Near-Surface Effects of Free Atmosphere Stratification in Free Convection     

Juan Pedro Mellado  Chiel C. van Heerwaarden  Jade Rachele Garcia 《Boundary-Layer Meteorology》2016,159(1):69-95

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Decomposition and analysis by atomic absorption photospectrometry of silicate rocks     

J. Saavedra  A.Garcia Sanchez  S.Rodriguez Perez 《Chemical Geology》1974,13(2):135-139

A rapid and simple method of analysis of silicate rocks using gold crucibles and fluoroboric acid as a solvent of the disintegrated material has been developed. The main elements are determined in a single treatment. The results obtained are comparable to the values recommended for samples of eleven standard rocks.  相似文献   

Time series surface-wave recovery from pressure gage     

Hsiang Wang  Dong-Young Lee  Allen Garcia 《Coastal Engineering》1986,10(4)

Recovery of surface-wave time series from pressure gage data is a time-consuming process and is not customarily carried out. Such information is, however, useful particularly in real-time for warning of freak waves or waves of unusual characteristics. Two simple numerical filters are developed here to serve such purpose. The first method is a linear filter with a built-in window to suppress high-frequency noise. The second method recovers the surface wave by computing the local surface curvature. These filters are very simple and can be programmed into a microprocessor to be integrated into field instrument packages.Both filters have been tested satisfactorily against conventional linear filters using simulated wave data and wave data collected in intermediate water depth. Neither filter requires pre-filtering of noise from raw data, which is commonly required to recover surface-wave information from sub-surface pressure data.  相似文献   

Food habits of Dipturus chilensis (Pisces: Rajidae) off Patagonia, Argentina   总被引：1，自引：0，他引：1  

Alonso  M. Koen; Crespo  E. A.; Garcia  N. A.; Pedraza  S. N.; Mariotti  P. A.; Vera  B. Beron; Mora  N. J. 《ICES Journal of Marine Science》2001,58(1):288-297

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Daily egg production of anchovy in European waters   总被引：7，自引：1，他引：7  

Somarakis  Stylianos; Palomera  Isabel; Garcia  Alberto; Quintanilla  Luis; Koutsikopoulos  Constantin; Uriarte  Andres; Motos  Lorenzo 《ICES Journal of Marine Science》2004,61(6):944-958

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Sediment distribution patterns on the Galicia-Minho continental shelf   总被引：1，自引：0，他引：1  

J. M. A. Dias  R. Gonzalez  C. Garcia  V. Diaz-del-Rio 《Progress in Oceanography》2002,52(2-4)

A sedimentological and bathymetric study of the Minho-Galicia Shelf shows a strong contrast between a southern shelf region with a thin partially relict cover of sands and gravel, and a northern region where fine-grained sediments predominate. This contrast is explained through differences in the sediment supply, the oceanographic environment (storms and ocean currents) and the morphology of the shelf which results from its underlying tectonic framework.Most sediment is supplied to the Galicia-Minho Shelf by river discharges onto the Minho Shelf, particularly that from the Douro River. In the northern part of the shelf the Galician Rías act as sediment traps rather than sediment suppliers. The bulk of the sediment washes out of the rivers during episodic storm events. While most of the coarse sediments remain deposited close to the coast, the fine-grained material is exported to the outer areas of the shelf. Subsequently, coarse sediments close to the coast are transported southwards by the littoral drift. Whereas the fine-grained material is frequently resuspended through the action of the large swells who influence reaches deep into the water. This frequent resuspension has a long-term sorting effect on the sediments. Furthermore, resuspended sediments on the middle and outer regions of the shelf are transported northwards by a poleward flowing bottom current.As a consequence of the differential transport of coarse sediments to the south, and of the fine-grained sediments to the north, the outer reaches of the Minho Shelf are relatively poor in recent sediments. In many areas relict sediments as well as features associated with ancient coastlines and river mouths, still appear as seabed features. In contrast, the northern regions of the shelf are covered by a thin veneer of fine-grained material that smooth other most of these fossil features.The fine-grained sediment fractions (mostly very fine sands to coarse silts) are deposited in two large mud patches, the Douro and the Galicia Mud Patches, which are situated at water depths of around 100–120 m. These two mud patches are both controlled by the local hydrodynamics and morphology. The Beiral de Viana, to the west of the Douro Mud Patch is a plateau, up to 20 m high lying parallel to the shelf-break and is a morphological expression of an underlying horst system. This plateau acts as a barrier that prevents the drift of some of the fine-grained material to the west, out over the shelf-break and the continental slope. The Galicia Mud Patch is situated on the eastern part of the Galician Shelf to the north of the Douro Mud Patch. It is situated near the extension of the Porto–Tomar fault, which results in the shelf being usually steep in this region, down to a depth of about 100 m. West of this area the slope is much more gentle. Northward transport of the sediment is strongly reduced by the E–W trending outcrops of plutonic and metamorphic rocks.  相似文献   

Mediterranean Marine Reserves: Fish Indices as Tests of Protection Efficiency   总被引：1，自引：0，他引：1  

J.-G. Harmelin    F. Bachet  F. Garcia 《Marine Ecology》1995,16(3):233-250

Abstract. The fish assemblages of a strictly protected area and of a neighbouring fished area, located off a Mediterranean urbanized coast (Carry-le-Rouet, France), were compared in order to select the most evident, constant, and easily recorded indices of the 'reserve effect'. Visual censusing was repeated simultaneously at both sites eight time a year during 3 years along four permanent transects layed on shallow rocky bottoms (9–14 m). Overall species richness was 16% higher in the reserve, but differences in average instantaneous richness were only marginally significant. The most contrasting results were shown by the occurrence frequency, abundance, and demographic structure of two types of target species. The type A target species group comprises 16 large meso- and macrocarnivores particularly threatened by spearfishing, including the common nectobenthic sparids Diplodus spp. Type B target species are represented by two small territorial fishes particularly impacted by angling: the serranid Serranus cabrilla and the terminal phase males of the labrid Coris julis . The size structure of Diplodus spp., S. cabrilla , and C.julis subpopulations strongly argues for the role of protected areas as a reservoir of large spawners. Fishing pressure is assumed to modify the social conditions of the C. julis local populations and to induce earlier sex change.  相似文献   

A phytoplankton class-specific primary production model applied to the Kerguelen Islands region (Southern Ocean)     

Julia Uitz  Hervé Claustre  F. Brian Griffiths  Joséphine Ras  Nicole Garcia  Valérie Sandroni 《Deep Sea Research Part I: Oceanographic Research Papers》2009,56(4):541-560

As part of the KErguelen: compared study of the Ocean and the Plateau in Surface water (KEOPS) project in late summer 2005, we examine the phytoplankton community composition and associated primary production in the waters surrounding the Kerguelen Archipelago, with the emphasis on two contrasted environments: (i) the Kerguelen Plateau, where a large bloom occurs annually, and (ii) the high-nutrient low-chlorophyll (HNLC) offshore waters. A biomarker pigment approach was used to assess the community composition in terms of chlorophyll biomass of three phytoplankton size classes, namely micro-, nano-, and picophytoplankton. The second objective was to evaluate a global class-specific approach for estimating the contribution of the three pigment-based size classes to the primary production in the study area. To do so, primary production rates associated with each phytoplankton class were computed from the class-specific chlorophyll biomass coupled to a class-specific primary production model, and compared with in situ measurements of size-fractionated ¹³C-based primary production. The iron-enriched bloom region was dominated by microphytoplankton (diatoms), which contributed 80–90% to the total primary production (of ≈1 g C m^?2 d^?1). In the HNLC area, the primary production was about 0.30 g C m^?2 d^?1, mainly (65%) achieved by small diatoms and nanoflagellates. The model results show a good overall agreement between predicted and measured total primary production rates. In terms of size classes, agreements were higher for the bloom region than for the HNLC waters. Discrepancies in this complex iron-limited area may be explained essentially by the smaller size of diatoms, or a different set of photophysiological properties.  相似文献   

Optical spectroscopy and Doppler tomography of Cygnus X-2     

P. Elebert  P. J. Callanan  M. A. P. Torres  M. R. Garcia 《Monthly notices of the Royal Astronomical Society》2009,395(4):2029-2038

We present phase resolved optical spectroscopy and Doppler tomography of V1341 Cygni, the optical counterpart to the neutron star low-mass X-ray binary (LMXB) Cygnus X-2 (Cyg X-2). We derive a radial velocity (RV) curve for the secondary star, finding a projected RV semi-amplitude of   K ₂= 79 ± 3 km s⁻¹  , leading to a mass function of  0.51 ± 0.06 M_⊙, ∼30  per cent lower than the previous estimate. We tentatively attribute the lower value of K ₂ (compared to that obtained by other authors) to variations in the X-ray irradiation of the secondary star at different epochs of observations. The limited phase coverage and/or longer timebase of previous observations may also contribute to the difference in K ₂. Our value for the mass function implies a primary mass of  1.5 ± 0.3 M_⊙  , somewhat lower than previous dynamical estimates, but consistent with the value found by analysis of type-I X-ray bursts from this system. Our Doppler tomography of the broad He  ii λ4686 line reveals that most of the emission from this line is produced on the irradiated face of the donor star, with little emission from the accretion disc. In contrast, the Doppler tomogram of the N  iii λ4640.64 Bowen blend line shows bright emission from near the gas stream/accretion disc impact region, with fainter emission from the gas stream and secondary star. This is the first LMXB for which the Bowen blend is dominated by emission from the gas stream/accretion disc impact region, without comparable emission from the secondary star. This has implications for the interpretation of Bowen blend Doppler tomograms of other LMXBs for which the ephemeris may not be accurately known.  相似文献   

Imaging the asymmetric dust shell around CI Cam with long baseline optical interferometry     

N. D. Thureau  J. D. Monnier  W. A. Traub  R. Millan-Gabet  E. Pedretti  J.-P. Berger  M. R. Garcia  F. P. Schloerb  A.-K. Tannirkulam 《Monthly notices of the Royal Astronomical Society》2009,398(3):1309-1316

We present the first high angular resolution observation of the B[e] star/X-ray transient object CI Cam, performed with the two-telescope Infrared Optical Telescope Array (IOTA), its upgraded three-telescope version (IOTA3T) and the Palomar Testbed Interferometer (PTI). Visibilities and closure phases were obtained using the IONIC-3 integrated optics beam combiner. CI Cam was observed in the near-infrared H and K spectral bands, wavelengths well suited to measure the size and study the geometry of the hot dust surrounding CI Cam. The analysis of the visibility data over an 8 yr period from soon after the 1998 outburst to 2006 shows that the dust visibility has not changed over the years. The visibility data show that CI Cam is elongated which confirms the disc-shape of the circumstellar environment and totally rules out the hypothesis of a spherical dust shell. Closure phase measurements show direct evidence of asymmetries in the circumstellar environment of CI Cam and we conclude that the dust surrounding CI Cam lies in an inhomogeneous disc seen at an angle. The near-infrared dust emission appears as an elliptical skewed Gaussian ring with a major axis   a = 7.58 ± 0.24 mas  , an axis ratio   r = 0.39 ± 0.03  and a position angle  θ= 35°± 2°  .  相似文献