Appearance of the persistently low tropopause temperature and ozone over the Bay of Bengal region

This paper reports the observation of persistently low tropopause temperatures (100 hPa temperatures, T 100 ) and ozone at 100 hPa throughout the year as compared to the corresponding zonal mean values over the Bay of Bengal (BOB) region. The long term mean T 100 (i.e., from January 2006–December 2009) over the BOB is ~2.2 K lower than the zonal mean values over this region. The multiple linear regression analysis has been carried out to study the role of convection and ozone in giving rise to the persistently low T 100 over the BOB. Results show that the low ozone mixing ratios contributes ~1.2 K and convection contributes ~0.35 K to the persistently low T 100 . The contribution of convection to the persistent low T 100 is mainly during the boreal monsoon season.