Assessing spatio-temporal variability and trends in modelled and measured Greenland Ice Sheet albedo (2000-2013)
Assessing spatio-temporal variability and trends in modelled and measured Greenland Ice Sheet albedo (2000-2013)
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DOI：
10.5194/tc-8-2293-2014
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发表时间：
2014-01-01
期刊：
影响因子：
5.2
通讯作者：
van den Broeke, M. R.
中科院分区：
文献类型：
--
作者：
Alexander, P. M.;Tedesco, M.;van den Broeke, M. R.
鉴于格陵兰冰盖表面冰在调节吸收的太阳辐射量和融水产生方面的作用，对格陵兰冰盖表面冰的精确测量和模拟至关重要。在这项研究中，我们评估的时空变化的GrIS在6月，7月和8月（JJA）期间2000-2013年。我们使用两个遥感产品来自中分辨率成像光谱仪（MODIS）收集的数据，以及从Modele Atmospheric Regionale（MAR）区域气候模型（RCM）和原位自动气象站的数据输出。我们的研究结果指出，遥感和RCM的时间-空间变异性之间的整体一致性，但揭示了70度N以北的两个遥感产品之间的差异高达0.08的平均分辨率。在低海拔地区，由RCM模拟的ECONDO值相对于遥感产品有正偏差，最高可达0.1，与观测值相比，变异性较低。我们推断这些差异是模拟裸冰反射率正偏差的结果。中分辨率成像分光光度计（MODIS）、区域气候模型（RCM）输出和现场观测一致表明，在2003-2013年期间，GrIS消融区的CONDO每十年减少-0.03至-0.06。然而，卫星产品显示，在堆积区内的区域，JJA的下降幅度为每十年-0.03至-0.04，这一点没有得到模型或实地观测的证实。这些发现似乎与以前的一项研究相矛盾，该研究发现个别月份的原位和MODIS趋势之间存在一致性。结果表明，需要进一步评估高海拔的海冰融化趋势，在高纬度地区的MODIS平均海冰融化的和解，以及在区域气候模型中准确模拟裸冰海冰融化的重要性。
Accurate measurements and simulations of Greenland Ice Sheet (GrIS) surface albedo are essential, given the role of surface albedo in modulating the amount of absorbed solar radiation and meltwater production. In this study, we assess the spatio-temporal variability of GrIS albedo during June, July, and August (JJA) for the period 2000-2013. We use two remote sensing products derived from data collected by the Moderate Resolution Imaging Spectroradiometer (MODIS), as well as outputs from the Modele Atmospherique Regionale (MAR) regional climate model (RCM) and data from in situ automatic weather stations. Our results point to an overall consistency in spatio-temporal variability between remote sensing and RCM albedo, but reveal a difference in mean albedo of up to similar to 0.08 between the two remote sensing products north of 70 degrees N. At low elevations, albedo values simulated by the RCM are positively biased with respect to remote sensing products by up to similar to 0.1 and exhibit low variability compared with observations. We infer that these differences are the result of a positive bias in simulated bare ice albedo. MODIS albedo, RCM outputs, and in situ observations consistently indicate a decrease in albedo of -0.03 to -0.06 per decade over the period 2003-2013 for the GrIS ablation area. Nevertheless, satellite products show a decline in JJA albedo of -0.03 to -0.04 per decade for regions within the accumulation area that is not confirmed by either the model or in situ observations. These findings appear to contradict a previous study that found an agreement between in situ and MODIS trends for individual months. The results indicate a need for further evaluation of high elevation albedo trends, a reconciliation of MODIS mean albedo at high latitudes, and the importance of accurately simulating bare ice albedo in RCMs.