Ocean Response to a Hurricane. Part 2. Data Tabulations and Numerical Modeling
Abstract
Field observations of the ocean's forced stage response to hurricanes Norbert (1984), Josephine (1984) and Gloria (1985) are analyzed and presented in a storm centered coordinate system. Data are simulated with two different numerical ocean models. All 3 hurricanes had a non-dimensional speed of O(1) and produced a strongly rightward biased response of the ocean surface mixed layer (SML) transport and current. This asymmetry arises because the wind stress vector rotates clockwise on the right side of the track and remains nearly parallel with the inertially rotating SML current during most of the hurricane passage. The maximum layer-averaged SML currents varied from 0.8 m/s in response to Josephine, a fairly weak hurricane, to 1.7 m/s in response to Gloria which was much stronger. In these cases the current amplitude is set primarily by the strength of the wind stress and its efficiency of coupling with the SML current, and the depth of vertical mixing of the SML - - all of which are local phenomena that can be accounted for in a one-dimensional model. However, in the Norbert case where the SML Burger number was appreciable, the SML current was also affected by significant pressure - coupling with the thermocline - - an inherently non-local phenomenon. Observations and results from a three- dimensional simulation model show appreciable upwelling by inertial pumping and strong thermocline - depth currents, up to 0.3 m/s, under the trailing edge of Norbert. The observed SML current has a vertical shear in direction of the local wind of about 0.01/s beneath the high stress regions of the hurricanes.
Document Details
- Document Type
- Technical Report
- Publication Date
- Jan 01, 1991
- Accession Number
- ADA236059
Entities
People
- George Z. Forristall
- James F. Price
- Thomas B. Sanford
Organizations
- Woods Hole Oceanographic Institution