Placing Greenland ice sheet ablation measurements in a multi-decadal context
Placing Greenland ice sheet ablation measurements in a multi-decadal context
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将格陵兰冰盖消融测量置于数十年背景下
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发表时间：
1969
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通讯作者：
S. Andersen
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作者：
D. As;R. Fausto;J. Cappelen;R. Wal;R. Braithwaite;H. Machguth;Charalampos Charalampidis;J. Box;A. Solgaard;A. Ahlstroem;K. Haubner;M. Citterio;S. Andersen
© 2016 GEUS.地质调查丹麦和格陵兰公报35，71-74。开放获取：www.geus.dk/publications/bull近年来，格陵兰冰盖的质量一直在以每年262 ± 21亿吨的平均速度流失（2007-2011; Andersen et al. 2015）。部分质量损失是由于熔体增加，减少了表面质量预算（恩德林等人，2014年）。此外，许多海洋终止出口冰川的加速增加了动态质量损失（Rignot等人，2008年）。这两种质量损失机制都与最近大气和海洋温度的升高有关（达顿等人，2015年）。例如，在2012年夏天，格陵兰岛经历了异常温暖的大气条件，导致几乎整个冰盖表面融化了两段时间（Nghiem等人，2012年），并导致有记录以来最大的年度冰盖质量损失（Khan等人，2015年）。这与2015年恢复到更平均的条件形成鲜明对比（Tedesco等人。2007年，启动了监测格陵兰冰盖方案，以监测地表物质收支和对物质变化的动态贡献。在监测中，C。20个自动气象站分布在格陵兰冰盖的8个区域（图1），主要是在消融区，那里的表面融化最为突出（货车As等人，2011年）。这些观测站记录了一套气象和辐射变量，这些变量允许地表能量收支闭合，并揭示了不同能量通量对融化的相对重要性。每个站点还通过声波高度测距仪、压力传感器和消融标桩监测消融（Fausto等人，2012）。表1显示，2015年融化季节产生的消融总量低于PROMICE平均值（即减少的表面质量损失），除了两个最北端的地区：KPC和THU。沿着西南冰盖边缘，2015年的消融异常似乎比平均水平低三分之一。然而，在解释中必须考虑的是，PROMICE观测期间包含了几个温暖的年份和夏季。图2显示，格陵兰沿海地区的大气温度波动很大，从世纪开始就有连续记录。PROMICE观测周期明显地被归类为温度高于平均水平的时期，无论是在相对温暖的南部还是寒冷的北部（图2）。这也可能意味着高于平均水平的消融，因此存在偏倚的PROMICE消融异常。因此，在更具代表性的背景下评估最近的消融测量更有见地。
© 2016 GEUS. Geological Survey of Denmark and Greenland Bulletin 35, 71–74. Open access: www.geus.dk/publications/bull In recent years, the Greenland ice sheet has been losing mass at an average rate of 262 ± 21 Gt yr–1 (2007–2011; Andersen et al. 2015). Part of this mass loss was due to increases in melt, reducing the surface mass budget (Enderlin et al. 2014). Also, the acceleration of many marine-terminating outlet glaciers increased the dynamic mass loss (Rignot et al. 2008). Both mass-loss mechanisms are linked to recent increases in atmospheric and oceanic temperatures (Dutton et al. 2015). For instance, in summer 2012 Greenland experienced exceptionally warm atmospheric conditions, causing nearly the entire ice-sheet surface to melt for two periods of several days (Nghiem et al. 2012) and contributing to the largest annual ice-sheet mass loss on record (Khan et al. 2015). This is in contrast to a return to more average conditions in 2015 (Tedesco et al. in press). In 2007 the Programme for Monitoring of the Greenland Ice Sheet (PROMICE) was initiated to monitor both the surface mass budget and dynamic contributions to mass change. For the monitoring, c. 20 automatic weather stations were distributed over eight regions of the Greenland ice sheet (Fig. 1), primarily in the ablation area where surface melting is most prominent (Van As et al. 2011). These stations record a suite of meteorological and radiative variables that allow for surface-energy budget closure, and reveal the relative importance of the different energy fluxes contributing to melting. Each station also monitors ablation by sonic height rangers, pressure transducers and ablation stakes (Fausto et al. 2012). Table 1 shows that the 2015 melt season yielded ablation totals below the PROMICE average (i.e. reduced surface mass loss) in all regions except the two northernmost ones: KPC and THU. Along the south-western ice sheet margin the 2015 ablation anomalies appear to be one third below average. However, what has to be accounted for in the interpretation is that the PROMICE observational period contained several warm years and summers. Figure 2 illustrates that there have been considerable fluctuations in atmospheric temperatures at Greenland coastal sites with continuous records dating back to the 19th century. The PROMICE observational period distinctly classifies as one with aboveaverage temperatures, both in the relatively warm south and colder north (Fig. 2). This is also likely to imply above-average ablation, and thus biased PROMICE ablation anomalies. It is therefore more insightful to evaluate recent ablation measurements in the context of a more representative Placing Greenland ice sheet ablation measurements in a multi-decadal context