中文摘要：

青藏高原积雪不仅是气候变化的敏感指示器，而且对亚洲季风区乃至全球气候具有显著影响。利用2002．2014年MODIS积雪覆盖范围产品及ERA．Interim再分析资料，采用气候统计诊断方法探究了青藏高原冬季积雪的时空变化特征及其与北极涛动（AO）的关系，结果表明：①高原冬季积雪空间分布差异明显，高原西部和东南部多雪，中部和北部少雪，东部积雪年际变化大，西部多雪区积雪较为稳定。②高原冬季积雪EOF分解第一模态具有东一西反位相变化特征，当高原东部积雪偏多（少）时，西部积雪偏少（多）。③该模态与AO密切相关。AO正位相时，东亚大槽减弱，南支槽加深东移，西太平洋副高加强使得更多暖湿气流到达高原，有利于高原东部降雪，而高原西南侧阿拉伯海附近存在反气旋异常，使得阿拉伯海的水汽不易抬升进入高原西部，高原西部盛行干燥的下沉气流异常，造成少雪的环流背景，且地表温度偏高不利于积雪维持，从而导致高原西部积雪的减少；AO负位相时，东亚大槽增强使得冬季风加强，高原东部受来自西北的干冷气流控制，不利于降雪产生，高原西南侧出现气旋异常，促使来自阿拉伯海和孟加拉湾的暖湿气流输送至高原西部，与来自西伯利亚的冷空气相遇，营造多雪的环流背景。

英文摘要：

The snow cover over the Tibetan Plateau （TP）, as a sensitive indicator of climate change, has a significant impact on regional and even global climate. MODIS 8-day snow cover extent products and ERA-Interim reanalysis data were employed to study the spatial and temporal variability of the snow cover over the TP and its relation to Arctic Oscillation （AO） by climatological statistical diagnosis. The spatial distribution of winter snow cover over the TP is far from uniformity, with high snow cover fractions （SCF） at the western edge and the southeast part of the TP but scarce snow in the northern and central parts. It is found that the SCF is out of phase between the eastern and western parts of the TP with respect to the leading mode of empirical orthogonal functions （EOF1）, namely, the positive （negative） anomalies in SCF over the eastern part of the TP are associated with negative （positive） anomalies in SCF over the western part. This pattern is positively correlated with AO. During the positive AO phase, the East Asian Trough weakens, together with intensive Southern Branch Trough. The warm moist flows easily lift to the eastern part of the TP because of intensive Subtropical High over the Western Pacific and result in excessive snowfall, while an anomalous anticyclone with its center to the southwest of the plateau leads to sinking dry air flows over the western TP, which is not prone to snowfall, and the corresponding higher surface temperature is also against maintaining the snow cover. During the negative AO phase, the East Asian Trough strengthens and so does the East Asian winter monsoon, with dry cold air flows over the eastern part of the TP, leading to less snowfall. On the other hand, an anomalous cyclone centered to the southwest of the plateau makes it easier for the warm moist flows from the Bay of Bengal and Arabian Sea to lift to the western part of the TP and meet the cold air from Siberia, thus prompting more snowfall over the western part of the TP.