On the Measurement of Geostrophic Ocean Currents by (NADIR) Satellite Altimeter.
Abstract
With the assumptions of accurately known marine geoid, satellite orbit, ionospheric and atmospheric propagation corrections, altimeter range precision, and dynamic components of sea-level deviations due to tides, barometric pressure, wind set-up, and storm surges, orbit inclination of 108 deg is shown to be the best choice among the three selected orbit inclinations (93 deg, 98 deg, and 108 deg) for the detection of geostrophic current vectors above 20 deg latitude. The second choice is 98 deg orbit inclination. The relationship shown as V sub R equals CV where V sub R is the true local geostrophic current speed, V is the geostrophic current speed evaluated with the Root-Mean-Square (RMS) altimeter range noise, and C is a coefficient, can be used to derive V sub R with the known C and V. The distribution of C and its lower and upper bounds can be calculated with the necessary ground truth programs. The RMS altimeter range noise, also, tends to bend the direction of the geostrophic current toward the east-west direction. In other words, the uncertainty in geostrophic current velocity determination is a function of the altimeter along-track slope measurement precision. Altimeter slope measurement uncertainty must be less than 0.1 seconds of arc to achieve a minimum uncertainty in geostrophic current speed determination of 5 cm/sec, a goal set for the National Oceanic Satellite System (NOSS).
Document Details
- Document Type
- Technical Report
- Publication Date
- Apr 10, 1980
- Accession Number
- ADA084986
Entities
People
- D. T. Chen
- S. L. Smith Iii
- V. E. Noble
Organizations
- United States Naval Research Laboratory