PLATEAU METEOROLOGY. X 6 min. 6 min Vol. 34 No. 4 August doi /j. issn X X / cosθcosφ P412.

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1 PLATEAU METEOROLOGY Vol. 34 No. 4 August X J doi /j. issn X / X X X X 6 μs 1 μs 1 6 μs μs X / cosθcosφ doi /j. issn P A min 28 X 6 min X a N AA liujun198802@ 126. com

2 Fig. 1 1 a 0 b 90 - Φ Working principle demonstration of a phased-array antenna. a Scanning angle is 0 b scanning angles are 90 - Φ d 1a N 1b θ θ = 2πdsin N λ 1b Ф Ф 1a 0 1b 90 - Ф Ф θ θ 2 X Fig. 2 Schematic diagram of the X - band airborne θ ~ weather radar system X 2

3 4 X A /D 31 FFT /PPP 32 CINRAD - SA S X m EEC X m m 4. 7 m PPI Table Parameters of the X - band airborne phased array weather radar XPAR and X - band on-wheel weather radar of 724 th Institute XRAD 724 / ± /kw < / db < /m / /μs /km

4 μs 1 μs 4 6 μs 1 μs 4a km a b 4b 2 4 3c d μs 1 μs Doviak et al a 4b - 15 ~ - 6 m s ~ 45 km μs 2 3a ~ d Table 2 Statistics result of radial reflectivity factor 6 μs 3a for XPAR and XRAD μs 3b 1 μs 3c /dbz μs 3d /dbz a ~ d

5 4 X Fig a b c d 724 dbz a 6 μs b c d 1 μs Comparisons of the reflectivity factor measured by X - band phased array antenna radar left and the smoothed 724 th Institute owned weather radar right at a b and c d on 1 July Unit dbz. a 6 μs pulse b c and d 1μs pulse 4 6 μs a 1 μs b 1 μs 724 Fig. 4 Radial velocity comparison for measured with 6 μs a and 1μs b pulse width of XPAR with 1μs pulse width of XRAD 2 6 μs dbz 1 μs 6 μs 1 μs dbz 1 μs 6 μs 6 μs 1 μs

6 < 1 dbz 7 dbz 1 μs km 6 μs km 5 km 1 μs 6 3 μs Knorr C = 10lg λ 2 / P t τθ - G t - G r L ε 1 λ P t G t G r τ 2 θ P L ε r L a L C τ 1 μs ε R G 6 μs 10lg6 db 0 λ 0 f 0 θ 7. 8 db 1 μs B0 φ B db 1 λ /λ μs 6 μs 0 1 / cosθcosφ 0. 9 dbz dbz db 1. 3 dbz θ φ Z = 1024ln2 L L ε ar 2 λ 2 P r P t G 0 θ B0 φ B0 cτπ 3 k 2 λ /λ dbz dbz 1 μs 6 μs < < 0. 5 db S ( ) λ λ cosθcosφ Table 3 3 Corrections for reflectivity factor of phased array antenna radar with angular shift to the normal direction of the panel db

7 4 X Fig μs a c e 1 μs 724 b d f a b c d e f Comparisons of reflectivity factor a b radial velocity c d and spectrum width e f measured with 6 μs pulse width by X - band phased array antenna radar a c e and 1 μs pulse width by the 724th Institute owned weather radar b d f at on 3 August /15 6b d ± 60 ± db 4 1 μs 6 μs 5b < 13 dbz ~ 22 dbz PAR 5e f ~ 5 m s - 1 5f a c X 1 6 μs 1 μs

8 Fig a b c d Distribution of measurements reflectivity factor a percentage of reflectivity factor capturing b radial velocity c and percentage of radial velocity capturing d by XPAR and XRAD at on 3 August μs dbz 1 μs lg 6 db 7. 8 db 0. 9 dbz 4 1 / cosθcosφ 2 X PRF 6 μs 1 μs 3 39

9 4 X S 1. J J doi /j. issn QIQC VAD J X J J J. J J. J doi /j. issn M. dition John Wiley & Sons Inc D. 10. D J RAD - SA J J M J USA McGraw - Hill Doviak R J Zrnic D S. Doppler Radar & Weather Observations J J. 15. J J J IEEE Transactions on J. J J J J doi /j. issn J J D J D. 8. X J Balanis C A. Antenna Theory Analysis and Design M. 3 rd e- 31. J CIN Skolnik M I. Introduction to Radar Systems M. New York M. San Diego California Academic Press M Knorr J B. Weather radar equation correction for frequency agile and phased array radars J. Aerospace and Electronic Systems

10 Comparative Analysis of X - Band Phased Array Antenna Weather Radar Measurements LIU Jun HUANG Xingyou HE Yuqin WANG Zhenhui WANG Jinhu Collaborative Innovation Center on Forecast and Evaluation of Meteorological Disasters Key Laboratory for Aerosol-Cloud-Precipitation of China Meteorological Administration Nanjing University of Information Science & Technology Nanjing China Abstract Compared with the mechanical antenna weather-radar phased array antenna w eather radar system has its special features of fast scanning and reliable data which play an essential role in monitoring and warning meso - scale severe w eather system. The parameters and characteristics of the X - band phased array antenna radar system XPAR as well as its activities in surface-based field campaigns are introduced. Measurements by XPAR and X - band mechanical antenna radar XRAD are compared including the measurement difference between 1 μs and 6 μs pulse widths of the XPAR itself. The analysis based on comparisons shows 1 The measurements from XPAR with pulse width of 1 μs and 6 μs pulse compression mode are close to the measurements from XRAD XPAR with pulse compression mode has even better data quality and good echo image particularly at distant region. 2 Due to the broad beam width the XPAR reflectivity factor is smooth the weak echo area decreases and strong echo area increases. 3 The non - uniform antenna gain of XPAR has influence on data quality but can be theoretically compensated by a gain factor of 1 / cosθcosφ for correcting radar reflectivity factor. Key words Phased array weather radar Pulse compression Comparative analysis Data quality

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