Assimilation of TOPEX/POSEIDON Altimeter Data with a Reduced Gravity Model of the Japan Sea

Byline: Naoki Hirose (1), Ichiro Fukumori (2), Jong-Hwan Yoon (3) Keywords: Data assimilation; Kalman filter; TOPEX/POSEIDON; sea level; Japan Sea; reduced-gravity model Abstract: Sea level data measured by TOPEX/POSEIDON over the Japan Sea from 1993 to 1994 is analyzed by assimilation using an approximate Kalman filter with a 1.5 layer (reduced-gravity) shallow water model. The study aims to extract signals associated with the first baroclinic mode and to determine the extent of its significance. The assimilation dramatically improves the model south of the Polar Front where as much as 20 cm.sup.2 of the observed sea level variance can be accounted for. In comparison, little variability in the northern cold water region is found consistent with the model dynamics, possibly due to significant differences in stratification. Author Affiliation: (1) Interdisciplinary Graduate School of Engineering Sciences, Kyushu University, Kasuga, 816-8580, Japan (2) Jet Propulsion Laboratory, California Institute of Technology, Pasadena, CA, 91109, U.S.A (3) Research Institute for Applied Mechanics, Kyushu University, Kasuga, 816-8580, Japan Article History: Registration Date: 01/10/2004