Spatio-temporal assessment of dust risk maps for solar energy systems using proxy data Yassine Charabi a, * , Adel Gastli b a Department of Geography, College of Arts & Social Sciences, Sultan Qaboos University, P.O. Box 42, Al-Koodh, Muscat, Oman b Department of Electrical and Computer Engineering, College of Engineering, Sultan Qaboos University, Muscat, Oman article info Article history: Received 19 June 2011 Accepted 23 December 2011 Available online 31 January 2012 Keywords: Aerosol optical depth Dust Solar energy Risk map abstract This paper presents a new approach for spatio-temporal assessment of dust risk map for solar energy systems in arid area using proxy open source data. The approach considers the recent NASA satellite data from the Multi-angle Imaging Spectro-Radiometer (MISR) which provides significant information about dust emission, transport, concentration and property evolution, through Aerosol Optical Depth (AOD). The analysis was conducted on Oman as a case study. The dust risk maps were developed based on the spatio-temporal evolution of MISR AOD in blue band (446 nm). These maps showed significant variations of AOD over the year. The summer season presents the highest risk of dust contamination because of the favorable regional weather synoptic conditions for the dispersion of mineral dust and creation of haze conditions. The annual average map of AOD was also developed and compared to the dust emission sources (desert sand locations), and the annual average maps of wind direction and air temperature at 100 m and 2 m above the ground, respectively. These maps show a good correlation between dust emission sources, wind and temperature profiles, and high atmospheric dust concentration captured by AOD. Finally, the impact of dust constraint on solar energy resource assessment and systems siting was investigated for Oman. It was found that a considerable reduction (64%) of the highly suitable land is obtained after consideration of dust concentration constraint. Ó 2011 Elsevier Ltd. All rights reserved. 1. Introduction The most favorable solar belt is lying between latitudes 15  and 35  North and South equator, embraces arid regions that are naturally endowed with the most favorable conditions for solar energy applications. These arid regions are characterized by having the greatest amount of solar radiation, more than 90% of which comes as direct radiation because of the limited cloud coverage and rainfall (less than 200 mm per year). Likewise, there is regularly over 3000 h of sunshine per year. For this reason they can count on solar radiation as a steadfast source of energy that can be readily exploited for a multitude of purposes. Beyond the availability of solar energy in abundance in these arid regions, the harness of solar radiation faces critical environ- mental risk mainly related to mineral dust deposition which can reduce considerably the revenue of any solar energy systems. The contamination of the solar collectors of any solar energy systems by dust deposition, leads to degradation of their optical properties with corresponding losses of efficiency and resulting in negative economic impact. The movement of a mineral dust particle, according to specific size and speed, is an efficient erodible agent that can affect the optical proprieties of any solar energy system which will require frequent cleaning using generally fresh water. Because of the general scarcity of fresh water in desert and semi- desert zones, this commodity should not be stressed or wasted for cleaning [1]. The general problems of collector surface maintenance have been reviewed in [2,3]. The optical effects of small particles of various sizes have been discussed in [4,5] and in a number of other papers. Typical sizes of particles in the atmosphere have been discussed in [6] and systematic measurements of the deposition velocities and fluxes of particulate contamination on the output of photovoltaic cells and performance of evacuated tube collectors, have been studied in [7,8] respectively. A computerized microscope system, for studying the physics of dust particles which adhere to various kinds of surfaces such as those of solar collectors have been developed in [1]. Dust accumulation on glass plates with different tilt angles have been studied and the transmittance of the plates under different climatic conditions have been measured in Mina, * Corresponding author. E-mail addresses: yassine@squ.edu.om (Y. Charabi), gastli@squ.edu.om (A. Gastli). Contents lists available at SciVerse ScienceDirect Renewable Energy journal homepage: www.elsevier.com/locate/renene 0960-1481/$ e see front matter Ó 2011 Elsevier Ltd. All rights reserved. doi:10.1016/j.renene.2011.12.005 Renewable Energy 44 (2012) 23e31