准噶尔盆地积雪储量的遥感反演及变化特征分析

Snow cover storage retrieval by remote sensing technology and variation analysis on the Junggar Basin

利用被动微波遥感SSM/I亮温数据反演的积雪深度,采用积雪密度经验算法,计算了准噶尔盆地1987-2008年逐日雪储量及其分布状况。结果表明:(1)准噶尔盆地年最大雪储量22 a平均为4.53×109m3,最大年份为1994/1995年冬季,雪储量达7.13×109m3,最小年份为1995/1996年冬季,雪储量为2.74×109m3。(2)准噶尔盆地冬季雪储量空间分布不均匀,雪储量较大的区域分布在阿尔泰山南麓和天山北麓,且由盆地边缘向中心逐渐减少,两个明显的低值区分别位于盆地西部克拉玛依地区附近和盆地东部北沙窝附近。(3)季节内变化特征表现为:11月上旬至2月中旬为雪储量缓慢累积的过程,3月上旬雪储量达到峰值,持续时间很短(约15 d),3月中旬至4月下旬雪储量迅速消退,季节内变化主要受降雪和气温年内分配的影响。(4)1987-2008年准噶尔盆地雪储量的年际变化较大,65%的区域呈现线性增加趋势,但不显著。(5)冬季降水量和气温是影响雪储量变化的主要因素,雪储量与冬季降水量呈显著正相关,与气温呈显著负相关关系。

North Xinjiang as one of the three stable snowcover areas in China, the change of its snow storages influence the ecosystem balance and the development of society and economy. However, there are no reports about the long term and large scale quantitative research on snow water resources in Xinjiang. Based on passive microwave remote sensing SSM/I brightness temperature data of snow depth sequence datasets in China, and considering the difference of two sensors, the paper selected the SSM/I brightness temperature data, and studied the retrieved daily snow depth data. The dataset was computed by projection transform and mode algorithm, and snow depth data was extracted. Considering the actual situation in Xinjiang, the daily snow storage change and its distribution in Junggar Basin from 1987 to 2008 were computed through adopting the snow density experience algorithm. Conclusions showed that： Firstly, the mean of maximum snow storage of Junggar Basin in the last 22 years is 4.53 × 10^9 m3, the year with the peak snow storage value 7.13 × 10^9 m^3 approximately is 1994/1995, the year with minimum value 2.74 × 10^9 m^3 is 1995/1996. Secondly, the spatial distribution of snow storage is uneven,＇the regions with more snow storages are the southern part of the Ahai Mountains and northern part of the Tianshan Mountains which showed a gradually descending tendency towards central Junggar Basin, while the two regions with obvious lower snow storage locate near Karamay district in western Junngar Basin （JB） and near north Shawo in eastern Junggar Basin. This distributing feature is mainly formed by the function of regional topography. Thirdly, the seasonal changing trait of snow storage in Junggar Basin is opposite to that in Tibetan plateau, which possesses characters of slowly accumulating process, shortly lasting time after approaching peak, swift degrading process. The maximum snow storage volume appears in spring （early March） , and the seasonal change is influenced by intra-annual distribution of snow and temperature. The variation characteristics of intra-season snow storages in Junggar Basin （JB） are obviously different from that in Tibetan Plateau （TP）, Where the snow covers are existing all-year, not only the increasing course of snow storages is faster, but also the decreasing course is much slower than that in JB, and the maximal value appears more earlier than that in JB （ the middle ten days of January）. Fourthly, the snow storage of Junggar Basin since 1987 has performed a tendency of obvious oscillating variation with slight ascendance, which was consistent with the warming and damping singles in northwest China. The inter-annual variation of average snow storages in winter isn＇t abrupt, but inter-annual oscillation range of maximum snow storages all-year is opposite to that. The precipitation and temperature mainly affect the variation of snow storages, and the snow storages have a significant positive correlation with wintertime precipitation, but it is opposite to the temperature in winter. Lastly, for the recent 22 a, the snow storages of 65 % regions in JB was with a linear increasing trend, with the increasing speed less than 0.08 g ·cm^-2. a- 1, and the regions where the snow storages is increasing distribute in northwest and southeast JB. The snow storages of 35% regions in JB was characterized by a decreasing trend, with the decreasing speed less than 0.04 g -cm -2a -1, and they concentrate in north slope area of the Tianshan Mountains and south slope areas of the Ahai Mountains. By statistical test, the increasing （decreasing） trend of the snow storages in southeast JB is evident, but it is not significant in other regions of JB.