The Arctic Coastal Dynamics Database: A New Classification Scheme and Statistics on Arctic Permafrost Coastlines     

Hugues Lantuit  Pier Paul Overduin  Nicole Couture  Sebastian Wetterich  Felix Aré  David Atkinson  Jerry Brown  Georgy Cherkashov  Dmitry Drozdov  Donald Lawrence Forbes  Allison Graves-Gaylord  Mikhail Grigoriev  Hans-Wolfgang Hubberten  James Jordan  Torre Jorgenson  Rune Strand ?deg?rd  Stanislav Ogorodov  Wayne H. Pollard  Volker Rachold  Sergey Sedenko  Steve Solomon  Frits Steenhuisen  Irina Streletskaya  Alexander Vasiliev 《Estuaries and Coasts》2012,35(2):383-400

Arctic permafrost coasts are sensitive to changing climate. The lengthening open water season and the increasing open water area are likely to induce greater erosion and threaten community and industry infrastructure as well as dramatically change nutrient pathways in the near-shore zone. The shallow, mediterranean Arctic Ocean is likely to be strongly affected by changes in currently poorly observed arctic coastal dynamics. We present a geomorphological classification scheme for the arctic coast, with 101,447?km of coastline in 1,315 segments. The average rate of erosion for the arctic coast is 0.5?m? year^?1 with high local and regional variability. Highest rates are observed in the Laptev, East Siberian, and Beaufort Seas. Strong spatial variability in associated database bluff height, ground carbon and ice content, and coastline movement highlights the need to estimate the relative importance of shifting coastal fluxes to the Arctic Ocean at multiple spatial scales.  相似文献   

Interpreting velocities from heat-based flow sensors by numerical simulation   总被引：1，自引：0，他引：1  

Su GW  Freifeld BM  Oldenburg CM  Jordan PD  Daley PF 《Ground water》2006,44(3):386-393

We have carried out numerical simulations of three-dimensional nonisothermal flow around an in situ heat-based flow sensor to investigate how formation heterogeneities can affect the interpretation of ground water flow velocities from this instrument. The flow sensor operates by constant heating of a 0.75-m-long, 5-cm-diameter cylindrical probe, which contains 30 thermistors in contact with the formation. The temperature evolution at each thermistor can be inverted to obtain an estimate of the ground water flow velocity vector using the standard interpretive method, which assumes that the formation is homogeneous. Analysis of data from heat-based flow sensors installed in a sand aquifer at the Former Fort Ord Army Base near Monterey, California, suggested an unexpected component of downward flow. The magnitudes of the vertical velocities were expected to be much less than those of the horizontal velocities at this site because the sensors were installed just above a clay aquitard. Numerical simulations were conducted to examine how differences in thermal conductivities may lead to spurious indications of vertical flow velocities. We found that a decrease in the thermal conductivity near the bottom of the sensor can perturb the temperature profiles along the instrument in such a manner that analyses assuming homogeneous thermal conductivity could indicate a vertical flow component even though flow is actually horizontal. This work demonstrates how modeling can be used to simulate instrument response to formation heterogeneity and shows that caution must be used in interpreting data from such devices.  相似文献   

Procedures,Resources and Selected Results of the Deep Ecliptic Survey     

Buie  M. W.  Millis  R. L.  Wasserman  L. H.  Elliot  J. L.  Kern  S. D.  Clancy  K. B.  Chiang  E. I.  Jordan  A. B.  Meech  K. J.  Wagner  R. M.  Trilling  D. E. 《Earth, Moon, and Planets》2003,92(1-4):113-124

The Deep Ecliptic Survey is a project whose goal is to survey a largearea of the near-ecliptic region to a faint limiting magnitude (R ～24) in search of objects in the outer solar system. We are collectinga large homogeneous data sample from the Kitt Peak Mayall 4-m and CerroTololo Blanco 4-m telescopes with the Mosaic prime-focus CCD cameras.Our goal is to collect a sample of 500 objects with good orbits to furtherour understanding of the dynamical structure of the outer solar system.This survey has been in progress since 1998 and is responsible for 272designated discoveries as of March 2003. We summarize our techniques,highlight recent results, and describe publically available resources.  相似文献   

Mapping the narrative positions of new political groups under the UNFCCC     

Andrew Jordan  Tim Rayner  Heike Schroeder  Neil Adger  Kevin Anderson  Alice Bows 《Climate Policy》2013,13(6):751-769

Since the mid-1990s, the aim of keeping climate change within 2?°C has become firmly entrenched in policy discourses. In the past few years, the likelihood of achieving it has been increasingly called into question. The debate around what to do with a target that seems less and less achievable is, however, only just beginning. As the UN commences a two-year review of the 2?°C target, this article moves beyond the somewhat binary debates about whether or not it should or will be met, in order to analyse more fully some of the alternative options that have been identified but not fully explored in the existing literature. For the first time, uncertainties, risks, and opportunities associated with four such options are identified and synthesized from the literature. The analysis finds that the significant risks and uncertainties associated with some options may encourage decision makers to recommit to the 2?°C target as the least unattractive course of action.  相似文献   

Erratum to: Analysis of overdeepened valleys using the digital elevation model of the bedrock surface of Northern Switzerland     

Peter Jordan 《Swiss Journal of Geoscience》2011,104(1):185-185

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The chromosphere-corona transition region in late-type stars     

C. Jordan 《Astrophysics and Space Science》1996,237(1-2):13-32

Observations of the Sun show that the chromosphere-corona transition region has a complex geometry and dynamic nature. In spite of this, observations of stellar transition regions show common behaviour as well as systematic trends. The basic methods used in making models of the transition region are set out. Observations relating to inhomogeneities in the solar transition region are summarized. The structure and energy balance of stellar transition regions and the trends emerging are discussed.  相似文献   

Modulation of near-inertial motions on the Mississippi-Alabama Shelf     

Buijsman  Maarten C.  Earls  Jordan  Weierbach  Helen 《Ocean Dynamics》2021,71(11):1087-1103

Ocean Dynamics - In this study, we diagnose the time variability and vertical structure of the high- and low-frequency motions on the Mississippi-Alabama Shelf as observed with a bottom-mounted...  相似文献   

Institutions for global environmental change     

Andrew Jordan  Timothy O&#x;Riordan 《Global Environmental Change》2002,12(4)

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Radio-continuum study of the nearby Sculptor group Galaxies. Part 2: NGC 55 at λ=20, 13, 6 and 3 cm     

Andrew N. O’Brien  Miroslav D. Filipović  Evan J. Crawford  Nicholas F. H. Tothill  Jordan D. Collier  Ain Y. De Horta  Graeme F. Wong  Danica Drašković  Jeff L. Payne  Thomas G. Pannuti  Jared P. Napier  Stephen A. Griffith  Wayne D. Staggs  Srdjan Kotuš 《Astrophysics and Space Science》2013,347(1):159-168

A series of new radio-continuum (λ=20, 13, 6 and 3 cm) mosaic images focused on the NGC 55 galactic system were produced using archived observational data from the Australia Telescope Compact Array. These new images are both very sensitive (down to rms=33 μJy) and feature high angular resolution (down to <4″). Using these newly created images, 66 previously unidentified discrete sources are identified. Of these sources, 46 were classified as background sources, 11 as H?ii regions and 6 as supernova remnant candidates. This relatively low number of SNR candidates detected coupled with the low number of large H?ii regions is consistent with the estimated low star formation rate of the galaxy at 0.06 M _⊙?year^?1. Our spectral index map shows that the core of galaxy appears to have a shallow spectral index between α=?0.2 and ?0.4. This indicates that the core of the galaxy is a region of high thermal radiation output.  相似文献   

First Results of the Regional Earthquake Likelihood Models Experiment   总被引：1，自引：0，他引：1  

Danijel Schorlemmer  J. Douglas Zechar  Maximilian J. Werner  Edward H. Field  David D. Jackson  Thomas H. Jordan 《Pure and Applied Geophysics》2010,167(8-9):859-876

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