Snow cover phenology has exhibited dramatic changes in the past decades. However, the distribution and attribution of the hemispheric scale snow cover phenology anomalies remain unclear. Using satellite-retrieved snow cover products, ground observations, and reanalysis climate variables, this study explored the distribution and attribution of snow onset date, snow end date, and snow duration days over the Northern Hemisphere from 2001 to 2020. The latitudinal and altitudinal distributions of the 20-year averaged snow onset date, snow end date, and snow duration days are well represented by satellite-retrieved snow cover phenology matrixes. The validation results by using 850 ground snow stations demonstrated that satellite-retrieved snow cover phenology matrixes capture the spatial variability of the snow onset date, snow end date, and snow duration days at the 95% significance level during the overlapping period of 2001–2017. Moreover, a delayed snow onset date and an earlier snow end date (1.12 days decade⁻¹, p < 0.05) are detected over the Northern Hemisphere during 2001–2020 based on the satellite-retrieved snow cover phenology matrixes. In addition, the attribution analysis indicated that snow end date dominates snow cover phenology changes and that an increased melting season temperature is the key driving factor of snow end date anomalies over the NH during 2001–2020. These results are helpful in understanding recent snow cover change and can contribute to climate projection studies.

中文翻译：

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2001–2020年北半球陆地积雪物候变化的分布和归因

在过去的几十年中，积雪的物候已显示出戏剧性的变化。但是，半球尺度积雪物候异常的分布和归属仍不清楚。利用卫星获取的积雪产品，地面观测和重新分析的气候变量，本研究探索了2001年至2020年北半球积雪发生日期，积雪结束日期和积雪持续时间的分布和归属。纬度和纬度分布卫星检索的积雪物候矩阵很好地表示了20年平均降雪日期，降雪日期和降雪天数。通过使用850个地面降雪站进行的验证结果表明，通过卫星检索的积雪物候矩阵可以捕获积雪开始日期，积雪结束日期，2001-2017年重叠期间，降雪持续时间天数达到95％的显着性水平。此外，降雪日期推迟，降雪日期提前（1.12天十年）^-1（p <0.05）根据卫星检索到的积雪物候矩阵在2001-2020年期间在北半球被检测到。此外，归因分析表明，降雪结束日期主导着雪盖物候变化，并且融化季节温度升高是2001–2020年全国NH降雪结束日期异常的关键驱动因素。这些结果有助于了解近期的积雪变化，并有助于进行气候预测研究。