Hurricane Directional Wave Spectrum Spatial Variation in the Open Ocean

TLDR

NASA’s airborne scanning radar altimeter aboard a NOAA WP‑3D hurricane research aircraft acquired open‑ocean wave data on 24 Aug 1998 during Hurricane Bonnie, a large storm with nearly 50 m s⁻¹ sustained winds, about 400 km east of Abaco Island, Bahamas. The study aimed to develop a simple model to predict the dominant wave propagation direction. By partitioning the SRA directional wave spectra, the authors determined the characteristics of the hurricane wave field components and mapped their spatial variation, enabling the model’s development. Sea‑surface directional wave spectra were measured for the first time in all quadrants of Hurricane Bonnie’s inner core over open ocean, revealing waves up to 19 m peak‑to‑trough, dominant propagation at significant angles to the downwind direction, and locations where three comparable‑energy wave fields intersected.

Abstract

The sea surface directional wave spectrum was measured for the first time in all quadrants of a hurricane's inner core over open water. The NASA airborne scanning radar altimeter (SRA) carried aboard one of the NOAA WP-3D hurricane research aircraft at 1.5-km height acquired the open-ocean data on 24 August 1998 when Bonnie, a large hurricane with 1-min sustained surface winds of nearly 50 m s−1, was about 400 km east of Abaco Island, Bahamas. The NOAA aircraft spent more than five hours within 180 km of the eye and made five eye penetrations. Grayscale coded images of Hurricane Bonnie wave topography include individual waves as high as 19 m peak to trough. The dominant waves generally propagated at significant angles to the downwind direction. At some positions, three different wave fields of comparable energy crossed each other. Partitioning the SRA directional wave spectra enabled determination of the characteristics of the various components of the hurricane wave field and mapping of their spatial variation. A simple model was developed to predict the dominant wave propagation direction.