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501.
502.
Arctic climate changes and possible conditions of Arctic navigation in the 21st century 总被引:1,自引:0,他引:1
Assessments of current and expected climatic changes in the Arctic Basin are obtained, including ice-cover characteristics
influencing the duration of the navigation season on the Northern Sea Route (NSR) along Eurasia and the Northwest Passage
(NWP) along North America. The ability of modern climate models to simulate the average duration of the navigation season
and its changes over recent decades is estimated. The duration of the navigation season for the NSR and NWP in the 21st century
is estimated using an ensemble of climate models. The assessments differ significantly for the NSR and NWP. Unlike the NSR,
the NWP reveals no large changes in the navigation season in the first 30 years of the 21st century. From the multimodel simulations,
the expected duration of the navigation period by the late 21st century will be approximately 3 to 6 months for the NSR and
2 to 4 months for the NWP under the moderate anthropogenic SRES-A1B scenario. 相似文献
503.
V. A. Rumyantsev L. K. Efimova G. S. Golitsyn V. Ch. Khon 《Izvestiya Atmospheric and Oceanic Physics》2010,46(1):21-28
In the region of the Ladoga Lake catchment basin, we perform data analysis on a set of different modern climate models with
different Intergovernmental Panel on Climate Change (IPCC) scenarios in the 20th and 21st centuries; this set includes global
models such as ECHAM4/OPYC3 (Max Planck Institute for Meteorology, Germany), HadCM3 (Hadley Centre Coupled Model, England),
and RCAO (Rossby Centre Regional Atmosphere-Ocean) models. Two variants of the boundary conditions for these climate models
(Rossby Center of Swedish Meteorological and Hydrological Institute, SMHI) are used. We present the results of a diagnosis
of the model-predicted near-surface temperature (T), precipitation (P), evaporation (E), and water budget (P-E) in the Ladoga
Lake catchment based on their comparison with empirical data in twentieth century. We obtain scenario estimates of the variations
of temperature and hydrologic regimes of Ladoga Lake catchment when IPCC IS92a, A2, and B2 scenarios are fulfilled, describing
the prognostic growth of anthropogenic emissions of greenhouse gases and aerosol to the atmosphere, and discuss the recommendations
for their use. 相似文献
504.
Rim Ladhar‐Chaabouni Amel Hamza‐Chaffai Yann Hardivillier Benoît Chénais Françoise Denis 《Marine Ecology》2010,31(2):355-363
The internal transcribed spacer 1 (ITS1) region of 29 individuals of Cerastoderma glaucum (from the Mediterranean Sea, the Atlantic and the North Sea) and 18 individuals of Cerastoderma edule (from the Atlantic and the North Sea) and the cytochrome c oxidase subunit I (COI) region of 43 individuals of C. glaucum (from the Mediterranean Sea, the Atlantic and the North Sea) and 9 individuals of C. edule (from the Atlantic and the North Sea) were PCR amplified and sequenced. The ITS1 sequences led us to describe 27 genetic haplotypes, while 21 genetic haplotypes were determined via the COI sequences. The ITS1 and the COI sequences revealed an important genetic variability within the Mediterranean population of C. glaucum, which contained two different phenotypes: orange foot and yellow foot. A genetic differentiation between the two phenotypes was revealed by the nucleotide diversity index (π) and is strengthened by the AMOVA analysis. This result leads us to suspect the presence of two different groups in the same population of C. glaucum. Nevertheless to be confirmed this hypothesis requires further studies using more locations and a larger number of sample sizes. 相似文献
505.
The passive satellite GFZ-1 has been orbiting the Earth since April 1995. The purpose of this mission is to improve the current
knowledge of the Earth's gravity field by analysing gravitational orbit perturbations observed at unique low altitudes, below
400 km. GFZ-1 is one target of the international satellite laser ranging ground network. An evaluation of the first 30 months
of GFZ-1 laser tracking data led to a new version of the global GRIM4-S4 satellite-only gravity field model: GRIM4-S4G. Information
was obtained from GFZ-1 data for spherical harmonic coefficients up to degree 100, which was not possible in any earlier satellite-only
gravity field solution. GFZ-1's contribution to a global 5 × 5° geoid and gravity field representations is moderate but visible
with a 1 cm and 0.1 mGal gain in accuracy on a level of 75 cm and 5 mGal, respectively.
Received: 10 November 1998 / Accepted: 19 April 1999 相似文献
506.
S. Rossano Ch. Brouder M. Alouani M. -A. Arrio 《Physics and Chemistry of Minerals》2000,27(3):170-178
The transition energies responsible for optical absorption spectra can be obtained by crystal-field analysis, but the transition
intensities are notoriously difficult to calculate. This paper examines the basic ingredients of the calculation of optical
spectrum intensities. Magnetic dipole and electric quadrupole transitions intensities are evaluated, as well as the direct
d(Ni2+) to p(O2−) electric dipole transitions. All these contributions are shown to be small in the optical range, so that spectral intensities
are due to the mixing of odd orbitals with the Ni2+ 3d
n
states.
Received: 11 November 1997 / Revised, accepted: 6 September 1999 相似文献
507.
508.
The aim of the present investigation has been to investigate numerically the orbits of particles in the gravitational field of barred galaxies for different models of such formations; with special attention to the families of direct periodic orbits in the co-rotating frame. 相似文献
509.
510.
H. Wieseneder K. Becherer J. Zemann E. Schroll Ch. Exner 《Mineralogy and Petrology》1969,13(3-4):293-298
Ohne Zusammenfassung 相似文献