Transition domain on 155 degree E meridian in 2002 and 2003
2004
Wagawa, T. (Hokkaido Univ., Sapporo (Japan)) | Isoda, Y. | Takagi, S. | Sakaoka, K.
The area between Subarctic Front (SAF) and Subarctic Boundary (SAB) is referred to as the Transition Domain (TD). The characteristic water mass in the TD is a dense part of Central Mode Water (D-CMW) with a density of 26.4-26.7 delta theta. Using the synoptic hydrographic data in June 2002 and June 2003 cruises around the TD (145 deg E-155 deg E), we described the distribution of water mass and the flows structure around the D-CMW. Some mode waters, i.e., Subtropical Mode Water (STMW) and D-CMW. were observed around the TD. and they were absorbed into the clockwise eddies. The westward propagation speed of observed eddies, about 1 cm sE-1, has the same order of the theoretical speed of the baroclinic first-mode Rossby wave. However, the local Rossby number of R = U/betaL2 (U is a typical velocity, beta is the planetary beta, L is the horizontal scale of eddy) for their eddies is less than 1.0. This suggests that the observed D-CMW within an eddy is gradually exchanged with the surrounding water during the westward propagation.
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