Abstract:
Satellite remote sensing provides important observational constraints for monitoring dust life
cycle and improving the understanding of its effects on local to global scales. The present
work analyses the dust-aerosol patterns over the arid environment of the Sistan region-in
southeastern Iran, by means of multiple satellite platforms aiming to reveal the spatiotemporal
distribution and trends. The dataset includes records of Aerosol Index (AI) from
Total Ozone Mapping Spectrometer (TOMS) (1978–2001) and 6-year AI records from the
Ozone Monitoring Instrument (OMI) aboard Aura. Moreover, the aerosol optical depth
(AOD) is analyzed through 11-year records from Multi-angle Imaging Spectro-Radiometer
(MISR) aboard Terra (2000-2010) and from Moderate Resolution Imaging Spectroradiometer
(MODIS) onboard Terra (2000-2007) and Aqua (2002-2011). The main focus is to determine
similarities and differences in dust variability over southwest Asia, in general, and the Sistan
region, in particular. The results show a marked seasonal cycle with high aerosol loading
during summer and lower in winter, while MISR, MODIS and TOMS/OMI observations
agree in both terms of monthly and seasonally mean spatial and temporal patterns. The higher
aerosol concentrations during summer are interpreted as a result of the combined effect of the
seasonal drying of the Hamoun lakes and the strong northerly Levar winds favoring dust
erosion from the alluvial deposits in Sistan . After prolonged drought period, the dust-aerosol
load over the area has increased in the beginning of the 2000s and decreased after 2004, thereby leading to an overall declining trend during the last decade. Such a trend is absent
during the winter period when dust emission over the region is minimal.
