Experience with the ULISS-30 inertial survey system for local geodetic and cadastral network control     

Rene Forsberg 《Journal of Geodesy》1991,65(3):179-188

The capability of the recently developed SAGEM ULISS-30 inertial survey system for performing local surveys at high accuracies have been tested in a field campaign carried out November 1989 on the island of Fyn, Denmark, in cooperation with the Swedish National Land Survey. In the test a number of lines between existing national geodetic control points were surveyed, along with points in the less reliably determined cadastral network, forming an irregular network pattern of 10–15 km extent. The survey involved frequent offset measurements (up to 50–100 m) with an ISS-integrated total station. The profile geometries were not particularly suited for inertial surveys, with narrow and rather winding roads, necessitating frequent vehicle turns. In addition to the pure inertial surveys a kinematic GPS/inertial test was also carried out, using a pair of Ashtech L-XII receivers. The inertial survey results, analyzed with a smoothing algoritm utilizing common points on forward/backward runs, indicate that 5-cm accuracies are possible on reasonably straight profiles of 5 km length, corresponding to a 10 ppm best-case accuracy for double-run traverses. On longer, more winding traverses error levels of 10–20 cm are typical. To handle the inertial data optimally, proper network adjustments are required. A discussion of suitable adjustment models of both conventional and collocation type is included in the paper.  相似文献   

Climate change impacts on U.S. Coastal and Marine Ecosystems   总被引：1，自引：0，他引：1  

Donald Scavia  John C. Field  Donald F. Boesch  Robert W. Buddemeier  Virginia Burkett  Daniel R. Cayan  Michael Fogarty  Mark A. Harwell  Robert W. Howarth  Curt Mason  Denise J. Reed  Thomas C. Royer  Asbury H. Sallenger  James G. Titus 《Estuaries and Coasts》2002,25(2):149-164

Increases in concentrations of greenhouse gases projected for the 21st century are expected to lead to increased mean global air and ocean temperatures. The National Assessment of Potential Consequences of Climate Variability and Change (NAST 2001) was based on a series of regional and sector assessments. This paper is a summary of the coastal and marine resources sector review of potential impacts on shorelines, estuaries, coastal wetlands, coral reefs, and ocean margin ecosystems. The assessment considered the impacts of several key drivers of climate change: sea level change; alterations in precipitation patterns and subsequent delivery of freshwater, nutrients, and sediment; increased ocean temperature; alterations in circulation patterns; changes in frequency and intensity of coastal storms; and increased levels of atmospheric CO₂. Increasing rates of sea-level rise and intensity and frequency of coastal storms and hurricanes over the next decades will increase threats to shorelines, wetlands, and coastal development. Estuarine productivity will change in response to alteration in the timing and amount of freshwater, nutrients, and sediment delivery. Higher water temperatures and changes in freshwater delivery will alter estuarine stratification, residence time, and eutrophication. Increased ocean temperatures are expected to increase coral bleaching and higher CO₂ levels may reduce coral calcification, making it more difficult for corals to recover from other disturbances, and inhibiting poleward shifts. Ocean warming is expected to cause poleward shifts in the ranges of many other organisms, including commercial species, and these shifts may have secondary effects on their predators and prey. Although these potential impacts of climate change and variability will vary from system to system, it is important to recognize that they will be superimposed upon, and in many cases intensify, other ecosystem stresses (pollution, harvesting, habitat destruction, invasive species, land and resource use, extreme natural events), which may lead to more significant consequences.  相似文献   

North African Lakes, Edited by R. J. Flower (Book Review)     

J. Curt Stager 《Journal of Paleolimnology》2002,28(4):491-492

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Holocene climate variability   总被引：17，自引：0，他引：17  

Paul A. Mayewski  Eelco E. Rohling  J. Curt Stager  Wibjrn Karln  Kirk A. Maasch  L. David Meeker  Eric A. Meyerson  Francoise Gasse  Shirley van Kreveld  Karin Holmgren  Julia Lee-Thorp  Gunhild Rosqvist  Frank Rack  Michael Staubwasser  Ralph R. Schneider  Eric J. Steig 《Quaternary Research》2004,62(3):243-255

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The gravity field and GGOS     

R. Forsberg  M.G. Sideris  C.K. Shum   《Journal of Geodynamics》2005,40(4-5):387

The gravity field of the earth is a natural element of the Global Geodetic Observing System (GGOS). Gravity field quantities are like spatial geodetic observations of potential very high accuracy, with measurements, currently at part-per-billion (ppb) accuracy, but gravity field quantities are also unique as they can be globally represented by harmonic functions (long-wavelength geopotential model primarily from satellite gravity field missions), or based on point sampling (airborne and in situ absolute and superconducting gravimetry). From a GGOS global perspective, one of the main challenges is to ensure the consistency of the global and regional geopotential and geoid models, and the temporal changes of the gravity field at large spatial scales. The International Gravity Field Service, an umbrella “level-2” IAG service (incorporating the International Gravity Bureau, International Geoid Service, International Center for Earth Tides, International Center for Global Earth models, and other future new services for, e.g., digital terrain models), would be a natural key element contributing to GGOS. Major parts of the work of the services would, however, remain complementary to the GGOS contributions, which focus on the long-wavelength components of the geopotential and its temporal variations, the consistent procedures for regional data processing in a unified vertical datum and Terrestrial Reference Frame, and the ensuring validations of long-wavelength gravity field data products.  相似文献   

Lagged response of nutrient leaching to reduced surpluses at the field and catchment scales          下载免费PDF全文

Barbro Ulén  Göran Johansson  Katarina Kyllmar  Lovisa Stjernman Forsberg  Gunnar Torstensson 《水文研究》2015,29(13):3020-3037

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A dynamic deterministic model of hydrocarbon generation in the Midgard Field drainage area offshore Mid-Norway     

E. S. Mo  T. Throndsen  P. Andresen  S. A. Bäckström  A. Forsberg  S. Haug  B. Tørudbakken 《International Journal of Earth Sciences》1989,78(1):305-317

The Midgard Field offshore mid-Norway is a gas-condensate accumulation with a thin oil leg reservoired in Early and Middle Jurassic sandstones. There are two potential source rocks in the area; the Late Jurassic Spekk Formation is a marine shale with type II kerogen and a rich potential for oil, and the Åre Formation of Early Jurassic age which is a thick coal-bearing sequence with type III kerogen and potential mainly for gas. Geochemical analyses indicate that both the condensate and the oil leg are sourced mainly from the coal-bearing Åre Formation. Any contribution from the Spekk Formation appears to be of minor importance. Computer simulation of hydrocarbon generation in the drainage area for the Midgard Field indicates that huge volumes are formed, and confirms that hydrocarbon generation from the Åre Formation is volumetrically far more important than from the Spekk Formation. The simulation results also exclude any contribution to the reservoired gas from the Spekk Formation.

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Zusammenfassung Das Midgard Feld vor der Küste Mittelnorwegens ist eine Gas-Kondensat-Akkumulation mit einem nur geringen Ölanteil innerhalb unter- und mitteljurassischer Sandsteine. In diesem Gebiet gibt es zwei mögliche Muttergesteine: Einmal die oberjurassische Spekk-Formation, bei der es sich um einen marinen Schiefer mit Typ II Kerogen handelt und die ein hohes Ölpotential darstellt. Zum anderen gibt es die unterjurassische Åre-Formation, eine mächtige Kohle-führende Folge mit Typ III Kerogen und ein möglicher Gaslieferant. Geochemische Analysen deuten darauf hin, daß sowohl das Gas-Kondensat als auch das Öl des Midgard Feldes auf diese Kohle-führende Åre-Formation zurückzuführen sind. Jede Zufuhr aus der Spekk-Formation scheint von geringer Bedeutung zu sein. Eine durch Computersimulation rekonstruierte Kohlenwasserstofferzeugung im Einzugsgebiet des Midgard Feldes spricht für eine hohe Bildungsrate und bestätigt die Annahme, daß die Kohlenwasserstoff-produktion der Spekk-Formation gegenüber der Åre-Formation zu vernachlässigen ist. Die Simulation ergab ferner, daß keinerlei Gas von der Spekk-Formation dem Reservoir zugeführt wurde.

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Résumé Le champ off-shore de Midgard (Norvège moyenne) est une accumulation de gaz condensé accompagnée d'un mince corps d'huile, accumulation renfermée dans des grès d'âge jurassique inférieur et moyen. Il existe dans le secteur deux sources possibles: la formation de Spekk (shale marins du Jurassique tardif, à kérogène de type II, possédant un riche potentiel en huile) et la formation d'Åre (série épaisse jurassique inférieure, à couches de charbon, à kérogène de type III et potentiel essentiellement en gaz). Les analyses géochimiques montrent que le gaz condensé et l'huile ont tous deux comme origine la formation charbonneuse de Åre. La formation de Spekk ne semble être intervenue que de manière subordonnée. Une simulation par ordinateur de la genèse de l'hydrocarbure dans l'aire d'alimentation du champ de Midgard fait apparaître que des volumes importants ont été formés et confirme la large prépondérance de la formation de Åre parmi les roches-mères. De plus, cette simulation exclut toute expèce de contribution de la formation de Spekk dans la genèse du gaz.

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Midgard / / . : Spekk — , 2, , Are , 3 . . . , Are. Spekk, , . Midgard , Are . , , Spekk .

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Atmospheric and oceanic heat transport: Simulations versus observations     

Curt Covey 《Climatic change》1988,13(2):149-159

Poleward transport of heat by the atmosphere as simulated by a recently developed general circulation model (GCM) is consistent with earlier GCM studies in being significantly greater than indicated from radiosonde (weather balloon) observations. However, total heat transport by the combined ocean-atmosphere system appears to be approximately the same in the models and in satellite observations of irradiances at the top of the atmosphere: in the models most of this transport takes place in the atmosphere whereas the combined satellite and radiosonde observations indicate that half or more of the transport takes place in the oceans. It is argued here that the atmospheric model results are generally closer to the truth than the radiosonde observations. If this is true, then the oceans transport less heat than often supposed, and conventional ideas about the genesis of climatic change through alterations in oceanic heat transport must be reexamined.  相似文献   

Book reviews     

Melinda Meade  Curt Covey  J. Salinger  T. Rabb  Peter Timmerman 《Climatic change》1983,5(2):193-200

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Simple gravity corer suitable for educators     

J. Curt Stager 《Journal of Paleolimnology》1992,7(3):253-255

Instructions for construction and use of a simple and inexpensive sediment coring device are presented. The sampler is suitable for use in high school and undergraduate science courses.  相似文献