Practicing community geography in times of crisis     

Shannon  Jerry  Torres  Hannah  Mariner  Kathryn A.  Hawthorne  Timothy L. 《GeoJournal》2021,87(2):151-157

Community geography emphasizes the centrality of community engagement to socially transformative research. This introduction to a special issue of GeoJournal on community geography outlines how this growing subfield provides a model for collaborative action with the crises of our time, from white supremacy through climate change. As the co-editors of this special issue, we summarize the contents of these 14 articles, grouping them by the shared themes of power, institutional partnerships, pedagogy, and methods.

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Penetrometry of granular and moist planetary surface materials: Application to the Huygens landing site on Titan     

Karl R. Atkinson  John C. Zarnecki  Martin C. Towner  Timothy J. Ringrose  Axel Hagermann  Andrew J. Ball  Mark R. Leese  Gunter Kargl  Mark D. Paton  Ralph D. Lorenz  Simon F. Green 《Icarus》2010,210(2):843-851

The Huygens probe landed on the then unknown surface of Titan in January 2005. A small, protruding penetrometer, part of the Surface Science Package (SSP), was pushed into the surface material measuring the mechanical resistance of the ground as the probe impacted the landing site. We present laboratory penetrometry into room temperature surface analogue materials using a replica penetrometer to investigate further the nature of Titan’s surface and examine the sensor’s capabilities. The results are then compared to the flight instrument’s signature and suggest the Titan surface substrate material consists of sand-sized particles with a mean grain size ～2 mm. A possible thin 7 mm coating with mechanical properties similar to terrestrial snow may overlie this substrate, although due to the limited data we are unable to detect any further layering or grading within the near-surface material. The unusual weakening with depth of the signature returned from Titan has, to date, only been reproduced using a damp sand target that becomes progressively wetter with depth, and supports the suggestion that the surface may consist of a damp and cohesive material with interstitial liquid contained between its grains. Comparison with terrestrial analogues highlights the unusual nature of the landing site material.  相似文献   

Sea level rise and tigers: predicted impacts to Bangladesh’s Sundarbans mangroves     

Colby Loucks  Shannon Barber-Meyer  Md. Abdullah Abraham Hossain  Adam Barlow  Ruhul Mohaiman Chowdhury 《Climatic change》2010,98(1-2):291-298

The Sundarbans mangrove ecosystem, shared by India and Bangladesh, is recognized as a global priority for biodiversity conservation. Sea level rise, due to climate change, threatens the long term persistence of the Sundarbans forests and its biodiversity. Among the forests’ biota is the only tiger (Panthera tigris) population in the world adapted for life in mangrove forests. Prior predictions on the impacts of sea level rise on the Sundarbans have been hampered by coarse elevation data in this low-lying region, where every centimeter counts. Using high resolution elevation data, we estimate that with a 28 cm rise above 2000 sea levels, remaining tiger habitat in Bangladesh’s Sundarbans would decline by 96% and the number of breeding individuals would be reduced to less than 20. Assuming current sea level rise predictions and local conditions do not change, a 28 cm sea level rise is likely to occur in the next 50–90 years. If actions to both limit green house gas emissions and increase resilience of the Sundarbans are not initiated soon, the tigers of the Sundarbans may join the Arctic’s polar bears (Ursus maritimus) as early victims of climate change-induced habitat loss.  相似文献   

Time-series analysis of six whale-fall communities in Monterey Canyon,California, USA     

Lonny Lundsten  Kyra L. Schlining  Kaitlin Frasier  Shannon B. Johnson  Linda A. Kuhnz  Julio B.J. Harvey  Gillian Clague  Robert C. Vrijenhoek 《Deep Sea Research Part I: Oceanographic Research Papers》2010,57(12):1573-1584

Dead whale carcasses that sink to the deep seafloor introduce a massive pulse of energy capable of hosting dynamic communities of organisms in an otherwise food-limited environment. Through long-term observations of one natural and five implanted whale carcasses in Monterey Canyon, CA, this study suggests that: (1) depth and related physical conditions play a crucial role in species composition; (2) the majority of species in these communities are background deep-sea taxa; and (3) carcass degradation occurs sub-decadally. Remotely operated vehicles (ROVs) equipped with studio quality video cameras were used to survey whales during 0.8 to seven year periods, depending on the carcass. All organisms were identified to the lowest possible taxon. Community differences among whale-falls seemed to be most strongly related to depth and water temperature. The communities changed significantly from initial establishment shortly after a carcass’ arrival at the seafloor through multiple years of steady degradation. The majority of species found at the whale-falls were background taxa commonly seen in Monterey Bay. While populations of species characterized as bone specialists, seep restricted, and of unknown habitat affinities were also observed, sometimes in great abundance, they contributed minimally to overall species richness. All whale carcasses, shallow and deep, exhibited sub-decadal degradation and a time-series of mosaic images at the deepest whale site illustrates the rapidity at which the carcasses degrade.  相似文献   

A BIOGRAPHICAL TRIBUTE TO PROFESSOR E. H. THOMPSON     

K. B. Atkinson  † 《The Photogrammetric Record》1977,9(50):193-211

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Deville and Photographic Surveying     

K. B. Atkinson 《The Photogrammetric Record》1995,15(86):189-195

Photographic surveying by Deville was published in 1895. This article marks the centenary of the publication of one of the earliest English language books on photogrammetry. Deville and his surveyors were responsible for the mapping of large areas in western Canada by photographic means. The techniques were explained in his book, originally written for his own staff when he was Surveyor General of Canada.  相似文献   

The electric field existing at stratospheric elevations as determined by tropospheric and ionospheric boundary conditions     

W. Atkinson  S. Lundquist  U. Fahleson 《Pure and Applied Geophysics》1971,84(1):46-56

Summary The feasibility of inferring ionospheric electric fields from measurements at balloon altitudes has been studied by analytical and numerical analysis, using a twodimensional model atmosphere with exponentially varying conductivity, and taking into account electric fields of tropospheric origin.This paper was presented byU. Fahleson.  相似文献   

The soil: An introduction to soil study in Britain. F. M. Courtney & S. T. Trudgill,Edward Arnold,London, 1976. No. of pages: 120. price: $3.25     

Ken Atkinson 《地球表面变化过程与地形》1977,2(1):94-95

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Effect of upwelling on phytoplankton productivity of the outer southeastern United States continental shelf     

James A. Yoder  Larry P. Atkinson  S. Stephen Bishop  Eileen E. Hofmann  Thomas N. Lee 《Continental Shelf Research》1983,1(4):385-404

Gulf Stream frontal disturbances cause nutrient-rich waters to frequently upwell and intrude onto the southeastern United States continental shelf between Cape Canaveral, Florida and Cape Hatteras, North Carolina. Phytoplankton response in upwelled waters was determined with three interdisciplinary studies conducted during April 1979 and 1980, and in summer 1978. The results show that when shelf waters are not stratified, upwelling causes productive phytoplankton (diatom) blooms on the outer shelf. Phytoplankton production averages about 2 g C m⁻² d⁻¹ during upwelling events, and ‘new’ production is 50% or more of the total. When shelf waters are stratified, upwelled waters penetrate well onto the shelf as a subsurface intrusion in which phytoplankton production averages about fives times higher than the nutrient-depleted overlying mixed layer. Phytoplankton within the intrusion deplete upwelled NO₃ in about 7 to 10 days, at which point no further net increase in phytoplankton biomass occurs.Current meter records show that upwelling occurs roughly 50% of the time on the outer shelf during November to April (shelf not stratified), and we estimate that seasonal primary production in upwelled waters is 175 g C m⁻² 6 months⁻¹ of which at least 50% is ‘new’ production. More than 90% of outer shelf primary and ‘new’ production occurs during upwelling and thus upwelling is the dominant process affecting primary productivity of the outer shelf. Our seasonal estimates of outer shelf primary and ‘new’ production are, respectively, three and ten times higher than previous estimates that did not account for upwelling.  相似文献   

Subcritical crack propagation in rocks: theory,experimental results and applications     

Barry Kean Atkinson 《Journal of Structural Geology》1982,4(1):41-56

The micromechanisms of tensile fracture are reviewed, with particular emphasis on the influence of chemical effects on fracture controlled by pre-existing cracks (stress corrosion). A fracture mechanism map for quartz is presented which was constructed using a combination of theoretical insights and experimental data. The manner in which stress corrosion will modify the predictions of fracture mechanism maps is discussed by reviewing the numerous theories of stress corrosion. Experimental data are presented on stress corrosion in tensile deformation of quartz, quartz rocks, calcite rocks, basaltic rocks, granitic rocks and other geological materials. Although the experimental evidence for stress corrosion is overwhelming, very few data were obtained under conditions that simulate those in the bulk of the earth's crust and so the extent of its geophysical significance is yet to be fully established. Examples are given, however, of how invoking stress corrosion as a rate-controlling deformation mechanism sheds new light on extremely diverse geophysical phenomena, such as: predicting the strength and sliding friction properties of rocks, modelling earthquake rupture, the stability of hot, dry-rock geothermal reservoirs, stimulation of oil and gas reservoirs, the crack-seal mechanism of rock deformation and low stress dilatancy, fracture mechanics of lunar rocks, magmatic intrusions and the relaxation of internal stresses in rock.  相似文献