Synoptic characteristics and ozone distributions associated with spring dust classes over the northern Arabian Peninsula

Abstract

The spring season can be classified into five dust classes over the northern Arabian Peninsula (AP), and they range from free (represented 3.3% of measured period) to strong (represented 21.4% of measured period) and were categorized based on their Total Ozone Mapping Spectrometer (TOMS) aerosol index (AI) values. The horizontal distribution of total ozone and the synoptic characteristics of these classes were analyzed using the TOMS total ozone and National Centers for Environmental Prediction (NCEP)/National Center for Atmospheric Research (NCAR) reanalysis meteorological data. The horizontal distribution of total ozone for the dust classes indicated that ozone increased (from 260 DU for dust-free to 280 DU for strong dust classes) over the southern study region. Meanwhile, the amount (from 380 DU for the dust-free to 360 DU for strong dust classes) and gradient of ozone decreased over the subtropical region as the dust class intensified, and the concentration of ozone toward the southern region was related to weak dust classes. The synoptic study indicated that the dust systems over the northern AP intensified when the atmospheric conditions were favorable for deepening the surface low pressure or a trough influenced the area and an upper-level pronounced trough and ridge occurred over the eastern and western AP. An examination of the dust cases indicated that the synoptic features that occurred with dust over the northern AP did not occur via the atmospheric systems themselves but rather via the relative relationships between these systems. Furthermore, the results confirmed that ozone over the northern (southern) AP decreased (increased) as the dust features strengthened (weakened).