| Chen Xingrong,Wang Hui,Zheng Fei,Cai Qifa. 2020. An ensemble-based SST nudging method proposed for correcting the subsurface temperature field in climate model. Acta Oceanologica Sinica, 39(3):73－80 |
| An ensemble-based SST nudging method proposed for correcting the subsurface temperature field in climate model |
| 发展基于集合样本估计的SST张驰逼近方法用于气候模式的次表层海温场订正 |
| Received:August 27, 2019 |
| DOI：10.1007/s13131-020-1568-2 |
| Key words:ensemble-based nudging method ECHAM5/MPI-OM SST assimilation simulation of subsurface temperature field |
| 中文关键词: 基于集合样本估计的张驰逼近方法 ECHAM5/MPI-OM SST同化 次表层海温场模拟 |
| 基金项目:The National Key R&D Program of China under contract No. 2017YFA0604201; the National Natural Science Foundation of China under contract Nos 41876012 and 41861144015. |
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| Abstract: |
| An ensemble-based assimilation method is proposed for correcting the subsurface temperature field when nudging the sea surface temperature (SST) observations into the Max Planck Institute (MPI) climate model, ECHAM5/MPI-OM. This method can project SST directly to subsurface according to model ensemble-based correlations between SST and subsurface temperature. Results from a 50 year (1960-2009) assimilation experiment show the method can improve the subsurface temperature field up to 300 m compared to the quality-controlled subsurface ocean temperature objective analyses (EN4), through reducing the biases of the thermal states, improving the thermocline structure, and reducing the root mean square (RMS) errors. Moreover, as most of the improvements concentrate over the upper 100 m, the ocean heat content in the upper 100 m (OHT_100 m) is further adopted as a property to validate the performance of the ensemble-based correction method. The results show that RMS errors of the global OHT_100 m convergent to one value after several times iteration, indicating this method can represent the relationship between SST and subsurface temperature fields well, and then improve the accuracy of the simulation in the subsurface temperature of the climate model. |
| 中文摘要: |
| 本研究提出了一个基于集合样本估计的SST（sea surface temperature，海表温度）张驰逼近方法，并用于改进马普研究所发展的气候模式ECHAM5/MPI-OM的次表层海温场模拟。该方法利用集合样本统计得到的SST和次表层海温场的相关性，可在同化SST观测时将其距平信息直接投影到次表层海温场上，进而直接调整气候模式的次表层海温。50年（1960-2009年）的长时间同化试验结果表明，与高质量的次表层海温分析场EN4数据相对比，该方法通过减小海洋热力场的模拟偏差，改进模式的温跃层结构，和减小模式模拟的均方根误差等途径，有效地改进了气候模式上300米的次表层海温模拟。与此同时，由于该方法的改进效果主要集中在海洋上100米范围，因此本研究进一步将海洋上层100米的热含量作为一个检测因子来评判该方法的优劣。长时间连续SST同化结果显示，全球海洋上层100米的热含量的均方根误差在通过几次同化时次迭代后会明显趋近至极值，基本保持不变，表明该方法可以有效地体现SST和次表层海温场的相关关系，提高气候模式对次表层海温的模拟性能。 |
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