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<p>By analyzing multisource observational data and reanalysis datasets during 1984–2015, we addressed the impact of the Tibetan Plateau (TP) thermal forcing on the Indian Ocean dipole (IOD) mode of sea surface temperature (SST) anomaly. The results demonstrate that May TP thermal forcing can effectively trigger the initial IOD development during May–June by inducing distinct atmospheric circulation responses between the Indian and Southeast Asian summer monsoon regions. Strong TP thermal forcing induces southerly anomalies off Africa, leading to negative SST anomaly in the western Indian Ocean. Based on the diagnosis equation of temperature changes in the mixed layer, we further demonstrate that these southerly anomalies cool the western Indian Ocean through two key mechanisms: enhanced latent heat flux loss via wind-evaporation-SST (WES) feedback and coastal upwelling amplification. Alternatively, strong TP thermal forcing also triggers anomalous upper-tropospheric cyclone across eastern China, resulting in intense convergence. This upper-tropospheric convergence drives opposing low-level flows—southerlies across the Indo-China Peninsula and northerlies across the Maritime Continent. Concurrently, the northwesterly anomalies offshore of Sumatra and Java weaken the prevailing southeasterlies, thereby suppressing coastal upwelling and reducing latent heat flux loss via WES feedback, which ultimately warms the southeastern Indian Ocean. The consequent westerly anomalies intensify and propagate westward in tandem with the evolving SST dipole through Bjerknes feedback, thus developing a negative IOD. Conversely, weak TP thermal forcing anomalies typically trigger positive IOD via inverse mechanisms. Our results reveals a new triggering mechanism for IOD events that provides new insights into understanding IOD diversity.</p>

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Occurrence of the Indian Ocean dipole mode associated with the thermal forcing over the Tibetan Plateau

  • 期刊论文

  • 发表日期：

    2026年5月19日

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  • Die Hu,
  • Anmin Duan,
  • Yuheng Tang,
  • Bin Tang

摘要

By analyzing multisource observational data and reanalysis datasets during 1984–2015, we addressed the impact of the Tibetan Plateau (TP) thermal forcing on the Indian Ocean dipole (IOD) mode of sea surface temperature (SST) anomaly. The results demonstrate that May TP thermal forcing can effectively trigger the initial IOD development during May–June by inducing distinct atmospheric circulation responses between the Indian and Southeast Asian summer monsoon regions. Strong TP thermal forcing induces southerly anomalies off Africa, leading to negative SST anomaly in the western Indian Ocean. Based on the diagnosis equation of temperature changes in the mixed layer, we further demonstrate that these southerly anomalies cool the western Indian Ocean through two key mechanisms: enhanced latent heat flux loss via wind-evaporation-SST (WES) feedback and coastal upwelling amplification. Alternatively, strong TP thermal forcing also triggers anomalous upper-tropospheric cyclone across eastern China, resulting in intense convergence. This upper-tropospheric convergence drives opposing low-level flows—southerlies across the Indo-China Peninsula and northerlies across the Maritime Continent. Concurrently, the northwesterly anomalies offshore of Sumatra and Java weaken the prevailing southeasterlies, thereby suppressing coastal upwelling and reducing latent heat flux loss via WES feedback, which ultimately warms the southeastern Indian Ocean. The consequent westerly anomalies intensify and propagate westward in tandem with the evolving SST dipole through Bjerknes feedback, thus developing a negative IOD. Conversely, weak TP thermal forcing anomalies typically trigger positive IOD via inverse mechanisms. Our results reveals a new triggering mechanism for IOD events that provides new insights into understanding IOD diversity.