Near-Inertial Current Variability During the Coastal Mixing and Optics Experiment, August 1996 through June 1997.

Observations from the Coastal Mixing and Optics moored array (deployed from August 1996 through June 1997) are used to describe near-inertial current variability over the New England shelf. Inertial band current variability is large, approximately 20% of the total observed variance, and episodic with peak speeds exceeding 40 cm~s^-1 Near-inertial current variability during CMO is characterized by a first baroclinic mode vertical structure and constant phase over 20 km separations. Several characteristics of inertial current variability co-vary with the seasonal variation in stratification over the New England shelf. Inertial band variability is stronger during stratified periods (late spring through early fall). The vertical structure is surface intensified during spring when stratification is also surface intensified. Episodes of inertial variability during the fall occur at subinertial frequencies (5-10% less than the local inertial frequency, f), while spring variability occurs at or above the inertial frequency. Wavelet analysis is used to identify the intrinsic frequency of bursts of inertial variability and compared to the effective inertial frequency estimated from the subtidal relative vorticity. Relative vorticity over the shelf during fall is approximately -0.05f, due to a seasonal strengthening of the along-shelf flow and cross-shelf gradients. The intrinsic and effective inertial frequencies are very similar