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91.
Dmitri V. Alexandrov Irina A. Bashkirtseva Alexey P. Malygin Lev B. Ryashko 《Pure and Applied Geophysics》2013,170(12):2273-2282
The influence of stochastic fluctuations in the atmosphere and in the ocean caused by different occasional phenomena (noises) on dynamic processes of sea ice growth with a mushy layer is studied. It is shown that atmospheric temperature variances substantially increase the sea ice thickness, whereas dispersion variations of turbulent flows in the ocean to a great extent decrease the ice content produced by false bottom evolution. 相似文献
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94.
Irina N. Belskaya Anny-Chantal Levasseur-Regourd Yuriy S. Efimov Edith Hadamcik 《Icarus》2009,199(1):97-105
New UBVRI polarimetric observations of ten asteroids, including space mission targets 1 Ceres and 21 Lutetia, are presented. These observations were obtained with the 1.25-m telescope of the Crimean Astrophysical Observatory and have been used to study the wavelength dependence of polarization for a sample of asteroids belonging to the M and low albedo classes. A more general analysis including also a larger data set of UBVRI polarimetric observations available in the literature for more than 50 main belt asteroids belonging to different taxonomic classes shows that the variation of the polarization degree Pr as a function of wavelength is generally well described by a linear trend. It typically does not exceed 0.2% in the studied spectral range 0.37-0.83 microns and tends to increase for increasing phase angle. Asteroids belonging to the S and M classes are found to exhibit a deeper negative branch and smaller positive polarization for increasing wavelength (negative sign of the slope of ΔPr/Δλ). Since the objects belonging to these classes are known to exhibit reddish reflectance spectra, the observed wavelength behavior of negative polarization contradicts the well-known inverse correlation of Pmin and albedo. Low albedo asteroids show larger dispersion of spectral slopes, but the overall trend is characterized by a shallower negative branch and a larger positive polarization for increasing wavelength (positive sign of the slope of ΔPr/Δλ). A few exceptions from this general trend are discussed. The observed variety in the wavelength dependence of asteroid polarization seems to be mainly attributed to surface composition. 相似文献
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96.
Irina Tupikova Michael Soffel Sergei Klioner 《Celestial Mechanics and Dynamical Astronomy》1999,74(3):147-152
Starting from the classical expansion of the perturbing function in the three‐body problem, the transformation to individual
orbital elements is performed in principle up to any degree in small parameters. Some corrections to the results presented
in the well‐known article by Yuasa on secular perturbations of asteroids are given. Consequences for the expansion of the
indirect part of the perturbing function are discussed.
This revised version was published online in July 2006 with corrections to the Cover Date. 相似文献
97.
The results of V-band polarimetric observations of the potentially hazardous near-Earth Asteroid (23187) 2000 PN9 at large phase angles are presented as well as its photometric observations in BVRI bands. Observations were made in March-April 2006 during its close approach to the Earth using the 1.82-m Asiago telescope (Italy) and the 0.7-m telescope at the Chuguevskaya Observational Station (Ukraine). We obtained polarimetric measurements at the phase angle of 115°, the largest phase angle ever observed in asteroid polarimetry. Our data show that the maximum value of the polarization phase curve reached 7.7% and occurred in the phase angle range of 90-115°. The measured values of linear polarization degree, BVRI colors and magnitude-phase dependence correspond to the S-type composition of this asteroid. Based on our observations the following characteristics of the Asteroid (23187) 2000 PN9 were obtained: a rotation period of 2.5325±0.0004 h, a lightcurve amplitude of 0.13 mag, an albedo of 0.24±0.06 and a diameter of 1.6±0.3 km. 相似文献
98.
In this paper we present specific features of TEC (total electron content of the ionosphere) behavior as possible precursors of Kythira (Southern Greece) earthquake of January
8, 2006 (M6.8). For this purpose, we used both the TEC data of GPS-IGS stations nearest to the epicenter, and TEC maps over Europe. The favorable circumstance for this analysis was the quiet geomagnetic situation during the period prior
to the earthquake. One day before the earthquake, a characteristic anomaly was found out as the day-time significant increase
of TEC at the nearest stations, up to the value of 50% relative to the background condition. To estimate the spatial dimensions
of seismo-ionospheric anomaly, the differential mapping method was used. The ionosphere modification as a cloud-like increase
of electron concentration situated in the immediate vicinity of the forthcoming earthquake epicenter has been revealed. The
amplitude of modification reached the value of 50% relative to the non-disturbed condition and was in existence from 10:00
till 22:00 UT. The area of significant TEC enhancement had a size of about 4000 km in longitude and 1500 km in latitude. 相似文献
99.
S. A. Khubunaya L. I. Gontovaya A. V. Sobolev I. V. Nizkous 《Journal of Volcanology and Seismology》2007,1(2):98-118
A 3D velocity model of the Earth’s crust beneath the Klyuchevskoy volcanic group has been constructed using the seismic tomography method. Anomalies of the velocity parameters related to the zones of magma supply to active volcanoes have been distinguished. Petrological data on the composition, temperature, and pressure of generation and crystallization of parental melts of Klyuchevskoy volcano magnesian basalts have been obtained. The parental melt corresponds to picrite (MgO = 13–14 wt %) with an ultimate saturation of SiO2 (49–50 wt %), a high H2O content (2.2–2.9%), and incompatible elements (Sr, Rb, Ba). This melt is formed at pressures of 15–20 kbar and temperatures of 1280–1320°C. Its further crystallization proceeds in intermediate magma chambers at two discrete pressure levels (i.e., greater than 6, and 1–2 kbar). The results of the petrological studies are in good agreement with the seismotomographic model. 相似文献
100.
GPS observations of the European permanent network were used to identify seismo-ionospheric precursors of Baltic Sea earthquake
of 21 September 2004. It is a very rare event for this region of Europe (magnitude of about 5.0). This value is the threshold
for the occurrence of seismic effects in the ionosphere. In total electron content (TEC) data over the region of the earthquake,
a specific ionospheric anomaly appeared one day before the earthquake was detected. The ionospheric variability had a positive
sign with an enhancement of about 4–5 TECU (1 TECU = 1016 electrons/m2) relative to the non-disturbed state of the ionosphere. The anomaly had a duration of 4–5 hours in the day time. The special
size of this anomaly was about 1000 km. The characteristic parameters of the anomaly show that it can be associated with ionospheric
precursors of an earthquake. 相似文献