Use of potential coefficient models for geoid undulation determinations using a spherical harmonic representation of the height anomaly/geoid undulation difference   总被引：9，自引：3，他引：9  

R. H. Rapp 《Journal of Geodesy》1997,71(5):282-289

 This paper suggests that potential coefficient models of the Earth's gravitational potential be used to calculate height anomalies which are then reduced to geoid undulations where such quantities are needed for orthometric height determination and vertical datum definition through a potential coefficient realization of the geoid. The process of the conversion of the height anomaly into a geoid undulation is represented by a height anomaly gradient term and the usual N–ζ term that is dependent on elevation and the Bouguer anomaly. Using a degree 360 expansion of 30′ elevations and the OSU91A potential coefficient model, a degree 360 representation of the correction terms was computed. The magnitude of N–ζ reached –3.4 m in the Himalaya Mountains with smaller, but still significant, magnitudes in other mountainous regions. Received: 6 May 1996; Accepted: 30 October 1996  相似文献   

Record of Late Pleistocene Glaciation and Deglaciation in the Southern Cascade Range. I. Petrological Evidence from Lacustrine Sediment in Upper Klamath Lake, Southern Oregon     

Richard L. Reynolds  Joseph G. Rosenbaum  Josh Rapp  Michael W. Kerwin  J. Platt Bradbury  Steven Colman  David Adam 《Journal of Paleolimnology》2004,31(2):217-233

Petrological and textural properties of lacustrine sediments from Upper Klamath Lake, Oregon, reflect changing input volumes of glacial flour and thus reveal a detailed glacial history for the southern Cascade Range between about 37 and 15 ka. Magnetic properties vary as a result of mixing different amounts of the highly magnetic, glacially generated detritus with less magnetic, more weathered detritus derived from unglaciated parts of the large catchment. Evidence that the magnetic properties record glacial flour input is based mainly on the strong correlation between bulk sediment particle size and parameters that measure the magnetite content and magnetic mineral freshness. High magnetization corresponds to relatively fine particle size and lower magnetization to coarser particle size. This relation is not found in the Buck Lake core in a nearby, unglaciated catchment. Angular silt-sized volcanic rock fragments containing unaltered magnetite dominate the magnetic fraction in the late Pleistocene sediments but are absent in younger, low magnetization sediments. The finer grained, highly magnetic sediments contain high proportions of planktic diatoms indicative of cold, oligotrophic limnic conditions. Sediment with lower magnetite content contains populations of diatoms indicative of warmer, eutrophic limnic conditions. During the latter part of oxygen isotope stage 3 (about 37–25 ka), the magnetic properties record millennial-scale variations in glacial-flour content. The input of glacial flour was uniformly high during the Last Glacial Maximum, between about 21 and 16 ka. At about 16 ka, magnetite input, both absolute and relative to hematite, decreased abruptly, reflecting a rapid decline in glacially derived detritus. The decrease in magnetite transport into the lake preceded declines in pollen from both grass and sagebrush. A more gradual decrease in heavy mineral content over this interval records sediment starvation with the growth of marshes at the margins of the lake and dilution of detrital material by biogenic silica and other organic matter.  相似文献   

Introduction to soil degradation processes in drylands     

Anders Rapp 《Climatic change》1986,9(1-2):19-31

Two efforts by UN organizations to diagnose and map the distribution and trends of soil degradation in drylands are briefly described and compared.Soil degradation by water is greatly accelerated under poor vegetation cover in the Tropics and Subtropics, probably for two major reasons: high rates of decomposition of organic matter and high intensities of rainfall. The consequences of soil losses and high water runoff can reach far downstream in the river basin, causing damage by sedimentation on floodplains and in reservoirs.Damages by wind erosion and deposition are also much accelerated by overexploitation of the meagre vegetation cover of drylands. Overgrazing, overcultivation, firewood collection are the consequences of human and animal pressure, leading to more or less long-lasting desertification. The finer material, clay, silt, and organic matter, is blown by dust storms over long distances and can be deposited as dry or wet fallout in oceans or on land under the dust trajectories.Salinization often affects highly productive soils under poor irrigation practices. It is therefore a form of dryland degradation which causes particularly high losses of potential crops.  相似文献   

    

Richard H. Rapp 《Journal of Geodesy》1972,46(3):343-349

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Reiner Rummel  Richard H. Rapp 《Journal of Geodesy》1978,52(4):297

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Undulation and anomaly estimation using Geos-3 altimeter data without precise satellite orbits   总被引：1，自引：0，他引：1  

R. Rummel  R. H. Rapp 《Journal of Geodesy》1977,51(1):73-88

The paper describes results obtained from the processing of 53 Geos-3 arcs of altimeter data obtained during the first weeks after the launch of the satellite in April, 1975. The measurement from the satellite to the ocean surface was used to obtain an approximate geoid undulation which was contaminated by long wavelength errors caused primarily by altimeter bias and orbit error. This long wavelength 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. The root mean square crossover discrepancy before this adjustment was ±12.4 meters while after the adjustment it was ±0.9 m. These adjusted undulations were used to construct a geoid map in the Geos-3 calibration area using a least squares filter to remove remaining noise in the undulations. Comparing these undulations to ones computed from potential coefficients and terrestrial gravity data indicates a mean difference of 0.25 m and a root mean square difference of ±1.92 m. The adjusted undulations were also used to estimate several 5^o, 2^o, and 1^o anomalies using the method of least squares collocation. The resulting predictions agreed well with known values although the 1^o x 1^o anomalies could not be considered as reliably determined.  相似文献   

Discussion: “Xenoliths in ultrapotassic volcanic rocks in the Lhasa block: direct evidence for crust–mantle mixing and metamorphism in the deep crust” by Wang et al. 2016 (Contributions to Mineralogy and Petrology) 171:62     

Aleksandr?S.?StepanovEmail author  Ian?Campbell  Robert?P.?Rapp  Jessica?Lowczak  Andrey?V.?Korsakov 《Contributions to Mineralogy and Petrology》2017,172(4):19

Wang et al. (Contrib Mineral Petrol 171:62, 2016a) present data on composition of xenolith from Southern Tibet and conclude that ulrapotassic melts from the region formed by melting mantle, and complex interaction with a crustal component. In this discussion we demonstrate that numerous observations presented by Wang et al. (2016a) can be explained by partial melting of crust followed by interaction between that melt and the mantle. We show that this model can explain the variability of magmas in such suits without evoking occurrence of coincidental, unrelated events. Moreover we demonstrate that our model of a crustal origin of the proto-shoshonite melts is now supported by independent lines of evidence such as geochemistry of restites after high- and ultrahigh- pressure melting and melt inclusion studies.  相似文献   

Editorial     

William Lotko  Markus Rapp  Bethan Keall 《Journal of Atmospheric and Solar》2010,72(5-6):375

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First continuous temperature measurements within polar mesosphere summer echoes     

F.-J. Lübken  J. Lautenbach  J. Höffner  M. Rapp  M. Zecha 《Journal of Atmospheric and Solar》2009,71(3-4):453-463

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Meteoric smoke particle properties derived using dual-beam Arecibo UHF observations of D-region spectra during different seasons     

J.T. Fentzke  D. Janches  I. Strelnikova  M. Rapp 《Journal of Atmospheric and Solar》2009,71(17-18):1982-1991

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