利用ICESat数据解算南极冰盖冰雪质量变化

南极冰盖冰雪质量变化反映了全球气候变化,并且直接影响着全球海平面变化.ICESat测高卫星的主要任务之一就是要确定南北两极冰盖的质量变化情况并评估其对全球海平面变化的影响.本文利用2003年10月至2008年12月的ICESat测高数据,针对南极DEM分辨率有限的特殊性,通过求解坡度改正值,解决重复轨道地面脚点不重合的问题,计算了南极大陆(86°S以北区域,后文所述南极冰盖均不包括86°S以南区域)在这5年里的冰雪质量变化情况,得到东南极冰盖的质量变化为-18±20Gt/a,西南极-26±6Gt/a,南极冰盖的冰雪质量变化为-44±21Gt/a,对全球海平面上升的影响约为0.12mm·a~(-1).解算结果表明,南极冰盖质量亏损主要集中在西南极阿蒙森海岸附近冰川以及东南极波因塞特角区域.

Mass change of the Antarctic ice sheet derived from ICESat laser altimetry

The mass change of the Antarctica ice sheet reflects global climate change, and can influence the global sea level directly. Since 2003 the ice, cloud and land elevation satellite(ICESat) laser altimetry mission has provided satellite altimetry data over the Antarctic up to 86°S. One of the primary missions of ICESat is to determine the change in the polar ice sheet and to assess the impact on global sea level. To better understand the effect of Antarctic ice sheet on the global sea level, this work uses the ICESat data to analyze the mass change of the Antarctic ice sheet. There are two methods for calculating the mass change of the Antarctic ice sheet using altimetry satellite data:cross point method and repeat track method. The repeat track method seems more commonly applied, in which the unmeasured topography between near repeat tracks need to be considered when comparing elevations from different tracks. We applied slope corrections between the different tracks to restrict all the different tracks to one reference track, and then calculated the surface elevation changes of the Antarctic ice sheet. The mass change of the Antarctic ice sheet was estimated by using the ice density model.The mass balance of Antarctic ice sheet was calculated to be-44±21 Gt/a including-26±6 Gt/a for West Antarctica and-18±20 Gt/a for East Antarctica using 5-year ICESat altimetry data from October 2003 to December 2008, and the contribution of the Antarctic ice sheet loss to global sea level is about 0.12 mm·a^-1.The comparison of our results with previous work shows a strong agreement. The results show that the mass losing of the Antarctic ice sheet is mainly concentrated near the Amundsen Sea in West Antarctica and Poinsett Cape in East Antarctica.