RA-2/MWR/DORIS Session
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RA-2/MWR/DORIS Session Instrument, Level 1b and Absolute Calibrations by M. Roca et al. PowerPoint PPT Presentation


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RA-2/MWR/DORIS Session Instrument, Level 1b and Absolute Calibrations by M. Roca et al. Instrument and Level 1b overview Absolute Range Calibration: preliminary results and next steps Absolute Sigma-0 Calibration: results and future plans. Instrument and Level 1b Overview. Instrument:

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RA-2/MWR/DORIS Session Instrument, Level 1b and Absolute Calibrations by M. Roca et al.

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Ra 2 mwr doris session instrument level 1b and absolute calibrations by m roca et al

RA-2/MWR/DORIS Session

Instrument, Level 1b and Absolute Calibrations

by M. Roca et al.

  • Instrument and Level 1b overview

  • Absolute Range Calibration: preliminary results and next steps

  • Absolute Sigma-0 Calibration: results and future plans


Instrument and level 1b overview

Instrument and Level 1b Overview

Instrument:

  • All parameter optimised by the Calibration review (last modification in September)

  • Instrument Performance have since been excellent !

    Level 1b:

  • Correction for datation and range bias was verified. Implementation in the IPF since v4.53.

  • Further correction in the sigma-0 computation implemented in the reference processor. To be in the next version of the IPF.

  • Modification of the PTR computation also included in the reference processor. To be in the next version of the IPF.


Ra 2 mwr doris session instrument level 1b and absolute calibrations by m roca et al

Absolute RangeCalibration

  • Regional calibration for maximum precision

  • Co-ordinated campaign using:

    • Buoys

    • Tide Gauges

    • Modelling

  • Permanent sites for long term monitoring


Absolute range calibration preliminary results

Absolute Range Calibration - Preliminary Results

  • A total of in-situ measurements:

    • 44 measurements of light GPS buoys (IEEC/ICM)

    • 2 moored GPS buoys (IfGN), with a total of 16 passes each

    • 6 coastal tide gauges (IMEDEA, ICM, LEGOS, SHOM…)

  • Propagation of in-situ measurements towards the satellite tracks through geophysical models.

  • Dedicated corrections to be applied to the altimeter estimated range (from Level 2 products) provided by several groups:

    • short arc orbits, by DEOS

    • atmospheric correction (with ECMWF and on-ground MWR), by TOS


Absolute range calibration preliminary results1

Absolute Range Calibration - Preliminary Results

bias estimation = 41 cm ?

quoted error = 6 cm ?

  • include coastal tide gauges in the bias estimation once errors in the MSS model at the coast have been reduced;

  • improved ionospheric correction;

  • new model for sea state bias developed by CLS to be applied;

  • formal computation of the error;

  • error to be reduced to 1 cm, as per requirement.

    Long term monitoring with Casablanca oil platform and Eivissa TG.

Objectives for EGU, April’2003:


Sigma 0 absolute calibration

Sigma-0 Absolute Calibration

  • Absolute Sigma-0 calibration never been attempted

  • Scientific needs demonstrated

  • Requirement:

    ±0.5 dB

    ±0.1 dB stability over

    3 years

  • Dedicated transponder developed at ESTEC


Sigma 0 absolute calibration results

Sigma-0 - Absolute Calibration Results

  • Transponder calibrated

    • RCS = 75.08 dB m^2;

    • rss = 0.11 dB; and

    • stability = 0.06 dB.

      RA-2 power bias = + 0.831 dB

      Estimated error =0.28 dB

  • Further improvement is expected with the analysis bias with the we need to retrieve more passes.

  • Future: a site will be identified in the vicinity of ESRIN, where the TRP will be located for further measurement, and eventually, drift monitoring.


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