# Presentation: 196469

## NOAA’s Role inGeosat Follow-On

- John Lillibridge
*NOAA Laboratory for Satellite Altimetry*

- GFO Cal/Val Workshop

- June 12, 2001

## NOAA’s Primary Responsibilities

- Archiving of SDRs, GDRs, and Orbits
- Calibration & Validation Activities
- Time Tag and USO drift monitoring
- IGDRs as check on NGDRs
- Validation of GDRs with Tide Gauges
- Preparation & Distribution of final GDRs

- GFO Cal/Val Workshop

- NOAA - June 12, 2001

## Data Archive

- NOAA/NODC as official “deep archive”
- Storage requirements
- SDRs			~ 400 Mb/month
- POE Orbits	~ 70 Mb/month
- Final GDRs	~ 250 Mb/month
- Total over 8 year mission: ~ 70 Gb
- NODC also data distributor (CD, DVD,FTP)

- GFO Cal/Val Workshop

- NOAA - June 12, 2001

## Precision Timing Issues

- Time-tag stability & uniformity
- Spacing between records ~ 0.98 s
- Ultra-Stable-Oscillator clock drift
- Changes in clock frequency alter range travel-time counts
- Timing biases between Range & Orbit
- msec level timing biases yield cm level errors at twice-per-rev

- GFO Cal/Val Workshop

- NOAA - June 12, 2001

## USO Height Correction

- GFO Cal/Val Workshop

- NOAA - June 12, 2001

## GFO’s Doppler beacon oscillator is drifting at a rate 10x worse than Geosat
The USO height correction is large, but is implicitly corrected during SDR production
The estimation of the USO height correction can suffer from large bookkeeping errors

- The USO height correction is large, but is implicitly corrected during SDR production
- The estimation of the USO height correction can suffer from large bookkeeping errors

- GFO Cal/Val Workshop

- NOAA - June 12, 2001

## IGDR vs. NGDR

- GFO Cal/Val Workshop

- NOAA - June 12, 2001

## Tide Gauge Comparisons

- GFO Cal/Val Workshop

- NOAA - June 12, 2001

## Real-Time GFO Altimetry

- GFO Cal/Val Workshop

- NOAA - June 12, 2001

## Cycle & Pass vs. Daily file segmentation
Redefine field for model wet tropo correction
Rearrange last 3 fields for byte-alignment
Add Land/Sea mask to flag bits
Include AGC high-rate data?

- Redefine field for model wet tropo correction
- Rearrange last 3 fields for byte-alignment
- Add Land/Sea mask to flag bits
- Include AGC high-rate data?

- NGDRGDR Upgrades: Format

- GFO Cal/Val Workshop

- NOAA - June 12, 2001

## GFO Track Collinearity

- GFO Cal/Val Workshop

- NOAA - June 12, 2001

## USO height correction (implicitly applied)
H-Cal and other instr. corrections (SPTR?)
Explicit reference to POE ephemeris file

- H-Cal and other instr. corrections (SPTR?)
- Explicit reference to POE ephemeris file

- NGDRGDR Upgrades: Headers

- GFO Cal/Val Workshop

- NOAA - June 12, 2001

## Precision Orbits from NASA/GSFC
NCEP wet & dry tropo. corrections
New Tide models: GOT2000, FES99, ...
Geoid, MSS & Bathymetry: EGM96, Sandwell & Smith
Analysis needed for optimal SSB correction
Improved Ionosphere model: CODE vs. JPL GIM, IRI2000
Global inverse barometer correction
Wind Speed Model?

- NCEP wet & dry tropo. corrections
- New Tide models: GOT2000, FES99, ...
- Geoid, MSS & Bathymetry: EGM96, Sandwell & Smith
- Analysis needed for optimal SSB correction
- Improved Ionosphere model: CODE vs. JPL GIM, IRI2000
- Global inverse barometer correction
- Wind Speed Model?

- NGDRGDR Upgrades: Data & Models

- GFO Cal/Val Workshop

- NOAA - June 12, 2001

## Orbit Accuracy in MOE+IGDR

- GFO Cal/Val Workshop

- NOAA - June 12, 2001

## Tide Model Comparison

- GFO Cal/Val Workshop

- NOAA - June 12, 2001

## Height Variability - no orbit error

- GFO Cal/Val Workshop

- NOAA - June 12, 2001