The Kuroshio Extension Front from Satellite Sea Surface Temperature Measurements

Shuiming Chen and Bo Qiu, University of Hawaii at Manoa, Honolulu, HI, United States
Abstract:
Position and strength of the surface Kuroshio Extension Front (KEF),
which is defined as the sea surface temperature (SST) gradient maximum
adjacent to the Kuroshio Extension (KE) axis (approximated by a
specific SSH contour consistently located at, or near, the maximum of
the SSH gradient magnitude), are studied using weekly, microwave SST
measurements from 1997 to 2014. The mean KEF meanders twice around
~36N between east coast of Japan and 153E. It then migrates southeast
to ~34N, just before reaching the Shatsky Rise (~158E), then
progresses mostly eastward. Spatially the KEF is strongest near the
Japan coast and seasonally it is strongest in winter and weakest in
summer. Low-frequency variations of its strength, most notably in its
upstream region, can be related to the known bimodal states of the
KE. During 2003-2005 when the KE was in its stable state, the winter
KEF SST gradient exceeded 10C/100km.