Capturing the Transition Between Saharan Air Layer and Convective Environments Using Radio Occultation

The Saharan Air Layer (SAL) has gained more prominence in recent years as its influence on air quality and tropical cyclone intensification are better understood. Previous studies have typically researched the SAL by measuring infrared radiation (IR) from multiple levels in the atmosphere, yet if there are clouds present above the SAL it cannot be accurately sampled. However, radio occultation (RO) profiles taken from the Constellation Observing System for Meteorology, Ionosphere, and Climate (COSMIC-2) satellite can create vertical profiles of the atmosphere regardless of cloud cover, similar to an atmospheric sounding. This study used RO to investigate the transition between SAL and convective environments along the southern edge of the SAL in the Atlantic Basin. Approximately 135 RO profiles from the Atlantic Basin were taken during the peak month of SAL activity (July) in 2022 to sample SAL and convective environments. RO profiles were overlaid with Cooperate Institute for Meteorological Satellite Studies (CIMSS) SAL images to identify pairs of profiles, one in convection and the other in SAL, up to 5° apart from each other. Skew-T diagrams of these profile pairs were plotted for 9-11 July 2022. 56 averaged SAL and convective profiles show near saturation in 250-150 mb levels consistently, potentially depicting cirrus clouds from tropical deep convection. Results suggest elements of both environments are present in many profiles, but analysis of more SAL events across a longer period, as well as insights into its thermodynamics are needed to investigate these interactions in-depth.