青藏高原增暖海拔依赖性研究进展

青藏高原平均海拔4000m以上,由于复杂的地形及其特殊的地理位置,对全球气候变化影响重大,已成为研究的热点和关键区.古气候代用指标、常规气象台站以及卫星反演资料表明,青藏高原变暖显著,最低气温升温趋势高于最高气温,冬季增温幅度最大,且存在海拔依赖性,即升温幅度随海拔高度上升而增大.在此基础上,不同大气环流模式试验以及未来气候变化情景下高原气候变化模拟结果也表现出明显的海拔依赖性.而模式资料分析表明,海拔依赖性的存在可能与高海拔地区冰雪反馈和云量有关.但由于青藏高原5000m以上常规观测台站稀少,难以获得连续的气象观测资料,而当前气候系统模式分辨率仍较低,缺乏对复杂地形描述和模拟,这使得海拔依赖性的研究存在一定的争议.因此,当前海拔依赖性研究还存在两个问题：第一,如何获取更高海拔地区的观测和模式资料,运用尽可能多的观测资料来检验海拔依赖性存在与否的问题,如6000m以上站点和格点;第二,如果这种依赖性确实存在,如何从物理机制上解释高原气候变暖的海拔依赖性.

Progresses in Studies of Elevation Dependence on Surface Warming over Tibetan Plateau

Tibetan Plateau has an average elevation of 4000 meters, due to the complex terrain and its special geographical location, so it has a great influence on global climate change and has become a hot topic and key areas of the study. Paleoelimate proxies, meteorological stations and data derived from the satellite show that TP has experienced significant warming. Monthly mean minimum temperature increase is most significant compared to the maximum, especially in winter. The air tem- perature increases with altitude. Meanwhile, outputs of different general community models also show the obvious elevation de- pendency under current and future climate change scenarios. Outputs of GCMs show that snow - albedo and cloud - radiation feedbacks may be responsible for the elevation dependency. However, the routine observation stations are scarce above 5000 m a. s. 1. on Tibetan Plateau and it is difficult to obtain continuous meteorological data. The reliability of GCM prediction is still low owing partly to the coarse spatial resolution of models and partly to the land surface processes in complex topographic areas like the TP. This makes our understanding of elevation - dependent climate remains challenging. Therefore, there exists two problems about elevation dependency of warming. Firstly, how to obtain observations and model data of higher elevations and use as much as obwervation datas to support and validate the problem of altitude dependence, such as above 6000 m a. s. 1.. secondly, if there is an elevation - dependent climate, how to explain the physical mechanisms about the altitude dependence of climate warming over Tibetan Plateau.