Jason-1 Altimeter Ground Processing Look-Up Correction Tables

Poseidon-2 is the dual frequency radar altimeter embarked on the CNES/NASA oceanographic satellite Jason-1 that was launched on 7 December 2001. The primary objective of the Jason-1 mission is to continue the high accuracy time series of altimeter measurements that began with TOPEX in 1992. To achieve this goal, it is necessary to improve each component of the ground processing continually. Among these components are the look-up correction tables that are used to correct the estimations (range, significant waveheight, and sigma naught) issued from the retracking algorithms (on-board and ground). Look-up tables were first computed taking into account the prelaunch characteristics of the altimeter. They have to be updated to take into account better all the in-flight characteristics of the altimeter and all the updated ground algorithms that can impact the estimation process. The aim of this article is to describe the radar altimeter simulator of performances that has been used to compute look-up tables, to display the freshly computed look-up tables, and to discuss the consequences of these new corrections on the products provided to the users. The updated look-up correction tables allow improvement of SWH estimation, in particular with respect to TOPEX SWH data. It is also shown that no range dependency on SWH has to be looked for in these tables, and that the on-board TOPEX and Poseidon-2 tracking systems may contain the differences explaining the relative sea state bias between both altimeters.

[1]  D. Barrick.  Remote sensing of sea state by radar , 1972 .

[2]  Yannice Faugère,et al.  Jason-1 global statistical evaluation and performance assessment: Calibration and cross-calibration results , 2004 .

[3]  Shailen D. Desai,et al.  Statistical Evaluation of the Jason-1 Operational Sensor Data Record Special Issue: Jason-1 Calibration/Validation , 2003 .

[4]  Donald E. Barrick,et al.  Chapter 3 Analysis and Interpretation of Altimeter Sea Echo , 1985 .

[5]  R. Moore,et al.  Radar Terrain Return at Near-Vertical Incidence , 1957, Proceedings of the IRE.

[6]  P. Vincent,et al.  Jason-1: Assessment of the System Performances Special Issue: Jason-1 Calibration/Validation , 2003 .

[7]  G. Carayon,et al.  Poseidon-2 Radar Altimeter Design and Results of In-Flight Performances Special Issue: Jason-1 Calibration/Validation , 2003 .

[8]  G. Carayon,et al.  JASON1 mission : POSEIDON-2 Radar Altimeter Design and Results of in flight Performances , 2002 .

[9]  P. Thibaut,et al.  The Poseidon-2 altimeter simulator of performances , 2001, IGARSS 2001. Scanning the Present and Resolving the Future. Proceedings. IEEE 2001 International Geoscience and Remote Sensing Symposium (Cat. No.01CH37217).

[10]  P. Queffeulou.  Long-Term Validation of Wave Height Measurements from Altimeters , 2004 .

[11]  Bruce J. Haines,et al.  The Jason-1 Mission Special Issue: Jason-1 Calibration/Validation , 2003 .

[12]  G. Brown.  The average impulse response of a rough surface and its applications , 1977 .

[13]  G. Hayne,et al.  Radar altimeter mean return waveforms from near-normal-incidence ocean surface scattering , 1980 .

[14]  B. Chapron,et al.  A new estimator of the sea state bias using a three frequency radar altimeter , 2001, IGARSS 2001. Scanning the Present and Resolving the Future. Proceedings. IEEE 2001 International Geoscience and Remote Sensing Symposium (Cat. No.01CH37217).

[15]  R. Ray,et al.  Simultaneous Ocean Wave Measurements by the Jason and Topex Satellites, with Buoy and Model Comparisons Special Issue: Jason-1 Calibration/Validation , 2003 .

[16]  L. Amarouche,et al.  Improving the Jason-1 Ground Retracking to Better Account for Attitude Effects , 2004 .

[17]  L. Amarouche,et al.  Comparison of the Ku-Band Range Noise Level and the Relative Sea-State Bias of the Jason-1, TOPEX, and Poseidon-1 Radar Altimeters Special Issue: Jason-1 Calibration/Validation , 2003 .

[18]  Ernesto Rodriguez,et al.  Altimetry for non‐Gaussian oceans: Height biases and estimation of parameters , 1988 .

[19]  P. Raizonville,et al.  Poseidon Radar Altimeter Flight Model Design and Tests Results , 1991, [Proceedings] IGARSS'91 Remote Sensing: Global Monitoring for Earth Management.

[20]  Philippe Gaspar,et al.  Nonparametric Estimates of the Sea State Bias for the Jason-1 Radar Altimeter , 2004 .