Altimeter's Capability of Reconstructing Realistic Eddy Fields Using Space-Time Optimum Interpolation |
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| Authors: | Tsurane Kuragano Masafumi Kamachi |
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| Institution: | (1) Oceanographic Research Department, Meteorological Research Institute, Tsukuba 305-0052, Japan |
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| Abstract: | Sea surface height anomaly maps of realistic eddy activity were obtained by applying space-time optimum interpolation to altimeter
data. Analysis error and rate of reconstructing eddy signals were investigated by taking account of: 1) dependency on orbit
configurations of single and multiple altimeters; 2) dependency on space-time scales of realistic, dominant eddies; and 3)
effect of space-time scales of eddy propagation. Large-scale sea surface height anomalies are subtracted from altimeter data
by applying an along-track filter to allow easy handling of eddy signals. The space-time scales of the first-guess error in
the optimum interpolation are statistically evaluated by fitting a space-time anisotropic Gaussian function to space-time-distributed
correlation coefficients of sea surface height using the TOPEX data. The results of the optimum interpolation clarify the
followings: 1) ERS has a better capability of reconstructing eddy signals than TOPEX. Comparison of maps from multi-altimeter
data shows that TOPEX+ERS has a better capability than Jason−1+TOPEX in lower latitudes and vice versa in higher latitudes,
though the differences are small. 2) The small space-time scale yields a low reconstruction rate in marginal seas and alongside
the equator. The persistent timescale is large, and westward propagation is dominant in the subtropical and subarctic regions,
where the reconstruction rates are high. 3) The optimum interpolation, taking account of eddy propagation, provides higher
reconstruction rates than that taking no account of the propagation. The effect of propagation on the optimum interpolation
is greater when it is applied to single-altimeter data than to multi-altimeter data.
This revised version was published online in July 2006 with corrections to the Cover Date. |
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| Keywords: | Altimeter sea surface height optimum interpolation resolution capability space-time scales orbit eddy TOPEX/POSEIDON ERS Jason-1 |
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