“…There are several ISOs that operate on different timescales, the most prominent being the 30-90-day, the 10-20-day, and the 3-7-day oscillations (Goswami et al, 1998(Goswami et al, , 2003Pillai & Chowdary, 2016). The 30-90-day mode commonly describes the Madden-Julian Oscillation (MJO), with a northward propagating phase referred to as either the monsoon intraseasonal oscillation (MISO) or boreal summer intraseasonal oscillation (BSISO; Ajayamohan et al, 2011;Girishkumar et al, 2017;Krishnamurti et al, 2017;Madden & Julian, 1971;Wheeler & Hendon, 2004;Zhang, 2005). The 10-20-day mode, or quasibiweekly oscillation, is a westward propagating system over the Bay of Bengal (BoB) and equatorial Indian Ocean (Chatterjee & Goswami, 2004; Kikuchi & Wang, 2009;Murakami, 1976;Roman-Stork et al, 2019).…”