The Analysis Of Monthly Features Of The Kuroshio Path And Axis At The Depth Of15m And Model Verification

Besed on thirty three years of Argos drifting buoys data which sail located atthe depth of15m from February1979to March2012, we plotted both annual andmonthly averaged distribution of the Kuroshio surface currents at the depth of15m,managed to confirm the axis of the currents by means of characteristic line method,defined the transition regions which velocity between0.4-0.6kn as the Kuroshioboundary, analyzed annual and monthly averaged Kuroshio main features andverified the Finite-volume Coastal Ocean Model(FVCOM) according it.The observation results of drifting buoys showed that: The annual averagedcurrent path of the Kuroshio is roughly a rectangular segment of a circle whichcenter at (13.5°N,142°E) and radius is about2235km, it will anticyclonically bentfirst to adjust the cyclonic bend of the meander in the Luzon Strait, Taiwan’snortheast, southwest of Kyushu and the Izu Ridge coast, the inflow of tributaries oroutflow of branches mainly occurred at the opening of the current path whichappeared at the bend; the Kuroshio axis overall deviate to the Kuroshio’s leftbouandary, from the Luzon’s northeast to the Taiwan’s east areas is most obvious,the south of Honshu Island area comes second, the Kuroshio at the East China Sea isthe most non-obvious; the Kuroshio velocity generally tended to increase from southto north, but not continuously increase along the current path, it showed a mutualcrisscross condition between the relatively flat path with higher velocity and the bentpath with lower veloctiy, the velocity is highest at the area from the south of ShikokuIsland to the west of Izu Islands. The monthly mean current fields showed that the2,5,8,11months are important inflection points of the Kuroshio’s current path andaxis, the1,4,7,10months are on behalf of the season. The Kuroshio’s path and axisare curviest during winter months, the intrusion to the edge of the sea is significant; and most straight during summer months, there are north flows along the left side ofthe Kuroshio; spring and autumn months with transitional features are more obvious.The model verification of FVCOM showed that: The numerical simulationresults generally demonstrate consistency with the observations, the difference ismainly in the details: the current speed is smaller and current width is wider than theobservation results as the whole; it showed that the east area of Boso Peninsula is thestream segment with the maximum current speed while the observation resultsshowed it is located at the area from the south of Shikoku Island to the west of IzuIslands; it not described well the Kuroshio stream regimen in the Osumi Strait andreflected the Kuroshio adjust status in the Izu Ridge et al.