Ocean heat content (OHC) change contributes substantially to global sea level rise, so it is a vital task for the climate research community to estimate historical OHC. While there are large uncertainties regarding its value, in this study, the authors discuss recent progress to reduce the errors in OHC estimates, including corrections to the systematic biases in expendable bathythermograph (XBT) data, filling gaps in the data, and choosing a proper climatology. These improvements lead to a better reconstruction of historical upper (0–700 m) OHC change, which is presented in this study as the Institute of Atmospheric Physics (IAP) version of historical upper OHC assessment. Challenges still remain; for example, there is still no general consensus on mapping methods. Furthermore, we show that Coupled Model Intercomparison Project, Phase 5 (CMIP5) simulations have limited ability in capturing the interannual and decadal variability of historical upper OHC changes during the past 45 years.
海洋热含量变化是全球变暖的一个重要观测事实，其直接贡献于海平面上升，因而对其进行准确估计是气候变化研究的一个重要科学问题。然而目前对热含量的估计仍然存在较大的不确定性。本文讨论了近些年热含量估计的主要研究进展，即对四种不确定性和偏差来源的研究：XBT数据的系统性偏差，温度廓线垂向分辨率不足，气候态的选取，如何“猜测”无观测区域的热含量数值。在合理考虑了这四类偏差之后，本文提出了一个新的历史上层海洋热含量估计。然而，挑战依然存在：何种方法能最准确的“猜测”无观测区域的热含量数值依然没有定论。此外，分析表明，CMIP5模式对上层热含量的长期趋势模拟较好，但对其年际和年代际的模拟不足。