The surface albedo of the Greenland Ice Sheet between 1982 and 2015 from the CLARA-A2 dataset and its relationship to the ice sheet's surface mass balance
The surface albedo of the Greenland Ice Sheet between 1982 and 2015 from the CLARA-A2 dataset and its relationship to the ice sheet's surface mass balance
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CLARA-A2数据集1982年至2015年间格陵兰冰盖的表面反照率及其与冰盖表面质量平衡的关系
DOI：
10.5194/tc-13-2597-2019
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发表时间：
2019
期刊：
影响因子：
--
通讯作者：
K. Anttila
中科院分区：
文献类型：
--
作者：
A. Riihelä;M. King;K. Anttila
抽象的。格陵兰冰盖正在以显著的速度失去质量，
这在一定程度上是由于地表融化导致的径流增加所致。因为冰层
冰盖表面的融化与地表反照率的变化密切相关，
研究冰盖反照率的数十年变化为深入了解
表面熔体及其表面质量平衡的相关变化。在这里，我们
首先分析CM SAF云、Albedo和
AVHRR数据第二版(CRLA-A2)地表辐射数据集地表反照率(SAL)，
覆盖1982-2015年，以获得每个夏季月份的年代际反照率趋势。
我们还研究了初夏期间的反照率变化率，
由MERRA-2(现代研究和应用回顾分析，第2版)的大气再分析数据支持，以识别变化
在初夏融化的强度下，以及它们可能的驱动因素。我们发现
夏季融化期间反照率下降的速度在
相对于20世纪80年代初的2000年，地表反照率现在经常
降低到海拔50-100 m以上的裸冰的典型值
冰盖。然而，南部边缘地区表现出相反的行为，
我们认为这是由于该地区降雪量增加所致。然后，我们从观测到的物质平衡估计中减去冰的流量
地心引力恢复和
气候实验(GRACE)卫星任务，以估计地表质量平衡。利用这些数据对Clara-A2反照率变化进行回归，以获得夏季聚集
1982-2015年夏季的替代地表质量平衡时间序列。这
将代理时间序列与最新的区域气候模式估计值进行比较
从MAR模型执行基于观察的测试，以确定
夏季地表质量的大小和变异性中的地表径流
平衡。我们证明了代理时间序列与MAR的一致性。
在数据和方法的相关不确定度范围内进行分析，
论证并证实了地表径流主导了快速
20世纪90年代至2010年代之间的表面质量损失时期。最后，将分析扩展到流域尺度进行检验。
出院-反照率关系。我们发现，在每年的时间尺度上，几乎没有证据表明地表融化导致冰流加速。
Abstract. The Greenland Ice Sheet is losing mass at a significant rate,
driven in part by increasing surface-melt-induced runoff. Because the ice
sheet's surface melt is closely connected to changes in the surface albedo,
studying multidecadal changes in the ice sheet's albedo offers insight into
surface melt and associated changes in its surface mass balance. Here, we
first analyse the CM SAF Cloud, Albedo and
Surface Radiation dataset from AVHRR data second edition (CLARA-A2) Surface Albedo (SAL),
covering 1982–2015, to obtain decadal albedo trends for each summer month.
We also examine the rates of albedo change during the early summer,
supported with atmospheric reanalysis data from MERRA-2 (Modern-Era Retrospective analysis for Research and Applications, version 2), to discern changes
in the intensity of early summer melt, and their likely drivers. We find
that rates of albedo decrease during summer melt have accelerated during the
2000s relative to the early 1980s and that the surface albedos now often
decrease to values typical of bare ice at elevations 50–100 m higher on
the ice sheet. The southern margins exhibit the opposite behaviour, though,
and we suggest this is due to increasing snowfall over the area. We then subtract ice discharge from the mass balance estimates observed by
the Gravity Recovery and
Climate Experiment (GRACE) satellite mission to estimate surface mass balance. The CLARA-A2 albedo changes are regressed with these data to obtain a summer-aggregated
proxy surface mass balance time series for the summer periods 1982–2015. This
proxy time series is compared with latest regional climate model estimates
from the MAR model to perform an observation-based test on the dominance of
surface runoff in the magnitude and variability of the summer surface mass
balance. We show that the proxy time series agrees with MAR through the
analysed period within the associated uncertainties of the data and methods,
demonstrating and confirming that surface runoff has dominated the rapid
surface mass loss period between the 1990s and 2010s. Finally, we extend the analysis to the drainage basin scale to examine
discharge–albedo relationships. We find little evidence of surface-melt-induced ice flow acceleration at annual timescales.