radar and radio thermal characteristics
A.K. Arakelyan, A.A. Arakelyan, A.K. Hambaryan, M.L. Grigoryan, V.V. Karyan, M.R. Manukyan, G.G. Hovhannisyan
Radiophysical methods and means of remote sensing, such as radars, Doppler-radars, radiometers and combined radar-radiometers have wide application for land and sea surface mapping, for remote retrieval of soil and sea surface, snow and vegetation, surface pollution and precipitation, clear air turbulence and clouds principal parameters. To achieve high accuracy and unambiguity in retrieval of sea salinity, sea water and near sea surface air temperatures, wind speed and direction, sea wave force, soil and snow moistures and temperatures, snow cover thickness and melting time, precipitation quantity (clouds water content), snowfall and rainfall parameters a synergy data of various independent and differing techniques and measurements carried out under test-control, quasi-field conditions is necessary.
In this paper the results of spatio-temporally collocated, multi-frequency, multi-polarization, microwave active-passive measurements of water surface radar and radio thermal characteristics changes due to clouds and rain are presented. The results have been obtained during the measurements carried out in quasi-field conditions from the measuring complex built in Armenia under the framework of ISTC Projects A-872 and A-1524. The measurements were carried out at various polarizations by C (~5,6GHz), Ku (~15GHz) and Ka-band (~37GHz) combined scatterometric-radiometric systems developed and built by ECOSERV ROC under the framework of the above Projects. Structural and operational features of the utilized systems and the whole measuring complex are considered too.
The represented results show that radar contrasts related to hand perturbed water surface and rain perturbed water surface are practically equal for all frequencies and polarizations. Cloud’s contribution in water surface (perturbed or smoothed) reflective characteristics is practicaly zero. Radiothermal contrasts due to hand perturbations of the water surface are higher than radiothermal contrasts due to rain perturbations of the water surface for all polarizations and frequencies. Cloud’s emission has a high contribution in water surface brightness temperature at all polarizations and frequencies. The value of this contribution increases with the frequency independentily of the polarization.