欧亚大陆积雪分布及其类型划分

利用1966-2012年欧亚大陆1152个地面气象台站积雪深度资料，对欧亚大陆积雪深度、累计积雪天数和连续积雪天数的空间分布进行了分析，以连续积雪天数为标准对欧亚大陆季节性积雪类型进行了划分，并与应用累计积雪天数对积雪区类型的划分进行了比较研究. 结果表明：欧亚大陆积雪分布具有显著纬度地带性特征，积雪深度、累计积雪天数和连续积雪天数的大值分布区均位于俄罗斯平原的东北部、科拉半岛、西西伯利亚平原、中西伯利亚高原以及俄罗斯远东北部大部分区域. 与累计积雪天数划分方法相比，利用连续积雪天数对欧亚大陆季节性积雪分区，在前苏联地区积雪类型分区差异并不显著，但蒙古和中国的稳定积雪区明显缩减，青藏高原无稳定积雪区，中国大部分地区为非周期性不稳定积雪区. 两种积雪分区划分方法比较结果显示，连续积雪天数划分方法更能体现积雪累积的连续性和持久性，更符合对稳定积雪和不稳定积雪的划分标准.

Classification and regionalization of the seasonal snow cover across the Eurasian Continent

In this study, long-term snow cover data from meteorological stations were used to investigate the spatial characteristics of snow depth, number of cumulative snow cover days and number of continuous snow cover days over the Eurasian Continent from 1966 to 2012. It is revealed that there is a significant latitude feature in snow cover distribution over the Eurasian Continent. The annual mean snow depth, number of cumulative snow cover days and number of continuous snow cover days were higher in the northeastern Russian Plain, Kola Peninsula and most northern areas of Western Siberia, Central Siberia and the Far East. Spatially, as compared with the seasonal snow cover areas classified by cumulative number of snow cover days, the seasonal snow cover areas classified by continuous number of snow cover days show that there is no obvious difference over the former USSR. However, there are significant decrease in stable snow cover areas in Mongolia and China; what's more, there is no stable snow cover areas over the Tibetan Plateau, with most areas covered by a periodic unstable snow cover over China. Temporally, 30 continuous snow cover days in seasonal snow cover area is better to reflect the continuation and persistence of snow accumulation and is more suitable to be the criterion for the classification of stable and unstable snow cover. It is proposed to use the number of continuous snow cover days of 30 days to classify seasonal snow cover as stable or unstable snow cover across the Eurasian Continent.