利用ICESat数据确定格陵兰冰盖高程和体积变化

两极冰盖消融是造成海平面上升的重要原因,作为世界第二大冰盖,格陵兰冰盖消融速度在进入21世纪以后明显加快,引起了广泛关注.本文利用ICESat卫星激光测高数据,探讨了坡度改正的方法,通过改进平差模型解决了病态问题,并采用重复轨道方法计算了2003年9月至2009年10月间格陵兰冰盖的体积和高程变化趋势,对格陵兰冰盖各冰川流域系统的变化情况进行了详细分析.结果表明,格陵兰冰盖在这6年间平均高程变化趋势为-16.79±0.84cm·a^-1,体积变化速率为-301.37±15.16km^3·a^-1,体积流失主要发生在冰盖边缘,其中DS1、DS8等流域的体积损失正在加剧,而高程在2000m以上的冰盖内陆地区表现出高程积聚的状态,但增长速度明显减缓.与现有研究成果的对比表明,算法优化后的本文结果更具可靠性.

Elevation and volume change determination of Greenland Ice Sheet based on icesat observations

The ablation of polar ice sheets is one of the major causes of sea level rise. The Greenland Ice Sheet, which is the second largest ice sheet in the world, has attracted extensive attention due to its accelerated melting rate since 21st century. In this paper, aiming at the detailed analysis of the variations for diverse glacier drainage systems at Greenland Ice Sheet, the viariations of elevation and volume of Greenland Ice Sheet are evaluated with ICESat altimetry observations during September, 2013 and October, 2009, while the calculation is realized by using repeated ground-tracking method. Meanwhile, two approaches were used to enhance the analytical reliability in this research. Firstly, the surface slope correction is considered by selecting suitable fitting function. Secondly, the adjustment model is improved by solving the ill-conditioned problems. Moreover, the variations for diverse glacier drainage systems at Greenland Ice Sheet were analyzed in detail. The results show that the Greenland Ice Sheet is melting with a mean annual elevation change rate of about -16.79±0.84 cm·a^-1 and a volume change rate of -301.37±15.16 km³·a^-1 in those 6 years. One more important finding is that the volume loss mainly occurs at the edge of the ice sheet with an accelerating speed in drainage systems like DS1 and DS8, while the central area of Greenland Ice Sheet above 2000m elevation shows a state of elevation accumulation and the rising speed is obviously slowing down. Due to the improved algorithms, the results in this study are more reliable by comparison with existing research findings.