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Abstract

Multi-Mission Crossover Analysis: Merging 20 years of altimeter data into one consistent long-term data record

Dr Denise DETTMERING(1), Dr Wolfgang BOSCH(1)

(1) DGFI, Germany

Session theme: Regional and Global CAL/VAL for Assembling a Climate Data Record

  • poster

    Abstract

    The satellite altimeter scenario of the past two decades provides continuous and precise monitoring of the ocean surface with a beneficial spatio-temporal sampling. Since 1992 two or more contemporary missions are continuously available. For climate studies a consistent long-term data record is a fundamental requirement. However, combining missions with different sampling
    capabilities requires a careful preprocessing and calibration of all altimeter systems.

    A global multi-mission crossover analysis is able to connect the measurement from individual missions and merge them to one consistent long-term data record even if some of the missions are
    not operating on a repeat ground track. Upgrading and harmonization to the most up-to-date models and corrections is performed in advance. Then, we realize the cross-calibration by a least squares adjustment minimizing single- and dual-satellite crossover differences in all combinations as well as consecutive differences of the radial component of single satellites. Minimizing consecutive differences ensures a certain degree of smoothness of the radial component without introducing an analytical error function. This method provides time series of radial errors for the complete missions? lifetimes, the associated auto-covariance functions, relative range biases, systematic differences in the center-of-origin realization, as well as geographically correlated error pattern for all missions analyzed.

    In this contribution we show results of a twenty years data record by cross-calibrating ERS1, Topex, ERS2, GFO, Jason1, Envisat, ICESat, Jason2, and CryoSat2. Special focus will be on the range biases of the different missions including their temporal behavior as well as on geographically correlated error patterns which map, if not corrected, directly to the sea surface.

     
    Corresponding author:

      Dr Denise Dettmering
      Deutsches Geodätisches Forschungsinstitut (DGFI)
      Alfons-Goppel-Strasse 11
      80539 Munich
      Germany
      E-mail:
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