GOCODYN

GOCODYN

GOCODYN logo designed by Vedrana Subotić.

GOCE for Coastal Ocean DYNamics and geodesy (GOCODYN) investigates improvements of the regional geoid models by Gravity field and steady-state Ocean Circulation Explorer (GOCE) data for both land and ocean applications in Fennoscandia.

prosjekt

About/Aims
Background

The GOCODYN project is a continuation and link to former investigations in the frame of the NovaGOCE project realized under Norwegian Research Council's Space research program. GOCODYN represents a collaboration between NMBU and international institutions, i.e., the Bavarian Academy of Sciences and Humanities (Germany) and DTU Space (Denmark), as well as the Norwegian Mapping Authority Kartverket as an external partner.

Objectives

Specific project objectives and tasks of GOCODYN are:

1. Quality assessments of coastal altimetry products.

2. Quality assessment of the height reference frame in Norway.                       

3. Determination of an optimal geoid using GOCE and regional geoid grids. 

4. Refinement of altimetry products.                                                                     

5. Investigation on applicability of a geoid based reference frame.

More about the project

The ocean's MDT represents the surface ocean circulation and can be determined by the methodically different approaches of geodesy and oceanography. The ocean approach implies using numerical ocean circulation models, while the geodetic approach refers to MDT as the height of mean sea surface (MSS) or mean sea level (MSL) above the geoid. Since GOCODYN's target area is the Norwegian coast, a necessity for GOCODYN is the availability of a regional geoid model, which has been provided by the project partner at the Norwegian Mapping Authority. The current version of this model does not yet take into account the latest release of GOCE products. Therefore, the project requires generating a preliminary geoid, blending the short scales of the regional model with the large-scale information from the latest GOCE release. The current PhD project of Martina Idžanović is closely related to the PhD work of Vegard Ophaug. He has already provided a preliminary version of a blended geoid and used this for a comparison between geodetic and ocean MDT models along the Norwegian coast in Ophaug et al. (2015). New-generation synthetic aperture radar (SAR) altimetry delivers observations in coastal areas, previously not covered by conventional altimetry. Therefore, the potential of SAR(In) altimetry, implemented on CS2, is highlighted in Idžanović et al. (2016) and Idžanović et al. (2018). The availabilty of new data enabled the improvement of MDT determination along the Norwegian coast and is shown in Idžanović et al. (2017). An additional focus of the current PhD work is realizing a vertical reference frame (VRF). Thereby, in addition to GOCE, different types of data (Global Navigation Satellite System (GNSS), spirit levelling, tide gauges, terrestrial gravimetry) will be combined and validated against each other. Considering the availability of dens terrestrial gravity data sets, a precise regional geoid model can replace levelling for the definition and realization of vertical reference frames (VRFs). Aspects of geoid-based VRFs will be investigated considering the special situation in Norway, taking into account both data availability and quality (Gerlach and Ophaug, 2017) as well as time variations of the geoid due to post glacial rebound (Ophaug et al., 2016).

  • GOCODYN black/green logo designed by Vedrana Subotić.
    Photo
    GOCODYN black/green logo designed by Vedrana Subotić.
  • Coastal mean dynamic topography based on CryoSat-2 and NKG2015. The mean value has been removed. 400 m isobaths from the 2014 General Bathymetric Charts of the Oceans (GEBCO) (Weatherall et al., 2015) grid are shown.
    Photo
    Coastal mean dynamic topography based on CryoSat-2 and NKG2015. The mean value has been removed. 400 m isobaths from the 2014 General Bathymetric Charts of the Oceans (GEBCO) (Weatherall et al., 2015) grid are shown.
  • GOCODYN white/green logo designed by Vedrana Subotić.
    Photo
    GOCODYN white/green logo designed by Vedrana Subotić.
  • Geostrophic ocean surface currents derived from CryoSat-2 and NMA2014.
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    Geostrophic ocean surface currents derived from CryoSat-2 and NMA2014.
  • Observation vectors (west and east areas) for each step of stepwise collocation in the study area of the Andes region in South America.
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    Observation vectors (west and east areas) for each step of stepwise collocation in the study area of the Andes region in South America.
  • Micro g LaCoste absolute gravimeters FG5 (left) and FG5-X (right) at NMBU's gravity lab.
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    Micro g LaCoste absolute gravimeters FG5 (left) and FG5-X (right) at NMBU's gravity lab.