| Ka波段云雷达非云回波质量控制及效果评估 |
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| 引用本文： | 曾正茂,郑佳锋,杨晖,郑敏,曾颖婷.Ka波段云雷达非云回波质量控制及效果评估[J].应用气象学报,2021,32(3):347-357. |
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| 作者姓名： | 曾正茂 郑佳锋 杨晖 郑敏 曾颖婷 |
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| 作者单位： | 1.福建省气象信息中心, 福州 350001 |
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| 摘 要： | 针对Ka波段毫米波云雷达观测中出现的非云回波，提出改进的质量控制方法，并利用2018年9月—2020年8月福建平和观测资料，定量评估质量控制效果及其对云-降水探测的影响。结果表明:提出的改进方法能较好改善雷达探测结果，可有效滤除非云回波。非云回波对3 km高度以下的弱云探测有重要影响，且非云回波的探测率与雷达灵敏度密切相关，整体随高度上升而下降；同时非云回波存在明显的日变化特征，午后—前半夜因湍流活动较强，非云回波的探测率也较高；后半夜—日出前因湍流活动减弱，非云回波的探测率逐渐下降。
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| 关 键 词： | 毫米波云雷达 非云回波 质量控制 效果评估 |
| 收稿时间： | 2020-11-06 |
Quality Control and Evaluation on Non-cloud Echo of Ka-band Cloud Radar |
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| Affiliation: | 1.Fujian Meteorological Information Center, Fuzhou 3500012.Fujian Key Laboratory of Severe Weather, Fuzhou 3500013.Plateau Atmosphere and Environment Key Laboratory of Sichuan Province, School of Atmospheric Sciences, Chengdu University of Information Technology, Chengdu 6102254.Fujian Meteorological Service Center, Fuzhou 350001 |
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| Abstract: | Aiming at non-cloud echoes in Ka-band millimeter wave cloud radar observation, an improved data quality control method is proposed. Using the observation at Pinghe of Fujian from September 2018 to August 2020, the quality of the radar is quantitatively evaluated to study the actual impact of data quality control on cloud-precipitation detection. The non-cloud echoes show the characteristics of weak radar reflectivity factor (Z) and strong depolarization ratio (R) at Pinghe. But statistics show that there is difference from those of Qinghai-Tibet Plateau or Guangdong. Therefore, using the radar reflectivity factor (Z) less than -5 dBZ and linear depolarization ratio (R) greater than -22 dB as the judgment condition, and with the aid of filtering, non-cloud echoes can be effectively filtered. At the same time, a typical example is used to verify the effectiveness of the algorithm. Non-cloud echoes have a significant effect on the detection of cloud below 3 km, especially weak echoes. Non-cloud echoes account for 9.20% of all radar reflectivity factor samples, and 34.05% of all radar linear depolarization ratio samples. For the weak echo below -5 dBZ, the impact of non-cloud echoes is more significant, which accounts for 67.20% of all radar reflectivity factor sample. The detection rate of non-cloud echoes matter is closely related to the radar sensitivity, and the overall decrease with the height increaseing. The detection rate of non-cloud echoes decreases with the height increaseing. Meanwhile, non-cloud echoes have a certain relationship with the boundary layer, with an obvious diurnal change trend. From afternoon to midnight, due to strong turbulent activity, the detection rate of non-cloud echo matter is also higher, and the peak occurs at 1700 BT. From midnight to sunrise, due to the weakening of turbulent motion, the detection rate of non-cloud echo gradually decreases, and the lowest value occurs at 0400 BT. Non-cloud echoes have a significant effect on the vertical distribution of cloud precipitation. After quality control, the number of samples at the height of 0.12-2.5 km for radar reflectivity factor decrease by 17.68%, and the number of samples at the height of 0.12-4 km for radar linear depolarization ratio decrease by 14.29%. |
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