Turbulence-Based Method for Determining Boundary Layer Heights from In-situ Airborne Profiles during ASIA-AQ

The planetary boundary layer confines moisture, turbulence, and locally emitted air pollutants, thus accurately discerning the height of this layer is important for constraining pollutant transport and distribution and improved regional weather and climate forecasting. Traditional methods of boundary layer height (BLH) determination rely on radiosonde measurements of potential temperature profiles. However, these sounding measurements lack the instrumentation needed to characterize the chemical composition of the boundary layer that can be provided by larger airborne platforms. In 2024, the NASA DC-8 flew over the Philippines, South Korea, Taiwan, and Thailand during the Airborne and Satellite Investigation of Asian Air Quality (ASIA-AQ) campaign. Measurements during this campaign included an extensive array of gas, particulate, and meteorological measurements. We will present results of a turbulence-based method using 3D winds to determine the boundary layer height across DC-8 vertical flight profiles, including missed approaches at urban airports. The results from this method were used to develop a boundary layer flag for the campaign, and the computed DC-8 BLHs were compared to mixed layer heights determined by an airborne-based LIDAR system.