9:30 AM - 9:45 AM
[ACG44-03] Air-sea moisture flux enhanced locally in the meandering Kuroshio
Keywords:moisture flux, western boundary currents, Kuroshio
The western boundary currents transport large amounts of heat and seawater from the subtropical to subarctic regions, and they also play an important role in transporting moisture from the ocean to the atmosphere. Recent studies reveal that the Kuroshio, the western boundary current in the North Pacific, enhances evaporation just above the current path and contributes to intensive heavy precipitation in Japan. The moisture supply originates from the water vapor flux from the ocean to the air-sea boundary layer induced by wind turbulences just above the sea surface. Our laboratory found that moisture flux was enhanced along the Kuroshio current in the cruise conducted south of Shikoku using the eddy correlation method. However, the universality and the factors of the flux enhancement along the strong currents are still unknown. We aim to elucidate the actual situations and the factors of enhanced air-sea turbulent moisture flux along the Kuroshio. An analysis of the hourly moisture flux estimated by the bulk method in the Kuroshio region reveals that the flux was enhanced locally in areas where the current was meandering sharply. Especially, in 2023, the Kuroshio flowed northward and meandered off Tohoku, where the moisture flux was enhanced locally. The local enhancement of the flux was also found in meandering Kuroshio off the Kii Peninsula. At these locations, the specific humidity of the air was found to be relatively low, resulting in a large difference in specific humidity between the air and the sea surface. Moreover, the flux was more enhanced when the northerly wind was blowing. These results suggest that the moisture flux is enhanced locally over the meandering area of the Kuroshio when less humid air flows in from land.