青藏高原冬春雪深分布与中国夏季降水的关系

Correlations of Snow Depth over the Tibetan Plateau in Winter and Spring with Precipitation in Summer over China

利用SSMR和SSM/I卫星遥感雪深反演资料,通过与高原测站雪深观测资料的对比分析,揭示了高原雪深的时空分布特征,在此基础上对积雪异常年中国夏季降水异常和大气环流进行了对比分析。结果表明,卫星遥感雪深资料可较真实反映出高原积雪的状况,并可反映出高原西部积雪的变化;高原冬、春季积雪EOF分解第1模态具有相同的空间分布,反映了高原冬、春季积雪分布具有相当的一致性,而春季积雪的第2模态则反映高原积雪的东西差异;冬、春季雪深EOF第1模态的时间序列与中国夏季降水的相关分析表明,大致以长江为界,我国东部地区呈现出南涝北旱的分布模态,春季高原东(西)部多(少)雪与东(西)部少(多)雪年的夏季,我国东部降水表现出长江以南(北)地区为大范围的降水偏多(少)。

The spatotemporal distributions of snow depth on the Tibetan Plateau are revealed by the monthly snow depth data from satellite remote sensing i. e. SSMR and SSM/I in December 1978-December 2005 and the monthly station observations in 1960-1998. The contrast analyses of snow depth with summer precipitation anomalies and atmospheric circulations in anomalous snow years, show that the satellite remote sensing data is able to reflect the actual condition of snow cover over the plateau and the snow change over the western Plateau;there is a good uniformity between the distributive characteristics of “south-flood and north-drought” of summer precipitation and the increase in snow depth over the plateau in winter and spring in the late-1980s. After the EOF decomposition of snow depth over the plateau in winter and spring, the first modes in both seasons show the same spatial distribution, which reflects the distribution of snow depth over the Plateau in winter is considerable consistent with that in spring. But the second EOF mode over the Tibetan Plateau in spring reflects difference of snow depth between the western and eastern Plateau. The correlation analysis between the summer precipitation over China and the time series of the first mode of snow depth on the Tibetan Plateau in winter and spring shows that the primary pattern of summer precipitation is a south-flood（the area south of the Yangtze River） and north-drought （the area north of the river） distribution over eastern China. Differences of composite summer precipitation between years when spring snow cover was thicker in the eastern of the Tibetan Plateau than in the western and years when spring snow cover was thicker in the western than in the eastern also reveal a south-more and north-less pattern of summer precipitation anomalies.