An HWRF Model Evaluation of Boundary Layer Thermodynamic Structure in Hurricane Maria Using NOAA Dropsonde and UAS Coyote Measurements

The tropical cyclone boundary layer produced by forecast models can be difficult to verify in the eyewall due to the lack of observations in that region. NOAA's P-3 Hurricane Hunter aircraft have been used to deploy unmanned aircraft system (UAS) Coyotes which are capable of continuously sampling the boundary layer in an eyewall. During missions into Hurricane Maria in 2017, UAS Coyotes collected in-situ observations in this data-sparse region, during which numerous dropsondes were also deployed. These Coyote observations and coincident dropsonde profiles provide a novel dataset to assess the boundary layer thermodynamic structure in HWRF model forecasts of Hurricane Maria. Equivalent Coyote tracks and dropsonde profiles are simulated from multiple 48-hour forecast fields by normalizing the Coyote and dropsonde paths performed in Hurricane Maria using storm relative radial and azimuthal locations. Once evaluated, these data are assimilated and new forecasts are generated. This study focuses on evaluating the hurricane boundary layer thermodynamic structure in Hurricane Maria using comparisons of observed data and their simulated counterparts at various forecast lead-times.