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Abstract

The Salton Sea is a large endorheic lake in southeastern California that is drying, thus exposing portions of the lakebed that were once submerged. This lakebed, known as playa, emits both gases and particles into the atmosphere that have adverse effects on local air quality. Aircraft data from the 2019 NASA Student Airborne Research Program (SARP) are used to determine the vertical distribution and classification of aerosols over the Salton Sea. During a high-altitude pass at 3,200 meters over the Salton Sea, the Differential Absorption LIDAR (DIAL) instrument was used to analyze aerosol optical properties. Following this, a lower altitude pass at 320 meters provided an opportunity to validate DIAL data through comparison with the in-situ Langley Aerosol Research Group (LARGE) instrument as well as the NOAA In-Situ Measurements of Aerosol Optical Properties (NOAA-AOP) instrument. We reference a published algorithm which classifies aerosols into eight types based on the lidar ratio at 532 nm, backscatter color ratio, aerosol depolarization spectral ratio, and aerosol depolarization at 532 nm. By further dividing the Salton Sea into two geographic regions, we analyze the different aerosol types that make up the vertical layers in the lowest kilometer of the atmosphere. We identify three altitude ranges at 200 m, 500 m, and 800 m to observe how different aerosols occupy the atmosphere near the surface. Further in-situ data from the Proton Transfer Reaction Time of Flight Mass Spectrometer (PTR-ToF-MS) instrument, and Whole Air Sampling (WAS) canister samples are used to evaluate the chemical characteristics of the atmosphere in the region. The lowest 200 meters of the atmosphere in the region is shown to be impacted by the Salton Sea as aerosol at this elevation shared similar optical and chemical properties to maritime aerosol. Gas phase analysis of the 200-meter layer shows high levels of dimethyl sulfide (DMS) in regions around the Salton Sea further demonstrating the maritime characteristics present in the region. On the other hand, at 800 meters, the northern region of the Salton Sea has a layer resembling urban aerosol. The southern region at 800 meters contains smoke aerosol which is likely the result of transport from a nearby wildfire. The observation of maritime aerosol over the Salton Sea is a new discovery that requires consideration in future aerosol classification studies over this and other inland saline lakes.

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