Spatiotemporal variations and long term trends analysis of aerosol optical depth over the United Arab Emirates

This research provides a comprehensive long term time series analysis of the spatiotemporal variability of aerosol optical depth (AOD) over the United Arab Emirates (UAE) using MODIS (Moderate-resolution imaging spectroradiometer) MAIAC (Multi-Angle Implementation of Atmospheric Correction) AOD (aerosol optical depth) product for the period 2003-2018. The UAE is located in one of the driest places on earth, the Arabian Peninsula, with two large extended desert regions that form major atmospheric dust sources in the world. The atmospheric dust emitted by these vast deserts is transported locally and regionally and it is the primary major contributor to the overall aerosol optical depth in this area. The investigation of the spatiotemporal trends of AOD over the UAE showed a significant obvious annual seasonal variability. Results showed a significant increase in AOD during summer due to high wind speed, resulting in scattered events of small to large scale haboobs within the study area, high temperature, and high relative humidity. The increased humidity levels are due to increased temperatures in the summer season leading to significant evaporation from the neighbouring water bodies (mainly the Arabian Gulf and the Sea of Oman) leading to a significant increase in water vapour levels in the atmosphere. Summar AOD values during the study period ranged between 0.42 - 0.73. The second highest AOD was observed in spring followed by winter. Spring AOD values ranged between 0.33-0.58 and winter values ranged between 0.25 - 0.41. The spatial distributions of AOD showed higher values over the coastal and desert areas. Coastal areas portrayed higher values as well likely due to the high levels of evaporation and increased anthropogenic activities such as coastal urban developments and automobile pollution. Time series analysis of the multitemporal dataset confirmed the SARIMA forecast model as the best fit which can be used to provide an accurate and reliable monthly forecast for the AOD concentrations in the UAE.