Impact of Two Intense Dust Storms on Aerosol Characteristics and Radiative Forcing over Patiala, Northwestern India

Abstract

Impact of dust storms on the aerosol characteristics and radiative forcing over Patiala, northwestern India has been studied during April-June of 2010 using satellite observations and ground-based measurements. Six dust events (DE) have been identified during the study period with average values of Aqua-MODIS AOD 550 and Microtops-II AOD 500 over Patiala as<mml:math xmlns:mml="http://www.w3.org/1998/Math/MathML"><mml:mrow><mml:mn>1.00</mml:mn><mml:mo>±</mml:mo><mml:mn>0.51</mml:mn></mml:mrow></mml:math>and<mml:math xmlns:mml="http://www.w3.org/1998/Math/MathML"><mml:mrow><mml:mn>0.84</mml:mn><mml:mo>±</mml:mo><mml:mn>0.41</mml:mn></mml:mrow></mml:math>, respectively while Aura-OMI AI exhibits high values ranging from 2.01 to 6.74. The Ångström coefficients α 380–870 and β range from 0.12 to 0.31 and 0.95 to 1.40, respectively. The measured spectral AODs, the OPAC-derived aerosol properties and the surface albedo obtained from MODIS were used as main inputs in SBDART model for the calculation of aerosol radiative forcing (ARF) over Patiala. The ARF at surface (SRF) and top of atmosphere (TOA) ranges from ∼−50 to −100 Wm −2 and from ∼−10 to −25 Wm −2 , respectively during the maximum of dust storms. The radiative forcing efficiency was found to be −66 Wm −2 AOD −1 at SRF and −14 Wm −2 AOD −1 at TOA. High values of ARF in the atmosphere (ATM), ranging between ∼+40 Wm −2 and +80.0 Wm −2 during the DE days, might have significant effect on the warming of the lower and middle atmosphere and, hence, on climate over northwestern India.