Spatial and Temporal Distribution of Snow Cover in Mountainous Area of Manasi River Basin based on MODIS

Snow is one of the most active factors in the nature which influences the redistribution of solar radiation energy and water resource.The distribution of snow cover over mountainous area of Manasi river basin will exert great impact on river runoff in snowmelt season.Based on snow cover frequency and snow cover fraction acquired from remotely sensed MODIS/Terra snow cover product from 2000 to 2010,the study discussed the spatial and temporal distribution of snow cover in mountainous area of Manasi river basin.There are abundant snow cover accumulation in January with several high snow cover frequency areas appear in lower altitude area in the north,moderate altitude area in the south and the source of Qingshui river and Taxi river.In general,the snow cover distributions show the same pattern and the snow cover frequencies both rise with altitude in April and October,while only a few areas with high altitude are covered by snow accumulation in July.Additionally,the snow cover frequencies maintain at high level throughout the year in the birthplace of Manasi river,Jingou river,Qingshui river and Taxi river,while it keeps in lower level in valley areas of middle and upper reaches of Manasi river.Furthermore,the snow cover fraction in January decreases from 95% in areas below 1 400 m to 41% in 2 600 m,and hereafter increases to about 80% in areas above 5 000 m.The snow cover fraction of January,April and October show similar tendency in most elevation zone with the highest value in the north,northeast and northwest slopes,followed by the east and west slopes,and the lowest in the south,southeast and southwest slopes.