The inner-annual variation of snow cover in mountainous area of Manas river basin is studied based on snow cover fraction of different altitude, slope and aspect acquired from remotely sensed snow cover product(MOD10A2) from 2000 to 2010. First,the mean snow cover fraction within a year shows a V-shape distribution, with the maximum snow cover fraction (67. 8%) in mid-January and the minimum (11. 9%) in mid-July. Second,the inner-annual variation of snow cover may be aggregated into three elevation zones,I. E. <1600m,1600 -3800m and >3800m. The fluctuation of snow cover fraction within a year decreases with the rising of altitude. Third, the peak value of snow cover fraction appears in January in areas below 3800m, while it has two peaks in April and October respectively in areas above 3800m. Fourth,the inner-annual variation of snow cover with different slope and aspect within the same elevation zone are quite similar, which indicates that the roles of slope and aspect in snow cover distribution are both less significant than altitude.%基于2000年～2010年的MODIS/Terra积雪8d合成数据(MOD10A2)与DEM数据,通过计算和分析不同高程带、不同坡向和不同坡度的积雪覆盖率,研究了新疆玛纳斯河山区雪盖的年内变化特征.结果表明:①研究区平均积雪覆盖率最高为一月中旬的67.8％,最低为七月中旬的11.9％,年内变化总体上呈V字型,积雪分布与气温关系密切；②可将研究区雪盖年内分布情况归纳为1600m以下、1600m～3800m和3800m以上共三个高程带,各高程带内雪盖分布的年内变化较为相似,不同高程带则差异明显.从年内波动情况来看,低海拔地区年内波动幅度最大,随着海拔上升,波动幅度逐渐减小；③3800m以下各坡向和坡度地区积雪覆盖率均表现为一月最高,七月最低,四月和十月介于二者之间,而3800m以上地区积雪覆盖率全年最高值则出现在四月和十月；④各坡度和坡向区域雪盖的年内变化与所在高程带的总体情况基本相似,说明坡度和坡向对雪盖分布的影响是在高程影响的基础上产生的.
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