| 北半球夏季季节内振荡年代际变化对西北太平洋群发台风突变减少的影响 |
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| 引用本文： | 张可,方娟,丛春华.北半球夏季季节内振荡年代际变化对西北太平洋群发台风突变减少的影响[J].气象学报,2023,81(1):152-162. |
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| 作者姓名： | 张可 方娟 丛春华 |
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| 作者单位： | 1.山东省气象防灾减灾重点实验室，济南，250031 |
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| 基金项目： | 国家重点研发计划项目（2018YFC1505901）、国家自然科学基金项目（41875067）、华东区域气象科技协同创新基金合作项目（QYHZ201812） |
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| 摘 要： | 利用台风最佳路径、bimodal IntraSeasonal Oscillation(bimodal ISO)指数和全球逐日向外长波辐射数据，研究了北半球夏季季节内振荡（Boreal Summer IntraSeasonal Oscillation,BSISO）年代际变化造成1996/1997年后西北太平洋群发台风突变减少的可能机制。分析显示，仅有包含3个及以上个数台风成员的“MTC3”群发出现了突变减少，此类台风更倾向在传播速度较慢、低频对流维持时间较长的BSISO活跃位相内出现，对次季节信号强度的要求相对较低。1996/1997年后，BSISO东传范围减小、周期延长、对流活跃位相日数缩短，导致西北太平洋长时间连续维持对流抑制位相，低频对流在145°E以东海域的强度减弱。当偏西海域有先导台风活动时，它向东南侧激发的罗斯贝波频散波列在（5°—20°N,145°—165°E）海域因没有低频对流耦合而快速消散，导致MTC3群发台风年代际突变减少。
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| 关 键 词： | 北半球夏季季节内振荡 台风群发 年代际变化 突变减少 |
| 收稿时间： | 2022-03-09 |
| 修稿时间： | 2022-08-07 |
Influence of the interdecadal variation of boreal summer intraseasonal oscillation on the abrupt decrease of multiple tropical cyclones in the western North Pacific |
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| Institution: | 1.Laboratory for Meteorological Disaster Prevention and Mitigation of Shandong，Jinan 250031，China2.Shandong Meteorological Observatory，Jinan 250031，China3.Key Laboratory of Mesoscale Severe Weather（Nanjing University），Ministry of Education，Nanjing 210023，China |
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| Abstract: | Using best-track data of typhoon, the bimodal ISO (IntraSeasonal Oscillation) index and global daily outgoing longwave radiation data, we study the possible mechanism of the interdecadal variation of Boreal Summer IntraSeasonal Oscillation (BSISO) that has caused sudden decrease of multiple tropical cyclones (MTC) in the western North Pacific (WNP) after 1996/1997. The analysis shows that only the "MTC3" events, which contain 3 or more typhoons, abruptly decreased after 1996/1997. They are more likely to occur in the BSISO active phase with a slower propagation speed and longer low-frequency convection. Moreover, the MTC3 events have relatively low requirements for the BSISO amplitude. After 1996/1997, the eastward propagation range of the BSISO convection reduced, the period prolonged, and the days of BSISO active phase decreased, resulting in a significant weakening of low-frequency signals to the east of 145°E. Tropical WNP tended to remain in inactive phase for a long time during this period. When a typhoon pre-exists in the WNP, the southeastward-propagating Rossby dispersion wave train casused by it always dissipates without coupled low-frequency convection to the east of 145°E, which leads to the sudden decrease of MTC3 events after 1996/1997. |
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