Assimilation Experiments of the Kuroshio Variabilities using TOPEX/Poseidon Altimetric Data

摘要

[ABSTRACT] As a first step towards constructing a regional ocean state estimation for the Kuroshio around Japan, we have studied the capability of short-range forecasting of the Kuroshio variability by assimilating TOPEX/Poseidon altimetric data into a regional 1 1/2-layer primitive equation model with a variational initialization scheme. Using the sea surface dynamic height data derived from TOPEX/Poseidon altimetry, we carried out prediction experiments of Kuroshio path variations from 1993 to 1994. Although we used a mean data from a 3-year simulation as the background field for initialization in our experiments, the Kuroshio path variation was nevertheless successfully reproduced for up to two months after the initialization. In particular, the eastward progression speed and the amplitude of the Kuroshio meander were quite similar to those observed. These results show a dramatic improvement in accuracy in both initialized velocity and vorticity fields and hence confirm the efficiency of our variational assimilation method for the initialization of short-range numerical forecasting of the Kuroshio path variations.