Scholarlink

<p>Based on atmosphere reanalysis data from ERA5 and sea surface temperature (SST) from Hadley Center, this study investigates the triggering effect of the subtropical Indian Ocean Dipole (SIOD) on the subsequent tropical Indian Ocean Dipole (IOD), as well as its interdecadal change, from 1960 to 2024. Results show that the correlations between the SIOD and IOD are not significant from 1960 to the late 1980s (WEAK period), whereas, stable positive correlations appear between them from the late 1980s onward (STRONG period). During the STRONG period, the positive SST anomalies (SSTA) in the southwestern Indian Ocean as well as the overlying anomalous anticyclonic circulation (AC), associated with the positive SIOD, are sustained and shift eastward under the positive wind-evaporation-SST (WES) feedback. This SSTA drives a vertical motion of the above atmosphere through diabatic heating, subsequently promoting the development of the low-level AC and its equatorward expansion by exciting Rossby wave trains and local meridional circulation. Ultimately, the development of IOD is triggered and enhanced through air–sea coupling processes, including the Bjerknes feedback, Walker circulation, and oceanic Rossby waves. In contrast, during the WEAK period, the responses of the aforementioned physical processes are weak, preventing an effective influence of the SIOD on the IOD. Further analysis indicates that the variation of Southern Annular Mode (SAM), particularly its intensity, plays a significant role in the interdecadal shift of the SIOD-to-IOD relationship. This paper provides new insights for understanding cross-latitude air–sea interactions and improving seasonal IOD prediction.</p>

错误：搜索内容不能为空，请输入英文关键词
错误：关键词超出字数限制，请精简
高级检索

Interdecadal change in triggering effect of subtropical Indian Ocean dipole on tropical Indian Ocean dipole and the role of Southern annular mode

  • 期刊论文

  • 发表日期：

    2026年7月23日

查看全文
  • Junqiao Feng,
  • Linlin Zhang,
  • Fujun Wang

摘要

Based on atmosphere reanalysis data from ERA5 and sea surface temperature (SST) from Hadley Center, this study investigates the triggering effect of the subtropical Indian Ocean Dipole (SIOD) on the subsequent tropical Indian Ocean Dipole (IOD), as well as its interdecadal change, from 1960 to 2024. Results show that the correlations between the SIOD and IOD are not significant from 1960 to the late 1980s (WEAK period), whereas, stable positive correlations appear between them from the late 1980s onward (STRONG period). During the STRONG period, the positive SST anomalies (SSTA) in the southwestern Indian Ocean as well as the overlying anomalous anticyclonic circulation (AC), associated with the positive SIOD, are sustained and shift eastward under the positive wind-evaporation-SST (WES) feedback. This SSTA drives a vertical motion of the above atmosphere through diabatic heating, subsequently promoting the development of the low-level AC and its equatorward expansion by exciting Rossby wave trains and local meridional circulation. Ultimately, the development of IOD is triggered and enhanced through air–sea coupling processes, including the Bjerknes feedback, Walker circulation, and oceanic Rossby waves. In contrast, during the WEAK period, the responses of the aforementioned physical processes are weak, preventing an effective influence of the SIOD on the IOD. Further analysis indicates that the variation of Southern Annular Mode (SAM), particularly its intensity, plays a significant role in the interdecadal shift of the SIOD-to-IOD relationship. This paper provides new insights for understanding cross-latitude air–sea interactions and improving seasonal IOD prediction.