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91.
Hubert Gall��e Alexandre Trouvilliez C��cile Agosta Christophe Genthon Vincent Favier Florence Naaim-Bouvet 《Boundary-Layer Meteorology》2013,146(1):133-147
For the first time a simulation of blowing snow events was validated in detail using one-month long observations (January 2010) made in Adélie Land, Antarctica. A regional climate model featuring a coupled atmosphere/blowing snow/snowpack model is forced laterally by meteorological re-analyses. The vertical grid spacing was 2 m from 2 to 20 m above the surface and the horizontal grid spacing was 5?km. The simulation was validated by comparing the occurrence of blowing snow events and other meteorological parameters at two automatic weather stations. The Nash test allowed us to compute efficiencies of the simulation. The regional climate model simulated the observed wind speed with a positive efficiency (0.69). Wind speeds higher than 12 m s ?1 were underestimated. Positive efficiency of the simulated wind speed was a prerequisite for validating the blowing snow model. Temperatures were simulated with a slightly negative efficiency (?0.16) due to overestimation of the amplitude of the diurnal cycle during one week, probably because the cloud cover was underestimated at that location during the period concerned. Snowfall events were correctly simulated by our model, as confirmed by field reports. Because observations suggested that our instrument (an acoustic sounder) tends to overestimate the blowing snow flux, data were not sufficiently accurate to allow the complete validation of snow drift values. However, the simulation of blowing snow occurrence was in good agreement with the observations made during the first 20 days of January 2010, despite the fact that the blowing snow flux may be underestimated by the regional climate model during pure blowing snow events. We found that blowing snow occurs in Adélie Land only when the 30-min wind speed value at 2 m a.g.l. is >10 m s ?1. The validation for the last 10 days of January 2010 was less satisfactory because of complications introduced by surface melting and refreezing. 相似文献
92.
Huu Hieu Ho Rudy Swennen Val��rie Cappuyns Elvira Vassilieva Tom Van Gerven Tan Van Tran 《Aquatic Geochemistry》2013,19(1):57-75
The speciation and mobility of some selected trace metals (As, Cu, Mn, Pb and Zn) in sediments with depth was investigated in the Cam River-mouth (Vietnam) by collecting sediment cores and analysing porewater and sediment composition, complemented with single (ammonium-EDTA) and sequential (BCR 3-step) extractions and mineralogical analysis (XRD). All trace metals show overall decreasing trends with depth in porewater as a result of anthropogenic input in upper sediment layers. High porewater concentrations of As, Mn and Pb in oxic and suboxic sediment layers may result in groundwater pollution. Sediment-bound Pb and Mn dominate in the reducible and the acid-soluble fraction, respectively, while Cu and Zn distribute rather evenly between four extracted fractions. The porewater metal speciation, as predicted by a geochemical model Visual MINTEQ version 3.0, indicates that the toxicity of Cu, Mn, Pb and Zn (presented by the proportions of free metal ions) decreases with depth, while the toxicity of As increases when As(III) becomes more abundant. The dissolved concentrations of trace metals are not only controlled by the precipitation/dissolution of discrete hydroxide/oxide, carbonate and phosphate minerals, but also by sorption processes on major sorbents (i.e. As on goethite, and Mn and Zn on calcite and dolomite). Sulphide minerals do not show any control even in the anoxic zone most likely because of the low concentration of sulphur. 相似文献
93.
The Imaging Magnetograph eXperiment (IMaX) for?the?Sunrise Balloon-Borne Solar Observatory 总被引:1,自引:0,他引:1
V. Mart��nez?Pillet J. C. del Toro Iniesta A. ��lvarez-Herrero V. Domingo J. A. Bonet L. Gonz��lez?Fern��ndez A. L��pez?Jim��nez C. Pastor J. L. Gasent?Blesa P. Mellado J. Piqueras B. Aparicio M. Balaguer E. Ballesteros T. Belenguer L. R. Bellot?Rubio T. Berkefeld M. Collados W. Deutsch A. Feller F. Girela B. Grauf R. L. Heredero M. Herranz J. M. Jer��nimo H. Laguna R. Meller M. Men��ndez R. Morales D. Orozco?Su��rez G. Ramos M. Reina J. L. Ramos P. Rodr��guez A. S��nchez N. Uribe-Patarroyo P. Barthol A. Gandorfer M. Knoelker W. Schmidt S. K. Solanki S. Vargas?Dom��nguez 《Solar physics》2011,268(1):57-102
The Imaging Magnetograph eXperiment (IMaX) is a spectropolarimeter built by four institutions in Spain that flew on board the Sunrise balloon-borne solar observatory in June 2009 for almost six days over the Arctic Circle. As a polarimeter, IMaX uses fast polarization modulation (based on the use of two liquid crystal retarders), real-time image accumulation, and dual-beam polarimetry to reach polarization sensitivities of 0.1%. As a spectrograph, the instrument uses a LiNbO3 etalon in double pass and a narrow band pre-filter to achieve a spectral resolution of 85 mÅ. IMaX uses the high-Zeeman-sensitive line of Fe i at 5250.2 Å and observes all four Stokes parameters at various points inside the spectral line. This allows vector magnetograms, Dopplergrams, and intensity frames to be produced that, after reconstruction, reach spatial resolutions in the 0.15??C?0.18 arcsec range over a 50×50 arcsec field of view. Time cadences vary between 10 and 33 s, although the shortest one only includes longitudinal polarimetry. The spectral line is sampled in various ways depending on the applied observing mode, from just two points inside the line to 11 of them. All observing modes include one extra wavelength point in the nearby continuum. Gauss equivalent sensitivities are 4 G for longitudinal fields and 80 G for transverse fields per wavelength sample. The line-of-sight velocities are estimated with statistical errors of the order of 5??C?40 m?s?1. The design, calibration, and integration phases of the instrument, together with the implemented data reduction scheme, are described in some detail. 相似文献
94.
S. Osterman J. Green C. Froning S. B��land E. Burgh K. France S. Penton T. Delker D. Ebbets D. Sahnow J. Bacinski R. Kimble J. Andrews E. Wilkinson J. McPhate O. Siegmund T. Ake A. Aloisi C. Biagetti R. Diaz W. Dixon S. Friedman P. Ghavamian P. Goudfrooij G. Hartig C. Keyes D. Lennon D. Massa S. Niemi C. Oliveira R. Osten C. Proffitt T. Smith D. Soderblom 《Astrophysics and Space Science》2011,335(1):257-265
The Cosmic Origins Spectrograph (COS) was installed in the Hubble Space Telescope in May, 2009 as part of Servicing Mission 4 to provide high sensitivity, medium and low resolution spectroscopy at far- and near-ultraviolet wavelengths (FUV, NUV). COS is the most sensitive FUV/NUV spectrograph flown to date, spanning the wavelength range from 900 Å to 3200 Å with peak effective area approaching 3000 cm2. This paper describes instrument design, the results of the Servicing Mission Orbital Verification (SMOV), and the ongoing performance monitoring program. 相似文献
95.
C. D. Ott E. O��Connor F. Peng C. Reisswig U. Sperhake E. Schnetter E. Abdikamalov P. Diener F. L?ffler I. Hawke C. A. Meakin A. Burrows 《Astrophysics and Space Science》2011,336(1):151-156
We present new approaches to the simulation of stellar collapse, the formation of black holes, and explosive core-collapse supernova nucleosynthesis that build upon open-source codes and microphysics. We discuss the new spherically-symmetric general-relativistic (GR) collapse code GR1D that is endowed with an approximate 1.5D treatment of rotation, comes with multiple nuclear equations of state, and handles neutrinos with a multi-species leakage scheme. Results from a first set of spinning black hole formation simulations are presented. We go on to discuss the derivative code GR1D+N which is tuned for calculations of explosive nucleosynthesis and includes a NSE/non-NSE equation of state treatment, and a nuclear reaction network. We present sample results showing GR1D+N??s performance in reproducing previous results with thermal-bomb-driven explosions. Finally, we introduce the 3?+?1 GR Zelmani core collapse simulation package and present first results obtained in its application to the 3D modeling of failing core-collapse supernovae. 相似文献
96.
97.
Aur��lien Bideaud Benoit Belier Alain Benoit Laurent Berg�� Philippe Camus Sophie Collin Louis Dumoulin Christian Hoffmann Stefanos Marnieros Alessandro Monfardini 《Experimental Astronomy》2011,32(2):179-191
Microbolometers are at present the most sensitive detectors for mm and sub-mm Astronomy. They are in use in most of the present instruments in that bandwidth. We have developed filled arrays of NbSi-based planar antenna coupled microbolometers. The fabrication details are given, together with characterization of the NbSi thermometers and optical results. The optical performances are potentially good for ground-based mm-wave astronomy applications, while the overall detectors performances are limited by low-frequency excess noise in the thermometric NbSi high-impedance sensors (Anderson insulator). 相似文献
98.
T. Dahm D. Becker M. Bischoff S. Cesca B. Dost R. Fritschen S. Hainzl C. D. Klose D. K��hn S. Lasocki Th. Meier M. Ohrnberger E. Rivalta U. Wegler Stephan Husen 《Journal of Seismology》2013,17(1):197-202
Various techniques are utilized by the seismological community, extractive industries, energy and geoengineering companies to identify earthquake nucleation processes in close proximity to engineering operation points. These operations may comprise fluid extraction or injections, artificial water reservoir impoundments, open pit and deep mining, deep geothermal power generations or carbon sequestration. In this letter to the editor, we outline several lines of investigation that we suggest to follow to address the discrimination problem between natural seismicity and seismic events induced or triggered by geoengineering activities. These suggestions have been developed by a group of experts during several meetings and workshops, and we feel that their publication as a summary report is helpful for the geoscientific community. Specific investigation procedures and discrimination approaches, on which our recommendations are based, are also published in this Special Issue (SI) of Journal of Seismology. 相似文献
99.
?????????2013????????????6.6?????????????300 km??Χ??6???????α???2009-01-01??2013-07-21??????????26????????????????????????????????????????????????????????????????????????????????????????????????????????????????????????????????????α?????????????????????????н?????????????????????????Щ?仯?????????6.6?????????????????? 相似文献
100.
��. Falize B. Loupias A. Ravasio C. D. Gregory A. Dizi��re M. Koenig C. Michaut C. Cavet P. Barroso J.-P. Leidinger X. Ribeyre J. Breil H. Takabe Y. Sakawa Y. Kuramitsu T. Morita N. C. Woolsey W. Nazarov S. Pikuz 《Astrophysics and Space Science》2011,336(1):81-85
In this paper, theoretical and experimental laboratory astrophysics results are presented from the POLAR project, the main focus of which is to design and diagnose an exact scaled accretion column using powerful lasers. These measurements allow the testing of the astrophysical models of accretion processes present in magnetic cataclysmic variables. 相似文献