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Atmos. Chem. Phys. Discuss., 11, 19179-19212, 2011
www.atmos-chem-phys-discuss.net/11/19179/2011/ doi:10.5194/acpd-11-19179-2011 © Author(s) 2011. This work is distributed under the Creative Commons Attribution 3.0 License. |
Estimation of NOx emissions from Delhi using car MAX-DOAS observations and comparison with OMI satellite data
1Max-Planck-Institute for Chemistry, Mainz, Germany
2Research and Technology Development Centre, Sharda University, Greater Noida, India
3School of Earth and Environmental Sciences, Schmid College of Science, Chapman University, Orange 92866, USA
Abstract. We present the first Multi-Axis- (MAX-) DOAS observations in India performed during April 2010 and January 2011 in Delhi and nearby regions. The MAX-DOAS instrument was mounted on a car roof, which allowed us to perform measurements along individual driving routes. From car MAX-DOAS observations along closed circles around Delhi, together with information on wind speed and direction, the NOx emissions from the greater Delhi area were determined: our estimate of 3.7 × 1025 molec s−1 is found to be slightly lower than the corresponding emission estimates using the EDGAR data base and substantially smaller compared to a recent study by Gurjar et al. (2004). We have also used the MAX-DOAS observations of the tropospheric NO2 VCD for validation of simultaneous satellite observations from the OMI instrument and found a good agreement of the spatial patterns. The absolute values show a reasonably good agreement. However, OMI data tends to underestimate the tropospheric NO2 VCDs in regions with high pollution levels, and tends to overestimate the tropospheric NO2 VCDs in more clean areas. These findings indicate possible discrepancies between the true vertical NO2 profiles and the profile assumptions in the OMI satellite retrieval.
Citation: Shaiganfar, R., Beirle, S., Sharma, M., Chauhan, A., Singh, R. P., and Wagner, T.: Estimation of NOx emissions from Delhi using car MAX-DOAS observations and comparison with OMI satellite data, Atmos. Chem. Phys. Discuss., 11, 19179-19212, doi:10.5194/acpd-11-19179-2011, 2011.