Comparisons of sea surface height variability observed by pressure-recording inverted echo sounders and satellite altimetry in the Kuroshio Extension |
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| Authors: | Jae-Hun Park D Randolph Watts Kathleen A Donohue Karen L Tracey |
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| Institution: | 1. Korea Ocean Research and Development Institute, Ansan, 426-744, Korea
2. Graduate School of Oceanography, University of Rhode Island, Narragansett, RI, 02882-1197, USA
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| Abstract: | Satellite-measured along-track and gridded sea surface height (SSH) anomaly products from AVISO are compared with in situ SSH anomaly measurements from an array of 43 pressure-recording inverted echo sounders (PIESs) in the Kuroshio Extension. PIESs measure bottom pressure (P bot) and round-trip acoustic travel time from the sea floor to the sea surface (τ). The P bot and τ measurements are used to estimate, respectively, the mass-loading and steric height variations in SSH anomaly. All comparisons are made after accurate removal of tidal components from all data. Overall good correlations are found between along-track and PIES-derived SSH anomalies with mean correlation coefficient of 0.97. Comparisons between the two measurements reveal that the mass-loading component estimated from P bot is relatively small in this geographical region. It improves regression coefficients about 5?% and decreases mean root-mean-squared (rms) differences from 7.8 to 6.4?cm. The AVISO up-to-date gridded product, which merges all available satellite measurements of Jason-1, Envisat, Geosat Follow-On, and TOPEX/Poseidon interlaced, shows better correlations and smaller rms differences than the AVISO reference gridded product, which merges only Jason-1 and Envisat. Especially, the up-to-date gridded product reveals 6.8?cm rms improvement on average at sites away from Jason-1 ground tracks. Gridded products exhibit low correlation (0.75–0.9) with PIES-derived SSH in a subregion where the SSH fluctuations have relatively high energy at periods shorter than 20?days. |
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