摘要
利用2013年8月北京C波段双偏振多普勒天气雷达体扫数据、探空资料和地面雨量站资料,获得反射率因子垂直廓线(vertical profile of reflectivity,VPR)识别零度层亮带,比较平均反射率因子垂直廓线(mean VPR,MVPR)、显著反射率因子垂直廓线(apparent VPR,AVPR)和显著相关系数垂直廓线(apparent vertical profile of correlation coefficient,AVPCC)3种零度层亮带订正方法的效果,并利用地面雨量站资料进行定量降水估计(quantity precipitation estimation,QPE)验证订正效果。结果表明:采用MVPR和0℃层高度能有效识别零度层亮带,零度层亮带厚度为0.8~1.5 km;经3种方法订正后,零度层亮带影响区得到了不同程度的抑制,其中MVPR法订正效果最差,基本未能减弱零度层亮带的影响,AVPR法和AVPCC法的订正效果较好,明显减弱了零度层亮带影响区的回波强度,订正后回波更均匀。利用地面雨量站数据进行QPE验证表明:经零度层亮带订正后雷达估测的降水与地面雨量站实测降水更接近,也表明AVPR法和AVPCC法效果更好。
The bright band is a layer of enhanced refleetivity due to melting of aggregated snow and ice crystals. The occurrence of a bright band causes significant overestimation in radar-based quantitative precipitation estimation （QPE）. The bright band signature can be normally identified from vertical profiles of reflectivi- ty （VPRs） of stratiform precipitation echoes and the freezing level height which is derived from radiosonde data. The VPRs correction is desirable to mitigate the bright band contamination and reduce the overesti- mation of the radar-based QPE. However, a well-defined bright band bottom, which is critical for the cor- rection of bright band, is sometimes not found in VPaRs. Fortunately, polarimetric variables, especially the correlation coefficient, can provide a much better depiction of vertical bright band structure than reflec- tivity. The volume scanning data of a C-band dual polarization radar from Beijing Meteorological Bureau, ra- diosonde data and measured rainfall data from ground rain gauge stations are used to test the methodology of the bright band identification and correction. Three bright band correction schemes including mean ver- tical profile of reflectivity （MVPR）, apparent vertical profile of reflectivity （AVPR） and apparent vertical profile of correlation coefficient （AVPCC）, which are derived from stratiform precipitation echoes, are ap- plied to the reflectivity field in the given tilt, and radar-based QPEs are derived from the corrected reflec- tivity field based on traditional Z-R relations. Results indicate that the bright band top, peak and bottom can be easily identified from the volume scanning MVPR and the freezing level height, and most of bright band depths are between 0.8 km and 1.5 kin. The AVPR and AVPCC schemes are shown to be more ef- fective in mitigating the bright band contamination and reducing the overestimation of radar-derived QPE associated with the bright band than the MVPR correction. Corrected reflectivity fields are physically co
出处
《应用气象学报》
CSCD
北大核心
2018年第1期84-96,共13页
Journal of Applied Meteorological Science
基金
公益性行业(气象)科研专项(GYHY201106046)
国家自然科学基金项目(41275039
41375039)
北京市自然科学基金项目(8141002)
国家重点研发计划(2017YFA0603504)
关键词
双偏振天气雷达
零度层亮带识别
零度层亮带订正
dual-polarization radar
identification of bright band
correction of bright band
