Characteristics of variations of water properties and density structure around the Kuroshio in the East China Sea |
| |
| Authors: | Eitarou Oka Masaki Kawabe |
| |
| Institution: | (1) Ocean Research Institute, University of Tokyo, 1-15-1 Minamidai, Nakano-ku, 164-8639 Tokyo, Japan |
| |
| Abstract: | Quarterly data of CTD at the PN line in the East China Sea during 1988–94 were analyzed to examine the variations of water
properties and density structure in relation to the Kuroshio. The Kuroshio flows over the continental slope at the PN line.
Water properties in the surface layer less than 100 db change greatly and show a clear seasonal cycle, while those in the
subsurface layer are much less variable. The small isobaric variations in the subsurface layer are almost due to the vertical
movement of isopycnals, on which the water properties vary little. The subsurface variations of salinity, temperature and
isopycnal depth are classified into four groups occurring in the four regions, divided vertically by the middle of the main
pycnocline and horizontally by the offshore edge of the Kuroshio, named Groups 1 (upper Kuroshio), 2 (upper offshore region),
3 (lower Kuroshio), and 4 (lower offshore region). The difference in averaged isopycnal depth between Groups 1 and 2 (3 and
4) is highly correlated with the vertical shear of the Kuroshio velocity in the upper (lower) pycnocline. The isopycnal depth
of Groups 1 and 3 has little annual cycle (with large intraseasonal variations in Group 3), while that of Groups 2 and 4 shows
a clear seasonal variation with the minimum in fall. As a result, the Kuroshio velocity is smallest in fall almost every year,
although the amplitude of seasonal variation and the season of maximum velocity are different from year to year. Interannual
variations of isopycnal depth are characterized by a large amplitude of Group 2 and an opposite phase between Groups 3 and
4, so that the variations of difference in isopycnal depth between Groups 1 and 2 and Groups 3 and 4, i.e., the upper and
lower shear of the Kuroshio velocity, are comparably significant. |
| |
| Keywords: | Kuroshio East China Sea water properties isopycnal depth seasonal variation interannual variation |
| 本文献已被 SpringerLink 等数据库收录！ |
|
