Wave and current in extratropical versus tropical cyclones

Data from QuikSCAT, ERA5, WAVERYS, drifters, and HYCOM + NCODA Reanalysis in the northern Pacific are analyzed under tropical cyclones (TCs) and extratropical cyclones (ECs). The EC (TC) has the stable (unstable) wind directions and wider (narrower) fetch resulting in a larger (smaller) significant wave height (Hs). For modest and weak wind speeds (W ≤ 26 m s−1), the current speed (U) is higher in low latitudes than in mid-latitudes since the oceanic mixed-layer thickness (ℎ) is not large enough. For strong wind speed (W > 26 m s−1), ℎ deepens more in low latitudes and causes lower U.