Understanding the Structure and Role of the Turbulent Boundary Layer in Hurricane Intensity Change
Abstract
The primary scientific goals of this proposal are: (1) to understand the structure and role of the turbulent boundary layer (BL) inthe tropical cyclone (TC) lifecycle with a focus on the rapid intensification (RI) process and (2) to estimate free parameters in turbulence parameterization schemes used in numerical models and evaluate their impacts on forecasts of TC RI. The proposed effort will analyze new radar remote sensing measurements in the TC BL from the Imaging Wind and Rain Airborne Profiler (IWRAP) on the NOAA P3 aircraft. New algorithms and processing of IWRAP data allows the characterization of radar reflectivity and three-dimensional (3D)winds (zonal, meridional, and vertical components) over nearly the full depth of the TC BL at up to 125 m/30 m grid spacing in the horizontal/verticaldimensions. Excellent quality data from IWRAP during the 2019 and 2020 hurricane seasons are available for several notable storms including: Hurricane Dorian (2019), Hurricane Laura (2020),Hurricane Teddy (2020), Hurricane Delta (2020) and others. While this data is sufficient to address the proposal objectives, new data will be included if it becomes available. The focus ofthe IWRAP data analysis will be on characterizing the kinematics of coherent turbulent structures (CTSs) in the TC BL across a range of storm intensities and intensity trends. These structures are believed to play an important role in the nonlinear dynamics of the TC BL and the larger scale vortex through the cycling of enthalpy, momentum and kinetic energy. The collection of IWRAP data described above will allow the first comprehensive study of CTSs in the TC BL including analysis of (1) the circulation patterns associated with the CTSs and (2) the turbulent fluxes of momentum from flight level down into the surface layer. Furthermore, to improve mesoscale numerical models used by the Navy and to evaluate large eddy simulations, the proposed project will estimate free parameters used in turbulence and BL parameterization schemes using the IWRAP data. These free parameters include: (1)turbulent length scales, (2)eddy viscosities and (3)the BL height, which will be examined as a function of radius, azimuth, height, storm intensity and intensity trend. In addition, I propose to collaborate with several existing ONR DRI team members who are also studying the TC BL. I havehad direct interactions with team members Richter, Zhang and Foster to demonstrate the value of the IWRAP data and the planned analysis contained in this proposal. All of these team members found this work to be very compelling for advancing TC science and significantly enhancing their own projects. Dr. David Richter is working on large eddy simulations of the TC BL to understand surface fluxes of enthalpy and momentum. Knowledge of the 3D wind field and turbulent momentum fluxes throughout most of the TC BL, which will be analyzed as part of this proposal, will help Richter motivate and evaluate his surface flux simulations. Dr. Jun Zhang is evaluating COAMPS simulations of TCs with traditional in situ observations. The IWRAP data will be of clear value to this effort due to the nearly full coverage of the TC BL for each radial pass through the storm. The combination of in situ and IWRAP data will enable a comprehensive evaluation of COAMPS and potential tests of new forecasts using these results. Lastly, Dr. Ralph Foster is working on satellite synthetic aperture radar (SAR) analysis of TCs to estimate mean wind and eddy viscosity profiles. Appropriate averaging of the IWRAP 3D wind fields will be useful for validating and extending the results of Foster#s work.
Document Details
- Document Type
- DoD Grant Award
- Publication Date
- Mar 08, 2024
- Source ID
- N000142412130
Entities
People
- Stephen R. Guimond
Organizations
- Hampton University
- Office of Naval Research
- United States Navy