Seasonal and interannual variability of tropospheric ozone over an urban site in India: A study based on MOZAIC and CCM vertical profiles over Hyderabad

Abstract

This study is based on the analysis of Measurement of Ozone and Water Vapor by AirbusIn-Service Aircraft (MOZAIC) data measured over Hyderabad, India during the years 2006-2008. Tropospheric profiles of O 3 show clear seasonality with high and low values during the premonsoon and monsoon seasons, respectively. Analysis of back trajectory and fire count data indicates major roles for long-range transport and biomass burning in the seasonal variation of O 3 . Typically, lower levels of O 3 in the monsoon season were due to the flow of marine air and negligible regional biomass burning, while higher levels in other seasons were due to transport of continental air. In the upper troposphere, relatively low levels of O 3 during the monsoon and postmonsoon seasons were associated with deep convection. In the free troposphere, levels of O 3 also show year-to-year variability as the values in the premonsoon of 2006 were higher by about 30 ppbv compared to 2008. The year-to-year variations were mainly due to transition from El Niño (2006) to La Niña (2008). The higher and lower levels of O 3 were associated with strong and weak wind shears, respectively. Typically, vertical variations of O 3 were anticorrelated with the lapse rate profile. The lower O 3 levels were observed in the stable layers, but higher values in the midtroposphere were caused by long-range transport. In the PBL region, the mixing ratio of O 3 shows strong dependencies on meteorological parameters. The Chemistry Climate Model (CCM2) reasonably reproduced the observed profiles of O 3 except for the premonsoon season.

Determining relationships and mechanisms between tropospheric ozone column concentrations and tropical biomass burning in Thailand and its surrounding regions

“…The relation of tropical biomass burning and tropospheric ozone had been studied during intense fires over Indonesia in 1996-1998 by Thompson et al (2001). The Indonesian fires of 2006 were studied by Ott et al (2010), Zhang et al (2011), Srivastava and Sheel (2013) and Sahu et al (2014). Results showed that biomass burning emissions are responsible for an increase in O 3 .…”

Seasonal and interannual variability of carbon monoxide based on MOZAIC observations, MACC reanalysis, and model simulations over an urban site in India

“…Because the simulation used in this study is the same as that in Sahu et al . [], it is only briefly mentioned here. In the simulation, the horizontal wind field was nudged toward the Japan Meteorological Agency Climate Data Assimilation System (JCDAS) analysis [ Onogi et al ., ].…”

“…The Global Fire Emissions Database, version 3 (GFEDv3) inventory [ van der Werf et al ., ] estimated the global annual totals to be in the range of 250 to 600 Tg/yr. Typically, the higher annual emissions from biomass burning sources coincide with a very intense El Niño–Southern Oscillation (ENSO) episode, also seen at regional scales [ Duncan et al ., ; Sahu et al ., ]. The 1997–2009 average global fire emissions of CO had a contribution of 44% from Africa and 22% from equatorial and Southeast Asia [ van der Werf et al ., ].…”

Representativeness of the IAGOS airborne measurements in the lower troposphere

“…Ding et al, 2008;Elguindi et al, 2010;Kalabokas et al, 2007Kalabokas et al, , 2013Petetin et al, 2016aPetetin et al, , 2016bSahu et al, 2014;Sauvage et al, 2005;Sheel et al, 2016;Tressol et al, 2008;Yamasoe et al, 2015). However, a part of the scientific community seems reluctant to use the IAGOS data for studying the lowermost PBL due to concerns about the representativeness of the IAGOS measurements close to the surface.…”