Regional structure of surface-air temperature fluctuations in northern Eurasia in the latter half of the 20th and early 21st centuries     

V. V. Popova  A. B. Shmakin 《Izvestiya Atmospheric and Oceanic Physics》2010,46(2):144-158

The first empirical orthogonal functions (EOF1s) of surface-air temperature fluctuations for Russia and its neighboring states within the period 1950–2005 are analyzed. The spatial distribution of the EOF1, the first principal components (PC1s) of the observed air temperature (averaged over the summer, July, December–March, and individual winter months), and their time variations (including trend parameters, some spectral characteristics, and the quantitative indices of relation to circulation indices (on the basis of multiple step-by-step regression)) are considered. Significant seasonal differences have been revealed: the winter air-temperature fluctuations are characterized by a higher (when compared to summer) spatial coherence, especially in the latitudinal direction. The EOF1 of the winter air temperature (averaged over December–March) describes its fluctuations for almost all of Russia; in this case, no less than 70% of the PC1 variability is due to variations in several circulation indices; the main contribution (60%) is made by both the North Atlantic Oscillation (NAO) and Scandinavian (SCAND) indices. On the whole, over the periods 1951–2005 and 1971–2005, the NAO contribution exceeds the SCAND contribution to the winter temperature variability; the NAO is associated with a more rapid increase in air temperature in 1968–1997 and with the 1971–2005 trend. In 1951–1970 the main contribution to air temperature fluctuations was made by SCAND; the SCAND contribution exceeds the NAO contribution in the periods 1951–2005 and 1971–2005. The 1971–2005 and 1968–1997 temperature trends are completely described by variations in the NAO (70%) and SCAND (30%) indices for January and February.  相似文献   

Oithona davisae: Naturalization in the Black Sea,Interannual and Seasonal Dynamics,and Effect on the Structure of the Planktonic Copepod Community     

Gubanova  A. D.  Garbazey  O. A.  Popova  E. V.  Altukhov  D. A.  Mukhanov  V. S. 《Oceanology》2019,59(6):912-919

Oceanology - Naturalization of the invasive copepod Oithona davisae is examined based on long-term (2003–2014) routine observations of zooplankton in Sevastopol Bay (the Black Sea). The study...  相似文献   

Search for Bright Masers in the Water Vapor Line towards the Dust Clumps of the Galaxy     

Ladeyshchikov  D. A.  Tsivilev  A. P.  Sobolev  A. M.  Popova  E. A. 《Astronomy Reports》2022,66(4):278-295

Astronomy Reports - The paper is devoted to the analysis of the observation results with the single-mirror radio telescope RT-22 (PRAO, LPI) in the water vapor maser line at 22 GHz in the direction...  相似文献   

On the stability of circumbinary planetary systems     

E. A. Popova  I. I. Shevchenko 《Astronomy Letters》2016,42(7):474-481

The dynamics of circumbinary planetary systems (the systems in which the planets orbit a central binary) with a small binary mass ratio discovered to date is considered. The domains of chaotic motion have been revealed in the “pericentric distance–eccentricity” plane of initial conditions for the planetary orbits through numerical experiments. Based on an analytical criterion for the chaoticity of planetary orbits in binary star systems, we have constructed theoretical curves that describe the global boundary of the chaotic zone around the central binary for each of the systems. In addition, based on Mardling’s theory describing the separate resonance “teeth” (corresponding to integer resonances between the orbital periods of a planet and the binary), we have constructed the local boundaries of chaos. Both theoretical models are shown to describe adequately the boundaries of chaos on the numerically constructed stability diagrams, suggesting that these theories are efficient in providing analytical criteria for the chaoticity of planetary orbits.  相似文献   

A dynamical system for the parker dynamo in the case of quadrupole symmetry of the magnetic field     

E. P. Popova 《Astronomy Reports》2013,57(4):310-315

Adynamical systemin the case of quadrupolar symmetry of the toroidal field is constructed. The system obtained reproduces the regimes of oscillations, vacillations, dynamo bursts, and a configuration with monotonically growing magnetic fields reaching stationary regimes. The ranges of dynamo numbers corresponding to these regimes are found. Butterfly diagrams for the steady-oscillation regime are constructed for both the poloidal and toroidal components of the magnetic field.  相似文献   

Modeling of the solar activity double cycle using dynamical systems     

E. P. Popova  K. A. Potemina 《Geomagnetism and Aeronomy》2013,53(8):941-944

The generation and evolution of the Sun’s magnetic field and other stars is usually related to the dynamo mechanism. This mechanism is based on the consideration of the joint influence of the α effect and differential rotation. Dynamo sources can be located at different depths of the convection zone and can have different intensities. Based on such a system, the dynamical system in the case of the stellar dynamo in a two-layer medium has been constructed with regard to meridional fluxes in order to model the double cycle that corresponds to the simultaneous presence of 22-year and quasi-biennial magnetic field oscillations. It has been indicated that the regime of mixed oscillations can originate because a dynamo wave moves oppositely to the meridional flows in the upper layer of the convection zone. This results in the deceleration of the toroidal field propagation and in the generation of slow oscillations. In deeper layers, the directions of a dynamo wave and meridional flows coincide with each other, as a result of which fast magnetic fields originate. Therefore, the total contribution of two oscillations with different frequencies corresponds to the appearance of quasi-biennial cycles against 22-year cycles. It has been indicated that the beating regime, which can be related to the secular oscillations of solar magnetic activity, originates in the system when the meridional flows are weak.  相似文献   

The results of marine electromagnetic sounding with a high-power remote source in the Kola Bay in the Barents Sea     

V. F. Grigoriev  S. M. Korotaev  M. S. Kruglyakov  D. A. Orekhova  I. V. Popova  E. D. Tereshchenko  P. E. Tereshchenko  Yu. G. Schors 《Izvestiya Physics of the Solid Earth》2013,49(3):373-383

The first Russian six-component seafloor electromagnetic (EM) receivers were tested in an experiment carried out in Kola Bay in the Barents Sea. The signals transmitted by a remote high-power ELF source at several frequencies in the decahertz range were recorded by six receivers deployed on the seafloor along the profile crossing the Kola Bay. Although not all the stations successfully recorded all the six components due to technical failures, the quality of the data overall is quite suitable for interpretation. The interpretation was carried out by the three-dimensional (3D) modeling of an electromagnetic field with neural network inversion. The a priori geoelectrical model of Kola Bay, which was reconstructed by generalizing the previous geological and geophysical data, including the data of the ground magnetotelluric sounding and magnetovariational profiling, provided the EM fields that are far from those measured in the experiment. However, by a step-by-step modification of the initial model, we achieved quite a satisfactory fit. The resulting model provides the basis for introducing the corrections into the previous notions concerning the regional geological and geophysical structure of the region and particularly the features associated with fault tectonics.  相似文献   

Crater clusters on Mars: Shedding light on martian ejecta launch conditions     

Olga P. Popova  William K. Hartmann  Derek C. Richardson 《Icarus》2007,190(1):50-73

We have identified two classes of crater clusters on Mars. One class is “small clusters” (crater diameter D∼ tens m, spread over few hundred m), fitting our earlier calculations for the breakup of weak stone meteoroids in the martian atmosphere [Popova, O.P., Nemtchinov, I.V., Hartmann, W.K., 2003. Meteorit. Planet. Sci. 38, 905-925]. The second class is “large clusters” (D∼ few hundred m, spread over 2 to 30 km), which do not fit any predictions for breakup of known meteoroid types. We consider a range of possible explanations. The best explanation relates to known, high-speed ejection of large, semi-coherent, fractured rock masses from the surface, as secondary debris from primary impacts. The clusters are probably due to breakup of partly fracture, few-hundred-meter scale weak blocks, especially during ascent (producing moderate lateral spreading velocities among the fragments during sub-orbital flight), and also during descent of the resulting swarm. These conclusions illuminate the launch conditions of martian meteorites, including fragmentation processes, although more work is needed on the lateral separation of fragments (during either atmosphere descent or ascent) due to the effects of volatiles in the projectiles. Martian meteorites probably come from smaller martian craters than the clusters' source craters. The latter probably have D?85 km, although we have not ruled out diameters as small as 15 km.  相似文献   

Anharmonicity of Stellar Cycles: A Wavelet Quantification     

S. Baliunas  P. Frick  D. Moss  E. Popova  D. Sokoloff  W. Soon 《Solar physics》2004,224(1-2):179-185

Two quantitative measures for the anharmonicity of stellar cycles, as recorded in the Ca II H and K chromospheric activity data as well as in simple dynamo models, are presented and discussed.  相似文献   

Time-spectra of chromospheric activity of old solar-type stars: detection of rotational signals from double wavelet analysis     

Peter Frick  Willie Soon  Elena Popova  Sallie Baliunas   《New Astronomy》2004,9(8):599-609

We introduce a novel technique, called the double wavelet analysis (DWA), for the determination of stellar rotation periods from time serial data. This first paper aims narrowly at the discussion, introduction and application of the DWA technique to records of surface magnetism in solar-type (relatively old) lower main sequence stars that are obtained by the Mount Wilson Observatory (MWO) HK Project. The technique takes a series of careful steps that seek to optimize wavelet parameters and normalization schemes, ultimately allowing fine-tuned, arguably more accurate, estimates of rotation-modulated signals (with, e.g., periods of days to months) in records that contain longer periodicities such as stellar magnetic activity cycles (with, e.g., period of years). The apparent rotation periods estimated from the DWA technique are generally consistent with results from both “first-pass” (i.e., ordinary) global wavelet spectrum and earlier classical periodogram analyses. But there are surprises as well. For example, the rotation period of the ancient subdwarf Goombridge 1830 (HD 103095), previously identified as ≈31 days, suggests under the DWA technique a significantly slower period of 60 days. DWA spectra also generally reveal a shift in the cycle period toward high frequencies (hence shorter periods) compared to the first-pass wavelet spectrum. For solar-type stars analyzed here, the character of the DWA spectrum and slope of the first-pass global wavelet spectrum produce a classification scheme that allows a star's record to be placed into one of three categories.  相似文献