Changes in surface ozone levels due to convective downdrafts over the Bay of Bengal

Abstract

[1] Simultaneous measurements of surface level ozone (O 3 ) and meteorological parameters were made over the Bay of Bengal (BOB) during a cruise between 14 September and 12 October 2002. Variations in surface O 3 , equivalent potential temperature (q E ) and associated meteorological parameters clearly show evidence of convective downdrafts during 18-19 September and 25-26 September. Sharp increase in O 3 mixing ratio is coupled with decrease in q E value in the detrained air. The vertical wind velocity and satellite images also indicate significant convective activities during these periods. The maximum changes in O 3 and q E were 26 ppbv and 12 K, respectively. These events comprise of both short and long time scale downdrafts. Citation: Sahu, L. K., and S. Lal (2006), Changes in surface ozone levels due to convective downdrafts over the Bay of Bengal, Geophys. Res. Lett., 33, L10807,

Observations of ambient trace gas and PM 10 concentrations at Patna, Central Ganga Basin during 2013–2014: The influence of meteorological variables on atmospheric pollutants

“…The post-monsoon season had the second highest O 3 concentrations suggesting the impact of biomass burning over IGB region providing significant reactive hydrocarbon species concentrations , Bisht et al, 2015Tiwari et al, 2015b). O 3 concentrations were comparable to those reported at other urban locations in India (Chelani, 2013;Debaje and Kakade, 2009;Beig et al, 2007;Sahu and Lal, 2006;Lal et al, 2012; references therein) as well as urban areas in China (Tu et al, 2007;Tang et al, 2009), but lower than rural and high altitude sites in India where NO emissions are much lower (24-36%) (Kumar et al, 2010a, b;Reddy et al, 2010). In Delhi, the mean O 3 concentration was much higher (23.6 ppb) than the Patna (Tiwari et al, 2015a) (Table 2).…”

Aerosol characteristics and particle production in the upper troposphere over the Amazon Basin

“…Over Amazonia with its high degree of convective activity, downdrafts are likely to play a more important role. Downward transport of UT air by downdrafts associated with deep convective activity has been shown to inject air with lower moisture content, lower equivalent potential temperature, and elevated O 3 into the PBL (Zipser, 1977;Betts et al, 2002;Sahu and Lal, 2006;Grant et al, 2008;Hu et al, 2010;Gerken et al, 2016). It would follow that the same mechanism also brings down aerosol-rich air from the UT into the PBL.…”

The impact of overshooting deep convection on local transport and mixing in the tropical upper troposphere/lower stratosphere (UTLS)

“…Betts et al, 2002;Sahu and Lal, 2006;Hu et al, 2010), only few report on downward mixing from the tropical stratosphere. Lu et al (2000) showed with 2-D cloud resolving modelling that convective towers that reach the tropical tropopause have the potential to transfer ozone-rich air down into the cloud anvil.…”