The radar altimetric observations 1:

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Part 3.

• The radar altimetric observations (1)
• Altimetry data
• Contributors to sea level
• Crossover adjustment
• From altimetry to Gravity and Geoid(2)
• Geodetic theory
• FFT for global gravity fields
• Least Squares Collocation
• The Global Altimetric Gravity Field (3)
• Accuracy assesment
• Applications

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Global Marine Gravity fields.

• Presently several global marine gravity fields
  are available on 2 by 2 resolution or better
  for free download on the Internet
• Hwang et al. 1999, 2001?
• Sandwell and Smith, v7.2, v8 v9, v10, v11, v12
• Andersen and Knudsen. KMS99, KMS02. (ftp.kms.dk)
  - Andersen05 shortly.
• Wang. GSFC98, GSFC 00
• Numerous local and global marine gravity
  anomalies have been created using a variety of
  successful techniques (e.g., Haxby (1987),
  Balmino et al. (1987), Sandwell (1992), Knudsen
  (1991), Knudsen et al. (1992), Tscherning et al.
  (1993),
• Several other global high resolution fields are
  available like CLS-SHOM (Hernandez and Shaeffer,
  2000) and OSU (Yi, 1995) maybe more??? lower
  quality.

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Sandwell and Smith.
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Comparisons

• Comparison by Trimmer et al., (2004),
• Compares the KMS02, the GSFC00 field by (Wang,
  2001) and the Sandwell and Smith (SSv8grav 2)
  with unclassified NIMA gravity observations in
  very difficult test region

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Comparison with marine observations (difficult
area)
Comparison in whole test area with 3,433,653
marine gravity observations. All values are in
mGal. Comparisons by Kenyon Trimmer (2004)
suggest that the accuracy Of KMS03 is around or
better than 3 mGal globally.
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Applications

• Inertial Navigation Ship, satellite, missile
  guidance, GPS
• Petroleum surveys extending seismic surveys
• Detailed mapping of the spreading ridges
• Mid Atlantic spreading zone north of Iceland
• Improving bathymetry mapping.( Equatorial
  Atlantic Spreading Zone)
• Lithospheric studies (strength, compensation
  mechanism)
• Mapping subduction zones, continental margins.
• Mapping of seamounts in the Pacific place.
• Mapping in Arctic regions.

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MidAtlantic spreading zone hardly detectable from
marine gravity
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Improving Bathymetry
ETOPO5
Bougouer correction (assuming infinite
slab) ?g0.04188 s mGal/m s density
contrast s water 1.0 g/cm3 s sediment 2.7
g/cm3 s 1.6 g/cm3
KMS99
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KMS01 Bath
SS v7.2
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Applications (Seamounts)
Systematic search for seamounts in the Pacific
plate from vertical gravity gradients in the
global high resolution altimetric gravity
field by Sandwell and Smith. Wessel and Lyons
(1997).