Investigations on the seasonal and inter-annual variations of the atmospheric aerosol optical depth in the United Arab Emirates using MODIS satellite data

Air pollution has a significant impact on human health. Aerosols or particulate matter (PM) with aerodynamic diameter less than 2.5 μm (PM2.5) is especially of major concern to human health because they can be inhaled easily into the lungs and cause serious respiratory health problems. It has been observed in the UAE that short-term exposures to common air contaminants such as fine particulate matter are linked with increased hospital admissions due to cardio-respiratory conditions, increased emergency room visits and work/school absenteeism, increased respiratory symptoms and decreased lung function. Long-term exposure is associated with increased deaths due to cardio-respiratory conditions, permanently damaged lung function, increased number of people with lung cancer, and increased premature births and low birth weight. The formation of such pollutants depends upon the sources of their precursors (natural or anthropogenic). The challenges of meeting air quality standards are impacted by identifying theses sources and further the trans-borders transport of the pollutants. Air quality monitoring has been always achieved with networks of ground monitoring stations and the use of models that evaluate emissions and predict changes in air quality. However, these ground monitors often miss pollution that is not within the sampling area of the measurement and are unable of capturing pollution for a large area. Satellite remote sensing is a viable method for monitoring air pollution over a large spatial extent on continuous basis. Advancement in satellite remote-sensing techniques has opened new corridors for the monitoring and mapping of air pollution over large regions. Currently, there are several satellites in orbit that have instruments suited for air quality measurements. This research project uses the Moderate Resolution Imaging Spectroradiometer (MODIS) atmospheric aerosol optical depth (AOD) product, as an indicator of air pollution, for investigating its seasonal and inter-annual variability over the United Arab Emirates (UAE). The research helps to highlight the formation of air pollutants (particulate matter) natural or anthropogenic in the UAE, their seasonal and inter-annual variability and spatial distribution. In this regard, the AOD images over the UAE were analysed from 2006-2015 along with corresponding meteorological observations of air temperature, wind speed, air pressure for the same period. The preliminary findings indicate significant rise of AOD during the summer period due to increased wind speed and high temperatures. The spatial distribution of AOD over the UAE shows that AOD is not particularly higher in desert areas as previously thought, but along coastal regions due to increased humidity and water vapour content during the summer months. Furthermore, AOD in the UAE is primarily influenced by climatic conditions than industrial anthropogenic effects particularly from the hydrocarbon industries.