Altimeter Signal-to-Noise for Deep Ocean Processes in Operational Systems     

Kirk R. Whitmer  Gregg A. Jacobs  Ole Martin Smedstad 《Marine Geodesy》2004,27(3):433-451

The ocean signal for this study is the sea surface height due to the slowly varying (greater than 5-day) ocean processes, which are predominantly the deep ocean mesoscale. These processes are the focus of present assimilation systems for monitoring and predicting ocean circulation due to ocean fronts and eddies and the associated environmental changes that impact real time activities in areas with depths greater than about 200 m. By this definition, signal-to-noise may be estimated directly from altimeter data sets through a crossover point analysis. The RMS variability in crossover differences is due to instrument noise, errors in environmental corrections to the satellite observation, and short time period oceanic variations. The signal-to-noise ratio indicates that shallow areas are typically not well observed due to the high frequency fluctuations. Many deep ocean areas also contain significant high frequency variability such as the subpolar latitudes, which have large atmospheric pressure systems moving through, and these in turn generate large errors in the inverse barometer correction. Understanding the spatial variations of signal to noise is a necessary prerequisite for correct assimilation of the data into operational systems.  相似文献   

Diel changes in food and feeding of small gadoids on a coastal bank     

Albert  Ole Thomas 《ICES Journal of Marine Science》1995,52(5):873-885

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The biology of the greater weever (Trachinus draco) in the commercial fishery of the Kattegat     

Bagge  Ole 《ICES Journal of Marine Science》2004,61(6):933-943

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Multi-satellite ocean tide modelling—the K₁ constituent     

Ole Baltazar Andersen  Per Knudsen 《Progress in Oceanography》1997,40(1-4)

All major ocean tide constituents are aliased into signals with periods less than 90 days from TOPEX/POSEIDON altimetry, except the K₁ constituent. The aliased K₁ has a period of 173 days. Consequently, it might be confounded with height variations caused by the semiannual cycle having a period of 183 days.The correlation between K₁ and the semiannual signal has been investigated both locally and globally using combinations of T/P, ERS-1 and GEOSAT observations. Subsequently, two empirical methods have been investigated to improve the mapping of K₁ from multiple satellites.At high latitudes, where the presence of crossing tracks cannot separate K₁ from the semiannual signal from TOPEX/POSEIDON, the importance of including ERS-1 and GEOSAT observations was demonstrated. A comparison with 29 pelagic and coastal tide gauges in the Southern Ocean south of 50°S gave 5.59 (M₂), 2.27 (S₂) and 5.04 (K₁) cm RMS agreement for FES95.1 ocean tide model. The same comparison for the best empirical estimated constituents based on TOPEX/POSEIDON + ERS-1 + GEOSAT gave 4.32, 2.21, and 4.29 cm for M₂, S₂ and K₁, respectively.  相似文献   

Low-frequency variability of surface air temperature over the Barents Sea: causes and mechanisms     

Eveline C. van der Linden  Richard Bintanja  Wilco Hazeleger  Rune G. Graversen 《Climate Dynamics》2016,47(3-4):1247-1262

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IVS contribution to ITRF2014   总被引：5，自引：4，他引：1  

Sabine Bachmann  Daniela Thaller  Ole Roggenbuck  Michael Lösler  Linda Messerschmitt 《Journal of Geodesy》2016,90(7):631-654

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Postglacial uplift and relative sea level changes in Finnmark,northern Norway     

Anders Romundset  Stein Bondevik  Ole Bennike 《Quaternary Science Reviews》2011,30(19-20):2398-2421

The outer coast of Finnmark in northern Norway is where the former Fennoscandian and Barents Sea ice sheets coalesced. This key area for isostatic modelling and deglaciation history of the ice sheets has abundant raised shorelines, but only a few existing radiocarbon dates constrain their chronology. Here we present three Holocene sea level curves based on radiocarbon dated deposits from isolation basins at the outermost coast of Finnmark; located at the islands Sørøya and Rolvsøya and at the Nordkinn peninsula. We analysed animal and plant remains in the basin deposits to identify the transitions between marine and lacustrine sediments. Terrestrial plant fragments from these transitions were then radiocarbon dated. Radiocarbon dated mollusk shells and marine macroalgae from the lowermost deposits in several basins suggest that the first land at the outer coast became ice free around 14,600 cal yr BP. We find that the gradients of the shorelines are much lower than elsewhere along the Norwegian coast because of substantial uplift of the Barents Sea. Also, the anomalously high elevation of the marine limit in the region can be attributed to uplift of the adjacent seafloor. After the Younger Dryas the coast emerged 1.6–1.0 cm per year until about 9500–9000 cal yr BP. Between 9000 and 7000 cal yr BP relative sea level rose 2–4 m and several of the studied lakes became submerged. At the outermost locality Rolvsøya, relative sea level was stable at the transgression highstand for more than 3000 years, between ca 8000 and 5000 cal yr BP. Deposits in five of the studied lakes were disturbed by the Storegga tsunami ca 8200–8100 cal yr BP.  相似文献   

Linear complementarity formulation for 3D frictional sliding problems     

J. Ole Kaven  Stephen H. Hickman  Nicholas C. Davatzes  Ovunc Mutlu 《Computational Geosciences》2012,16(3):613-624

Frictional sliding on quasi-statically deforming faults and fractures can be modeled efficiently using a linear complementarity formulation. We review the formulation in two dimensions and expand the formulation to three-dimensional problems including problems of orthotropic friction. This formulation accurately reproduces analytical solutions to static Coulomb friction sliding problems. The formulation accounts for opening displacements that can occur near regions of non-planarity even under large confining pressures. Such problems are difficult to solve owing to the coupling of relative displacements and tractions; thus, many geomechanical problems tend to neglect these effects. Simple test cases highlight the importance of including friction and allowing for opening when solving quasi-static fault mechanics models. These results also underscore the importance of considering the effects of non-planarity in modeling processes associated with crustal faulting.  相似文献   

A Middle Weichselian interstadial lake deposit on Sejerø, Denmark: macrofossil studies and dating     

Ole Bennike  Michael Houmark‐Nielsen  Peter Wiberg‐Larsen 《第四纪科学杂志》2007,22(6):647-651

Studies of lake sediments on Sejerø in southern Kattegat indicate a treeless arctic environment with the dwarf shrub Salix polaris, herbs and wetland mosses. The mean July temperature was around 8 to 10°C. An AMS radiocarbon age determination of a Salix twig yielded an age of around 36 000 ¹⁴C yr BP, which is in accordance with previous conventional dating of bulk sediment samples. Copyright © 2006 John Wiley & Sons, Ltd.  相似文献   

IAG Newsletter     

Ole Baltazar Andersen 《Journal of Geodesy》2003,76(11-12):715-718

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