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ABSTRACT The ability of the stratospheric Quasi-Biennial Oscillation ( QBO) to modulate tropospheric circulation allows it to modulate tracks of tropical cyclones ( TCs). This possibility is examined using data on the cyclone tracks over the Bay of Bengal ( BOB) during the period 1948-2010. TC tracks (excluding the El Niño-Southern Oscillation years) when stratified as per the phases of QBO show the evidence of influence of stratospheric QBO on tracks. In pre-monsoon and post-monsoon seasons, during easterly phase of QBO, cyclones move westward/northwestward while during westerly phase they move northward/northeastward. The evidence of influence of QBO on modulation of TC tracks is reported for the first time during pre-satellite period (1948-1978) and satellite period (1979-2010) over the BOB. The QBO influence is observed to be significantly stronger during easterly phase as compared to that in the westerly phase. Numbers of cyclones are more during easterly phase (during pre-monsoon and post-monsoon) than during the westerly phase. A mechanism is proposed whereby QBO of the zonal winds in the stratosphere influences the movement of cyclone tracks in the BOB by redistributing deep convection associated with cyclones by modulating steering winds. The possible interaction between QBO and cyclone activity is investigated through the variation of tropopause height, geo-potential height and Outgoing Longwave Radiations. © 2013 Royal Meteorological Society [ABSTRACT FROM AUTHOR]

Abstract: The possible influence of stratospheric quasi–biennial oscillation on cyclone passages in the Bay of Bengal (BOB) is examined using Indian Ocean cyclone tracking data obtained from Joint Typhoon Warning Center (JTWC) during the period 1991–2008. During this period 52 cyclones traversed the BOB. The numbers of cyclones are more during east phase (29) of QBO as compared to west phase (23) of QBO. The QBO influence is observed to be significant during easterly phase than westerly phase. The numbers of cyclone are more during post-monsoon season as compared to pre-monsoon season. In post-monsoon season, during east phase, cyclones move westward/north westward while during westerly phase they move northward/north eastward. During pre-monsoon season, cyclones move northward/north eastward irrespective of phases of QBO. The possible interaction between the stratospheric QBO and cyclone during post-monsoon season is investigated from variation of winds, geopotential height, tropopause pressure, OLR and SST. [Copyright &y& Elsevier]

Vertical profiles of carbon monoxide (CO) and ozone retrieved from Tropospheric Emission Spectrometer have been analyzed during two super cyclone systems Mala and Sidr. Super cyclones Mala and Sidr traversed the Bay of Bengal (BOB) region on April 24-29, 2006 and November 12-16, 2007 respectively. The CO and ozone plume is observed as a strong enhancement of these pollutants in the upper troposphere over the BOB, indicating deep convective transport. Longitude-height cross-section of these pollutants shows vertical transport to the upper troposphere. CO mixing ratio ~90 ppb is observed near the 146-mb level during the cyclone Mala and near 316 mb during the cyclone Sidr. Ozone mixing ratio ~60-100 ppb is observed near the 316-mb level during both the cyclones. Analysis of National Centers for Environmental Prediction (NCEP) reanalysis vertical winds (omega) confirms vertical transport in the BOB. [ABSTRACT FROM AUTHOR]