“凤凰”台风期间海面风、浪的高频地波雷达OSMAR071遥感

介绍了OSMAR071高频地波雷达系统“凤凰”台风期间海面风、浪遥测结果。文中给出高频地波雷达OSMAR071 风、浪反演算法：利用SBM模型结合多波束采样法反演风向;利用改进的Barrick模型进行有效波高的反演;利用SMB关系式进行风速反演。将雷达定点观测结果与浮标数据进行对比,表现出很好的一致性,其中有效波高相关系数为0.72,均方根误差为0.48 m,风向相关系数为0.97,均方根误差为27.7°,风速的相关系数为0.6,均方根误差为 3.5 m/s。文中还对影响探测精度的因素进行了分析。     

Resonance orbits of near-Earth asteroids

Asteroid 99942 Apophis is one of the most hazardous NEAs (near-Earth asteroids) today. Some specific features of its travel are the possibility of repeated Earth approaches, loss of forecast precision due to trajectory dispersions, and nondeterministic motion. These specific features do not only characterize Apophis. Special methods are needed to find possible collision trajectories among these travels. These trajectories are located in the vicinity of resonance collision orbits.The present paper discusses methods of detecting hazardous trajectories in the event of nondeterministic motion and characterizing these trajectories as applied to asteroid Apophis, precision losses in the event of trajectory dispersions, conditions of determinacy losses, and hazardous trajectories in the vicinity of resonance orbits.     

Forthcoming close angular approaches of planets to radio sources and possibilities to use them as GR tests

During close angular approaches of solar system planets to astrometric radio sources, the apparent positions of these sources shift due to relativistic effects and, thus, these events may be used for testing the theory of general relativity; this fact was successfully demonstrated in the experiments on the measurements of radio source position shifts during the approaches of Jupiter carried out in 1988 and 2002. An analysis, performed within the frames of the present work, showed that when a source is observed near a planet’s disk edge, i.e., practically in the case of occultation, the current experimental accuracy makes it possible to measure the relativistic effects for all planets. However, radio occultations are fairly rare events. At the same time, only Jupiter and Saturn provide noticeable relativistic effects approaching the radio sources at angular distances of about a few planet radii. Our analysis resulted in the creation of a catalog of forthcoming occultations and approaches of planets to astrometric radio sources for the time period of 2008–2050, which can be used for planning experiments on testing gravity theories and other purposes. For all events included in the catalog, the main relativistic effects are calculated both for ground-based and space (Earth-Moon) interferometer baselines.     

Analysis of the upper limit of the Southworth-Hawkins <Emphasis Type="Italic">D</Emphasis> criterion for the Pons-Winneckid and Perseid meteoroid streams

The value of the upper limit of the Southworth-Hawkins D criterion for the Pons-Winneckids (June Bootid) and Perseids meteor streams is analyzed on the basis of the comparison of the parent comet orbit with the model orbits of meteoroids ejected at different points of the comet orbit with the most likely ejection velocities. The change of the D values is investigated depending on the dynamic evolution of the streams by integrating forward the orbital elements of the model particles using the Cowell method taking into account the perturbations from all planets. It is shown that after ten rotations, for Pons-Winneckids the upper limit of the D criterion is higher than 0.5 and for Perseids the D criterion does not exceed 0.2.     

POLAR investigation of the Sun—POLARIS

The POLAR Investigation of the Sun (POLARIS) mission uses a combination of a gravity assist and solar sail propulsion to place a spacecraft in a 0.48 AU circular orbit around the Sun with an inclination of 75° with respect to solar equator. This challenging orbit is made possible by the challenging development of solar sail propulsion. This first extended view of the high-latitude regions of the Sun will enable crucial observations not possible from the ecliptic viewpoint or from Solar Orbiter. While Solar Orbiter would give the first glimpse of the high latitude magnetic field and flows to probe the solar dynamo, it does not have sufficient viewing of the polar regions to achieve POLARIS’s primary objective: determining the relation between the magnetism and dynamics of the Sun’s polar regions and the solar cycle.

GAUGE: the GrAnd Unification and Gravity Explorer

The GAUGE (GrAnd Unification and Gravity Explorer) mission proposes to use a drag-free spacecraft platform onto which a number of experiments are attached. They are designed to address a number of key issues at the interface between gravity and unification with the other forces of nature. The equivalence principle is to be probed with both a high-precision test using classical macroscopic test bodies, and, to lower precision, using microscopic test bodies via cold-atom interferometry. These two equivalence principle tests will explore string-dilaton theories and the effect of space–time fluctuations respectively. The macroscopic test bodies will also be used for intermediate-range inverse-square law and an axion-like spin-coupling search. The microscopic test bodies offer the prospect of extending the range of tests to also include short-range inverse-square law and spin-coupling measurements as well as looking for evidence of quantum decoherence due to space–time fluctuations at the Planck scale.     

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

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.     

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

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.     

Long-term variability and methods of forecasting dates of ice break-up in the mouth area of the Ob and Yenisei rivers

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.     

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

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.