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Rapp, R. H.

Publications and source records attributed to Rapp, R. H..

26 records · Page 2
All sourcesNASA NTRSDOE OSTI
NASA NTRS1977

Undulation and anomaly estimation using Geos-3 altimeter data without precise satellite orbits

Geos-3 altimeter data was used to obtain an approximate geoid undulation which was contaminated by long wavelength errors caused primarily by altimeter bias and orbit error. This error was reduced by fitting, with a low degree polynomial, the raw undulation data to the undulations implied by the GEM 7 potential coefficients in an adjustment process that included conditions on tracks that cross. These adjusted undulations were used to construct a geoid map in the Geos-3 calibration area using a least squares filter to remove the remaining noise in the undulations.

Rummel, R.↗
NASA NTRS1976

The influence of the atmosphere on geoid and potential coefficient determinations from gravity data

For the precise computation of geoid undulations the effect of the attraction of the atmosphere on the solution of the basic boundary value problem of gravimetric geodesy must be considered. This paper extends the theory of Moritz for deriving an atmospheric correction to the case when the undulations are computed by combining anomalies in a cap surrounding the computation point with information derived from potential coefficients. The correction term is a function of the cap size and the topography within the cap. It reaches a value of 3.0 m for a cap size of 30 deg, variations on the decimeter level being caused by variations in the topography. The effect of the atmospheric correction terms on potential coefficients is found to be small, reaching a maximum of 0.0055 millionths at n = 2, m = 2 when terrestrial gravity data are considered. The magnitude of this correction indicates that in future potential coefficient determination from gravity data the atmospheric correction should be made to such data.

Rummel, R.↗
NASA NTRS1975

Methods for the computation of detailed geoids and their accuracy

Two methods for the computation of geoid undulations using potential coefficients and 1 deg x 1 deg terrestrial anomaly data are examined. It was found that both methods give the same final result but that one method allows a more simplified error analysis. Specific equations were considered for the effect of the mass of the atmosphere and a cap dependent zero-order undulation term was derived. Although a correction to a gravity anomaly for the effect of the atmosphere is only about -0.87 mgal, this correction causes a fairly large undulation correction that was not considered previously. The accuracy of a geoid undulation computed by these techniques was estimated considering anomaly data errors, potential coefficient errors, and truncation (only a finite set of potential coefficients being used) errors. It was found that an optimum cap size of 20 deg should be used. The geoid and its accuracy were computed in the Geos 3 calibration area using the GEM 6 potential coefficients and 1 deg x 1 deg terrestrial anomaly data. The accuracy of the computed geoid is on the order of plus or minus 2 m with respect to an unknown set of best earth parameter constants.

Rapp, R. H.↗
NASA NTRS1974

Procedures and results related to the direct determination of gravity anomalies from satellite and terrestrial gravity data

The equations needed for the incorporation of gravity anomalies as unknown parameters in an orbit determination program are described. These equations were implemented in the Geodyn computer program which was used to process optical satellite observations. The arc dependent parameter unknowns, 184 unknown 15 deg and coordinates of 7 tracking stations were considered. Up to 39 arcs (5 to 7 days) involving 10 different satellites, were processed. An anomaly solution from the satellite data and a combination solution with 15 deg terrestrial anomalies were made. The limited data samples indicate that the method works. The 15 deg anomalies from various solutions and the potential coefficients implied by the different solutions are reported.

Rapp, R. H.↗
NASA NTRS1974

Results from the direct combination of satellite and gravimetric data

Results have been obtained for the solution of 184 15-deg equal-area blocks directly from the analysis of satellite orbits, and from a combination of the satellite results with terrestrial gravity material. This test computation, made to verify the method, used 17,632 optical observations from ten satellites in 29 arcs averaging in length seven days. Analysis of the satellite results were made by comparing the solved for anomalies with the terrestrial anomaly set, and by developing the solved for anomalies into potential coefficients which were compared to the GEM 3 set of potential coefficients to degree 12. These comparisons indicated improvement in each solution as more arcs were added. The programs used in this solution can easily be used to solve for smaller size blocks and handle additional data types. The only limitation will be computer core availability and computer time.

Rapp, R. H.↗
NASA NTRS1973

The earth's gravitational field from the combination of satellite and terrestrial data

This paper reviews techniques and results in the combination of gravimetric and satellite data. The estimation of mean anomalies for use in combination studies is discussed with the location of current gravity material being described. Specific techniques for combination solutions are discussed for various models. These models include those where the gravitational field is represented by a set of potential coefficients, or by a set of discrete blocks distributed on the earth. The potential coefficient solutions compared are those of the SAO Standard Earth II and III, the Goddard Earth Model 4, and a solution by the author. These solutions are compared in terms of coefficients, undulation and anomaly differences, and implied anomaly degree variances. In addition, comparisons were made through terrestrial anomaly comparisons, astrogeodetic undulation comparisons, and orbit fitting tests.

Rapp, R. H.↗
NASA NTRS1972

The formation and analysis of a 5 deg equal area block terrestrial gravity field

A set of 23,355 1 degree x 1 degree mean free air anomalies were used to predict a set of 5 degree equal area anomalies and their standard errors. Using the 1 degree data incorporating geophysically predicted values of ACIC, 1283 5 degree blocks were computed. Excluding the geophysically predicted anomalies 1249 blocks were computed. The 1 degree data were also used to compute covariance functions and the equatorial gravity and flattening implied by this data. The predicted anomalies were supplemented by model anomalies to form a complete 1654 global anomaly field. These data were used in a weighted least squares to determine potential coefficients to degree 15, and in a summation type formulation to determine potential coefficients to degree 25. These potential coefficients sets are compared to recent satellite determinations.

Rapp, R. H.↗