| Utilization of Specific Attenuation for Rainfall Estimation in Southern China |
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| 作者姓名： | 张阿思 黄朝盈 陈 生 ZHANG Peng-fei 胡东明 肖柳斯 |
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| 摘 要： | This study uses rain gauge observations to assess the performance of different radar estimators R(ZH), R(KDP)and R(A) in estimating precipitation based on the observations of an S-band polarimetric radar over southern China during a typical convective storm and an extremely severe typhoon, i. e., Typhoon Manghkut. These radar estimators were derived from observations of a local autonomous particle size and velocity(Parsivel) unit(APU) disdrometer. A key parameter, alpha(α), which is the ratio of specific attenuation A to specific differential phase K_(DP) with three fixed values(α=0.015 dB deg~(-1), α=0.0185 dB deg~(-1) and α=0.03 dB deg~(-1)) was examined to test the sensitivity of the R(A) rain retrievals. The results show that:(1) All radar estimators can capture the spatio-temporal patterns of two precipitation events, R(A) with α =0.0185 dB deg~(-1) is well correlated with gauge measurement via higher Pearson's correlation coefficient(CC) of 0.87, lower relative bias(RB) of 16%, and lower root mean square error(RMSE) of 17.09 mm in the convective storm while it underestimates the typhoon event with RB of 35%;(2) R(A) with α=0.03 dB deg~(-1) shows the best statistical scores with the highest CC(0.92), lowest RB(7%) and RMSE(25.74 mm) corresponding to Typhoon Manghkut;(3) R(A) estimates are more efficient in mitigating the impact of partial beam blockage. The results indicate that α is remarkably influenced by the variation of drop size distribution. Thus, more work is needed to establish an automated and optimized α for the R(A) relation during different rainfall events over different regions.
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| 关 键 词： | QPE S-band dual polarization weather radar southern China |
| 收稿时间： | 2020-09-06 |
Utilization of Specific Attenuation for Rainfall Estimation in Southern China |
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| ZHANG A-si,UANG Chao-ying,CHEN Sheng,ZHANG Peng-fei,HU Dong-ming and XIAO Liu-si.Utilization of Specific Attenuation for Rainfall Estimation in Southern China[J].Journal of Tropical Meteorology,2021,27(1):48-61. |
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| Authors: | ZHANG A-si UANG Chao-ying CHEN Sheng ZHANG Peng-fei HU Dong-ming and XIAO Liu-si |
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| Institution: | 1. School of Atmospheric Sciences/ Key Laboratory of Tropical Atmosphere-Ocean System, Sun Yat-sen University, Zhuhai, Guangdong 519000 China; 2. Southern Laboratory of Ocean Science and Engineering, Zhuhai, Guangdong
519000 China; 3. Cooperative Institute for Mesoscale Meteorological Studies, University of Oklahoma, and NOAA/ OAR/National Severe Storms Laboratory, OKC 73072 USA; 4. Guangzhou Meteorological Observatory, Guangzhou 511430 China |
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| Abstract: | This study uses rain gauge observations to assess the performance of different radar estimators R(ZH), R(KDP)and R(A) in estimating precipitation based on the observations of an S-band polarimetric radar over southern China during a typical convective storm and an extremely severe typhoon, i. e., Typhoon Manghkut. These radar estimators were derived from observations of a local autonomous particle size and velocity(Parsivel) unit(APU) disdrometer. A key parameter, alpha(α), which is the ratio of specific attenuation A to specific differential phase K_(DP) with three fixed values(α=0.015 dB deg~(-1), α=0.0185 dB deg~(-1) and α=0.03 dB deg~(-1)) was examined to test the sensitivity of the R(A) rain retrievals. The results show that:(1) All radar estimators can capture the spatio-temporal patterns of two precipitation events, R(A) with α =0.0185 dB deg~(-1) is well correlated with gauge measurement via higher Pearson's correlation coefficient(CC) of 0.87, lower relative bias(RB) of 16%, and lower root mean square error(RMSE) of 17.09 mm in the convective storm while it underestimates the typhoon event with RB of 35%;(2) R(A) with α=0.03 dB deg~(-1) shows the best statistical scores with the highest CC(0.92), lowest RB(7%) and RMSE(25.74 mm) corresponding to Typhoon Manghkut;(3) R(A) estimates are more efficient in mitigating the impact of partial beam blockage. The results indicate that α is remarkably influenced by the variation of drop size distribution. Thus, more work is needed to establish an automated and optimized α for the R(A) relation during different rainfall events over different regions. |
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| Keywords: | QPE S-band dual polarization weather radar southern China |
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