Atmos. Chem. Phys. Discuss., 13, 21837-21881, 2013
www.atmos-chem-phys-discuss.net/13/21837/2013/
doi:10.5194/acpd-13-21837-2013
© Author(s) 2013. This work is distributed
under the Creative Commons Attribution 3.0 License.
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This discussion paper has been under review for the journal Atmospheric Chemistry and Physics (ACP). Please refer to the corresponding final paper in ACP.
WRF-Chem simulations of a typical pre-monsoon dust storm in northern India: influences on aerosol optical properties and radiation budget
R. Kumar1,2, M. C. Barth2, G. G. Pfister2, M. Naja3, and G. P. Brasseur1,4
1Advanced Study Program, National Center for Atmospheric Research, Boulder, USA
2Atmospheric Chemistry Division, National Center for Atmospheric Research, Boulder, USA
3Aryabhatta Research Institute of Observational Sciences, Nainital, India
4Climate Service Center, Helmholtz Zentrum Geesthacht, Hamburg, Germany

Abstract. The impact of a typical pre-monsoon season (April–June) dust storm event on the regional aerosol optical properties and radiation budget in northern India is analyzed. The dust storm event lasted from 17 to 22 April 2010 and the WRF-Chem model estimated total dust emissions of 7.5 Tg over the model domain. Both in situ (AERONET) and satellite observations show significant increase (>50%) in local to regional scale aerosol optical depth (AOD) and decrease (>70%) in the Angström exponent (α) during this period. Amongst the AERONET sites in this region, Kanpur was influenced the most where the AOD reached up to 2.1 and the α decreased to −0.09 during the dust storm period. The WRF-Chem model reproduced the spatial and temporal distributions of dust plumes and aerosol optical properties but generally underestimated the AOD. The average MODIS and WRF-Chem AOD (550 nm) values in high dust laden region are estimated as 0.80 ± 0.30 and 0.68 ± 0.28, respectively. Model results show that dust particles cool the surface and the top of the atmosphere, and warm the atmosphere. The regionally averaged radiative perturbation due to dust aerosols is estimated as −2.0 ± 3.0 W m−2 at the top of the atmosphere, 2.3 ± 1.8 W m−2 in the atmosphere and −4.4 ± 3.1 W m−2 at the surface. The impact of these radiative perturbations on the surface energy budget is estimated to be small on a regional scale but significant locally.

Citation: Kumar, R., Barth, M. C., Pfister, G. G., Naja, M., and Brasseur, G. P.: WRF-Chem simulations of a typical pre-monsoon dust storm in northern India: influences on aerosol optical properties and radiation budget, Atmos. Chem. Phys. Discuss., 13, 21837-21881, doi:10.5194/acpd-13-21837-2013, 2013.
 
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