| C-band Frequency Modulation Continuous Wave(C-FMCW) vertically pointing radar was developed with newly signal processing technology. C-FMCW radar use the two-dimensional FFT signal processing technology, which the single channel FFT echo power signal processing after the lowest for weak signal-170 dbm quantitative measurement, quantitative calibration is difficult. For a standard signal source analog echo point frequency, frequency signal to the broadening of the conversion, to measure the signal power attenuation, the minimum input power up to-169.77 dbm to get the calibration curve, and the calibration curve inflection point to confirm the radar noise power is about-168 dbm. Spectral density of reflectivity can computed from spectrum of quantitative calibration. The data observed from C-FMCW radar compared with SA scanning radar from June o f 2013 on Dingyuan, Anhui province. The comparison analysis use the data from the 48 km and 83 km CINRAD/SA Bengbu and Hefei radar of August 24 precipitation event. This event includes the two stages with convective cloud and stratiform cloud. Reflectivity vertical distribution in the stratiform cloud of C-FMCW radar and CINRAD/SA weather radar are basic agreement, show the calculation of is C-FMCW radar system reasonable. The average C-FMCW radar and SA radar in Bengbu root mean square difference is 1.75 d B, average and root mean square error of Hefei SA radar 2.02 dB. C-FMCW radar detective data in 2013 from June to August in DingYuan, Anhui to identify the bright bind of the precipitation cloud detection data in the 46 hours. The result is that 40% of the precipitation cloud has the clear bright bind structural feature and during the precipitation make up 15% of the surface precipitation amount. The Jianghuai rainy season stratiform cloud, convective cloud and the mixed precipitation system all appear the bright bind. In the stratiform cloud the bright bind has the longest appearing time and the most stable structure. The bright bind appears in the decay stage of the convective precipitation in the late. The continuous bight bind structure in the mixed precipitation system is broken by the strengthened convection distribution. The micro-physics process in the fusion layer is complicated. The change of the reflectivity near the fusion layer excludes the effect of the phase change and the particle number concentra tion change and can give the vapor increase and decrease process in the melting process. Use the maximum reflectivity Zp in the melting process to analyze the melting layer layering. The melting process in the upper layer mainly is adsorption growth. The lower layer is the particle breakup process. The melting process in the bright bind is relatively stable in the stable stratiform cloud. The aggregation increase is strongest in the mixed precipitation cloud. The melting increase is slower in the decay stage of the convective precipitation cloud.A preliminary analysis using the products and spectral density of reflectivity, it is show that C-FMCW radar has a good prospect in the identification for the Different particle phase thickness in precipitation cloud body, research the boundary layer of clear atmosphere. And also can help to recognize the strong variations vertical motion in the heavy rain clouds. Plateau observation experiments carried out in Naqu Tibet July and August of 2014. The paper gives three kinds of typical examples plateau precipitation cloud observations and reveals the structural features of the plateau precipitation Cloud. |
