The correlation signals of the incoherent, quasi-coherent and coherent backscatterings from clouds were analytically derived for pulse-pair operation through the unified formalism based on the Eulerian description, clarifying the characteristics of each scattering. In the course of the derivation, the coupling effect of spectral broadening between the Doppler fading and vertical wind shears was shown to be substantial for the spaceborne radar, indicating that the conventional estimation is subject to fail.
Based on this analysis, a variety of polarized pulse patterns were considered to determine the measured accuracy of Doppler velocity as a function of cloud reflectivity and the pulse-pair interval. The data earlier acquired on the experiments of the airborne cloud radar with Doppler function [Horie et al. 1999]* were adopted for this calculation. Taking a data-average over a flight distance of 1 km, we can expect the accuracy of 0.7 m/sec for clouds of 20 dBz, and that of 0.2 m/sec for clouds of 10 dBZ, while for the average over a distance of 10 km, we can expect the accuracy of 0.2 m/sec for clouds of 20 dBZ, and that of 0.06 m/sec for clouds of 10 dBZ. The advantages and disadvantages including the ground clutters and the effect of beam-pointing inaccuracy for each pulse-pattern will be discussed with the interpretation of measured Doppler velocity to design the optimal operation parameters.
* Horie, H., Iguchi, T., Hanado, H., Kuroiwa, H., Okamoto, H. and Kumagai, H. (2000), Development of a 95 GHz Airborne Cloud Profiling Radar (SPIDER) Technical Aspects-, IEICE Trans. Commun., Vol. E83-B, pp. 2010-2020
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