Scattering of the Low Frequency Pulsar Radiation

We report the results of the measurements and analysis of the pulse broadening due to interstellar scattering on 43 pulsars at 102 MHz. This is the largest uniform sample of direct measurements of pulsar scatteringτ_sc, which make it feasible to analyze the dependence of this value on other pulsar parameters. The measured dependence of τ_scon dispersion measure τ_sc (DM)=40(DM/100)^2.1 is close to theoretically expected relation τ_sc (DM)∝ DM². A frequency dependence of the scattering pulse broadening is weaker than commonly accepted τ_sc ∝ ν^-4.4. This revised version was published online in July 2006 with corrections to the Cover Date.     

Giant pulses of pulsar radio emission

We present a brief review of observational manifestations of pulsars with giant pulses radio emission, based on the survey of the main properties of known pulsars with giant pulses, including our detection of 4 new pulsars with giant pulses.     

Detection of giant pulses from the pulsar PSR B0031-07

Giant pulses have been detected from the pulsar PSR B0031-07. A pulse with an intensity higher than that of the average pulse by a factor of 50 or more is encountered approximately once per 300 observed periods. The peak flux density of the strongest pulse was 530 Jy, which is a factor of 120 higher than the peak flux density of the average pulse. The giant pulses are a factor of 20 narrower than the integrated profile and are clustered about its center.     

The Temperature Regime of the Surface Layer of the Phobos Regolith in the Region of the Potential Fobos–Grunt Space Station Landing Site

Because of the absence of the atmosphere, the short duration of the Phobos day (7.7 hours), and the presence of a highly porous and fine-grained soil on the Phobos surface, all components of the future Russian Fobos–Grunt lander will operate under frequent and sharp temperature changes: from positive to extremely low negative temperatures. As a consequence, information about the temperature regime directly on the surface of the Martian satellite and in the near-surface layer appears to be extremely important. The proposed publication contains both the information about the thermophysical properties of the surface regolith of Phobos, derived from observations made with the Mariner 9 orbiter, the Viking orbiter, the Fobos-2 spacecraft, and the Mars Global Surveyor orbiter, and the results of the numerical modeling of the thermal regime of the surface regolith layer (on diurnal and seasonal time scales) in the area of the potential Fobos–Grunt landing site. We performed this modeling by taking into account the seasons on Mars and the effects due to the eclipse of Phobos by Mars.     

Microwave radiometry of Mars from the Mars 2 and 3 orbiters (preliminary results)

A 3.4-cm wavelength radiometer aboard the Mars 2 and 3 orbiters observed the brightness temperature due to planetary thermal emission in two orthogonal polarizations as a function of position on Mars. Preliminary results for two orbits of Mars 3 show a correlation between subsurface temperature and dielectric constant, interpreted as an effect of porosity.     

Basic principles of automatic calibration of multi-parameter models used in operational systems of flash flood forecasting

This paper initiates a series of three articles on automatic calibration of operational multi-parameter models used for flash flood forecasting in automated regime. The main point expressed in this series is that proper calibration of even a single model for a single basin is not a trivial problem, but in automated forecasting systems, when thousands or even millions of basins should be parametrized simultaneously, priorities change. Now the computational efficiency becomes the most critical; an implemented calibration procedure must be fast and efficient rather than giving “the best“ parameters yet computationally expensive. The first article of the series contains critical analysis of the “mainstream“ in hydrological models calibration and presents basic principles of the Stepwise Line Search algorithm and its modifications, practically feasible and robust parametrization approaches that would be suitable for automated systems used for flash flood forecasting.     

Post-processing and forecasts updating in automated systems of flash flood forecasting

This paper completes the series of three articles devoted to automated forecasting of flash floods [3, 5] and describes an effective approach of forecast updating through post-processing operations, which can be useful only in conjunction with such fast and efficient real-time re-calibration algorithms as SLS-based methods are. In particular, a proposed methodology is aimed to reduce negative consequences of scarce or low-quality data that can corrupt optimized parameters and, therefore, lower forecasting efficiency. A new modification of SLS-based optimization that supposes simultaneous re-calibration of the model and correction of the model input by generating of ensemble noises (SLS-E) is presented.     

A study of the bound water,water ice,and frost distribution over the Martian surface: Treatment and correcting of the data of observations with the OMEGA spectrometer onboard <Emphasis Type="Italic">Mars Express</Emphasis>

The results of the analysis of the spectral observations of Mars carried out with the OMEGA spectrometer onboard the Mars Express spacecraft are presented. The data from one of the spectrometer’s channels working in the near-IR spectral range (0.93–2.69 μm) were analyzed. This range includes the characteristic absorption bands of both condensed water phases (ice and frost) and bound water contained in hydrated minerals of the Martial soil. From the 1.93-μm band indicating the presence of these minerals, global maps of the bound-water index have been made. They show a noticeable latitude dependence of the index: the largest values refer to high latitudes (>60°), while they gradually diminish toward the equator. Seasonal variations of the spectral index obtained by the 1.93-μm band are connected with the hydration-dehydration processes occurring in hydrogenous minerals when the temperature of the soil and the relative humidity in the near-surface atmospheric layer are changing. The evolution of the spectral absorption bands of water ice (1.2 and 1.5 μm) dependent on the season testifies to the changes in the microstructure of the surface layer in the North ploar cap caused by the sublimate re-crystallization processes in the ice sheet. The spatial pattern of the location of the areas where the microstructure most quickly grows could be formed under the influence of the stationary atmospheric waves.