A Comprehensive Analysis of Aerosol Optical Depth Changes on Diurnal, Synoptic, and Seasonal Timescales over the Texas Panhandle: Insights into Aerosol – Boundary Layer Interactions in an Arid Region

The ongoing changes in the Earth's climate and the resulting global warming have blurred the demarcations between short-term weather events and long-term climatological patterns, leading to a continuous range of atmospheric processes.Central to understanding this continuum are the meteorological processes unfolding within the atmospheric boundary layer (ABL), a vital zone situated approximately 1-2 kilometers above the Earth's surface. This layer serves as a reservoir for various natural and anthropogenic pollutants, including aerosols. The uncertainty surrounding the estimated radiative forcing due to the interaction of anthropogenic aerosols and radiation is a prominent challenge within climate models. Notably, the most substantial warming observed over the last century transpired in drylands. In both arid and semi-arid regions, dust is a prominent anthropogenic aerosol which significantly impact the Earth's albedo. However, a comprehensive estimation of the resulting radiative forcing in these regions remains elusive, primarily due to lack of high-resolution aerosol observations.

Our goal is to investigate how both synoptic and mesoscale processes influence aerosol characteristics and the efficacy of ABL thermodynamics in governing the aerosols and radiation interactions in drylands. The Southern High Plains Plateau, particularly the Texas panhandle, provides an ideal setting for examining the influence of aerosol transport and associated physicochemical changes on aerosol optical thickness (AOT) at different wavelengths (i.e., for various sizes) within the ABL because of frequent frontal and dryline passages, particularly during spring and early summer months (Feb-June). A new Aerosol Robotic Network (AERONET) site has been recently (June 2023) established in Lubbock, Texas, within an initiative of NASA’s mission for Increasing Participation of Minority Serving Institutions (IPMSI) to obtain high-resolution AOT observations in west Texas. In the first phase of our study, an intercomparison framework has been established using the Visible Infrared Imaging Radiometer Suite (VIIRS) AOT products, on board the Suomi National Polar-orbiting Partnership (S-NPP) and the Joint Polar Satellite System Program (JPSS-I/NOAA-20) satellite, and the corresponding spatiotemporal AERONET AOT L2 product. The data was collected from the satellite archive and 11 operational AERONET sites over the study region between 1 Jan to 31 Dec 2022. We explored this intercomparison to reveal the relationship between aerosol types and the uncertainty and high bias in VIIRS aerosol products during dryline passages, attributable to a large change from lower AOT to presumably high aerosol loading from westerly-southwesterly flows which brings an abundance of anthropogenic dust from the semi-arid agricultural regions. We further investigated the ABL thermodynamic features such as the modifications in surface temperature, relative humidity, incident direct shortwave radiation, and ABL depths during these events by leveraging the high-resolution measurements obtained from the 150 surface stations comprising the West Texas Mesonet, and available radiosonde and lidar measurements. The results from this study will offer new insights into refining ABL parameterizations to enhance the accuracy of weather and climate forecasting.