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    • Keywords


      Ozone; carbon monoxide; methane; monsoon; Bay of Bengal; MACC reanalysis.

    • Abstract


      In situ measurements of near-surface ozone (O₃), carbon monoxide (CO), and methane (CH₄) were carried out over the Bay of Bengal (BoB) as a part of the Continental Tropical Convergence Zone (CTCZ) campaign during the summer monsoon season of 2009. O₃, CO and CH₄ mixing ratios varied in the ranges of 8–54 ppbv, 50–200 ppbv and 1.57–2.15 ppmv, respectively during 16 July–17 August 2009. The spatial distribution of mean tropospheric O₃ from satellite retrievals is found to be similar to that in surfaceO₃ observations, with higher levels over coastal and northern BoB as compared to central BoB. The comparison of in situ measurements with the Monitoring Atmospheric Composition & Climate (MACC) global reanalysis shows that MACC simulations reproduce the observations with small mean biases of1.6 ppbv, –2.6 ppbv and 0.07 ppmv for O₃, CO and CH4, respectively. The analysis of diurnal variation of O₃ based on observations and the simulations from Weather Research and Forecasting coupled with Chemistry (WRF-Chem) at a stationary point over the BoB did not show a net photochemical build up during daytime. Satellite retrievals show limitations in capturing CH₄ variations as measured by in situ sample analysis highlighting the need of more shipborne in situ measurements of trace gases over thisregion during monsoon.

    • Author Affiliations


      I A Girach1 Narendra Ojha2 Prabha R Nair1 Yogesh K Tiwari3 K Ravi Kumar4 5

      1. Space Physics Laboratory, Vikram Sarabhai Space Centre, Thiruvananthapuram 695 022, India.
      2. Department of Atmospheric Chemistry, Max Planck Institute for Chemistry, 55128 Mainz, Germany.
      3. Indian Institute of Tropical Meteorology, Pune 411 008, India.
      4. National Institute of Polar Research, Tachikawa, Japan.
      5. Department of Environmental Geochemical Cycle Research, JAMSTEC, Yokohama, Japan.
    • Dates

  • Journal of Earth System Science | News

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