Teleconnection of Atlantic Nino with summer monsoon rainfall over northeast India

In the current climate, a better understanding of the factors that cause variability in Indian summer monsoon rainfall over northeast India is critical because it is susceptible to climate change. The variability and remote teleconnections keep altering owing to this change in climate reign. Therefore, the variability and teleconnections should be studied with recent datasets. In the present study, the northeast India summer monsoon rainfall is elucidated, showing the vital role of Atlantic Nino during the recent four decades. The Atlantic Nino intensifies the intertropical convergence zone (ITCZ) across Atlantic and West Africa. Consequently creates a widespread upper-tropospheric divergence, inciting successive positive-negative geopotential height anomalies. These changes in upper-tropospheric geopotential height and mid-latitude wave originating from North Atlantic following the path passing over northeast India, creating a similar pattern as Pacific-North America Pattern manifests the linkage between Atlantic Nino and northeast India summer monsoon rainfall by increasing the upper-tropospheric positive geopotential height anomaly over there. A Pacific-Japan type pattern is also associated with the positive phase of Atlantic Nino, which restricts the cross-equatorial flow from transporting moisture towards the South China Sea and enhancing the moisture transport towards northeast India. And this triggers the convection process, thereby strengthening the monsoonal rainfall over there. These results are also confirmed by using the CFSv2 model sensitivity experiment and a case study of the year 2017.

Automated summary

The study highlights the significant impact of Atlantic Nino on northeast India summer monsoon rainfall, intensifying the intertropical convergence zone between Atlantic and West Africa, altering atmospheric circulation and triggering upper-tropospheric anomalies, leading to strengthened rainfall processes.