Predictability of North Atlantic Sea Surface Temperature and Upper-Ocean Heat Content
Predictability of North Atlantic Sea Surface Temperature and Upper-Ocean Heat Content
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DOI：
10.1175/jcli-d-18-0509.1
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发表时间：
2019-05-01
影响因子：
4.9
通讯作者：
Li, Laifang
中科院分区：
文献类型：
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作者：
Buckley, Martha W.;DelSole, Tim;Li, Laifang
由于大西洋海表温度 (SST) 对大西洋飓风以及邻近陆地的温度和降水产生强烈的气候影响，了解大西洋海表温度 (SST) 的可预测程度非常重要。然而，不同模型对大西洋海温和上层海洋热含量 (UOHC) 的可预测程度存在很大差异。在这项工作中，北大西洋海表温度和 UOHC 可预测时间尺度的下限纯粹是通过基于局部自相关的去相关时间尺度测量的网格化海洋观测来估计的。冬季海表温度和 UOHC 的去相关时间尺度在副极地环流中最长，最大时间尺度约为 4-6 年。冬季海表温度和 UOHC 通常具有相似的去相关时间尺度，但在混合层非常深的区域（例如拉布拉多海）除外，其中 UOHC 的时间尺度要大得多。冬季气候混合层深度的空间变化解释了北大西洋温带冬季海表温度去相关时间尺度区域变化的 51%-73%（分析的三个数据集的范围）和 UOHC 去相关时间尺度的区域变化的 26%-40%（分析的三个数据集的范围）。这些结果表明，UOHC 的前阶去相关时间尺度是由海洋的热记忆决定的。
Understanding the extent to which Atlantic sea surface temperatures (SSTs) are predictable is important due to the strong climate impacts of Atlantic SST on Atlantic hurricanes and temperature and precipitation over adjacent landmasses. However, models differ substantially on the degree of predictability of Atlantic SST and upper-ocean heat content (UOHC). In this work, a lower bound on predictability time scales for SST and UOHC in the North Atlantic is estimated purely from gridded ocean observations using a measure of the decorrelation time scale based on the local autocorrelation. Decorrelation time scales for both wintertime SST and UOHC are longest in the subpolar gyre, with maximum time scales of about 4-6 years. Wintertime SST and UOHC generally have similar decorrelation time scales, except in regions with very deep mixed layers, such as the Labrador Sea, where time scales for UOHC are much larger. Spatial variations in the wintertime climatological mixed layer depth explain 51%-73% (range for three datasets analyzed) of the regional variations in decorrelation time scales for UOHC and 26%-40% (range for three datasets analyzed) of the regional variations in decorrelation time scales for wintertime SST in the extratropical North Atlantic. These results suggest that to leading order decorrelation time scales for UOHC are determined by the thermal memory of the ocean.