Analysis of thermal inversions in the Khareef Salalah region in the Sultanate of Oman

Meteorology and topography (shape of the land) are two of the most important environmental factors that control the movement of pollutants in the atmosphere. A well-known example of the importance of topography and meteorology is the so-called monsoon season in Salalah (Khareef Salalah) in the Sultanate of Oman. The purpose of this paper is to investigate the role of the elevated stable layer, particularly during monsoon season in Salalah. The study addresses the statistical analysis of inversion parameters. It will also improve our common understanding of the monsoon and how it is dominated by inversions. In this work, the monthly characteristics of inversions are investigated using the daily radiosonde measurements to a height of 2 km over a period of 1 year. Both surface-based and elevated inversions are investigated. Based on the analysis of data recovered from weather balloons, the study shows a strong monthly change in inversion frequency, depth, and strength. Overall, inversions are less common in summer (55.4% in May) than in winter (82.8% in January). The surface-based inversion frequency is at a minimum in summer and at a maximum in winter. The surface-based inversions reach a maximum depth in winter and are almost absent during summer. An opposite trend in elevated inversion is seen. Most summer inversions are elevated, and a maximum in their frequencies is found during May to September. The elevated inversions are generally deeper and stronger than the surface-based inversions. The correlation coefficient for the relationships between the inversion depth and temperature difference across the inversion was determined for both the surface-based and elevated inversions. It was 0.82 for the surface-based inversion, whereas it was appreciably lower (0.39) for the elevated inversion. Moreover, the correlation coefficient between the log inversion depth and the log temperature difference across the elevated inversion was high (i.e., 0.75).