Analysis of the optical emission of the young precataclysmic variables HS 1857+5144 and ABELL 65     

V. V. Shimansky  S. A. Pozdnyakova  N. V. Borisov  I. F. Bikmaev  V. V. Vlasyuk  O. I. Spiridonova  A. I. Galeev  S. S. Mel’nikov 《Astrophysical Bulletin》2009,64(4):349-364

We analyze the physical state and the properties of the close binary systems HS 1857+5144 and Abell 65. We took the spectra of both systems over a wide range of orbital phases with the 6-m telescope of the Special Astrophysical Observatory of the Russian Academy of Sciences (SAO RAS) and obtained their multicolor light curves with the RTT150 and Zeiss-1000 telescopes of the SAO RAS. We demonstrate that both Abell 65 and HS 1857+5144 are young precataclysmic variables (PV) with orbital periods of P _orb = 1. ^d 003729 and P _orb = 0. ^d 26633331, respectively. The observed brightness and spectral variations during the orbital period are due to the radiation of the cold component, which absorbs the short-wave radiation of the hot component and reemits it in the visual part of the spectrum. A joint analysis of the brightness and radial velocity curves allowed us to find the possible and optimum sets of their fundamental parameters. We found the luminosity excesses of the secondary components of HS 1857+5144 and Abell 65 with respect to the corresponding Main Sequence stars to be typical for such objects. The excess luminosities of the secondary components of all young PVs are indicative of their faster relaxation rate towards the quiescent state compared to the rates estimated in earlier studies.  相似文献   

A mathematical model of water and sediment flow in open river channels     

M. V. Shmakova  A. N. Kondrat’ev 《Russian Meteorology and Hydrology》2008,33(6):394-399

A one-dimensional mathematical model of water and sediment flow in open channels is proposed based on the forces influencing a water stream and bottom and stream sediments. The equations of water and sediment flow are closed by the equations of continuity of stream, velocity of particle motion in a stream, and the equation of balance of kinetic energy and moving particles: joint calculation of stream hydraulic characteristics and sediment discharge is performed. Hydraulic resistances are retrieved not from the Chezi formula, but based on the balance of forces and kinetic energy. A sediment discharge is calculated from velocities and the number of moving solid particles instead of empirical relationships whose accuracy is usually low. The model is verified against the data of experiments in hydraulic flumes with glass and sand bottom. Comparison with independent data in the glass flume in a wide range of water discharges and bottom inclinations showed a high accuracy of calculation of hydraulic characteristics (relative error is less than 4%). The experimental data showed that the accuracy of sediment discharge calculated by the model exceeds the accuracy of the calculation using traditional empirical formulas.  相似文献   

Long-term variability and methods of forecasting dates of ice break-up in the mouth area of the Ob and Yenisei rivers   总被引：1，自引：0，他引：1  

E. V. Shevnina  Z. S. Solov’eva 《Russian Meteorology and Hydrology》2008,33(7):458-465

Long-term characteristics of the onset dates of spring ice phases at hydrological stations in the mouth areas of the Ob and Yenisei rivers for 1936–2006 are obtained. The correlations are analyzed between these dates and the frequency of different synoptic processes over the Atlantic and Eurasia in the fall-winter months, the dates when the accumulated temperatures at meteorological stations in the middle parts of the river basins reach 5, 10, 20, 30, and 40°C, and the dates of the start of ice drift at the upstream sections of the Yenisei. Prognostic relations are suggested and test forecasts of the onset dates of ice phases are verified. The percentage of correct forecasts was 67–86%, which makes it possible to recommend the relations for using in prognostic practice. The forecast lead time ranges from 3 to 110 days.  相似文献   

A field version of the AMK-03 automated ultrasonic meteorological complex     

A. A. Azbukin  A. Ya. Bogushevich  V. A. Korol’kov  A. A. Tikhomirov  V. D. Shelevoi 《Russian Meteorology and Hydrology》2009,34(2):133-136

In this paper, a new field version of the automated ultrasonic meteorological complex AMK-03 is described. This complex is intended for measuring instant values of the main meteorological variables, such as air temperature, horizontal and vertical components of the wind speed and direction, relative humidity, and atmospheric pressure. These data are obtained and processed with 40 Hz sensors and then accumulated in a logger. In this complex, data acquisition via eight extra sensors (including soil and/or water temperature sensors) is foreseen. The data are recorded onto changeable flash cards (whose capacity is at least 256 Mb). To the logger data decoding and processing, special software is developed. The complex is supplied with batteries that provide its autonomic operation for at least 96 hours. Together with its transportation case, its weight does not exceed 19 kg. The AMK-03 complex has been registered in the State Register of the Measuring Instruments of Russia.  相似文献   

Distribution of extreme characteristics of atmospheric circulation from reanalysis data and hydrodynamic modeling     

A. V. Murav’ev  I. A. Kulikova  E. N. Kruglova 《Russian Meteorology and Hydrology》2009,34(7):431-441

On the basis of reanalysis data and hydrodynamic modeling the spatial-temporal features of Wallace-Gutzler circulation indices, calculated at daily intervals, are studied. The circulation index extremes are interpreted as “weather regimes” with the alteration closely related to the low frequency variability of the atmospere. The outliers and extreme values are studied using nonparametric statistics and exploratory techniques. On the basis of the experiments performed assessments of the potential predictability of the outlier and extreme value characteristics for the summer and winter seasons are given.  相似文献   

Reconstructed droughts for the southeastern Tibetan Plateau over the past 568 years and its linkages to the Pacific and Atlantic Ocean climate variability   总被引：6，自引：2，他引：4  

Keyan Fang  Xiaohua Gou  Fahu Chen  Jinbao Li  Rosanne D’Arrigo  Edward Cook  Tao Yang  Nicole Davi 《Climate Dynamics》2010,35(4):577-585

We present a Palmer Drought Severity Index reconstruction (r = 0.61, P < 0.01) from 1440 to 2007 for the southeastern Tibetan Plateau, based on tree rings of the forest fir (Abies forrestii). Persistent decadal dry intervals were found in the 1440s–1460s, 1560s–1580s, 1700s, 1770s, 1810s, 1860s and 1980s, and the extreme wet epochs were the 1480s–1490s, 1510s–1520s, 1590s, 1610s–1630s, 1720s–1730s, 1800s, 1830s, 1870s, 1930s, 1950s and after the 1990s. Comparisons of our record with those identified in other moisture related reconstructions for nearby regions showed that our reconstructed droughts were relatively consistent with those found in other regions of Indochina, suggesting similar drought regimes. Spectral peaks of 2.3–5.5 years may be indicative of ENSO activity, as also suggested by negative correlations with SSTs in the eastern equatorial and southeastern Pacific Ocean. Significant multidecadal spectral peaks of 29.2–40.9 and 56.8–60.2 years were identified. As indicated by the spatial correlation patterns, the decadal-scale variability may be linked to SST variations in the northern Pacific and Atlantic Oceans.  相似文献   

Model estimates of the fog parameters on the coasts of the Siberian reservoirs     

E. D. Nadezhina  V. I. Matsak  A. A. Semioshina  I. M. Shkol’nik 《Russian Meteorology and Hydrology》2010,35(12):791-798

Features are considered of using a two-dimensional model of the atmospheric boundary layer for estimation of coastal fog parameters for the Siberian reservoirs, based on reanalysis and on output data of a regional climate model. The model fog characteristics are compared with observations at the reservoirs of Surgut power plants. Examples are given of the fog characteristic calculation for the projected Evenki hydrosystem. It is shown that the data of regional climate model can be used if the changes are taken into account of background climate in the area of the projected reservoir.  相似文献   

Variation in the number of days with heavy precipitation on the territory of Russia for the period of 1936–2000     

E. G. Bogdanova  S. Yu. Gavrilova  B. M. Il’in 《Russian Meteorology and Hydrology》2010,35(5):344-348

Time variations in the number of days with heavy precipitation based on data of 93 stations on the territory of Russia are analyzed. Time series of precipitation, corrected by the elimination of main systematic errors of their measurement at the level of their diurnal sums, are used, when computing. The diurnal precipitation sum, exceeding the average long-term diurnal precipitation maximum by three times, was taken as the threshold quantitative criterion, defining “the day with heavy precipitation” concept. This value varies within 10–15 mm/day on the territory of Russia. Extremums fluctuate from 5 to 40 mm/day. Absolute values of linear trends of the annual number of days with heavy precipitation are comparatively small, they fluctuate within ±4 days on the whole territory of Russia. In relative terms, these variations are rather significant, reaching ±40% and more of the corresponding average value for 65 years. The comparison of the spatial distribution of characteristics of linear trends of the annual number of days with heavy precipitation and annual precipitation sum indicates their close conformity.  相似文献   

Time changes of atmospheric precipitation in Russia from the corrected data during 1936–2000     

E. G. Bogdanova  S. Yu. Gavrilova  B. M. Il’in 《Russian Meteorology and Hydrology》2010,35(10):706-714

Homogeneous time series of atmospheric precipitation with corrected systematic errors of measurements at 100 stations in Russia for the period of 1936–2000 are obtained. Combined effects are considered of all kinds of systematic errors of standard network precipitation-measuring instruments (the raingauge with the Nifer shield and the Tret’yakov raingauge) on the measured precipitation totals. Comparative analysis is carried out of the measured and corrected long-term mean characteristics of precipitation amounts (annual totals, warm and cold season totals, and different types of precipitation). On the basis of the obtained archives of precipitation homogeneous time series, linear trends are estimated for the period under consideration with estimation of their statistical significance. Schematic charts are plotted and analyzed of time changes in the annual precipitation amounts and in the amounts of different types of precipitation.  相似文献   

Analytical estimations of the efficiency of climate warming prevention by controlled aerosol emissions into the stratosphere     

A. V. Chernokul’skii  A. V. Eliseev  I. I. Mokhov 《Russian Meteorology and Hydrology》2010,35(5):301-309

Analytical solutions of globally averaged energy-balance model to estimate the efficiency of controlled forcing on the climate in the result of sulfate aerosol emissions into the stratosphere are obtained. According to obtained results, the sulfate aerosol emissions, needed to prevent the warming, make up from 2 to 12 Mt S/year in the end of the 21st century depending on the anthropogenic impact scenario and aerosol parameters. In the case of the cessation of such compensative emissions of sulfate aerosols, the global temperature increase rate may reach 3 K per decade, that is several times more than values, derived when taking account of greenhouse effect only.  相似文献