The UBV orbital phase curves of Rhea,Dione, and Tethys     

Guy N. Blair  Frazer N. Owen 《Icarus》1974,22(2):224-229

Orbital phase curves are reported for Rhea (SV), Dione (SIV), and Tethys (SIII). Variations of 0.2 mag. and 0.8 mag. were found for Rhea and Dione respectively, while no variation of Tethys was detected. Some color variations are also reported.  相似文献   

PLANT ADAPTATION,FIRM ENVIRONMENTS AND LOCATION ANALYSIS     

Guy P. F. Steed 《The Professional geographer》1971,23(4):324-328

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Effects of scattered solar radiation and absorption by SO₂ on the photodissociation processes in the stratosphere of Venus     

Jean-Paul Parisot  Guy Moreels  Jean-Marc Zucconi 《Icarus》1980,44(3):640-650

In the stratosphere of Venus, the available luminous flux which locally produces the photodissociation processes at a given altitude may be divided into three parts: direct incoming downward flux, flux resulting from the reflection on the surface of the clouds, and flux due to molecular scattering. A relatively simple computation method has been used to evaluate the relative importance of these three parts at altitudes between 65 and 100 km. It is shown that the extra contribution of the reflected and scattered fluxes to photodissociation processes cannot be neglected in the uv and visible regions. In the case of SO₂, for instance, which presents an absorption band in the uv, the photodissociation coefficient is increased 30% due to these effects. Calculations of the photodissociation coefficients of CO₂, O₃, H₂S, and SO₂ are presented. As a result of the increase by 60% in the ozone photolysis rate, the calculated O₂ infrared band at 1.27 μm is larger by a factor of nearly 2 than is expected from a calculation without taking albedo or scattering into account.  相似文献   

Seasonal changes in macrophyte and macrozoobenthos assemblages in three coastal lagoons under varying degrees of eutrophication   总被引：9，自引：0，他引：9  

Bachelet  Guy; de Montaudouin  Xavier; Auby  Isabelle; Labourg  Pierre-Jean 《ICES Journal of Marine Science》2000,57(5):1495-1506

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Factors affecting rural landholders’ adaptation to climate change: Insights from formal institutions and communities of practice     

Christopher M. Raymond  Guy M. Robinson 《Global Environmental Change》2013,23(1):103-114

This study explores the factors affecting rural landholders’ adaptation to climate change from the perspectives of formal institutions and communities of practice. Semi-structured interviews were conducted with formal institutions (e.g. South Australian government agencies) and communities of practice (e.g. farm systems groups) within two natural resource management regions in South Australia. Both groups noted that rural landholders autonomously adapt to a variety of risks, including those induced by climate variability; however, the types and levels of adaptation varied among individuals as a result of variety of barriers to adaptation. The lack of communication and engagement processes established between formal institutions and communities of practice was one major barrier. The paper presents and discusses a model for transferring knowledge and information on climate change among formal institutions, communities of practice, trusted individual advisors and rural landholders, and for supporting the co-management of climate change across multiple groups in rural agricultural areas in Australia and elsewhere.  相似文献   

Levelling co-located GNSS and tide gauge stations using GNSS reflectometry     

Alvaro Santamaría-Gómez  Christopher Watson  Médéric Gravelle  Matt King  Guy Wöppelmann 《Journal of Geodesy》2015,89(3):241-258

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Effects of exposure to petroleum hydrocarbons upon the metabolism of the common sole Solea solea     

Davoodi F  Claireaux G 《Marine pollution bulletin》2007,54(7):928-934

On December 12th, 1999, the oil tanker Erika sank off the southern coast of Brittany (France), releasing 20000-30000tons of heavy oil in the open sea. Among the affected coastal habitats were important nurseries for numerous flatfish species and particularly for the common sole, Solea solea. To investigate the potential impact of the spill on this economically significant resource, we employed Fry's concept of metabolic scope for activity to assess the deleterious effect of fuel exposure on the functional integrity of juvenile sole. Fish were captured from uncontaminated areas and experimentally exposed to contamination conditions mimicking those encountered during the weeks that followed the Erika spill. Using respirometry techniques we measured basal and active metabolic rates, and calculated aerobic metabolic scope, in control and fuel-exposed sole. We then compared the ability of control and fuel-exposed sole to face an episode of reduced oxygen availability. We found that whereas basal metabolic rate was not altered in fuel-exposed fish, active metabolic rate (-27%), and therefore aerobic metabolic scope, were impacted. These changes in metabolic scope were viewed as indicating changes in fishes' ability to face environmental contingencies. Finally the ability of sole to face an episode of reduced oxygen availability was found to be significantly altered following fuel exposure as indicated by a 65% increase in the critical oxygen level. It is concluded that fuel-exposed sole are functionally impaired and less able to face environmental challenges. The link between these results and the recently reported fall in the abundance of the year class that suffered the Erika oil spill is discussed.  相似文献   

Long-term ice sheet–climate interactions under anthropogenic greenhouse forcing simulated with a complex Earth System Model     

Miren Vizcaíno  Uwe Mikolajewicz  Matthias Gröger  Ernst Maier-Reimer  Guy Schurgers  Arne M. E. Winguth 《Climate Dynamics》2008,31(6):665-690

Several multi-century and multi-millennia simulations have been performed with a complex Earth System Model (ESM) for different anthropogenic climate change scenarios in order to study the long-term evolution of sea level and the impact of ice sheet changes on the climate system. The core of the ESM is a coupled coarse-resolution Atmosphere–Ocean General Circulation Model (AOGCM). Ocean biogeochemistry, land vegetation and ice sheets are included as components of the ESM. The Greenland Ice Sheet (GrIS) decays in all simulations, while the Antarctic ice sheet contributes negatively to sea level rise, due to enhanced storage of water caused by larger snowfall rates. Freshwater flux increases from Greenland are one order of magnitude smaller than total freshwater flux increases into the North Atlantic basin (the sum of the contribution from changes in precipitation, evaporation, run-off and Greenland meltwater) and do not play an important role in changes in the strength of the North Atlantic Meridional Overturning Circulation (NAMOC). The regional climate change associated with weakening/collapse of the NAMOC drastically reduces the decay rate of the GrIS. The dynamical changes due to GrIS topography modification driven by mass balance changes act first as a negative feedback for the decay of the ice sheet, but accelerate the decay at a later stage. The increase of surface temperature due to reduced topographic heights causes a strong acceleration of the decay of the ice sheet in the long term. Other feedbacks between ice sheet and atmosphere are not important for the mass balance of the GrIS until it is reduced to 3/4 of the original size. From then, the reduction in the albedo of Greenland strongly accelerates the decay of the ice sheet.  相似文献   

Color imaging of Mars by the High Resolution Imaging Science Experiment (HiRISE)     

W. Alan Delamere  Livio L. Tornabene  Kris Becker  Nathan T. Bridges  Dennis Gallagher  Laszlo Keszthelyi  Guy K. McArthur  Moses Milazzo  Nicolas Thomas 《Icarus》2010,205(1):38-52

HiRISE has been producing a large number of scientifically useful color products of Mars and other planetary objects. The three broad spectral bands, coupled with the highly sensitive 14 bit detectors and time delay integration, enable detection of subtle color differences. The very high spatial resolution of HiRISE can augment the mineralogic interpretations based on multispectral (THEMIS) and hyperspectral datasets (TES, OMEGA and CRISM) and thereby enable detailed geologic and stratigraphic interpretations at meter scales. In addition to providing some examples of color images and their interpretation, we describe the processing techniques used to produce them and note some of the minor artifacts in the output. We also provide an example of how HiRISE color products can be effectively used to expand mineral and lithologic mapping provided by CRISM data products that are backed by other spectral datasets. The utility of high quality color data for understanding geologic processes on Mars has been one of the major successes of HiRISE.  相似文献   

Microborer ichnocoenoses in Quaternary corals from New Caledonia: reconstructions of paleo-water depths and reef growth strategies in relation to environmental changes     

Richet Rémy  Chazottes Véronique  Cabioch Guy  Frank Norbert  S. Burr George 《Quaternary Science Reviews》2011,30(19-20):2827-2838

Coral reef growth and development depend on several environmental factors, including tectonic and climatic parameters and local ecological drivers. Reef growth is especially sensitive to sea-level variations. Paleo-water depth reconstructions are essential tools used to determine reef growth patterns during different periods of reef growth. Assemblages of corals and/or coralline algae have been commonly used in such paleodepth reconstructions. This study shows that using microendolith ichnocoenoses can sometimes provide better accuracy than traditional coralgal analyses, particularly in the depth-range 0–10 m where coralgal assemblages usually show broad distribution ranges. Holocene and Pleistocene cores from two barrier reef sites on the west coast of Grande Terre in New Caledonia are examined here. Holocene reef development at these sites feature examples of microendolith ichnocoenoses that document rapid environmental changes and small sea-level variations of about 2–5 m in amplitude, and record these changes with more accuracy than coral and coralline algae assemblages which are highly dependant on the hydrodynamic energy of the setting. During the Pleistocene, which was less chronologically constrained, the microendolith ichnocoenoses also reflect paleo-water depths and reef-growth patterns at different periods of reef history.  相似文献