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The aim of the study is to correlate the role of the Madden-Julian Oscillation (MJO) with the genesis of the cyclonic storms that occurred during the year 2013 in the Indian Ocean/Bay of Bengal (BOB) region. The MJO is the major fluctuation in tropical weather on weekly to monthly timescales. This eastward propagating tropical disturbance was first identified by Madden and Julian (J Atmos Sci 28:702–708, 1971). The MJO can be characterised as an eastward moving ‘pulse’ of cloud and rainfall near the equator that typically recurs every 30–60 days and has a global wave number one structure with a spatial wavelength of roughly 12,000–20,000 km (Nakazawa, J Meteorol Soc Jpn 64:17–34, 1986). The MJO is characterised by an eastward progression of large regions of both enhanced and suppressed tropical rainfall, observed mainly over the Indian and Pacific Ocean. This oscillation is associated with eastward-moving convection with an enhanced convective phase followed by a non-convective (suppressed convection) phase at any one location. The low-level wind fields associated with MJO are characterised by fluctuations between easterly and westerly phases and can be observed in several other parameters such as surface pressure, upper tropospheric wind, and proxies for deep convection such as outgoing long-wave radiation (OLR).
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- The Influence of Madden-Julian Oscillation on the Bay of Bengal Tropical Cyclogenesis During the Year 2013
P. C. S. Rao
S. A. Nair