Variations in the biomass of Antarctic krill (Euphausia superba) around the South Shetland Islands, 1996-2006   总被引：1，自引：0，他引：1  

Reiss  Christian S.; Cossio  Anthony M.; Loeb  Valerie; Demer  David A. 《ICES Journal of Marine Science》2008,65(4):497-508

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The complex X-ray spectrum of the isolated neutron star RBS1223     

Axel D. Schwope  Valeri Hambaryan  Frank Haberl  Christian Motch 《Astrophysics and Space Science》2007,308(1-4):619-623

We present a first analysis of a deep X-ray spectrum of the isolated neutron star RBS1223 obtained with XMM-Newton. Spectral data from four new monitoring observations in 2005/2006 were combined with archival observations obtained in 2003 and 2004 to form a spin-phase averaged spectrum containing 290 000 EPIC-pn photons. This spectrum shows higher complexity than its predecessors, and can be parameterised with two Gaussian absorption lines superimposed on a blackbody. The line centers, E ₂≃2E ₁, could be regarded as supporting the cyclotron interpretation of the absorption features in a field B∼4×10¹³ G. The flux ratio of those lines does not support this interpretation. Hence, either feature might be of truly atomic origin.   相似文献   

Preprocessing of gravity gradients at the GOCE high-level processing facility   总被引：3，自引：0，他引：3  

Johannes Bouman  Sietse Rispens  Thomas Gruber  Radboud Koop  Ernst Schrama  Pieter Visser  Carl Christian Tscherning  Martin Veicherts 《Journal of Geodesy》2009,83(7):659-678

One of the products derived from the gravity field and steady-state ocean circulation explorer (GOCE) observations are the gravity gradients. These gravity gradients are provided in the gradiometer reference frame (GRF) and are calibrated in-flight using satellite shaking and star sensor data. To use these gravity gradients for application in Earth scienes and gravity field analysis, additional preprocessing needs to be done, including corrections for temporal gravity field signals to isolate the static gravity field part, screening for outliers, calibration by comparison with existing external gravity field information and error assessment. The temporal gravity gradient corrections consist of tidal and nontidal corrections. These are all generally below the gravity gradient error level, which is predicted to show a 1/f behaviour for low frequencies. In the outlier detection, the 1/f error is compensated for by subtracting a local median from the data, while the data error is assessed using the median absolute deviation. The local median acts as a high-pass filter and it is robust as is the median absolute deviation. Three different methods have been implemented for the calibration of the gravity gradients. All three methods use a high-pass filter to compensate for the 1/f gravity gradient error. The baseline method uses state-of-the-art global gravity field models and the most accurate results are obtained if star sensor misalignments are estimated along with the calibration parameters. A second calibration method uses GOCE GPS data to estimate a low-degree gravity field model as well as gravity gradient scale factors. Both methods allow to estimate gravity gradient scale factors down to the 10⁻³ level. The third calibration method uses high accurate terrestrial gravity data in selected regions to validate the gravity gradient scale factors, focussing on the measurement band. Gravity gradient scale factors may be estimated down to the 10⁻² level with this method.  相似文献   

Modelling observed and future runoff from a glacierized tropical catchment (Cordillera Blanca, Perú)   总被引：1，自引：1，他引：0  

Irmgard Juen  Georg Kaser  Christian Georges 《Global and Planetary Change》2007,59(1-4):37

Monthly runoff from the 34.3% glacierized tropical catchment of Llanganuco in the tropical Cordillera Blanca, Perú, is successfully simulated and compared with a measured 44 year time series. In the investigation area, the climate is characterized by all-year round homogenous temperature conditions and a strong variability in air humidity and moisture content of the atmosphere. Thus, contrary to the mid latitudes, the seasonal variation in glacier melt strongly depends on moisture-related variables, rather than on air temperature. The here presented ITGG-2.0-R model aims for these requirements. The lack of moisture-related input data other than precipitation demands for an intermediate calibration step. Net shortwave radiation, the emissivity of the atmosphere and a sublimation/melt ratio are related to precipitation amounts. Runoff is well simulated and correlates with the measured record with r² = 0.76. Seasonally obtained r² are only slightly smaller. On a long-term, the cumulative deviation is minor, and the mean annual cycle of runoff is reproduced rather well (r² = 0.99). Based on four different IPCC climate change scenarios, future runoff is simulated. All runoff scenarios are modelled for the respective steady-state glacier extent. This leads to a reduction in the glacier size and a decreased amount of glacier melt. On the other hand, direct runoff increases due to larger glacier free areas. Consequently, mean annual runoff remains almost unchanged, but the seasonality intensifies considerably with more runoff during the wet and less runoff during the dry season.  相似文献   

WASP-1b and WASP-2b: two new transiting exoplanets detected with SuperWASP and SOPHIE   总被引：1，自引：0，他引：1  

A. Collier Cameron  F. Bouchy  G. Hébrard  P. Maxted  D. Pollacco  F. Pont  I. Skillen  B. Smalley  R. A. Street  R. G. West  D. M. Wilson  S. Aigrain  D. J. Christian  W. I. Clarkson  B. Enoch  A. Evans  A. Fitzsimmons  M. Fleenor  M. Gillon  C. A. Haswell  L. Hebb  C. Hellier  S. T. Hodgkin  K. Horne  J. Irwin  S. R. Kane  F. P. Keenan  B. Loeillet  T. A. Lister  M. Mayor  C. Moutou  A. J. Norton  J. Osborne  N. Parley  D. Queloz  R. Ryans  A. H. M. J. Triaud  S. Udry  P. J. Wheatley 《Monthly notices of the Royal Astronomical Society》2007,375(3):951-957

We have detected low-amplitude radial-velocity variations in two stars, USNO-B1.0 1219–0005465 (GSC  02265–00107 = WASP–1  ) and USNO-B1.0 0964–0543604 (GSC  00522–01199 = WASP–2  ). Both stars were identified as being likely host stars of transiting exoplanets in the 2004 SuperWASP wide-field transit survey. Using the newly commissioned radial-velocity spectrograph SOPHIE at the Observatoire de Haute-Provence, we found that both objects exhibit reflex orbital radial-velocity variations with amplitudes characteristic of planetary-mass companions and in-phase with the photometric orbits. Line-bisector studies rule out faint blended binaries as the cause of either the radial-velocity variations or the transits. We perform preliminary spectral analyses of the host stars, which together with their radial-velocity variations and fits to the transit light curves yield estimates of the planetary masses and radii. WASP-1b and WASP-2b have orbital periods of 2.52 and 2.15 d, respectively. Given mass estimates for their F7V and K1V primaries, we derive planet masses 0.80–0.98 and 0.81–0.95 times that of Jupiter, respectively. WASP-1b appears to have an inflated radius of at least 1.33 R _Jup, whereas WASP-2b has a radius in the range 0.65–1.26 R _Jup.  相似文献   

A high-resolution geophysical investigation of sediment distribution controlled by catchment size and tides in a multi-basin turbid outwash fjord: Simpson Bay,Prince William Sound,Alaska     

Christian J. Noll  Timothy M. Dellapenna  Andrea Gilkinson  Randall W. Davis 《Geo-Marine Letters》2009,29(1):1-16

Surficial sediment distribution within Simpson Bay is a function of antecedent bedrock and recently deposited glacial geology, as well as active physical processes both within Simpson Bay and Prince William Sound (PWS). Simpson Bay is a turbid, outwash fjord located in northeastern PWS, Alaska. Freshwater from heavy precipitation, and the melting of high alpine glaciers enter the bay through bay head rivers and small shoreline creeks. The catchment has a high watershed/basin surface area ratio (∼8:1), and easily erodible bedrock that contribute to high sediment loads. The system can be divided into three discrete basins, each with specific morphologic and circulatory characters. Side scan sonar, swath bathymetry, and seismic profiles reveal that bathymetric highs are areas of outcropping glacial surfaces. High backscatter coupled with surface grab samples reveal these surfaces to be composed of coarse sediment and bedrock outcrops. Bathymetric lows are areas of low backscatter, and grab samples reveal these areas to be ponded deposits of organic-rich estuarine muds. The data provide evidence of terminal morainal bank systems, and glacial grounding line deposits at the mouth of the bay and rocky outcrops were identified as subsurface extensions of aerial rocky promontories. Radioisotope analyses of short cores reveal that the bay has an average accumulation rate of approx. 0.5 cm year⁻¹, but that this varies in function of the watershed/basin surface area ratios of the different basins. The interaction of tidal currents and sediment source drives sediment distribution in Simpson Bay. Hydrographic data reveal high spatial variability in surface and bottom currents throughout the bay. Subsurface currents are tide dominated, but generally weak (5–20 cm s⁻¹), while faster currents are found along shorelines, outcrops, and bathymetric highs. Bathymetric data reveal steep slopes with little to no modern sediment throughout the bay, suggesting lack of deposition due to tidal currents.  相似文献   

Si–C interactions during degradation of the diatom Skeletonema marinoi     

Brivaëla Moriceau  Madeleine Goutx  Catherine Guigue  Cindy Lee  Robert Armstrong  Marie Duflos  Christian Tamburini  Bruno Charrire  Olivier Ragueneau 《Deep Sea Research Part II: Topical Studies in Oceanography》2009,56(18):1381-1395

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Development and validation of a finite element morphological model for shallow water basins     

Christian Ferrarin  Georg Umgiesser  Andrea Cucco  Tai-Wen Hsu  Aron Roland  Carl L. Amos 《Coastal Engineering》2008

Recognising the importance of understanding sediment dynamics to evaluate the status of a coastal lagoon environment, this work has been focused on the investigation of the hydrodynamic and sediment transport processes occurring in such basins. In order to describe the lagoon system, a modelling approach combining hydrodynamics, waves and sediment dynamics has been developed. The framework of the numerical model consists of a finite element hydrodynamic model, a third generation finite element spectral wave model and a sediment transport and morphodynamic model for both cohesive and non-cohesive sediments. The model adopts the finite element technique for spatial integration, which has the advantage to describe more accurately complicated bathymetry and irregular boundaries for shallow water areas. The developed model has been applied to test cases and to a very shallow tidal lagoon, the Venice Lagoon, Italy. Numerical results show good agreement with water level, waves and turbidity measurements collected in several monitoring stations inside the Lagoon of Venice. Such a model represents an indispensable tool in analysing coastal problems and assessing morphological impacts of human interference.  相似文献   

Ultraviolet Studies of Interacting Binaries     

Boris T. Gänsicke  Domitilla de Martino  Thomas R. Marsh  Carole A. Haswell  Christian Knigge  Knox S. Long  Steven N. Shore 《Astrophysics and Space Science》2006,306(3):177-177

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Introduction to “tectonics and sedimentation of Southeast Asian continental margin and marginal seas”     

Zhen Sun  Chun-Feng Li  Guo-Liang Zhang  Hans Christian Larsen 《Marine Geophysical Researches》2015,36(2-3):99-100

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