Publications

Alsubhi, AS; Alsubhi, YH (2025). Seasonality of dust optical depth over Arabian Peninsula using MIDAS data. INTERNATIONAL JOURNAL OF REMOTE SENSING.

Abstract
We assess the spatiotemporal dynamics and overall seasonality of dust optical depth (DOD) at 550 nm, and their trend changes over the 2003-2017 period for the Arabian Peninsula. For this, we employ columnar daily mid-visible (550 nm) total DOD (totDOD) at fine spatial resolution (0.1 degrees x 0.1 degrees) from the MIDAS (ModIs Dust AeroSol) dataset (2003-2017), which combines the aerosol optical depths from the Moderate Resolution Imaging Spectroradiometer (MODIS)-Aqua with the dust fractions from the Modern-Era Retrospective Analysis for Research and Applications, version 2 (MERRA-2) reanalysis. We analysed the overall seasonality using a dimensionless seasonality index (SI), obtained by multiplying the information theory-based relative entropy (RE) that measures the distance of the actual totDOD distribution relative to the clear-sky totDOD distribution with annually integrated totDOD intensities. For trend analysis, we employed the Mann-Kendall trend test to detect trends and Theil-Sen's slope method to find their true slopes. Our results suggest that the totDOD is generally lower than 0.1 between November and January suggesting clear-sky but higher than 0.2 between February and October indicating dusty-sky conditions, although varying across the countries. The magnitude and timing of peak totDOD over Saudi Arabia is similar to that of the Arabian Peninsula. For the rest, the magnitude of the peak ranges between 0.28 over Jordan and 1.93 over Bahrain and occurs during April and August, with smaller states featuring higher magnitude occurring later in the year. The seasonality index is generally higher, reaching 1.0, except for Rub' al Khali, the northwestern KSA and Jordan, where SI values are around 0.2. Besides low RE estimates, the SI over the Arabian Peninsula is generally higher due to higher totDOD levels where both RE and SI feature positive trends, indicating appreciable seasonality which is increasing in the future.

DOI:
10.1080/01431161.2025.2496534

ISSN:
1366-5901