1980~2019年北疆积雪时空变化与气候和植被的关系

利用1980~2019年中国长时间序列的AVHRR逐日无云积雪面积产品和气象站实测雪深资料计算积雪日数、积雪初日、积雪终日、积雪期、雪深等积雪物候参数，研究积雪物候的时空分布变化，同时结合ECMWF-ERA5再分析资料和GIMMS NDVI3g数据集分别提取气象因子（气温、降水）和植被因子（返青期、枯黄期、生长期），探究北疆积雪物候变化对气象因子和植被因子的响应。结果表明：北疆近40 a间的平均积雪日数为81.62 d/a，73%的区域为稳定积雪区，积雪初日在11月、终日在3月，积雪期为每年11月初至次年3月底4月初；空间上呈现不均匀分布，其中阿勒泰山地区、天山地区、大部分塔城盆地和额尔齐斯谷地区为主要积雪区，1980~2019年间北疆积雪覆盖面积比例、积雪日数和积雪期逐年降低，积雪初日基本没变，但积雪终日显著提前；ECMWF-ERA5再分析资料表明1980~2019年北疆积雪期降水量无明显变化，但积雪覆盖面积比例显著降低，说明降雪区雪深可能增加，这与北疆气象站实测雪深逐渐增加结果相吻合；平均气温与积雪期积雪覆盖面积比例、积雪日数、积雪期长度相关性较大，呈现显著负相关，积雪期降水量与积雪物候参数呈现正相关；积雪物候及其气候效应引起北疆自然植被返青期显著提前，植被生长期延长的特征。

The Relationship between the Temporal and Spatial Changes of Snow Cover and Climate and Vegetation in Northern Xinjiang from 1980 to 2019

Using the AVHRR daily cloud-free snow cover products of China's long-term series from 1980 to 2019 and the measured snow depth data from weather stations to calculate snow phenology parameter such as snow cover days， snow start days， melt out of snow cover days，length of Snow Period ，snow depth， etc. to study the temporal and spatial distribution of snow phenology. At the same time， combined with ECMWF-ERA5 reanalysis data and GIMMS NDVI3g data set to extract meteorological factors （temperature， precipitation） and vegetation factors （The start of growing season， the end of growing season，and the length of growing season）， and explore the response of snow phenology changes in northern Xinjiang to meteorological factors and vegetation factors. The results show that the average snow cover days in northern Xinjiang in the past 40 years is 81.62 days/year， 73% of the area is stable snow cover， the snow start days is in November， the melt out of snow cover days is in March， and the length of Snow Period is early November every year to the end of March and early April of the following year； the spatial distribution is uneven， of which the Altay Mountains， the Tianshan Mountains， most of the Tacheng Basin and the Irtysh Valley are the main snow-covered areas. From 1980 to 2019， the proportion of snow cover， snow cover days and the length of Snow Period in northern Xinjiang decreased year by year，the snow start days remained basically unchanged， but the snow start days was significantly advanced.ECMWF-ERA5 reanalysis data showed that there was no significant change in precipitation during the snow cover period in northern Xinjiang from 1980 to 2019， but the significant decrease in the proportion of snow cover indicates that the snow depth in the snowfall area may increase， which is consistent with the gradual increase in snow depth measured by the Northern Xinjiang Meteorological Station.The average temperature is highly correlated with the proportion of snow cover during the snow cover period， the snow cover days， and the length of the snow period， showing a significant negative correlation. The precipitation during the snow cover period is positively correlated with snow cover phenology parameters；snow phenology and its climatic effects have caused the start of growing season to be significantly earlier， and the length of growing season is extended in Northern Xinjiang.