基于面向对象分类的马兰冰帽变化与气候响应

以Landsat遥感影像和数字高程数据为基础数据,利用面向对象分类方法提取了马兰冰帽1990、2000、2015年3期冰川边界,并分析了冰帽变化情况。结果表明:马兰冰帽在近25 a来一直处于退缩状态。由1990年的195.87 km~2减少到2015年的188.60 km~2,退缩了7.27 km~2,占1990年冰帽面积的3.71%,退缩速率为0.15%·a~(-1);不同时段内冰帽变化速率具有差异性,1990—2000、2000—2015年2个时段内冰帽退缩速率分别为0.16%·a~(-1)、0.14%·a~(-1),冰帽退缩速率处于减慢状态;不同朝向的冰川发育特点和变化差异显著,南坡冰川退缩速率较北坡慢。25 a来,研究区域内夏季平均气温升高了2.21℃,升温显著,增温率为0.67℃·(10a)~(-1),年降水量增加了53.52 mm,线性增加率为16.22 mm·(10a)~(-1),增加速度缓慢。由此推断,夏季气温显著升高是引起马兰冰帽持续退缩的主要原因。同时,研究发现地形条件对冰川规模变化也产生重要影响。

Variation of the Malan Ice Cap and Its Response to Climate Change Based on Object-oriented Extraction Method

Based on remote sensing images and digital elevation data,in this paper the glacier borders in 1990,2000,and 2015 were extracted using the object-oriented classification method.Moreover,change of the Malan Ice Cap was analyzed based on the work above in recent 25 years.The results showed that the Malan Ice Cap was in a retreat since 1990.Area of the ice cap was diminished by 7.27 km2 and from 195.87 km2 in 1990 to 188.60 km2 in 2015,the total loss accounted for 3.71％ of the area in 1990,and the retreat rate was 0.15％ · a-1.The Malan Ice Cap performed a diversity of retreat rate during the two periods of 1990-2000 and 2000-2015.The retreat rates during the two periods were 0.16％ · a-1 and 0.14％ · a-1 respectively,and it was obvious that the ice cap was in a slow retreat.The development or variation of the glaciers with different aspects was quite different.In this study,much work was done to try to find the causes resulting in the glacier change.Four meteorological stations were selected for simulating climate change in the study area.The results revealed that the summer mean temperature was increased by 2.21 ℃ in recent 25 years,and the linear heating rate was 0.67 ℃ · (10a)-1.However,the precipitation was increased insignificantly,and the linear increasing rate was 16.22 mm · (10a)-1 in recent 25 years.It was obvious that the temperature increase in summer was the dominant factor resulting in the retreat of the Malan Ice Cap,and glacier scale and terrain also affected the glacier change.