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) in,the tropical cyclone (TC) lifecycle with a focus on the rapid intensification (RI) process and (2) to estimate free parameters in tu,rbulence parameterization schemes used in numerical models and evaluate their impacts on forecasts of TC RI. The proposed effort wil,l analyze new radar remote sensing measurements in the TCBL 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) w,inds (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 ho,rizontal/vertical dimensions. Excellent quality data from IWRAP during the 2019 and 2020 hurricane seasons are available for severa,l notable storms including: Hurricane Dorian (2019), Hurricane Laura (2020), Hurricane Teddy (2020), Hurricane Delta (2020) and oth,ers. While this data is sufficie,s of the 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 as,sociated with the CTSs and (2) the turbulent fluxes of momentum from flight level down into the surface layer. Furthermore, to impr,ove mesoscale numerical models used by the Navy and to evaluate large eddy simulations, the proposed project will estimate free para,meters 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 B,L. I have had direct interactions with team members Richter,Zhang and Foster to demonstrate the value of the IWRAP data and the plan,ned analysis contained in this proposal. All of these team members found this work to be very compelling for advancing TC science a,nd significantly enhancing their own projects. Dr. David Richter is working on large eddy simulations of the TC BL to understand s,urface fluxes of enthalpy and momentum. Knowledge of the 3D wind field and turbulent momentum fluxes throughout most of the TC BL, w,hich will be analyzed as part of this proposal, will help Richter motivate and evaluate his surface flux simulations. Dr. Jun Zhan,g is evaluating COAMPS simulations of TCs with traditional in situ observations. The IWRAP data will be of clear value to this effo,rt 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 visc,osity 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
- Jan 14, 2022
- Source ID
- N000142212078
Entities
People
- Stephen R. Guimond
Organizations
- Office of Naval Research
- United States Navy
- University of Maryland, Baltimore County