Impact of model physics on estimating the surface mass balance of the Greenland ice sheet
Impact of model physics on estimating the surface mass balance of the Greenland ice sheet
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DOI：
10.1029/2007gl030700
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发表时间：
2007-09-01
影响因子：
5.2
通讯作者：
Rutt, Ian
中科院分区：
文献类型：
--
作者：
Bougamont, Marion;Bamber, Jonathan L.;Rutt, Ian
格陵兰冰盖融化加剧导致海平面上升的长期预测仅使用正度日模型得出。然而，对未来气候应用这一简单的表面熔融参数化究竟有什么不确定性是未知的。我们比较了正度日和能量平衡/积雪模式在气候变暖下估算格陵兰冰盖表面质量平衡的行为。这两个模型首先使用10年的ERA-40气候学调整为给出类似的现代质量平衡值，然后运行300年，强制使用GCM的输出，其中大气二氧化碳增加到工业化前水平的4倍。结果表明，正度日模型比能量平衡模型对气候变暖更敏感，产生的年径流量几乎是固定冰盖几何形状的两倍。大约一半的差异是由于产生的融化体积的差异，另一半是由于积雪中重新冻结速度的差异。我们的结果表明，模拟的积雪属性在几十年的时间尺度上随着气候的变化而演变，对冰盖的质量平衡有潜在的巨大影响；这一演变在正度日模型中是不存在的。
Long-term predictions of sea level rise from increased Greenland ice sheet melting have been derived using Positive Degree Day models only. It is, however, unknown precisely what uncertainties are associated with applying this simple surface melt parameterization for future climate. We compare the behavior of a Positive Degree Day and Energy Balance/Snowpack model for estimating the surface mass balance of the Greenland ice sheet under a warming climate. Both models were first tuned to give similar values for present-day mass balance using 10 years of ERA-40 climatology and were then run for 300 years, forced with the output of a GCM in which atmospheric CO2 increased to 4 times preindustrial levels. Results indicate that the Positive Degree Day model is more sensitive to climate warming than the Energy Balance model, generating annual runoff rates almost twice as large for a fixed ice sheet geometry. Roughly half of this difference was due to differences in the volume of melt generated and half was due to differences in refreezing rates in the snowpack. Our results indicate that the modeled snowpack properties evolve on a multidecadal timescale to changing climate, with a potentially large impact on the mass balance of the ice sheet; an evolution that was absent from the Positive Degree Day model.