青藏高原积雪时空变化特征及年际异常成因  

Spatial-temporal Variability of the Snow Depth over the Qinghai-Tibetan Plateau and the Cause of Its Interannual Variation

作　　者：保云涛 游庆龙[1] 谢欣汝 BAO Yuntao;YOU Qinglong;XIE Xinru(Key Laboratory of Meteorological Disaster,Ministry of Education（KLME）/Joint International Research Laboratory of Climate and Environment Change（ILCEC）/Collaborative Innovation Center on Forecast and Evaluation of Meteorological Disasterx（CIC-FEMD;Nanjing University of Information Scienee and Technology（NUIST）,Nanjing 210044,Jiangsu,China)

机构地区：[1]南京信息工程大学气象灾害教育部重点实验室/气候与环境变化国际合作联合实验室/气象灾害预报预警与评估协同创新中心,江苏南京210044

出　　处：《高原气象》2018年第4期899-910,共12页Plateau Meteorology

基　　金：国家自然科学基金项目(41771069);江苏省杰出自然科学基金项目(BK20140047);江苏高校优势学科建设工程资助项目(PAPD)

摘　　要：利用国家气象信息中心提供的日积雪深度的台站观测资料以及JRA55提供的大气环流再分析资料,分析了1961 2013年前冬(11月至次年1月)和后冬(2 4月)青藏高原中东部地区积雪深度(以下简称积雪)的时空变化特征,探究了影响高原中东部整体积雪异常和年际变化的环流形态及水汽条件。结果表明,高原积雪以显著的年际变化和年代际变化为主,在空间分布上具有明显的不均匀性,海拔越高,积雪的年际变率越大。不论前冬还是后冬,高原中东部积雪最主要的变化形势均为全区一致型。1961 2013年前冬和后冬积雪无明显的长期变化趋势,前冬的积雪在1996年以前显著增加,1996年以后转为减少趋势。从高原积雪年际变化的成因来看,前冬积雪很可能同时受北极涛动和高原附近位势高度年际变化的主导,后冬积雪受高原附近位势高度变化的主导,并受北极涛动年际变化的调节。当高原积雪偏多时,阿拉伯海到青藏高原以东地区的位势高度偏低,导致南支槽活跃,高原南侧西风急流加强,槽前携带的水汽增加,副热带高压偏北偏强同时其外围携带的水汽增加;贝加尔湖脊加强有利于引导冷空气南下,冷空气和暖湿空气在高原东部交汇使得高原中东部降雪和积雪增加。Based on daily snow depth observation data from National Meteorological Information Center and atmospheric circulation data from JRA55 reanalysis,the spatial-temporal variability of snow depth over the middle east area of Qinghai-Tibetan Plateau（ QTP） in early winter（ November to subsequent January） and late winter（February to April） during 1961 2013 was analyzed. The circulation patterns and water vapor conditions affecting the snow depth anomalies and its interannual variations over the QTP were analyzed. The results show that,interannual and interdecadal variations of snow depth over the QTP is significant. Spatial distribution of snow depth is uneven,the interannual variability of snow depth increases with the increases of altitude. Changes of the snow depth are consistent with the region in early and late winter. Trend of snow depth are not obvious in both early and late winter during 1961 2013. Snow depth increases significantly before 1996 and decreases insignificantly after 1996. The interannual variability of snow depth in early winter is likely to be dominated by interannual variations of both Arctic Oscillation（ AO） and geopotential height near the QTP. In late winter,the interannual variability of snow depth is likely to be dominated by the geopotential height near the QTP and adjusted by interannual variations of AO. When snow depth over QTP is significantly positive,geopotential height anomaly from Arabian Sea to eastern QTP is negative,causing the animation of southern branch trough,westerly jet to the southern side of the plateau strengthens,increasing the water vapor flux in front of the trough. Meanw hile,the subtropical high moves northw ard and becomes strong,increasing the water vapor flux in its peripheral areas.Strengthening of the Lake Baikal ridge leads cold air southw ard and meet with warm and humid air from low-latitudes in the eastern plateau,which is conducive to more snow fall and more snow depth over the QTP.

关 键 词：青藏高原 积雪分布 时空特征 北极涛动 环流成因 

分 类 号：P466[天文地球—大气科学及气象学]