ISSN:0149-0419    

DOI:10.1080/01490418009387990

出版商:Taylor & Francis Group    

年代:1980

数据来源: Taylor

摘要:

The International Symposium on Interaction of Marine Geodesy and Ocean Dynamics was held during 10–13 October 1978 in Miami, Florida. This report summarizes the deliberations of four concurrent workshops which followed the general technical sessions, and reports the resolution of a final plenary workshop held on the last day.

ISSN:0149-0419    

DOI:10.1080/01490418009387991

出版商:Taylor & Francis Group    

年代:1980

数据来源: Taylor

摘要:

Within the marine geodetic research center at the Technical University Hannover there is one project that deals with methods for precise marine positioning, including satellite Doppler techniques. In 1977 a Doppler measuring campaign of eight weeks was performed for the precise positioning of the German research rig FPN in the North Sea. The results of this campaign, including an antenna height variation study and the comparison with trans‐horizon electromagnetic distance measurements over sea, are presented and discussed. Height differences turn out to be reproduced by the Doppler solution within a few decimeters, and distance differences remain below 1 m. During the summer of 1978 a first experiment with Doppler positioning of a buoy near the research rig was carried out. Experiences and preliminary results of this experiment are presented.

ISSN:0149-0419    

DOI:10.1080/01490418009387992

出版商:Taylor & Francis Group    

年代:1980

数据来源: Taylor

摘要:

With the launch of SEASAT‐1 in June 1978, an altimeter of improved performance joined GEOS‐3, which had been operational for three years. The advances in design that resulted in <10 cm rms height precision are discussed and some early onorbit performance results presented. In addition to improved resolution and a higher pulse rate, both of which acted to reduce height noise, the SEASAT‐1 altimeter incorporated a microcomputer which allowed flexibility in choice of tracker characteristics and provided for on‐board computation of significant waveheight. Under consideration for future missions are a multi‐beam capability to increase the swath coverage, the primary thrust being more rapid development of current maps, and an uplink programming capability for the microcomputer to facilitate on‐board processing in a way which permits post‐launch algorithm modification. Addition of a rainfall detection mode to the altimeter has also been proposed, and consideration has been given to the reliability improvements needed to support a three‐year mission.

ISSN:0149-0419    

DOI:10.1080/01490418009387993

出版商:Taylor & Francis Group    

年代:1980

数据来源: Taylor

摘要:

The sea level in the Florida Straits is part of the controversial issue of sea level slope along continental boundaries (Balazs, 1973; Sturges, 1974; Mourad, 1975; Chew, 1977). In this paper we show a case where the sea level topography off Miami is significantly affected by a downstream difference in centrifugal force. This case centers on an application of the turning vorticity equation (Chew, 1975) to the observation of Schmitz and Richardson (1966), wherein the divergence effect of Bernoulli acceleration is taken into account in an estimation of centrifugal force. On one hand, the analysis shows a downstream increase in centrifugal force in conjunction with a concurrent decrease in average cross‐stream sea level slope. On the other hand, the generally held notion of cross‐stream geostrophy in conjunction with a downstream increase in average cross‐stream slope is shown to be inconsistent with the observation.

ISSN:0149-0419    

DOI:10.1080/01490418009387994

出版商:Taylor & Francis Group    

年代:1980

数据来源: Taylor

摘要:

A least‐squares analysis is performed on simulated satellite altimeter data to investigate the separability of global ocean tide information from a noisy signal containing systematic orbit error. Numerical solutions of the Laplace Tidal Equations for the principal tidal constituents are used to generate the observed measurements based on simulated four‐day SEASAT orbits over a 200‐day interval. The global ocean tide is modeled as a sum of constituents represented by harmonic expansions, and the orbit error model parameters and tide model parameters are adjusted simultaneously. Good recovery of principal features of the numerical ocean tide solutions are obtained only when the systematic orbit error is adequately modeled in the estimation procedure.

ISSN:0149-0419    

DOI:10.1080/01490418009387995

出版商:Taylor & Francis Group    

年代:1980

数据来源: Taylor

摘要:

Geoid heights derived from GEOS‐3 radar altimeter measurements have been used to predict an ocean‐area gridded 1°×1° geoid height data base. These geoid heights are compared at 1°×1° grid intersections with similar values computed via spherical harmonic expansion, utilizing several different geo‐potential coefficient sets, and also with the Calibration Geoid which was computed using Stokes’ Integral and mean gravity anomalies. The gridded 1°×1° geoid height data base has been utilized to compute preliminary ocean‐area mean gravity anomalies. Comparisons are made between these preliminary 1°×1° mean gravity anomaly values and similar quantities computed from ship‐acquired gravity data.

ISSN:0149-0419    

DOI:10.1080/01490418009387996

出版商:Taylor & Francis Group    

年代:1980

数据来源: Taylor

摘要:

A detailed derivation of improved ocean tidal equations in continuous (COTEs) and discrete (DOTEs) forms is presented. These equations feature the Boussinesq linear eddy dissipation law with a novel eddy viscosity that depends on the lateral mesh area, i.e., on mesh size and ocean depth. Analogously, the linear law of bottom friction is used with a new bottom friction coefficient depending on the bottom mesh area. The primary astronomical tide‐generating potential is modified by secondary effects due to the oceanic and terrestrial tides. The fully linearized equations are defined in a single‐layer ocean basin of realistic bathymetry varying from 50 m to 7,000 m. The DOTEs are set up on a 1oby 1ospherically graded grid system, using central finite differences in connection with Richardson's staggered computation scheme. Mixed single‐step finite differences in time are introduced, which enhance decay, dispersion, and stability properties of the DOTEs and facilitate—in Part II of this paper—a unique hydrodynamical interpolation of empirical tide data. The purely hydrodynamical modeling is completed by imposing boundary conditions consisting of no‐flow across and free‐slip along the mathematical ocean shorelines. Shortcomings of the constructed preliminary M2ocean tide charts are briefly discussed. Needed improvements of the model are left to Part II.

ISSN:0149-0419    

DOI:10.1080/01490418009387997

出版商:Taylor & Francis Group    

年代:1980

数据来源: Taylor

摘要:

The strictly mathematical ocean tide model developed in Part I of this paper is modified in order to include realistic hydrodynamical barrier effects of narrow ocean ridges and other large bottom irregularities. This modification begins with a hydrodynamical redefinition of the ocean bathymetry at over 3,000 grid points, increasing simultaneously the depth data range to: 10m ? 7,000m. In a second step a unique hydrodynamical interpolation technique is developed that incorporates into the model over 2,000 empirical tide data collected around the world at continental and island stations. This interpolation is accomplished by a controlled cell‐wise adjustment of the bottom friction coefficient and by allowing a monitored in‐ or out‐flow across the mathematical ocean boundary and so, redefining a more physical shoreline. Extensive computer experiments were conducted to study the characteristics of the novel friction laws and hydrodynamical interpolation methods. The computed M2‐tide data along with all (specially labeled) empirical constants are tabulated in map form for four typical 30° by 50° ocean areas. It is estimated that the tabulated tidal charts permit a prediction of the M2‐tide elevation of the ocean surface over the geoidal level with an accuracy of better than 5 cm anywhere in the open ocean and with somewhat less accuracy near rough shorelines. With the forthcoming construction of the lesser S2, N2, and K2; K1;O1, P1, and Q1; and Mf, Mm, and Ssa tidal constituents, the total tide‐prediction error can be kept below the 10‐cm bound posed by applied researchers of today.

ISSN:0149-0419    

DOI:10.1080/01490418009387998

出版商:Taylor & Francis Group    

年代:1980

数据来源: Taylor

摘要:

The present paper reports on results obtained with research work related to the SEASAT‐A North Sea project. In the North Sea test area, a regional gravimetric geoid of high precision and resolution (50 km) has been calculated, using a combination of the present available terrestrial gravity data and the GEM 8 earth model. The accuracy of this geoid has been estimated by comparing it with the astrogeodetic geoid calculated for the adjoining land areas, and with the GEOS‐3 altimetric geoid for the German Bay. It is found that in the region of good gravity coverage (6' x 10' mean anomalies), geoid height differences can be derived with an accuracy of ±0.2 ... 0.6 m, depending on the point distance (50. . .500 km). Gravimetric deflections of the vertical have an accuracy of ±0.5?... 1.0? in this range. These results correspond to the accuracy obtainable by astrogeodetic methods in flat areas and by GEOS‐3 satellite altimetry. The accuracy of geoid differences decreases to ±0.7. . .1.0 m (range 50...1,000 km) if only 1o× 1omean anomalies exist in the calculation area.

ISSN:0149-0419    

DOI:10.1080/01490418009387999

出版商:Taylor & Francis Group    

年代:1980

数据来源: Taylor