The importance of insolation changes for paleo ice sheet modeling
The importance of insolation changes for paleo ice sheet modeling
复制标题
日照变化对于古冰盖建模的重要性
DOI：
10.5194/tc-8-1419-2014
复制
发表时间：
2014
期刊：
影响因子：
--
通讯作者：
H. Goelzer
中科院分区：
文献类型：
--
作者：
A. Robinson;H. Goelzer
过去大陆冰盖的消长在很大程度上是对不断变化的气候强迫的反应。由于消融是陆地冰盖质量损失的主要组成部分，因此地表融化的计算是古冰盖模拟的一个重要方面。在假定近地表温度将大部分气候强迫传递到冰盖的情况下，地表融化的计算通常不考虑日照变化。为了评估这将如何影响古模拟，我们在这里调查了不同轨道配置对估计格陵兰冰盖上融化的重要性。我们发现，在Eemian高峰期，日照增加对地表熔融异常的贡献率为20-50%。然而，这一百分比强烈依赖于当时的温度异常。对于较高的温度异常，日照变化的作用不那么重要。这种关系在冰盖上并不是均匀的，因为太阳辐射对融化的贡献受到当地地表反照率的影响。在耦合模拟中，与使用不考虑入射变化的模型相比，由太阳辐射引起的额外融化转化为冰体积损失的三倍。我们还引入了一个简单的修正因子，允许降低复杂性的熔融模型来解释日照变化。
The growth and retreat of continental ice sheets in the past has largely been a response to changing climatic forcing. Since ablation is the principal component of mass loss for land-based ice sheets, the calculation of surface melt is an important aspect of paleo ice sheet modeling. Changes in insolation are often not accounted for in calculations of surface melt, under the assumption that the near-surface tem- perature transmits the majority of the climatic forcing to the ice sheet. To assess how this could affect paleo simulations, here we investigate the importance of different orbital config- urations for estimating melt on the Greenland ice sheet. We find that during peak Eemian conditions, increased insolation contributes 20-50 % to the surface melt anomaly. However, this percentage depends strongly on the temperature anomaly at the time. For higher temperature anomalies, the role of in- solation changes is less important. This relationship is not homogenous over the ice sheet, since the contribution of in- solation to melt is modulated by the local surface albedo. In coupled simulations, the additional insolation-induced melt translates into up to threefold more ice volume loss, com- pared to output using a model that does not account for inso- lation changes. We also introduce a simple correction factor that allows reduced-complexity melt models to account for changes in insolation.