Variability of low-level jet over the Arabian Sea and its association with Indian summer monsoon rainfall

In this paper, the influence of emerging low level jet (LLJ) core zone on the Indian summer monsoon rainfall (ISMR) examined during the period 1981-2020 using ERA5 reanalysis, Indian Monsoon Data Assimilation and Analysis (IMDAA) along with Indian Meteorology Department (IMD) rainfall. The analysis spans the entirety of India, encompassing various regions, including Central India (68 degrees-87 degrees E, 15 degrees N-26 degrees N), Northeast India (83 degrees-98.5 degrees E, 21 degrees-30 degrees N), Northwest India (69 degrees-84 degrees E, 22 degrees-37 degrees N), and the Southern Peninsula (74 degrees-85 degrees E, 7 degrees-19 degrees N). Our analysis found a significant correlation between the magnitude of LLJ core zone and ISMR across these regions, except for North-East India, in both data sets (0.5-0.8) at a 0.01 significance level. ERA5 and IMDAA, both data sets, reflect the spatial climatological aspects of LLJ at seasonal and sub-seasonal scales. However, compared to the ERA5 data, the amplitude of LLJ wind is lower in the IMDAA data over the evolving core zone. This study provides pivotal insights into the dynamics of the core LLJ zone and its relationship with ISMR, including its associations with varying Indian monsoon patterns and teleconnections with the El Nino-Southern Oscillation (ENSO) and the Indian Ocean Dipole (IOD) phases. This study hold significant implications for various sectors reliant on accurate monsoon predictions and weather forecasting. By elucidating the evolving dynamics of the core zone of the LLJ and its connection with ISMR, the research provides a valuable framework for enhancing the precision of monsoon forecasting models.