Spatio-temporal analysis of aerosol optical depth and its response to drought and climatic variables in an arid environment: a case study of Saravan County, Iran

Abstract

Saravan County, a significant date-producing region in Iran, has experienced an increasing frequency and intensity of dust storms in recent years. These events pose substantial threats to the regional economy, agricultural productivity, and public health. Prior research indicates that dust storms in this area are associated with a 30-40% reduction in Mazafati date yields, a notable decrease in fruit total sugar content, and a 40% increase in respiratory-related medical center visits. This study investigates the spatiotemporal variations of dust Aerosol Optical Depth (AOD) in Saravan County, Sistan and Baluchestan Province, over a period (2000-2022). MODIS satellite data (1 km resolution AOD product) and climatic and hydrological indices were employed to analyze trends and spatial correlations within a GIS environment. The Mann-Kendall test revealed significant increasing trends (p < 0.05) for the Palmer Drought Severity Index (PDSI), precipitation, evapotranspiration, maximum temperature, wind speed, and AOD, whereas minimum temperature exhibited a decreasing trend. Spatial correlation analysis indicated a negative correlation (r = −0.45 to −0.68) between AOD and precipitation, runoff, and soil moisture indices. Conversely, evapotranspiration, maximum temperature, minimum temperature, and wind speed indices displayed a positive correlation (r = 0.52 to 0.79) with AOD. The novelty of this study lies in mechanistically explaining the climatic paradox of how the region is becoming dustier despite a trend toward wetter conditions, identifying escalating thermal stress as the dominant driver over precipitation in this hyper-arid, economically sensitive environment.