Meteor-F detector of space dust

The instrument for the registration of the physicodynamical parameters of meteor particles applied in the spacecraft of the Phobos-Grunt project and the methods of its calibration are described in the paper.     

A system of proper environmental geology categories

This article discusses the rationale for the structure of the conceptual and terminological framework and categories of ecological geology, which has important methodological significance for its development. The authors consider their own ecological and geological categories and justify the logical structure of the concept and terminology base of modern ecological geology as a single integrated system.     

Retrospective short-term forecast of the 1996 Andreanov (Aleutian Islands) tsunami

A brief review of the problem of short-term (operative) tsunami forecasting is presented. A method of short-term tsunami forecasting based on the sea level data at remote points is described. The forecast is based only on the seismological information about the coordinates of the earthquake’s epicenter. The application of this method for a retrospective forecast of the 1996 Andreanov tsunami demonstrates a satisfactory coincidence with the predicted and observed tsunami waveforms. The results are compared with the modeling prediction of the same event by other authors. The suggested method of the operative tsunami forecast can serve a basis for the development of a unique programming complex for operative forecasting and can be realized within regional and local tsunami warning services. The method can be used in tsunami warning systems at the stage of their development.     

Satellite observations and numerical simulation results for the comprehensive analysis of ash cloud transport during the explosive eruptions of Kamchatka volcanoes

Ash clouds resulting from explosive volcanic eruptions pose a real threat to human life (for aircraft flights, airport operations, etc.); therefore, the detection, monitoring, and forecast of their movement is an urgent and important issue. The features and examples of application of the new tool developed on the basis of "Monitoring of Active Volcanoes of Kamchatka and the Kurile Islands" information system (VolSatView) are described. It allows the integrated monitoring and forecasting of ash cloud transport using the data of remote sensing and mathematical modeling as well as the assessment of the parameters of explosive events.     

Analysis of the Variability of the Optical Properties of Water in the Black Sea in Summer 1998 According to the Data of a SeaWiFS Satellite Instrument

We study examples of surveys of the Black Sea performed with the help of a SeaWiFS satellite instrument. It is shown that the results of measurements carried out in spectral channels of 510 and 555nm give information on the basic specific features of the space and time variability of the characteristics of absorption and scattering of light in seawater. The use of a spectral channel of 412nm is inefficient due to the low reliability of the results of the procedure of atmospheric correction performed according to standard algorithms. The results of model calculations demonstrate that the predominant contribution to the absorption of light in the Black Sea in summer is made by the yellow substance.     

Improved interpretation of the data of observations of the black sea by a SeaWiFS satellite instrument in autumn 1998

By analyzing, as an example, the data of observations of the Black Sea from the space in autumn 1998, we conclude that, in some cases, the atmospheric distortions manifest themselves in all measuring channels of SeaWiFS instruments and lead to significant errors in determining the concentration of chlorophyll according to the standard NASA algorithm. After additional rejection of the data with negative values of the spectral brightness of the sea surface at a wavelength of 412 nm, the results of evaluation the concentration of chlorophyll are in good agreement with the available data of direct measurements. We also present a detailed discussion of some specific features of operation of the NASA algorithm of atmospheric correction playing an important role in the interpretation of the data of observations of the Black Sea. __________ Translated from Morskoi Gidrofizicheskii Zhurnal, No. 2, pp. 68–79, March–April, 2008.     

Observations of a complex solar radio burst with fine structure on 3 May 1973

The simultaneous high resolution recordings of dynamic spectra in the range 93–220 MHz and polarization at 204 MHz of a complex type II–IV event which started at 08:33 UT on 3 May 1973 shown a sporadic zebra pattern. In contrast with the unpolarized type II burst, the stripes in the emission and absorption of the zebra pattern were fully polarized and most likely corresponded to the ordinary wave. As to spectral and polarization characteristics, the fiber bursts with intermediate frequency drift did not differ from the stripes of the zebra pattern. The microstructure of the type II burst was characterised by a lot of spikes with variable frequency drift, duration 0.1 s and instantaneous bandwidth ≈1 MHz.     

Radio astronomy ultra-low-noise amplifier for operation at 91 cm wavelength in high RFI environment

An ultra-low-noise input amplifier intended for a use in a radio telescope operating at 91 cm wavelength is presented. The amplifier noise temperatures are 12.8?±?1.5 and 10.0?±?1.5?K at ambient temperatures of 293 and 263?K respectively. The amplifier does not require cryogenic cooling. It can be quickly put in operation thus shortening losses in the telescope observation time. High linearity of the amplifier (output power at 1 dB gain compression P_1dB?≥?22 dBm, output third order intercept point OIP3?≥?37 dBm) enables the telescope operation in highly urbanized and industrialized regions. To obtain low noise characteristics along with high linearity, high-electron-mobility field-effect transistors were used in parallel in the circuit developed. The transistors used in the amplifier are cost-effective and commercially available. The circuit solution is recommended for similar devices working in ultra-high frequency band.