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41.
On stochastic stability of regional ocean models to finite-amplitude perturbations of initial conditions 总被引:1,自引:0,他引:1
We consider error propagation near an unstable equilibrium state (classified as an unstable focus) for spatially uncorrelated and correlated finite-amplitude initial perturbations using short- (up to several weeks) and intermediate (up to 2 months) range forecast ensembles produced by a barotropic regional ocean model. An ensemble of initial perturbations is generated by the Latin Hypercube design strategy, and its optimal size is estimated through the Kullback–Liebler distance (the relative entropy). Although the ocean model is simple, the prediction error (PE) demonstrates non-trivial behavior similar to that existing in 3D ocean circulation models. In particular, in the limit of zero horizontal viscosity, the PE at first decays with time for all scales due to dissipation caused by non-linear bottom friction, and then grows faster than (quasi)-exponentially. Statistics of a prediction time scale (the irreversible predictability time (IPT)) quickly depart from Gaussian (the linear predictability regime) and becomes Weibullian (the non-linear predictability regime) as amplitude of initial perturbations grows. A transition from linear to non-linear predictability is clearly detected by the specific behavior of IPT variance. A new analytical formula for the model predictability horizon is introduced and applied to estimate the limit of predictability for the ocean model. 相似文献
42.
Vsevolod M. Gavshin Leonid V. Miroshnichenko 《Geostandards and Geoanalytical Research》2000,24(2):241-246
West Siberian brown coals from the Kansk-Achinsk basin and their combustion products are generally characterized by a low uranium content. In some places where brown coal has been altered (losing density, becoming cracked or friable), the uranium content has increased by concentrations ranging from 1001000 μg g−1 . At these locations distinct signs of underground fires are visible. The uranium distribution patterns suggest that the burnt organic matter was a source of uranium and altered varieties of coal serve as a geochemical barrier to uranium transport. 相似文献
43.
Leonid M. Baskin 《Polar research》2000,19(1):23-29
The dynamic state of reindeer husbandry in northern Russia during the 20th century was studied as a basis for predicting the consequences of the current drastic changes taking place there. Similar forms and methods of reindeer husbandry were used with different frequencies and effectiveness throughout the century. In the future reindeer husbandry will conform to market requirements, landscape features and national traditions. In some areas, the more sophisticated methods of management developed in conjunction with large-scale, highly productive reindeer husbanry, could be lost and a subsistence economy, including hunting, could predominate. 相似文献
44.
Varghese Swamy Leonid S. Dubrovinsky Masanori Matsui 《Physics and Chemistry of Minerals》1997,24(6):440-446
We investigated the lattice vibrational properties and lattice dynamical behaviour of diopside by combining laser micro-Raman spectroscopic measurements with quasi-harmonic lattice dynamic simulation using a transferable interatomic potential. We obtained polarized Raman spectra from a Fe-poor natural diopside and the temperature dependencies of the Raman modes to 1125?K from high-temperature Raman spectra of a Fe-poor and a Fe-rich natural diopside. The various modes display different temperature dependencies: from ?0.021?cm?1/K to ?0.004?cm?1/K. The temperature shift of low frequency modes is generally higher. A comparison of experimentally determined frequencies and symmetries of vibrational modes of the optical type (Raman and infrared) obtained in this and earlier studies with those calculated by us suggests that a consistent characterization of the vibrational properties was achieved. The good agreement between the experimental and simulated data on the temperature-dpendencies of the Raman modes (within 5%), crystal structure (2%), bulk modulus (5%), volume thermal expansivity (6%), and constant volume heat capacity (0.2%) testifies to the applicability of the transferable interatomic potential and the lattice dynamic model to predicting the vibrational, physical, and thermodynamic properties. The simulated properties from the lattice dynamic calculations are very similar to those obtained by molecular dynamic calculations with the same potential model. 相似文献
45.
The growth rate of the upper-hybrid waves with different velocities of superthermal electrons is computed considering a finite
temperature of the background plasma and relativistic corrections. Based on these computations two examples of high-frequency
zebra structures are interpreted. The sequence of the continuum, zebra structure, and continuum observed in the 29 October
2000, event is explained as an increase and following decrease of the velocity of superthermal electrons in the range of v=0.1–0.3 c. On the other hand, the zebra structure observed during the 18 March 2003 event represents an example with fast electron
acceleration. 相似文献
46.
47.
Results of the analysis of the Comet Halley spectrophotometry,which has been carried out by H.K. Nazarchuk in 1985 with the
TVscanner of the 6-meter telescope (SAO, Russia) are presented. Timevariations in the intensities of the CN, CH, C2 and NH2bands were investigated using the series of spectra obtained inthe spectral region λλ=410÷ 510 nm. Theauto-correlation functions
for all the bands, thecross-correlation functions for C2 lines and their Fouriertransformations are calculated to determine the frequencies andperiods of the variations. A possibility
is considered thathigh-amplitude fast variations of spectral lines in Comet Halleyare caused by solar flares. The daily numbers
of solar spots andproton fluxes with energies of more then 1 MeV are compared withthe spectral variations of these lines.
It is shown that in theobservation periods the comet was projected onto an active regionof the Sun, but, among all the kinds
of solar activity, mainlythe solar proton flux with energies less than 4 MeV coincides intime with fast intensity variations
in the spectral lines. Analgorithm of cross-correlation analysis of discrete samplingseries with gaps is built, and average
cross-correlation coefficientsare calculated. 相似文献
48.
正1 Introduction In the south of Eastern Transbaikalia in the border area with China and Mongolia,there are at least 300 saline without outlet lakes.They are confined to the semi-arid zone Daurian steppes with pronounced continental salinization processes and are mostly located on the bottoms of the intermountain basins.Their origin is related to evaporative concentration of fresh waters lakes filling. 相似文献
49.
正In recent years,lakes,including salted,attract the attention of researchers,also when reconstructing last climate changes using the bottom sediments(Solotchina et al.,2008,et al.).In this case the different geochemical 相似文献
50.
Igor S. Falkovich Alexander A. Konovalenko Anatoliy A. Gridin Leonid G. Sodin Igor N. Bubnov Nikolay N. Kalinichenko Sergey L. Rashkovskii Dmitriy V. Mukha Peter L. Tokarsky 《Experimental Astronomy》2011,32(2):127-145
We have developed an active dipole that is intended for use in new generation low frequency array applications. The preamplifier of the active dipole has very high linearity (input IP2 = 70 dBm, input IP3 = 31 dBm) and low noise temperature (100?C360 K). The frequency dependence of the dipole impedance and the match between the dipole and preamplifier have been optimized to achieve Galactic noise limited operation. The ratio between the antenna temperature due to Galactic noise and the noise temperature of the preamplifier is 10 ± 1.5 dB over the whole 10 to 70 MHz range. The total cost of the active cross-dipole is 220 euro. 相似文献