Identification of the fronts from the Kuroshio Extension to the Subarctic Current using absolute dynamic topographies in satellite altimetry products

• Published in: Journal of oceanography Vol. 74; no. 4; pp. 393 - 420
• Main Authors: Nakano, Hideyuki, Tsujino, Hiroyuki, Sakamoto, Kei, Urakawa, Shogo, Toyoda, Takahiro, Yamanaka, Goro
• Format: Journal Article
• Language: English
• Published: Tokyo Springer Japan 01-08-2018; Springer Nature B.V
• Subjects: Archiving; Climatology; Contours; Dynamic height; Dynamic topography; Earth and Environmental Science; Earth Sciences; Freshwater & Marine Ecology; Fronts; Oceanographic data; Oceanography; Original Article; Satellite altimetry; Satellites; Shape; Slope; Topography; Topography (geology); Kuroshio bifurcation northern branch; Subarctic boundary current; Front identification; Kuroshio extension; Subarctic current; AVISO
• ISSN: 0916-8370; 1573-868X
• DOI: 10.1007/s10872-018-0470-4

The climatologies and variabilities of the fronts associated with the Kuroshio Extension (KE), the Kuroshio Extension Northern Branch (KENB), the flow along the Subarctic Boundary (SAB), and the Subarctic Current (SAC) are identified by a new method based on the absolute dynamic height product from the archiving, validation, and interpretation of satellite oceanographic data (the AVISO product). The fronts are detected by examining the specific contour values of the absolute dynamic topography (ADT) in the AVISO product. The (time-varying) specific contour values are decided from the local maxima of the averaged surface geostrophic velocity along the ADT. Assuming the specific contours as the front locations, we obtain an occurrence frequency map of the four front locations, and determine the monthly variability of the fronts over the 1993–2015 period. The results are validated by hydrographic observations. The KE and KENB east of the Shatsky Rise migrate southward several times at a speed of ~ 0.2 cm s
−1
, while the SAB and SAC are mostly stationary.