mass and energy exchange (SAE) is the linkage between the Tibetan Plateau and the global atmospheric system. The more than half area of the plateau is covered by great mountain systems, and therefore, SAE in the Tibetan mountains is an important component of the SAE over the plateau. This project was designed to reveal the local circulation and introduced SAE on the northern slope of Mt Everest, as an example of the Tibetan mountains. Observation campaigns, statistic and diagnostic analysis, and numerical simulation were conducted in this research, and resulted in the achievements: 1) the observation data with high spatial and temporal coverage and resolution regarding to the radiation and thermal conditions, local circulations and SAE in the Tibetan mountains; 2) understanding of the local circulation and their driving forces. The local circulation on the northern slope of Mt. Everest is dominated by a strong noon-midnight down-valley flow, with a monthly mean maximum over 12 m/s. The local circulation is thermally driven by the strong solar radiation over the inhomogeneous surface, mainly composed of the glacier wind and mountain-valley wind; 3) understanding of SAE in the Tibetan mountains. The complex topography in the Tibetan mountains traps more solar radiation, the near surface turbulence transfers the energy from the surface to the air, and the local circulation brings the energy from the near surface air to the free atmosphere aloft. This SAE in the Tibetan mountains differs from the SAE over the relatively flat areas of the plateau which is dominated by the turbulent transfer. 4) reveal of the impacts of South Asian summer monsoon (SASM) on the local circulation and SAE in the Himalayas. The active SASM causes low solar radiation, weak local circulation and SAE, and SASM break brings high solar radiation, strong local circulation and SAE in the Himalayas; 5) a numerical simulation system suitable for the atmospheric studies of the Tibetan Plateau, with high resolution up to 500 meters.
【中文摘要】青藏高原地区的地气交换过程是青藏高原与全球大气相联系的纽带。青藏高原一半以上的面积被大型山地覆盖,其中的地气交换是整个高原交换过程的重要组成部分。强烈的太阳辐射在这些山地的复杂下垫面上形成特殊而强烈的局地大气环流,在高原大型山地的地气交换中扮演重要角色。本项目以喜马拉雅山珠穆朗玛峰北坡绒布河谷为代表,采用强化观测、统计和诊断分析、数值模拟方法,研究青藏高原大型山地的局地环流系统及其在地气交换中的作用。主要成果包括:1)获得了青藏高原山区高时空分辨率的第一手观测资料,内容包括:大气辐射和热力条件、局地环流、近地面大气湍流交换等;2)揭示了喜马拉雅山区局地环流变化规律以及驱动机理,认为:喜马拉雅山北坡局地环流是一种强太阳辐射在复杂地形条件下驱动的复合热力环流,即山谷风-冰川风复合环流;3)揭示了青藏高原大型山地中的地气交换过程,指出高原大型山地的局地环流在地气交换中起着重要作用,提高了地面大气与对流层大气间的交换能力;4)认识了南亚季风活动对喜马拉雅山区局地环流和地气交换过程的影响;5)获得了适合青藏高原大型山地大气研究的高分辨套网格数值模式。