Publications

Aim of the report consists in describing basic methodology for future small satellite system designated for measuring with high accuracy and spatial resolution parameters of the atmosphere and ionosphere as a communication media. This system will use radio occultation method in different schemes: satellite-to-satellite, satellite-ground, satellite-air-plane (or helicopter) in the atmosphere with purposes of analyzing corresponding communication channels and influences on characteristics of the channels meteorological and ionospheric phenomena, effects of radio waves propagation including multibeam, refraction, diffraction and wave guide mechanisms. The basic methodology may be applied for developing small satellites that will use radio sygnals emitted by radio navigation, radio communication satellites for precise measuring effects of radio waves propagation at low elevation angles and for global monitoring radio communication channels passed through the atmosphere and ionosphere. The second task consists in revealing new information on wave phenomena in the atmosphere and ionosphere that are important for telecommunication conditions in the difficult accessible regions (communications with air-planes in polar and sea zones, communications through the ionosphere between two satellites using high frequency band), observing dangerous atmospheric processes and ecological changes. Nowadays near Earth's space is broadly used for telecommunication and radio navigation. The near Earth's space as radio communication media now may be studied by using signals of existing satellites designed for television, radio navigation and communication. This signals may be received by small satellite system for analysis of parameters of corresponding information channels. Also signals emitted from the Earth's surface may be received by small satellite system for investigation ground-satellite communication channel. The small satellite systems for this purposes are now under development. During 1990-1998 in Russia practical testing of radio occultation method for monitoring atmosphere and ionosphere channels between the orbital station 'MIR' and geo-stationary (GEO) satellite had been provided at wavelength of 2 and 32 cm. Experiments of radio occultation measurements of altitude distribution of the electron density in the ionosphere and the refraction in the neutral atmosphere had been carried out in USA during 1995-1999 using two frequency in decimeter range. High precision radio fields emitted by GPS navigational system and a small satellite known as Micro-Lab-1 were used for verification. It was established that radio occultation in decimeter wavelength range allows to determine the physical parameters of the media important for telecommunication: the temperature altitude profile in the atmosphere and electron density distribution in the ionosphere. As it followed from combining phase and amplitude GPS/MET data analysis, vertical resolution of 0.3 - 0.5 km may be achieved in the upper atmosphere region. Combined phase and amplitude analysis reveals wave-like structures with spatial periods from 1-2 km to 8-10 km in the vertical electron density distribution in the D-and E-layers. Variations in the gradient of the electron density from ±5×103 to ±8×103 electrons/(cm3km) at the altitudes of 72 - 95 km were observed. Also wave structures in the E-layer (height interval 102-110 km) with vertical period 0.5-2 km and amplitude 2-3×103 electrons×cm-3 were revealed. These wave-like structures are important for understanding the role of gravity waves and their contribution to the dynamics of the mesosphere. The structures in the electron density distribution may be connected with neutral wind velocity profile. Maximums in electron density distribution correspond to minimum neutral wind velocity values, thus determining vertical positions of wind shears in the upper atmosphere. The examples of application of the derived methodology to radio occultaion data analysis show it usefulness for future small satellite systems.

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Igarashi, K.; Armand, N. A.; Pavelyev, A. G.; Reigber, C.; Wickert, J.; Hocke, K.; Beyerle, G.; Matyugov, S. S.; Yakovlev, O. I. (2001): Application of small satellites for high precision measuring effects of radio waver propagation. 3rd IAA Symposium on Small Satellites for Earth Observation (Berlin 2001), 43-48.