Research of Rainfall Estimation using X-Band Polarimetric Radar

摘要

@@ 1. Introduction After sev eral d ecades o f research, p olarimetric w eather r adar is n ow g radually u sed into operational observation to improve the m easurement accuracy of rainfall as compared with the conventional Doppler weather radar. (Bringi and Chandrasekar 2001; Ryzhkov 2003). The three key p arameters o f p olarimetric w eather r adar a re h orizontal polarization (ZH), di fferential reflectivity ( ZDR) an d specific d ifferential p hase ( KDP). W ith at tenuation co rrection issues properly a ddressed, s ome a dvantages of X -band p olarimetric r adar h ave b een i ncreasingly evident over longer wavelength radar operating at C or S band. The sensitivity of KDP is the one of the most significant advantages. For the same rain rate, KDP at X -band w avelength is more than three times larger than that at S band, and about twice as large as that at C band. In addition, KDP can be immune to radar miscalibration, microwave attenuation, and partial beam blockage. It is also less co ntaminated by h ail and is less affected by drop size distribution (DSD) variations (Zmic and Ryzhkov 1996). Combination of KDP and ZH can improve the rain rate estimation to some extent, which is frequently used for selfconsistency of the calibration and retrieval process.