Numerical investigation of coastal circulation dynamics near Cape Hatteras, North Carolina, in January 2005

Abstract

A realistic regional ocean model is used to hindcast and diagnose coastal circulation variability near Cape Hatteras, North Carolina, in January 2005. Strong extratropical winter storms passed through the area during the second half of the month (January 15–31), leading to significantly different circulation conditions compared to those during the first half of the month (January 1–14). Model results were validated against sea level, temperature, salinity, and velocity observations. Analyses of along-shelf and cross-shelf transport, momentum, and kinetic energy balances were further performed to investigate circulation dynamics near Cape Hatteras. Our results show that during the strong winter storm period, both along-shelf (southward) and cross-shelf (seaward) transport increased significantly, mainly due to increases in geostrophic velocity associated with coastal sea level setup. In terms of momentum balance, the wind stress was mainly balanced by bottom friction. During the first half of month, the dominant kinetic energy (KE) balance on the shelf was between the time rate of KE change and the pressure work, whereas during the stormy second half of month, the main shelf KE balance was achieved between wind stress work and dissipation.