Greenland ice sheet mass balance: distribution of increased mass loss with climate warming; 2003–07 versus 1992–2002
Greenland ice sheet mass balance: distribution of increased mass loss with climate warming; 2003–07 versus 1992–2002
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DOI：
10.3189/002214311795306682
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发表时间：
2011
影响因子：
3.4
通讯作者：
H. Zwally;Jun Li;A. Brenner;M. Beckley;H. Cornejo;J. Dimarzio;M. Giovinetto;T. Neumann;J. Rob
中科院分区：
文献类型：
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作者：
H. Zwally;Jun Li;A. Brenner;M. Beckley;H. Cornejo;J. Dimarzio;M. Giovinetto;T. Neumann;J. Rob
本文利用ICESat激光高度计计算了2003-2007年格陵兰冰盖的质量变化，并与1992-2002年的ERS雷达和机载激光高度计的结果进行了比较。2003-2007年期间，地理信息系统继续向内陆发展，边缘变薄，但与20世纪90年代相比，地表融化和加速流动显著增加了边缘变薄。净余额从1990年代的7±3GT a−1小幅下降到2003年至2007年的171±4GT a−1，对近期全球海平面上升的贡献为0.5 mm a−1。我们将质量变化分为两个部分：(1)来自融化和冰动力的变化；(2)来自降水和累积速率的变化。我们使用降雪压实模型来计算温度和堆积速率变化所驱动的海拔变化，并计算适当的密度来将堆积驱动的变化转换为质量变化。在−2K(10a)−1变暖期间，融化和冰动力增加的损失(17-206GT a∼1)是降水增益量(10-35GT a−1)的7倍以上。在海拔2000m以上，冰川消融速率从44GT a−1下降到28GT a−1，而海拔2000m以下冰川消融速率从51GT a GT 1增加到198GT a GT 1。出口冰川平衡线以下冰川减薄的加强表明，融化增加对出口冰川有显著影响，并加速了冰川的流动。在年代际时间尺度上，高海拔地区变薄的加剧似乎是由与边缘变薄的动力耦合引起的。
Abstract We derive mass changes of the Greenland ice sheet (GIS) for 2003–07 from ICESat laser altimetry and compare them with results for 1992–2002 from ERS radar and airborne laser altimetry. The GIS continued to grow inland and thin at the margins during 2003–07, but surface melting and accelerated flow significantly increased the marginal thinning compared with the 1990s. The net balance changed from a small loss of 7 ± 3 Gt a−1 in the 1990s to 171 ± 4 Gt a−1 for 2003–07, contributing 0.5 mm a−1 to recent global sea-level rise. We divide the derived mass changes into two components: (1) from changes in melting and ice dynamics and (2) from changes in precipitation and accumulation rate. We use our firn compaction model to calculate the elevation changes driven by changes in both temperature and accumulation rate and to calculate the appropriate density to convert the accumulation-driven changes to mass changes. Increased losses from melting and ice dynamics (17–206 Gt a−1) are over seven times larger than increased gains from precipitation (10–35 Gt a−1) during a warming period of ∼2 K (10 a)−1 over the GIS. Above 2000 m elevation, the rate of gain decreased from 44 to 28 Gt a−1, while below 2000 m the rate of loss increased from 51 to 198 Gt a−1. Enhanced thinning below the equilibrium line on outlet glaciers indicates that increased melting has a significant impact on outlet glaciers, as well as accelerating ice flow. Increased thinning at higher elevations appears to be induced by dynamic coupling to thinning at the margins on decadal timescales.