Deriving historical equilibrium-line altitudes from a glacier length record by linear inverse modelling
Deriving historical equilibrium-line altitudes from a glacier length record by linear inverse modelling
复制标题
通过线性反演模型从冰川长度记录导出历史平衡线高度
DOI：
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发表时间：
2003
期刊：
影响因子：
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通讯作者：
J. Oerlemans
中科院分区：
文献类型：
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作者：
E. J. Klok;J. Oerlemans
冰川在历史时期曾有波动，许多冰川的长度波动是已知的。从这些冰川长度记录中，可以提取根据平衡线高度（ELA）或质量平衡重建描述的气候重建。为了从大量冰川长度记录中得出气候信号，需要一个考虑冰川主要特征但很少使用冰川本身信息的模型。因此，基于冰川长度变化可以通过线性响应方程描述的假设，建立了一个简单的分析模型。需要历史长度观测、气候敏感性和冰川的响应时间来计算历史平衡线高度。气候敏感性和长度响应时间都是根据连续性方程的扰动分析计算得出的。该模型在 17 个欧洲冰川长度记录上进行了测试。结果显示，从公元 1920 年到 1950 年，大多数冰川的 ELA 平均增加了 54 m。将分析模型的结果与使用数值流线模型计算并根据历史温度和降水记录得出的质量平衡重建进行了比较。研究结果使我们相信，分析模型对于获取有关历史质量平衡率和 ELA 的信息非常有用。
Glaciers have fluctuated in historic times and the length fluctuations of many glaciers are known. From these glacier length records, a climate reconstruction described in terms of a reconstruction of the equilibrium-line altitude (ELA) or the mass-balance can be extracted. In order to derive a climate signal from numerous glacier length records, a model is needed that takes into account the main characteristics of a glacier, but uses little information about the glacier itself. Therefore, a simple analytical model was developed based on the assumption that the change in glacier length can be described by a linear response equation. Historical length observations, the climate sensitivity and the response time of a glacier were needed to calculate historical equilibrium-line altitudes. Both climate sensitivity and length response time were calculated from a perturbation analysis on the continuity equation. The model was tested on 17 European glacier length records. The results revealed that the ELA of most glaciers increased on average 54 m between AD 1920 and 1950. The results of the analytical model were compared to mass-balance reconstructions calculated with a numerical flowline model and derived from historical temperature and precipitation records. The findings lead us to believe that the analytical model could be very useful to gain information about the historical mass-balance rates and ELAs.