MURI SASCWATCH: Study on Air-Sea Coupling with WAves, Turbulence, and Clouds at High winds 23-000005369
Abstract
Air-sea fluxes at high winds have long been highly uncertain due to the complex processes involved and the difficulties in making observations in hazardous conditions, yet their characterization is crucial for understanding and forecasting extreme weather events such as tropical cyclones (TCs). Given its importance to naval operations, the Office of Naval Research has a long history of supporting fieldwork, theoretical analysis, and numerical modeling aimed at gaining physical insight and improved parameterizations, and these studies have largely formed the foundation of what is currently known about air-sea transfer at high winds. Despite this, however, roadblocks in two key areas continue to plague efforts in reducing uncertainty in the high-wind air-sea flux coefficients neededfor accurate model forecasts: surface waves and boundary layer turbulence. Within TCs, neither the surface wave spectral propertiesnor near-surface turbulence statistics have been directly characterized in a comprehensive way, and many efforts to estimate fluxesrely on inferences or untested assumptions. The next frontier in understanding the complex ocean-wave-atmosphere coupled system requires a detailed investigation of turbulence and waves within TCs, using a suite of observational and simulation tools. The proposedwork will fill this gap.A diverse team of PIs and collaborators has been established to tackle this longstanding problem, pulling in expertise in extreme-weather observations, air-sea interaction, turbulence simulation, coupled modeling, and TC meteorology. Thereare two main thrusts to the proposed work: observational missions targeting direct measurements of wave properties and direct flux measurements, and numerical modeling efforts aimed at both resolving the physics associated with turbulence and spray within the TC boundary layer, as well as the complete ocean-wave-atmosphere coupled mesoscale modeling. The observational efforts will consist of two flights made in each of the first three years of the proposed work. The first of these flights is #heavy#, where 166 instrumentswill be deployed ahead of and within a TC to provide spatially dense and contemporaneous measurements of directional wave spectra and ocean mixed layer properties made before, during, and after storm passage. This includes a combination of EM-APEX and ALAMO floats, ADWSD drifters, dropsondes and AXBTs, and an sUAS. The #light# deployment will include a smaller subset of these. These measurements will be done in coordination with the USAFR 53rd WRS and NOAA HRD, as the PIs have extensive experience working with both, and will be supplemented by aircraft (NOAA P-3 and USAF WC-130J) measurements typically made in the same storms. These measurements will provide the first-ever spatial map of spectral wave properties under a TC, along with a suite of atmospheric measurements made directly above, and facilitate a leap forward in our understanding of wind-wave alignment and storm-relative dependence of drag and scalar fluxes. These measurements will be complemented by coupled ocean-wave-atmosphere modeling using the SKRIPS coupled model, where the observed storms can be systematically dissected in terms of the relevant physical processes required for accurate model representation. In addition, a suite of large-eddy simulation (LES) idealized studies will be conducted using the NTLP and CM1 models, for directly testing the role of turbulence and spray on air-sea fluxes. Broadly, the project objectives are to measure, simulate, and ultimately quantify the role of waves and turbulence in high-wind air-sea fluxes, and provide a seamless transition from low to high winds, both in terms of process-level insight as well as model parameterization. With this, current and future DoD efforts to better predict maritime environmental conditions will benefit, protecting life and property.Approved for Public Release
Document Details
- Document Type
- DoD Grant Award
- Publication Date
- Nov 08, 2024
- Source ID
- N000142412554
Entities
People
- David H Richter
Organizations
- Office of Naval Research
- United States Navy
- University of Notre Dame