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摘要

雪深是积雪重要的物理属性之一,准确的获取雪深对积雪水文与水资源、气候变化、雪灾等研究至关重要。目前,广泛用于长时间序列雪深研究的是气象站观测雪深数据和被动微波遥感(如SMMR、SSM/I和SSMI/S)反演雪深数据。本文对这两种数据的雪深最大值和平均值在中国地区的空间分布、年际变化进行对比,分析两种数据的分布特征。结果表明:空间上,站点观测雪深与站点对应遥感像元雪深在东北地区相关性最好,新疆地区次之,青藏高原地区相关性较差。两种雪深在稳定积雪区分布较为一致,在大于40cm的深雪区和雪深小于5cm的南方地区站点观测雪深的最大值明显高于遥感反演雪深的最大值。时间上,相比于1980~2019年这一时间段,1989~2019年间站点雪深与遥感雪深在各典型积雪区的相关性明显提高。进而对比近30a中国地区两种雪深的变化,结果显示两种数据在青藏高原东南部雪深有一致的显著(p<0.05)减少趋势,在东北平原地区雪深有一致的显著(p<0.05)增加趋势。分布在青藏高原地区的气象站大多选址在海拔较低的地方,不能很好的反映对应微波遥感像元中高海拔地区及山区内雪深的平均分布和变化情况,而被动微波遥感雪深反演受积雪特性变化的影响,对短时间内雪深变化较大的极端降雪事件不敏感。
Snow depth is one of the most important physical properties of snow, and accurate estimation of snow depth is critical to human production and life, such as water resources management, climate change research, disaster early warning and management. At present, snow depth data observed by meteorological stations and retrieved by passive microwave re-mote sensing (SMMR, SSM/I and SSMI/S) have been widely used for long time series snow depth research. In order to clarify the advantages and disadvantages of these data in the study of snow depth change, this paper compares the spa-tial distribution and inter-annual variation of the maximum snow depth and mean snow depth of these in China. The results show that the distribution of the two types of snow depth is consistent in the stable snow cover areas, but the maximum snow depth observed by metrological stations is significantly greater than the maximum retrieved by remote sensing in the deep snow area of more than 40cm and the snow depth of less than 5cm in southern China. The correlation between the two snow depth data is the best in northeast China, the second in Xinjiang, and the worst in Qing-hai-Tibet Plateau. It is more suitable to use the passive microwave snow depth data after 1988 to study the snow depth changes in China. Because the SMMR sensor (1978.10.26~1987.8.20) has low time resolution and serious data loss in the middle and low latitudes, resulting in poor quality of the corresponding snow depth data. Forthemore, comparing the changes of the two types of snow depth in China in recent 30 years, the results show that the changes of those are basically the same in different regions, with a significant increase in the northeast Plain and a significant decrease in the western and southeastern parts of the Qinghai-Tibet Plateau. Meteorological stations, influenced by their site selection, cannot reflect the high altitudes snow depth and mountain district time distribution and the change of situation. However, the snow depth retrieved by passive microwave remote sensing is affected by snow thickness, sea-sonal variation of snow density, liquid-water content of snowpacks, snow grain size and other factors. Therefore, it can-not reflect the extreme snowfall events with rapid changes of snow attribute in a short time.