Hydrographic observations in the Japan Sea with an underwater glider

Intensive hydrographic observations obtained with an underwater glider revealed the vertical structure with high horizontal resolution, as well as the temporal variation, of the Subpolar Front and the Tsushima Warm Current in the Japan Sea. Even when sea surface current velocities were large (>0.50 m s ^-1 ), the glider was able to completed the observations along the planned straight line. The glider detected changes in the frontal structures and the water mass distributions on spatial scales smaller than O(10 km) and on timescales smaller than O(1 month). We showed that the assimilation of glider data by an ocean dynamic model increased velocity magnitudes in the simulated flow field.