The Signature of Inertial and Tidal Currents in Offshore Wave Records

Abstract

he roughness of the sea surface can be affected by strong currents. Here, long records of surface wave heights from buoy observations in the northeastern Pacific Ocean are examined. The data show the influence of tidal currents, but the first evidence of wave-height modulation (up to 20%) at a frequency that is slightly higher than the local inertial frequency is also found. This finding shows the effect on surface waves of near-inertial currents, which are typically the most energetic currents in the open ocean. The result has implications for wave forecasting but also provides valuable information on the frequency, strength, and intermittency of the associated near-inertial motions.