The ecology of Sepia australis (Cephalopoda: Sepiidae) along the south coast of South Africa     

Mqoqi  Mandisile; Lipinski  Marek R.; Salvanes  Anne G. V. 《ICES Journal of Marine Science》2007,64(5):945-955

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Currents and turbulent diffusion in the bottom boundary layer of the Barents Sea     

V. M. Kushnir  E. Hansen  L. A. Petrenko  V. K. Pavlov  A. N. Morozov  S. V. Stanichnyi  S. V. Fedorov 《Physical Oceanography》2007,17(5):278-295

The numerical analysis of the stationary field of current velocity on the upper boundary of the bottom boundary layer in the Barents Sea is performed on the basis of a simplified model taking into account the fields of wind velocity and density of water for the principal periods of the seasonal cycle and the bottom topography. The analysis is based on the climatic BarKode database and the data on the wind velocity over the Barents Sea for the last 50 yr. The numerical results demonstrate that the field of bottom currents is fairly nonuniform and the current velocities vary from several fractions of 1 cm/sec to 5 cm/sec in the zones with noticeable slopes of the bottom. The estimates of the thickness of the bottom boundary layer are obtained for the constant coefficient of bottom friction C _f = 0.04. In the major part of the water area of the Barents Sea, the thickness of the bottom boundary layer is close to 1 m. In the regions with significant slopes of the bottom, it increases to 2–2.5 m and, in the two zones of intensification of the bottom currents, becomes as large as 5 m. The maximum estimate of the coefficient of turbulent viscosity is close to 5 cm²/sec. The mean value of the coefficient of vertical density diffusion K _S is equal to 2.34 cm²/sec and its standard deviation is equal to 1.52 cm²/sec. __________ Translated from Morskoi Gidrofizicheskii Zhurnal, No. 4, pp. 31–49, September–October, 2007.  相似文献   

Thermochaline Convection in the Edge-Ice Zone in the Barents Sea to the East of Spitsbergen     

Kushnir  V. M.  Hansen  E.  Pavlov  V. K.  Morozov  A. N. 《Physical Oceanography》2003,13(6):361-374

The analysis of the thermochaline (double-diffusive) convection in the edge-ice zone of the Barents Sea to the east of Spitsbergen was performed by using the data of two hydrological surveys of the Norwegian Polar Institute in 1999 and 2000. The Turner's model, where the critical Rayleigh number is determined by using the empirical relationship between the Nusselt number and the Rayleigh number normalized to its critical value, was used for analysis. The results of calculation of thickness of the convective layer were compared with the data of supervision. The estimates of the vertical convective velocity were obtained.  相似文献   

Policy and knowledge in fisheries management: a policy brief   总被引：1，自引：3，他引：1  

Schwach  Vera; Bailly  Denis; Christensen  Anne-Sofie; Delaney  Alyne E.; Degnbol  Poul; van Densen  Wim L. T.; Holm  Petter; McLay  H. Anne; Nielsen  Kare Nolde; Pastoors  Martin A.; Reeves  Stuart A.; Wilson  Douglas C. 《ICES Journal of Marine Science》2007,64(4):798-803

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A three-dimensional hydrodynamic model of estuarine circulation with an application to Southampton Water, UK     

Anne Levasseur  Lei Shi  Neil C. Wells  Duncan A. Purdie  Boris A. Kelly-Gerreyn   《Estuarine, Coastal and Shelf Science》2007,73(3-4):753-767

A three-dimensional hydrodynamic model has been developed to simulate water mass circulation in estuarine systems. This model is based on the primitive equation in Cartesian coordinates with a terrain-following structure, coupled with a Mellor–Yamada 2.5 turbulence scheme. A fractional-step method is applied and the subset of equations is solved with finite volume and finite element methods. A dry–wet process simulates the presence of the tidal flat at low water. River inputs are introduced using a point-source method. The model was applied to a partially mixed, macrotidal, temperate estuary: Southampton Water, UK. The model is validated by comparisons with sea surface elevation, ADCP measurements and salinity data collected in 2001. The mean spring range 2(M₂ + S₂) and the mean neap range 2(M₂ − S₂) are modelled with an error relative to observation of 12 and 16%, respectively. The unique tidal regime of the system with the presence of the ‘young flood stand’ corresponding to the slackening conditions occurring at mid flood and ‘double high water’ corresponding to an extension of the slackening conditions at high tide is accurately reproduced in the model. The dynamics of the modelled mean surface and bottom velocity closely match the ADCP measurements during neap tides (rms of the difference is 0.09 and 0.01 m s⁻¹ at the bottom and at the surface, respectively), whereas at spring the difference is greater (rms of the difference is 0.25 and 0.20 m s⁻¹ at bottom and surface, respectively). The spatial and temporal variation of the degree of stratification as indicated by salinity distributions compares well with observations.  相似文献   

Variation in the Sizes of Chthamalid ­Barnacle Post-Settlement Cyprids on European Shores     

Ruth M. O'Riordan  Jane Delany    David McGrath    Alan A. Myers  Anne Marie Power    Neil F. Ramsay  Damaso Alvarez  Teresa Cruz  Federica G. Pannacciulli    Pedro Range  & Giulio Relini 《Marine Ecology》2001,22(4):307-322

Abstract. As part of a wider study on the settlement and recruitment of Chthamalus spp. in Europe, this study investigated whether chthamalid cyprids can be separated by length on a European scale. Variation in cyprid length with latitude and temporal variation at selected localities were also examined. The lengths of cyprids collected between 1996 – 1999 on nine rocky shores in Europe are reported. Elminius modestus cyprids were found only at Roscoff, NW France and could be distinguished due to their carapace shape and length. They showed a unimodal length distribution, measuring between 450 and 625 µm, with no variation in length between the two sampling dates (1997 and 1998). Based on carapace shape and length, the remaining cyprids in the collections were identified as one of three chthamalid species, Chthamalus montagui, Chthamalus stellatus or Euraphia depressa. Bimodal length distributions of chthamalid cyprids were seen on some shores, while others had a single small‐sized modal group (representing C. montagui on Atlantic shores and/or E. depressa in the Mediterranean) separated from a few distinctly larger cyprids (C. stellatus). Metamorphs collected simultaneously with cyprid collections were identified as C. stellatus or C. montagui, except at Roscoff, where E. modestus were also found. In southern Portugal, where all metamorphs collected were C. montagui and adult C. montagui were the dominant barnacles, most cyprids measured between 350 and 550 µm long and this size distribution coincides with the distribution expected for C. montagui. Cyprids collected on these four more southerly Portuguese shores had the same modal length class (475 µm) and this remained constant between successive years at Luz and Albufeira, Algarve. The smallest (350 µm long) wild chthamalid cyprids found were from southern Portugal and Italy. In Spain, France and Ireland the smallest chthamalid cyprid was 425 µm long. The results from the present study support the hypothesis that on Atlantic shores cyprids of C. montagui can be separated from those of C. stellatus based on size, although there is some variation in cyprid length with latitude as well as temporal variation at selected localities.  相似文献   

Diversity in global patterns of observed precipitation variability and change on river basin scales     

Anne M. Lausier  Shaleen Jain 《Climatic change》2018,149(2):261-275

Comprehensive characterization of diversity in global patterns of precipitation variability and change is an important starting point for climate adaptation and resilience assessments. Capturing the nature of precipitation probability distribution functions (PDF) is critical for assessing variability and change. Conventional linear regression-based analyses assume that slope coefficients for the wet and dry tails of the PDF are consonant with the conditional mean trend. This assumption is not always borne out in the analyses of historical records. Given the relationship between sea surface temperature (SST) and precipitation, recent trends in global SST complicate interpretations of precipitation variability and risk. In this study, changes in the PDF of annual precipitation (1951–2011) at the global river basin scale were analyzed using quantile regression (QR). QR is a flexible approach allowing for the assessment of precipitation variability conditioned on the leading empirical orthogonal function (EOF) patterns of global SST that reflect El Niño–Southern Oscillation and Atlantic Multi-decadal Oscillation. To this end, the framework presented (a) offers a characterization of the entire PDF and its sensitivity to the leading modes of SST variability, (b) captures a range of responses in the PDF including asymmetries, (c) highlights regions likely to experience higher risks of precipitation excesses and deficits and inter-annual variability, and (d) offers an approach for quantifying risk across specified quantiles. Results show asymmetric responses in the PDF in all regions of the world, either in single or both tails. In one instance, QR detects a differential response to the leading patterns of SST in the Tana basin in eastern Africa, highlighting changes in variability as well as risk.  相似文献   

Upcoming international events     

Anne Marie de Grosbois 《Environmental Geology》2008,56(1):219-224

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MODIS-NDVI-based mapping of the length of the growing season in northern Fennoscandia     

Stein Rune Karlsen  Anne Tolvanen  Eero Kubin  Jarmo Poikolainen  Kjell Arild Høgda  Bernt Johansen  Fiona S. Danks  Paul Aspholm  Frans Emil Wielgolaski  Olga Makarova 《International Journal of Applied Earth Observation and Geoinformation》2008

Northern Fennoscandia is an ecologically heterogeneous region in the arctic/alpine-boreal transition area. Phenology data on birch from 13 stations and 16-day MODIS-NDVI composite satellite data with 250 m resolution for the period 2000 to 2006 were used to map the growing season. A new combined pixel-specific NDVI threshold and decision rule-based mapping method was developed to determine the onset and end of the growing season. A moderately high correlation was found between NDVI data and birch phenology data. The earliest onset of the growing season is found in the narrow strip of lowland between the mountains and the sea along the coast of northern Norway. The onset follows a clear gradient from lowland to mountain corresponding to the decreasing temperature gradient. In autumn, the yellowing of the vegetation shows a more heterogeneous pattern. The length of the growing season is between 100 and 130 days in 55% of the study area.  相似文献   

Arctic communities perceive climate impacts on access as a critical challenge to availability of subsistence resources     

Todd J. Brinkman  Winslow D. Hansen  F. Stuart Chapin  Gary Kofinas  Shauna BurnSilver  T. Scott Rupp 《Climatic change》2016,136(3-4):413-425

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