SEASAT altimeter height calibration

Abstract

The SEASAT altimeter has been calibrated for height bias using four overflight passes of Bermuda that were supported by the Bermuda laser. The altimeter data was corrected for tides, by using recorded tide gage data; for propagation effects, by using meteorological data taken around the time of each pass; for acceleration lag; and for sea state bias, including both surface effects and instrumental effects. Altimeter data for each of the four passes was smoothed and extrapolated across the island. Interpolation between passes then produced an equivalent altimeter measurement to the geoid at the laser site, so that the altimeter bias could be estimated without the use of a geoid model. The estimated height bias was 0.0±0.07 m.

Dynamic sea surface topography, gravity, and improved orbit accuracies from the direct evaluation of Seasat altimeter data

“…The bias values recovered in this analysis are in excellent agreement with the previously quoted results of Rapp for a 75 cm adjustment to the ae = 6378137 m indicating 6378136.25 m is a better value. The value we obtained from SEASAT after the 11 cm correction is removed is ae = 6378136.14 m. An independent calibration of the SEASAT altimeter using laser tracking as the satellite overflew Bermuda estimated that hB = 0 7 cm (Kolenkiewicz and Martin, 1982).…”

Gravimetric Methods – Satellite Altimeter Measurements

“…This was done with both GEOS-3 and Seasat (Kolenkiewicz and Martin, 1982;Martin and Kolenkiewicz, 1981) and was successful even in the presence of meter-level orbit errors because the overflight site at Bermuda also had a NASA laser ranging station. This was done with both GEOS-3 and Seasat (Kolenkiewicz and Martin, 1982;Martin and Kolenkiewicz, 1981) and was successful even in the presence of meter-level orbit errors because the overflight site at Bermuda also had a NASA laser ranging station.…”

Global mean sea surface computation using GEOS 3 altimeter data

“…This error is primarily due to errors in the gravity field model. Lerch et al [1981] indicated that the GEOS 3 rms radial ephemeris error was about 1 m for 5-day orbit arcs computed using the GEM 10B earth gravity model for the analysis of laser tracking data. Analyses [e.g., Douglas and Goad, 1978;Marsh and Williamson, 1980] of the character of satellite radial position error have shown that the major effects occurred near the frequency of once per orbital revolution.…”

“…Second, a subset of these arcs was chosen which provided the maximum coverage from the altimeter data in each arc. The orbits were computed using the GEM 10B[Lerch et al, 1981], earth gravity model, laser tracking station coordinates derived by Marsh et al order to study the relationship between orbit error and geographic area, the rms crossover differences for each region for 1975 and 1976 are presented on this map. The greater overall consistency of the 1975 values versus the 1976 values is attributed to the fact that the GEOS 3 tracking data included in the development of GEM 10B were primarily from 1975 and thus the GEM 10B may be more closely tailored to the GEOS 3 orbit dynamics in 1975 than in 1976.…”