Physical processes within the North Water (NOW) polynya     

D. Barber  R. Marsden  P. Minnett  G. Ingram  L. Fortier 《大气与海洋》2013,51(3):163-166

Abstract

Two‐state, first‐order, single‐site Markov models for daily precipitation occurrence were developed for each winter rainy season over the historical period of record at five long‐term meteorological stations in the lower Fraser Valley of British Columbia, Canada. Monotonic temporal trends in the independent elements of the transition matrices were then assessed. Although the results remain tentative, there is some evidence for a regionally coherent long‐term negative trend in the probability of wet‐to‐dry state transitions, P10 (or a positive trend in the probability of a wet day being followed by another wet day, P11). In contrast, there is no evidence for a regionally coordinated and consistent trend in the probability of dry‐to‐wet state transitions, P01 (or, therefore, in the probability of a dry day being followed by another dry day, P00). These results appear loosely consistent with previous statistical climate change impact studies in the region, and might be physically interpreted as suggesting a gradual increase in the local typical duration of a Pacific frontal storm during hydrologic winter, with no systematic trend in the average duration of a dry‐day interlude. Additionally, the probability of any day‐to‐day precipitation state transition (from wet to dry, or from dry to wet), PST, has been tentatively interpreted to exhibit an area‐wide negative long‐term trend, suggesting an overall increase in precipitation memory. The findings provide some additional regional context for several issues in hydrometeorological modelling, climatology, and environmental impact assessment.  相似文献   

On the relationship between spatial patterns of sea‐ice type and the mechanisms which create and maintain the North Water (NOW) polynya     

C.J. Mundy  D.G. Barber 《大气与海洋》2013,51(3):327-341

Abstract

Polynyas represent polar oceanic areas with anomalous low sea‐ice concentrations. The North Water (NOW) Polynya refers to a region at the northern end of Baffin Bay which encompasses three separate polynyas. This paper examines the spatial patterns of sea‐ice cover within the NOW region during the winter, spring and fall of 1998 in the context of polynya formation and maintenance mechanisms. To accomplish this a sea‐ice classification scheme for RADARSAT‐1 ScanSAR imagery, obtained between 21 January and 7 December 1998, was developed and implemented within a Geographic Information System (GIS).

The results identify a clear and consistent spatial structure of sea‐ice cover throughout the winter, spring and fall of 1998. Temporally, the polynya opened southward along the Canadian coast and westward away from the Greenland coast. Comparison with parallel oceanographic, atmospheric and ice motion studies suggested that the polynya was primarily controlled by a latent heat mechanism with the exception of the west Greenland coast between Whale Sound and Cape York. The underlying mechanism used to explain the polynya's occurrence along this location is delayed ice formation during freeze‐up and a resultant thinner winter ice cover causing earlier spring ablation than surrounding areas. Arguments for oceanic and/or atmospheric sensible heat contributions are made.  相似文献   

Trophic ecology of the sea urchin Spatangus purpureus elucidated from gonad fatty acids composition analysis     

Barberá C  Fernández-Jover D  López Jiménez JA  González Silvera D  Hinz H  Moranta J 《Marine environmental research》2011,71(4):235-246

Irregular sea urchins such as the spatangoid Spatangus purpureus are important bioturbators that contribute to natural biogenic disturbance and the functioning of biogeochemical cycles in soft sediments. In the coastal waters of the Balearic Islands S. purpureus occurs in soft red algal beds, and can reach high densities. The diet of S. purpureus is unknown and it is particularly difficult to analyze the stomach contents of this group; therefore, we analyzed the fatty acid (FA) composition of the gonads and potential food resources in order to assess the trophic relationships of this species. The FA profiles of the gonads of S. purpureus agree well with the FA composition of the potential trophic resources (algae and sediment) and reveals changes between localities with different available resources. Three polyunsaturated FAs mainly contributes in the composition in the S. purpureus gonads: eicosapentaenoic acid (C20:5n-3) and arachidonic acid (C20:4n-6), both abundant in the macroalgal material, and palmitoleic acid (C16:1n-7), which is characteristic of sediment samples. Trophic markers of bacterial input and carnivorous feeding were significantly more abundant in sea urchins caught on bottoms with less vegetation. The current study demonstrates that the FA content of S. purpureus gonads is a useful marker of diet, as differences in the profiles reflected the variations in detritus composition. The results of this study show that this species has omnivorous feeding behavior; however, viewed in conjunction with available abundance data the results suggest that phytodetritus found within algal beds is an important carbon source for this species.  相似文献   

Properties of luminous red galaxies in the Sloan Digital Sky Survey     

Tom Barber  Avery Meiksin  Tara Murphy 《Monthly notices of the Royal Astronomical Society》2007,377(2):787-805

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Resolving the Degeneracy: Experimental Tests of the New Self Creation Cosmology and a Heterodox Prediction for Gravity Probe B     

Garth A. Barber 《Astrophysics and Space Science》2006,305(2):169-176

The new theory of Self Creation Cosmology has been shown to yield a concordant cosmological solution that does not require inflation, exotic non-baryonic Dark matter or unknown Dark Energy to fit observational constraints. In vacuo there is a conformal equivalence between this theory and canonical General Relativity and as a consequence an experimental degeneracy exists as the two theories predict identical results in the standard tests. However, there are three definitive experiments that are able to resolve this degeneracy and distinguish between the two theories. Here these standard tests and definitive experiments are described. One of the definitive predictions, that of the geodetic precession of a gyroscope, has just been measured on the Gravity Probe B satellite, which is at the present time of writing in the data processing stage. This is the first opportunity to falsify Self Creation Cosmology. The theory predicts a ‘frame-dragging’ result equal to GR but a geodetic precession of only 2/3 the GR value. When applied to the Gravity Probe B satellite, Self Creation Cosmology predicts an E–W gravitomagnetic/frame-dragging precession, equal to that of GR, of 40.9 milliarcsec/yr but a N–S gyroscope (geodetic + Thomas) precession of just 4.4096 arcsec/yr.  相似文献   

The United Kingdom Infrared Telescope Deep Impact observations: Light curve, ejecta expansion rates and water spectral features     

Robert J. Barber  Tom Stallard  Paul Hirst  Andy Adamson 《Icarus》2007,187(1):167-176

We present results from the United Kingdom Infrared Telescope observations of the impact of Deep Impact with Comet 9P/Tempel 1, on July 4, 2005 UT. These observations were carried out in conjunction with the worldwide observing campaign co-ordinated by K.J. Meech [Meech, K.J., and 208 colleagues, 2005. Science 310, 265-269]. The UKIRT team was the first to observe and announce the successful impact. At 05:50:52 (±2.5 s) UT the visible camera that is used to guide the telescope on the comet showed the start of a rapid rise in intensity, such that the visible brightness of Tempel 1 approximately doubled in 70 s. After that time there was a steady increase in the visible flux from the comet until it reached a maximum around 35 min post-impact, at which point it was more than ten times its original intensity. From an average of the time to maximum brightness and the time to noticeable intensity decline, we deduce that the material ejected by the impact expanded with a range of velocities between ∼125 and ∼390 m/s. We also observed water emission lines in the spectral region from 2.8945 to 2.8985 μm. We noted several water lines, which are known to be pumped by sunlight. But there was a lower intensity spectral component, which we propose may result from solar heating of icy grains freshly exposed by the impact.  相似文献   

Water production and release in Comet 153P/Ikeya-Zhang (C/2002 C1): accurate rotational temperature retrievals from hot-band lines near 2.9-μm     

Neil Dello Russo  Michael A DiSanti  Erika L Gibb  Robert J Barber 《Icarus》2004,168(1):186-200

Multiple non-resonance fluorescence lines of water (H₂O) were detected in Comet 153/P Ikeya-Zhang (2002 C1) between UT 2002 March 21.9 (R_h=0.51 AU) and April 13.9 (R_h=0.78 AU), using the Cryogenic Echelle Spectrometer (CSHELL) at the NASA Infrared Telescope Facility. Analysis of 2.9-μm water lines enabled accurate determination of rotational temperatures on three dates. The derived H₂O rotational temperatures were 138⁺⁶₋₅, 141⁺¹⁰₋₉, and 94±3 K on UT 2002 March 22.0, March 23.0, and April 13.8, respectively. Water production rates were retrieved from spectral lines measured in nineteen separate grating settings over seven observing periods. The derived heliocentric dependence of the water production rate was Q=(9.2±1.1)×10²⁸[R_h^{(−3.21±0.26)}] molecules s⁻¹. The spatial distribution of H₂O in the coma was consistent with its release directly from the nucleus (as a native source) on all dates.  相似文献   

On the winter evolution of snow thermophysical properties over land‐fast first‐year sea ice     

Alexandre Langlois  C. J. Mundy  David G. Barber 《水文研究》2007,21(6):705-716

The geophysical, thermodynamic and dielectric properties of snow are important state variables that are known to be sensitive to Arctic climate variability and change. Given recent observations of changes in the Arctic physical system (Arctic Climate Impact Assessment, 2004), it is important to focus on the processes that give rise to variability in the horizontal, vertical and temporal dimensions of the life‐history of snow on sea ice. The objectives in this study are to present these ‘state’ variables and to investigate the processes that govern variability in the vertical, horizontal and temporal dimension by using a case study over land‐fast first‐year sea ice for the period December 2003 to June 2004. Results from two sampling areas (thin and thick snowpacks) show that differences in snowpack thickness can substantially change the vertical and temporal evolution of snow properties. During the late fall and early winter (cooling period) we measured no significant changes in the physical properties, except for thin snow‐cover salinity, which decreased throughout the period. Fall‐snow desalination was only observed under thin snowpacks with a rate of ?0·12 ppt day^?1. Significant changes occurred in the late winter and early spring (warming period), especially for snow grain size. Snow grain kinetic growth of 0·25–0·48 mm·day^?1 was measured coincidently with increasing salinity and wetness for both thin and thick snowpacks. Copyright © 2006 John Wiley & Sons, Ltd.  相似文献   

Methods for evaluating in-stream attenuation of trace organic compounds     

Jeffrey H. Writer  Steffanie K. Keefe  Joseph N. Ryan  Imma Ferrer  Michael E. Thurman  Larry B. Barber 《Applied Geochemistry》2011

Wastewater treatment plants are often the most substantial contributor of trace organic compounds including pharmaceuticals, steroidal hormones, and surfactants to surface waters. Studying stream reaches below wastewater treatment plants provide valuable information on the environmental persistence of these compounds. Three methods for conducting field investigations to evaluate in-stream attenuation of trace organic compounds are presented: (1) using intrinsic tracers in wastewater, (2) environmental sampling coupled with dye studies to assess travel times between sample locations, and (3) Lagrangian sampling. Advantages and limitations of each method are discussed, along with key findings from several investigations.  相似文献   

Contaminants in cetaceans from UK waters: status as assessed within the Cetacean Strandings Investigation Programme from 1990 to 2008     

Law RJ  Barry J  Barber JL  Bersuder P  Deaville R  Reid RJ  Brownlow A  Penrose R  Barnett J  Loveridge J  Smith B  Jepson PD 《Marine pollution bulletin》2012,64(7):1485-1494

Since 1990, tissue samples from UK-stranded and -bycaught cetaceans have been available for study of contaminant burdens. These have been used to study spatial and temporal trends in concentrations in UK waters, and to investigate potential associations between contaminants and health status. We describe the current status of cetaceans (primarily harbour porpoises, Phocoena phocoena) in UK waters in relation to pollution. Concentrations of BDEs, HBCD, and the organochlorine pesticides are declining. In contrast, concentrations of CBs have plateaued following earlier reductions due to regulation of use, and further reductions are likely to take decades. Blubber PCB concentrations are still at toxicologically significant levels in many harbour porpoises and regularly occur at even higher levels in bottlenose dolphins and killer whales due to their higher trophic level in marine food chains. Further reductions in PCB inputs into the marine environment are needed to mitigate risk from PCB exposure in these species.  相似文献