In situ observations of submesoscale open ocean wave variability due to currents
Abstract
Accurately predicting open ocean surface waves is critical to safety at sea, efficiency of maritime activities, and anticipation ofdownstream impacts to coastlines and coastal communities. Our capacity to predict surface waves is limited by both fundamental understanding of the complex dynamics at the air-sea interface (e.g., wave-current interactions) and the methodology to utilize that theory within a heavily parameterized modeling system such as a typical global spectral wave model. Of specific value to maritime safety and efficiency is the impact of currents on the wave field, including modification of the distribution of expected wave heights and an associated increased risk of extreme waves in regions with strong currents. However, the difficulty of observing submesoscale surface currents along with the co-located wave state in situ has limited full understanding of these complex interactions and subsequent parameterizations.In this work, we will use novel instruments to obtaina long-dwell dataset of in situ co-located observations of surface waves and surface currents. The Spotter buoy platform will be augmented with a current meter to observe #buoy slippage# and estimate the Eulerian surface current from the Lagrangian velocity of the buoy. The onboard wave processing will be augmented to estimate statistics of the wave height distribution in addition to the existing wave spectra. With this combined observation set, the hypothesis that a local time series of current velocities can be related to deviations in the expected wave height distribution will be tested. Further, a predictive parameterization for the impact of currents on the wave height distribution (e.g., increased probability of high individual wave heights) will be developed and evaluated. This parameterization would then be formulated for utilization with inputs from a global current product and third generation spectral wave model (e.g., WAVEWATCH III) to arrive at reliableestimates of the sea state for use in, for example, maritime navigation.This work would yield a historically unavailable observation dataset of open ocean co-located current and wave observations in an energetic region (e.g., Agulhas, Southern Ocean or North Atlantic). This would advance prior work limited to coastal observation platforms and regional basins (e.g., the North Sea) to enable progress in understanding the complex dynamics in the historically under-observed open ocean. Beyond the analysis in this work, this dataset has relevance across many applications investigating Lagrangian dynamics, intercomparison with satellite products and model outputs, and data assimilation. The hardware development, novel dataset and enhanced parameterizations produced in this work will directly address the Physical Oceanography program objectives of research on ###Lagrangian dynamics and transport at the submesoscale and smaller# and #novel uses of existing or emerging remote, autonomous or in-situ instruments, and the use of such data to improve ocean state predictions#.
Document Details
- Document Type
- DoD Grant Award
- Publication Date
- Nov 09, 2024
- Source ID
- N000142412592
Entities
People
- Isabel Houghton
Organizations
- Office of Naval Research
- United States Navy