3.2    Atmospheric River Detection during Extreme Rainfall

Given the topographical configuration of the Meghna Basin stated above that favors the condensation of the moisture when obstructed by the hilly region of Meghalaya, the presence of the atmospheric river is investigated to validate whether the atmospheric river intensified the rainfall that occurred in Meghalaya. The detection of atmospheric rivers has been conducted for the entire month of June 2022. The movement of high moisture flow from the Arabian Sea towards the Bay of Bengal, influenced by the southwest monsoon trade winds, has been observed to subsequently shift towards the Pacific Ocean. However, a moisture flux is expressed in terms of higher Integrated Vapor Transport (IVT) going towards Bangladesh and the North Eastern part of India from the Arabian Ocean through the Himalayan region starting from 11 June. The continuous flow of moisture was enhanced by the convergence of local moisture along its trajectory, leading to the formation of an Atmospheric River on June 15, 2022, as depicted in Figure 5(b) at 12:00 AM. The atmospheric river had a continuous presence for a duration of 12 hours, which coincided with the onset of intense precipitation in the region of Cherapunjee. The dissipation of the atmospheric river commenced on the 16th of June. The moisture flux in the North Eastern region of India and Bangladesh was strengthened as a result of the convergence of moisture flux originating from the Bay of Bengal. The record-breaking rainfall observed on 17 June 2022 can be attributed to the confluence of a high-intensity water vapor stream, as illustrated in Figure 5(c)(d).