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<p>Indian Summer Monsoon (ISM) rainfall is known to be influenced by extratropical circulation anomalies at varying timescales, which can transmit high-latitude signals to the monsoon region. Here, we investigate the atmospheric response to sea-ice loss in the Barents–Kara Sea (BKS) and its influence on ISM using atmospheric reanalysis and idealized atmosphere-only time-slice experiments from the Polar Amplification Model Intercomparison Project (PAMIP). Observations show that the recent increase in ISM rainfall, particularly over northwest India (NWI), is associated with an intensified mid-latitude Eurasian Rossby wave train that strengthens the South Asian High and alters the upper-level monsoon circulation. The ability of the models to capture this Eurasian wave train (EWT) and the efficiency with which sea ice forcing excites it are further assessed. The results indicate that a poleward shift of the subtropical jet enhances upper-level divergence and outflow over South Asia, thereby favouring increased moisture transport from the Bay of Bengal and rainfall over NWI. These observed features are reproduced in idealised numerical model experiments with forced sea ice loss in the BKS region, only when the EWT is realistically represented and efficiently excited by the sea ice forcing. The results highlight a dynamical pathway for potential contributions from BKS sea ice loss to the observed increasing trend in NWI rainfall and provide insight into the inter-model spread in producing this teleconnection.</p>

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Potential contribution of Barents–Kara Sea ice loss to the increased rainfall over northwest India through atmospheric teleconnection

  • 期刊论文

  • 发表日期：

    2026年5月28日

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  • Sourav Chatterjee,
  • Doug M Smith,
  • Nuncio Murukesh,
  • M. Ravichandran

摘要

Indian Summer Monsoon (ISM) rainfall is known to be influenced by extratropical circulation anomalies at varying timescales, which can transmit high-latitude signals to the monsoon region. Here, we investigate the atmospheric response to sea-ice loss in the Barents–Kara Sea (BKS) and its influence on ISM using atmospheric reanalysis and idealized atmosphere-only time-slice experiments from the Polar Amplification Model Intercomparison Project (PAMIP). Observations show that the recent increase in ISM rainfall, particularly over northwest India (NWI), is associated with an intensified mid-latitude Eurasian Rossby wave train that strengthens the South Asian High and alters the upper-level monsoon circulation. The ability of the models to capture this Eurasian wave train (EWT) and the efficiency with which sea ice forcing excites it are further assessed. The results indicate that a poleward shift of the subtropical jet enhances upper-level divergence and outflow over South Asia, thereby favouring increased moisture transport from the Bay of Bengal and rainfall over NWI. These observed features are reproduced in idealised numerical model experiments with forced sea ice loss in the BKS region, only when the EWT is realistically represented and efficiently excited by the sea ice forcing. The results highlight a dynamical pathway for potential contributions from BKS sea ice loss to the observed increasing trend in NWI rainfall and provide insight into the inter-model spread in producing this teleconnection.