On the other hand, the temperature map of the tomography obsvations was measured in just a 11-minute interval (i. e., a “true” snapshot but really 2 hrours since it is a 3d inverse with all paths) with a 240-km horizontal resolution as explained in the Inversion section. That is why the lens-shaped water mass and cold watermass do not appear in the tomography result of the vertical section they came in after the tomography map was made. The range-averaged temperature differnce (ΔT) between the XCTD and tomoglaphy data in the vertical section is less than 0.5 ℃ over the entile depth (see the right panel of Figure 2(b)). This range-averaged temperature difference comes from the expected uncertainty of the tomographic result mentioned in the section of Inversion as well as the uncertainty of the XBT/CTD section, including the non-simultaneity of the measurements.
Variable 1000km-scale three-dimensional temperature fields in the Kuroshio Extension region are well detected by the present tomography experiment. A more comprehensive analysis of the present tomography data including the reciprocal transmission data will be done not only for temperature structures but also for barotropic and baroclinic velocity. We expect to extract more information on the dynamics of the Kuroshio Extension at this site through the data analysis.
Acknowledgments
We thank Drs. A. Kaneko and B. Howe for critically reviewing the manuscript. We also thank Drs. H. Mitsudera, Y. Yoshikawa, B. Dushaw for critical sugagestions and valuabl discussion. Messrs. T. Zaima and N. Yoshioka contributed to the ray identification and the supply of the SSDH maps of the T/P altimeter data, respectively.
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