| Distinctive MJO Activity during the Boreal Winter of the 2015/16 Super El Nino in Comparison with Other Super El Nino Events |
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| 作者姓名： | Xuben LEI Wenjun ZHANG Pang-Chi HSU Chao LIU |
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| 作者单位： | Key Laboratory of Meteorological Disaster, Ministry of Education/Joint International Research Laboratory of Climate and Environmental Change/Collaborative Innovation Center on Forecast and Evaluation of Meteorological Disasters, Nanjing University of Information Science & Technology, Nanjing 210044, China |
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| 基金项目： | and the National Nature Science Foundation of China ;This work was supported by the National Key R&D Program of China |
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| 摘 要： | Many previous studies have demonstrated that the boreal winters of super El Nino events are usually accompanied by severely suppressed Madden-Julian oscillation(MJO) activity over the western Pacific due to strong descending motion associated with a weakened Walker Circulation. However, the boreal winter of the 2015/16 super El Nino event is concurrent with enhanced MJO activity over the western Pacific despite its sea surface temperature anomaly(SSTA)magnitude over the Nino 3.4 region being comparable to the SSTA magnitudes of the two former super El Nino events(i.e.,1982/83 and 1997/98). This study suggests that the MJO enhanced over western Pacific during the 2015/16 super El Nino event is mainly related to its distinctive SSTA structure and associated background thermodynamic conditions. In comparison with the previous super El Nino events, the warming SSTA center of the 2015/16 super El Nino is located further westward, and a strong cold SSTA is not detected in the western Pacific. Accordingly, the low-level moisture and air temperature(as well as the moist static energy, MSE) tend to increase in the central-western Pacific. In contrast, the low-level moisture and MSE show negative anomalies over the western Pacific during the previous super El Nino events.As the MJO-related horizontal wind anomalies contribute to the further westward warm SST-induced positive moisture and MSE anomalies over the western tropical Pacific in the boreal winter of 2015/16, stronger moisture convergence and MSE advection are generated over the western Pacific and lead to the enhancement of MJO convection.
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| 关 键 词： | super El Nino Madden-Julian oscillation moisture diagnosis |
Distinctive MJO Activity during the Boreal Winter of the 2015/16 Super El Ni?o in Comparison with Other Super El Ni?o Events |
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| Xuben LEI,Wenjun ZHANG,Pang-Chi HSU,Chao LIU.Distinctive MJO Activity during the Boreal Winter of the 2015/16 Super El Nino in Comparison with Other Super El Nino Events[J].Advances in Atmospheric Sciences,2021,38(4):555-568. |
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| Authors: | Xuben LEI Wenjun ZHANG Pang-Chi HSU Chao LIU |
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| Abstract: | Many previous studies have demonstrated that the boreal winters of super El Ni?o events are usually accompanied by severely suppressed Madden-Julian oscillation (MJO) activity over the western Pacific due to strong descending motion associated with a weakened Walker Circulation. However, the boreal winter of the 2015/16 super El Ni?o event is concurrent with enhanced MJO activity over the western Pacific despite its sea surface temperature anomaly (SSTA) magnitude over the Ni?o 3.4 region being comparable to the SSTA magnitudes of the two former super El Ni?o events (i.e., 1982/83 and 1997/98). This study suggests that the MJO enhanced over western Pacific during the 2015/16 super El Ni?o event is mainly related to its distinctive SSTA structure and associated background thermodynamic conditions. In comparison with the previous super El Ni?o events, the warming SSTA center of the 2015/16 super El Ni?o is located further westward, and a strong cold SSTA is not detected in the western Pacific. Accordingly, the low-level moisture and air temperature (as well as the moist static energy, MSE) tend to increase in the central-western Pacific. In contrast, the low-level moisture and MSE show negative anomalies over the western Pacific during the previous super El Ni?o events. As the MJO-related horizontal wind anomalies contribute to the further westward warm SST-induced positive moisture and MSE anomalies over the western tropical Pacific in the boreal winter of 2015/16, stronger moisture convergence and MSE advection are generated over the western Pacific and lead to the enhancement of MJO convection. |
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| Keywords: | super El Ni?o Madden-Julian oscillation moisture diagnosis |
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