| Resonance Effect in Interaction Between South Asian Summer Monsoon and ENSO During 1958–2018 |
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| 引用本文： | 袁 帅,徐建军,陈仲良.Resonance Effect in Interaction Between South Asian Summer Monsoon and ENSO During 1958–2018[J].热带气象学报(英文版),2020,26(2):137-149. |
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| 作者姓名： | 袁 帅 徐建军 陈仲良 |
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| 摘 要： | The study has shown that the shear component of the vertical integrated kinetic energy (Ks) over the box (40oE–100oE, 0o–20oN) can be used as a measure of the intensity of the South Asian summer monsoon (SASM). Based on its value averaged between June and August, the SASM can be divided into strong and weak monsoon episodes. Between 1958 and 2018, there existed 16 (16) strong (weak) monsoon episodes. Based on the calendar year, the relationship between the SASM and the ENSO episodes can be grouped into six patterns: weak monsoon - El Ni?o (WM-EN), normal monsoon - El Ni?o (NM-EN), weak monsoon - non ENSO (WM-NE), strong monsoon - La Ni?a (SM-LN), normal monsoon - La Ni?a (NM-LN) and strong monsoon - non ENSO (SM-NE). Previous studies have suggested that the WM-EN and SM-LN patterns reflect the correlated relationship between the SASM and El Ni?o/Southern Oscillation (ENSO) events. Therefore, we name these two strongly coupled categories WM-EN and SM-LN as the resonance effect. Two important circulations, Walker circulation (WC) and zonal Asian monsoon circulation (MC), in the vertical plane are found to be not always correlated. MC is controlled by thermal gradients between the Asian landmass and the tropical Indian Ocean, while the WC associated with the ENSO event is primarily the east-west thermal gradient between the tropical South Pacific and the tropical Indian Ocean. Furthermore, the gradient directions caused by different surface thermal conditions are different. The main factor for the resonance effect is the phenomenon that the symbols of SSTA in the tropical Indian Ocean and the equatorial eastern Pacific are the same, but are opposite to that of the SSTA near the maritime continent.
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| 关 键 词： | the South Asian Summer Monsoon ENSO resonance effect monsoon circulation Walker circulation |
| 收稿时间： | 2019-10-12 |
Resonance Effect in Interaction Between South Asian Summer Monsoon and ENSO During 1958-2018 |
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| YUAN Shuai,XU Jian-jun and CHEN J C L.Resonance Effect in Interaction Between South Asian Summer Monsoon and ENSO During 1958-2018[J].Journal of Tropical Meteorology,2020,26(2):137-149. |
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| Authors: | YUAN Shuai XU Jian-jun and CHEN J C L |
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| Affiliation: | 1. College of Ocean and Meteorology Guangdong Ocean University, Zhanjiang, Guangdong 524088 China; 2. South China Sea Institute of Marine Meteorology, Guangdong Ocean University, Zhanjiang, Guangdong 524088 China; 3. Southern Marine Science and Engineering Guangdong Laboratory (Zhanjiang), Zhanjiang, Guangdong 524088 China; 4. School of Energy and Environment, City University of Hong Kong, Hongkong 999077 China; 5. AOES, College of Science, George Mason University, Fairfax, Virginia 22030 USA |
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| Abstract: | The study has shown that the shear component of the vertical integrated kinetic energy (Ks) over the box (40oE-100oE, 0-20oN) can be used to measure the intensity of the South Asian summer monsoon (SASM). Based on its value averaged between June and August, the SASM can be divided into strong and weak monsoon episodes. Between 1958 and 2018, there existed 16 (16) strong (weak) monsoon episodes. Based on the calendar year, the relationship between the SASM and ENSO episodes can be grouped into six patterns: weak monsoon - El Ni?o (WM-EN), normal monsoon - El Ni?o (NM-EN), weak monsoon - non ENSO (WM-NE), strong monsoon - La Ni?a (SM-LN), normal monsoon - La Ni?a (NM-LN) and strong monsoon - non ENSO (SM-NE). Previous studies suggest that the WM-EN and SM-LN patterns reflect the correlated relationship between the SASM and El Ni?o/Southern Oscillation (ENSO) events. Therefore, we name these two strongly coupled categories WM-EN and SM-LN as the resonance effect. Two important circulations, i.e., Walker circulation (WC) and zonal Asian monsoon circulation (MC), in the vertical plane are found to be not always correlated. The MC is controlled by thermal gradients between the Asian landmass and the tropical Indian Ocean, while the WC associated with ENSO events is primarily the east-west thermal gradient between the tropical South Pacific and the tropical Indian Ocean. Furthermore, the gradient directions caused by different surface thermal conditions are different. The main factor for the resonance effect is the phenomenon that the symbols of SSTA in the tropical Indian Ocean and the equatorial eastern Pacific are the same, but are opposite to that of the SSTA near the maritime continent. |
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| Keywords: | the South Asian Summer Monsoon ENSO resonance effect monsoon circulation Walker circulation |
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