近25a布喀达坂峰冰川变化与气候的响应

Response of glacier in the Bukatage Mountains to climate change from 1990 to 2015

利用面向对象分类方法,从Landsat影像中提取了1990年、2000年、2010年、2015年4期布喀达坂峰地区冰川空间分布数据,并利用GIS技术分析研究区最近25 a来冰川变化,探讨了冰川对气候变化的响应关系。结果表明:布喀达坂峰冰川总面积退缩了7.28 km^2,退缩速率为0.29km^2·a^(-1),占1990年的1.78%,且1990—2000年、2000—2010年、2010—2015年各个时段内冰川退缩速率呈较快—快—慢的状态,不同朝向的冰川退缩速率略有差异,南坡山谷冰川退缩速率最快,北坡坡面冰川次之,中段平顶冰川退缩速率最慢;冰川表面运动速度沿中流线向冰川侧脊和冰川末端递减,符合冰川运动一般规律,而不同类型的冰川其表面运动速度的时空变化具有差异性。研究发现,夏季均温的显著升高和年降水量的缓慢增加的共同作用是引起布喀达坂峰冰川退缩的主要原因。此外,地势条件和冰川自身结构等因素对冰川变化的作用也不容忽视。

Based on Landsat images, this paper extracted glacier borders 2000,2010,and 2015 respectively by using object-oriented classification and in the Bukatage Mountains in 1990, analyze the glacier changes in recent 25 years. This paper also investigated the relationship between the glacier re- treat and climate changes based on the data collected by 49 meteorological stations around the study area by simula- ting the climate changes using annual precipitation and summer mean temperature. The results showed that generally the summer mean temperature and annual precipitation played a decisive role for glacier melting. The total glacier area was decreased by an overall loss of 7.28 km2, the equivalent of an annual retreat rate as 0.29 km2 · a- 1. The rate of the glacier retreat appeared slightly differently over the course with a bigger rate during the period from 1990 to 2000, a big rate from 2000 to 2010 and a small rate from 2010 to 2015. Moreover, the retreat rate of glacier was showed differently in various orientation. The southern slope valley part of the glacier, the northern slope part and the middle flat part formed the list in descending order of the retreat rate. To further study glacier changes in the Bukatage Mountains, this paper also studied the glacier surface flow velocity with two typical glaciers. The results showed that the glacier surface flow velocity was gradually decreased from the middle streamline to both its lateral ridges and the glacier tongue, which is conformant to the general rule of glacier surface velocity. Moreover, the glac- ier surface velocity differed from each other based on glacier type. Temperature variation and terrain played an im- portant role in the glacier surface flow velocity. It is acknowledged that the glacier changes the rising summer temperature and less precipitation besides the effects caused by the terrain itself. were mainly affected by and the glacier scale of