Abstract's details
JPL Gridded Altimetry Products
Event: 2015 Ocean Surface Topography Science Team Meeting
Session: Others (poster only)
Presentation type: Type Poster
Contribution: PDF file
Abstract:
JPL Gridded Altimetry Products
Victor Zlotnicki (1), Zheng Qu (2), Josh Willis (1), Brian Beckley (3).
(1) Jet Propulsion Laboratory, California Institute of Technology, Pasadena, CA USA
(2) Raytheon Co., Pasadena, CA USA
(3) SGT Inc at NASA Goddard Space Flight Center
Under NASA’s “Making Earth System Data Records for Use in Research Environments” (MEaSUREs) program we are carrying out improvements to altimetry data, such as orbits, sea state bias, etc, in a collaboration between the Jet Propulsion Laboratory, Goddard Space Flight Center, U. South Florida, U. Colorado and U. New Hampshire. As part of this activity, we are generating a new set of altimetric grids. The alongtrack data for the T/P, J1, J2 series use the GSFC std1504 orbits computed at the Goddard Space Flight Center (with improvements to the gravity field, J!/J2 surface forces, station positions, and SLR/DORIS tracking. The std1504 gravity model includes 5x5 degree/order using stacked solutions of linear, annual, semi-annual terms estimated over two spans: 1993-2002, 2003-2014). GOT4.10 (GSFC Ocean+load) tide model, cross-track gradient correction based on slopes from DTU10 MSS, as well as GDR-D versions of the remaining corrections. For the ‘other’ satellite (ERS-1,2, Envisat, SARAL/AltiKa) we use R. Scharroo’s RADS products, indicating the least squares gridding process that these have long wavelength errors and increased noise level; for near-real time AltiKa we use S. Desai’s data product, crossover-adjusted to Jason-2. We currently use the same covariance functional form used in the Dibarboure/LeTraon series of papers and currently used by CLS/CNES, but with a newly-derived map of spatial zero-crossings of the covariance function (and its RMS), as well as a new, time-varying- set of propagation velocities computed directly from consecutive grids estimates without propagation. The maps are weekly, on a 1/6 degree grid. We evaluate the maps by withholding J1/J2 data for one day every so often and comparing the interpolated results with the withheld altimetric data; the final maps include all the data. We present results in terms of spectral content, RMS discrepancy and other quality measures. Contact: victor.zlotnicki[at]jpl.nasa.gov
Victor Zlotnicki (1), Zheng Qu (2), Josh Willis (1), Brian Beckley (3).
(1) Jet Propulsion Laboratory, California Institute of Technology, Pasadena, CA USA
(2) Raytheon Co., Pasadena, CA USA
(3) SGT Inc at NASA Goddard Space Flight Center
Under NASA’s “Making Earth System Data Records for Use in Research Environments” (MEaSUREs) program we are carrying out improvements to altimetry data, such as orbits, sea state bias, etc, in a collaboration between the Jet Propulsion Laboratory, Goddard Space Flight Center, U. South Florida, U. Colorado and U. New Hampshire. As part of this activity, we are generating a new set of altimetric grids. The alongtrack data for the T/P, J1, J2 series use the GSFC std1504 orbits computed at the Goddard Space Flight Center (with improvements to the gravity field, J!/J2 surface forces, station positions, and SLR/DORIS tracking. The std1504 gravity model includes 5x5 degree/order using stacked solutions of linear, annual, semi-annual terms estimated over two spans: 1993-2002, 2003-2014). GOT4.10 (GSFC Ocean+load) tide model, cross-track gradient correction based on slopes from DTU10 MSS, as well as GDR-D versions of the remaining corrections. For the ‘other’ satellite (ERS-1,2, Envisat, SARAL/AltiKa) we use R. Scharroo’s RADS products, indicating the least squares gridding process that these have long wavelength errors and increased noise level; for near-real time AltiKa we use S. Desai’s data product, crossover-adjusted to Jason-2. We currently use the same covariance functional form used in the Dibarboure/LeTraon series of papers and currently used by CLS/CNES, but with a newly-derived map of spatial zero-crossings of the covariance function (and its RMS), as well as a new, time-varying- set of propagation velocities computed directly from consecutive grids estimates without propagation. The maps are weekly, on a 1/6 degree grid. We evaluate the maps by withholding J1/J2 data for one day every so often and comparing the interpolated results with the withheld altimetric data; the final maps include all the data. We present results in terms of spectral content, RMS discrepancy and other quality measures. Contact: victor.zlotnicki[at]jpl.nasa.gov