青藏高原雪盖的季节内变化及其影响

回顾了青藏高原雪盖的季节内变化及其影响研究的新进展。高原大部分地区雪盖不稳定且持续时间短,导致高原雪盖具有显著的季节内快速变化特征。局地气温和降水的季节内变化是控制高原雪盖季节内变化的直接原因,这种直接关系是区域大气环流季节内活动的结果。高原雪盖季节内变化还与大尺度大气环流的季节内活动有关,热带季节内振荡、北极涛动和北大西洋涛动引起的大气季节内过程可解释部分高原雪盖季节内变率。高原雪盖季节内变化通过雪-反照率效应迅速对大气施加影响,雪盖造成的冷异常通过大气平流过程影响高原及其下游地区,造成东亚高空急流和东亚大槽增强。由于高原雪盖季节内变化的重要影响,数值预报中高原雪盖的初始场和预报场会影响次季节预报技巧。

Intraseasonal variability of Tibetan Plateau snow cover and its influence

This paper reviews recent progresses in the study on intraseasonal variability of Tibetan Plateau snow cover (TPSC) and its influence.TPSC is unstable and frequently in short duration.Such unique characteristics may lead to fast variation in TPSC within a seasonal period.Surface air temperature (SAT) and precipitation are factors governing TPSC variation on the intraseasonal time scale.The direct relationships of TPSC with SAT and precipitation are the result of intraseasonal variation in regional atmospheric circulation.The intraseasonal variation of TPSC is also related to the large-scale atmospheric circulation.The Madden-Julian Oscillation,the Arctic Oscillation and the North Atlantic Oscillation can explain some of the intraseasonal variability of TPSC.The atmospheric response to intraseasonal variability of TPSC is rapidly through snow-albedo effect.The intraseasonal variability of TPSC influences regional and downstream atmospheres,which leads to changes in East Asian trough and westerly jet.Such variations of atmosphere result from anomalous thermal advection from the Tibetan Plateau forced by TPSC.Due to the significant influence of intraseasonal variability of TPSC,better TPSC initialization and forecast can improve subseasonal forecast.