AN IMPROVED MAPPING METHOD OF MULTISATELLITE ALTIMETER DATA

Abstract Objective analysis of altimetric data (sea level anomaly) usually assumes that measurement errors are well represented by a white noise, though there are long-wavelength errors that are correlated over thousands of kilometers along the satellite tracks. These errors are typically 3 cm rms for TOPEX/Poseidon (T/P), which is not negligible in low-energy regions. Analyzing maps produced by conventional objective analysis thus reveals residual long-wavelength errors in the form of tracks on the maps. These errors induce sea level gradients perpendicular to the track and, therefore, high geostrophic velocities that can obscure ocean features. To overcome this problem, an improved objective analysis method that takes into account along-track correlated errors is developed. A specific data selection is used to allow an efficient correction of long-wavelength errors while estimating the oceanic signal. The influence of data selection is analyzed, and the method is first tested with simulated data. The me...

[1]  Y. Ménard.  Observations of eddy fields in the northwest Atlantic and northwest Pacific by SEASAT altimeter data , 1983 .

[2]  Carl Wunsch,et al.  The accuracy of altimetric surfaces , 1984 .

[3]  P. Mazzega,et al.  An experiment to invert Seasat altimetry for the Mediterranean and Black Sea mean surfaces , 1989 .

[4]  Lee-Lueng Fu,et al.  Sea level variabilities in the Gulf Stream between Cape Hatteras and 50°W: A Geosat study , 1990 .

[5]  C. Tai.  How to Observe the Gyre to Global-Scale Variability in Satellite Altimetry: Signal Attenuation by Orbit Error Removal , 1991 .

[6]  Analysis of Errors Due to Polynomial Adjustment of Altimeter Profiles , 1991 .

[7]  E. J. Christensen,et al.  TOPEX/POSEIDON mission overview , 1994 .

[8]  P. L. Traon,et al.  The eddy field associated with the Azores Front east of the Mid‐Atlantic Ridge as observed by the Geosat altimeter , 1994 .

[9]  Yi Chao,et al.  A Comparison Between the TOPEX/POSEIDON Data and a Global Ocean General Circulation , 1995 .

[10]  C. Tai,et al.  Orbit and tide error reduction for the first 2 years of TOPEX/POSEIDON data , 1995 .

[11]  Satellites work in tandem to improve accuracy of data , 1995 .

[12]  Ichiro Fukumori,et al.  Assimilation of TOPEX sea level measurements with a reduced‐gravity, shallow water model of the tropical Pacific Ocean , 1995 .

[13]  An Inversion Method to Determine Ocean Surface Currents Using Irregularly Sampled Satellite Altimetry Data , 1995 .

[14]  Philippe Gaspar,et al.  Using Topex/Poseidon Data to Enhance ERS-1 Data , 1995 .

[15]  Fabrice Hernandez,et al.  Mapping mesoscale variability of the Azores Current using TOPEX/POSEIDON and ERS 1 altimetry, together with hydrographic and Lagrangian measurements , 1995 .

[16]  Richard Smith,et al.  Global Ocean Circulation from Satellite Altimetry and High-Resolution Computer Simulation , 1996 .

[17]  Andreas Oschlies,et al.  Assimilation of Geosat altimeter data into an eddy-resolving primitive equation model of the North Atlantic Ocean , 1996 .

[18]  Jean-Michel Brankart,et al.  Optimal Analysis of In Situ Data in the Western Mediterranean Using Statistics and Cross-Validation , 1996 .