A Paleoclimate Model of Northern Hemisphere Ice Sheets
A Paleoclimate Model of Northern Hemisphere Ice Sheets
复制标题
北半球冰原的古气候模型
DOI：
10.1016/0033-5894(81)90100-9
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发表时间：
1981
影响因子：
2.3
通讯作者：
Albert Lunde
中科院分区：
文献类型：
--
作者：
G. E. Birchfield;J. Weertman;Albert Lunde
提出了一种基于气候变化天文理论的冰原生长和消融预测模型。这项研究的部分目的是通过将水圈-大气的作用简化到极端，分离出在不同冰负荷下冰盖物理和地球响应的作用。明确地模拟了冰盖物理和岩石圈-软流圈在冰荷载作用下的响应。固定纬度的日照异常直接影响雪线的纬向位移。在平均海平面上计算的累积速率a和消融速率a '被指定为外部常数；A, A '随冰盖高度线性降低。根据最后两个主要冰川的冰体积记录的一般形状对模型进行粗略调整，决定了外部常数。模型预测的最后一次大冰期几个事件的年龄与放射性年龄相当。确定了过去60万年的6个冰川终止期（I-VI），预测年龄与两个深海岩心的δ18O记录比较合理。冰体积作为周期函数的模型功率谱与δ18O记录的谱的直接比较表明，在100,000年附近的功率明显低估。如果使用一种定量但启发式的方法来考虑地质记录中明显的“红噪声”谱，则可能进行更有利的比较。该模型预测支持了冰盖物理的非线性是导致晚更新世地质记录中10万年周期性的假设。
A model for predicting the growth and decay of ice sheets based on the astronomical theory of climate change is presented. The purpose of the study in part is to isolate the role of the ice-sheet physics and earth response under varying ice load by simplifying to the extreme the role of the hydrosphere-atmosphere. Ice sheet physics and the response of the lithosphere-asthenosphere under the ice load are modeled explicitly. Insolation anomalies (taken at a fixed latitude) directly force latitudinal displacement of the snow line. Accumulation rate a, and ablation rate a′ evaluated at mean sea level are specificed as external constants; a,a′ decrease linearly with ice sheet elevation. Rough tuning of the model to the general shape of the ice-volume record of the last two major glacials determines the external constants. Model predictions of the ages of several events in the last major glaciation compare well with the radiological ages. The six glacial terminatios (I–VI) over the last 600,000 yr are identified and the predicted ages compare reasonably well with the δ18O record for two deep-sea cores. A direct comparison of model power spectra of ice volume as a function of period with spectra of the δ18O record shows apparent underprediction of power near 100,000 yr. When a quantitative but heuristic method for taking into account the “red noise” spectrum evident in the geological records is used, a much more favorable comparison is possible. The model prediction lends support to the hypothesis that the nonlinearity of the ice-sheet physics is responsible for the 100,000-yr periodicity in the geological record of the late Pleistocene.