%0 Journal Article
%T Impact of Two Intense Dust Storms on Aerosol Characteristics and Radiative Forcing over Patiala, Northwestern India
%A Deepti Sharma
%A Darshan Singh
%A D. G. Kaskaoutis
%J Advances in Meteorology
%D 2012
%I Hindawi Publishing Corporation
%R 10.1155/2012/956814
%X 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 AOD550 and Microtops-II AOD500 over Patiala as and , respectively while Aura-OMI AI exhibits high values ranging from 2.01 to 6.74. The £¿ngstr£¿m coefficients ¦Á380¨C870 and ¦Â 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£¿2AOD£¿1 at SRF and £¿14£¿Wm£¿2AOD£¿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. 1. Introduction Atmospheric aerosols exert climate forcing by perturbing the Earth¡¯s radiative balance directly by extinction of the solar and Earth radiation and, indirectly, by acting as cloud condensation nuclei (CCN) affecting the cloud albedo, cloud lifetime, precipitation rate, and hydrological cycle [1, 2]. Mineral dust aerosols constitute a major fraction of atmospheric aerosols over the globe and have an important role in regulating the global climate [3, 4]. However, considerable uncertainties exist in quantifying the impact of mineral dust on global radiative forcing mainly due to heterogeneous mixture of optical, physical, and chemical properties of dust aerosols [5, 6], in addition to their spatial, vertical, and temporal distributions [7]. The optical properties of dust aerosols vary spatially and temporally due to regional variations of soil characteristics and mixing of dust with other aerosol species, such as black carbon (BC) [8, 9]. Sand and dust storms are widespread natural phenomena that transport dust aerosols to long distances from the source region and represent an important process of land-atmosphere interaction [10, 11]. Apart from perturbing the radiation-energy balance of the Earth-atmosphere system, dust storms also affect atmospheric heating and stability [12], chemical and biological ecosystems [13],
%U http://www.hindawi.com/journals/amete/2012/956814/