The role of deep sea heat storage in the secular response to climatic forcing
The role of deep sea heat storage in the secular response to climatic forcing
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DOI：
10.1029/jc085ic11p06667
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发表时间：
1980-11
影响因子：
--
通讯作者：
M. Hoffert;A. Callegari;C. Hsieh
中科院分区：
文献类型：
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作者：
M. Hoffert;A. Callegari;C. Hsieh
这里考虑世界海洋对气候响应的影响，重点是传递到充分混合的表层下方的水域和极地底层水形成区域的热量。建立了一个上升流扩散模型来解决这个问题，其有效传输特性是根据化学海洋学家测量的放射性碳、位温和其他示踪剂的稳态垂直剖面来校准的。关于大气温度对外部气候强迫的响应问题的关键问题是表面混合层和深海之间的热交换速率是否与行星辐射场和大气混合层系统之间的传热速率相当。分析中出现的一个重要模型参数是极地海洋变暖系数∏，等于极地海洋温度相对于区域平均混合层温度变化的变化率。对于 0 到 2 范围内的 ∏ 值，模型预测响应时间在 8 到 20 年范围内才能达到阶跃函数气候强迫的 63% 平衡温度变化，并预测 50 到 1000 年才能获得 90% 的平衡响应。这些可以与仅海洋混合层模型得到的大约 4 年的响应时间进行比较。为了研究二氧化碳气候问题，基于化石燃料二氧化碳的历史增长和系统处于辐射对流平衡时随时获得的温度增量的对数标度定律，使用了更现实的时间相关强迫函数。我们的结果表明，深海热储存的影响可能会使平衡模型预测的公元 1980 年至 2000 年期间温度增量的全部值延迟 10 至 20 年。还考虑了模型对周期性强迫的响应、结果的敏感性以及模型结果对十年到千年时间尺度上的气候变化的影响。
The influence of the world oceans on climatic response is considered here with emphasis on the heat transferred to waters beneath the well-mixed surface layer and to polar bottom water forming zones. An upwelling-diffusing model is formulated to treat this problem whose effective transport properties are calibrated from the steady state vertical profiles of radiocarbon, potential temperature and other tracers measured by chemical oceanographers. The key issue with regard to the question of atmospheric temperature response to external climatic forcing is whether heat is exchanged between the surface mixed layer and deep sea at rates comparable to heat transfer rates between the planetary radiation field and the atmosphere-mixed layer system. An important model parameter appearing in the analysis is the polar sea warming coefficient ∏ equal to the rate of change of polar sea temperature relative to changes in areally averaged mixed layer temperature. For ∏ values in the range of 0 to 2 the models predicts response times in the range of 8 to 20 years to attain 63% of the equilibrium temperature change for a step function climatic forcing, and 50 to 1000 years to get 90% of the equilibrium response. These may be compared with the roughly 4 year response time one gets with an oceanic mixed layer only model. To study the carbon dioxide climate problem, a more realistic time-dependent forcing function is used based on the historical growth of fossil fuel CO2 and a logarithmic scaling law for the temperature increment which would obtain at any instant if the system were in radiative-convective equilibrium. Our results suggest the influence of deep sea thermal storage could delay the full value of temperature increment predicted by equilibrium models by 10 to 20 years in 1980 to 2000 A.D. time frame. Also considered is the model response to periodic forcing, the sensitivity of the results, and the implications of the model results with regard to climatic changes on a decadal to millenial timescale.