C.King April 27, 2016
RADS satellite altimeter data for ECCO v4 (LLC90) assimilation

RADS (Radar Altimeter Database System project; Scharroo et al 2013) 
is part of NEONET (Netherlands Earth Observation NETwork), for exploitation 
of remote-sensing expertise and data. 
DEOS (The Delft Institute for Earth-Oriented Space Research) 
has built a data base that contains validated and cross-calibrated altimeter 
data products that are consistent in accuracy, format, correction and 
reference system parameters.   http://rads.tudelft.nl

The following corrections and flags were applied:
     CNES GDR-E orbital altitude [m]              425 
     Ku-band range corrected for instr. effects   601
     ECMWF dry tropospheric correction [m]        701
     radiometer wet tropospheric correction [m]   801
     smoothed dual-frequency ionospheric correct  903
     static inverse barometer correction [m]     1002
     solid earth tide [m]                        1101
     GOT4.10 ocean tide [m]                      1222
     GOT4.10 load tide [m]                       1322
     pole tide [m]                               1401
     CLS non-parametric sea state bias [m]       1502
   ||DTU10 mean sea surface height [m]           1614 topex,jason1,ers,env,gfo
   ||DTU15 mean sea surface height [m]           1618 jason2,cryosat2,saral
     Ku-band significant wave height [m]         1701
     Ku-band backscatter coefficient [dB]        1801
     std dev of Ku-band range [m]                2002
     number of valid Ku-band measurements (MLE3) 2101
     flag word                                   2601
     std dev of Ku-band significant wave height  2802
     std dev of Ku-band backscatter coefficient  2902
     off-nadir pointing angle squared from wavef 3002
     reference frame offset [m]                  3801
     sea ice concentration [%]                   4701

The along-track sea surface height anomaly fields have been 
daily bin-averaged onto the ECCO v4 model grid,
using gcmfaces (see Forget et al 2015), and organized by year.
Outliers have been removed using a standard deviation scheme (see Forget and Ponte 2015).
Missing values and land are masked with -9999.

The codes that implement the above data processing can be found in 
http://mitgcm.org/viewvc/MITgcm/MITgcm_contrib/ecco_utils/input_ecco_processing/code_sla/

The names of this dataset are:
RADS_TJ_mar2016_YYYY    where YYYY=1992:2015  Topex, Jason
RADS_GFO_C2_mar2016_YYYY                      GFO, Cryosat-2
RADS_ERS_ENV_SA_mar2016_YYYY                  ERS, ENV, Saral

References:
 Scharroo, R., E. W. Leuliette, J. L. Lillibridge, D. Byrne, M. C. Naeije, and G. T. Mitchum, 
  RADS: Consistent multi-mission products, in Proc. of the Symposium on 20 Years of Progress in 
  Radar Altimetry, Venice, 20-28 September 2012, Eur. Space Agency Spec. Publ., ESA SP-710, p. 4 pp., 2013.
 Forget, G., J.-M. Campin, P. Heimbach, C. N. Hill, R. M. Ponte, and C. Wunsch, 2015:
  ECCO version 4: an integrated framework for non-linear inverse modeling and global ocean
  state estimation. Geoscientific Model Development, 8, 3071-3104, doi:10.5194/gmd-8-3071-2015
 Forget, G. and R. Ponte, 2015: The partition of regional sea level variability. Progress 
  in Oceanography, (137), 173–195, doi:10.1016/j.pocean.2015.06.002

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