By using the cloud echoes fi rst successfully observed by China’s indigenous 94-GHz SKY cloud radar, the macrostructure and microphysical properties of drizzling stratocumulus clouds in Anhui Province on 8 June 2013 ...By using the cloud echoes fi rst successfully observed by China’s indigenous 94-GHz SKY cloud radar, the macrostructure and microphysical properties of drizzling stratocumulus clouds in Anhui Province on 8 June 2013 are analyzed, and the detection capability of this cloud radar is discussed. The results are as follows. （1） The cloud radar is able to observe the time-varying macroscopic and microphysical parameters of clouds, and it can reveal the microscopic structure and small-scale changes of clouds. （2） The velocity spectral width of cloud droplets is small, but the spectral width of the cloud containing both cloud droplets and drizzle is large. When the spectral width is more than 0.4 m s-1, the radar refl ectivity factor is larger （over-10 dBZ）. （3） The radar’s sensitivity is comparatively higher because the minimum radar refl ectivity factor is about-35 dBZ in this experiment, which exceeds the threshold for detecting the linear depolarized ratio （LDR） of stratocumulus （commonly -11 to -14 dBZ; decreases with increasing turbulence）. （4） After distinguishing of cloud droplets from drizzle, cloud liquid water content and particle eff ective radius are retrieved. The liquid water content of drizzle is lower than that of cloud droplets at the same radar refl ectivity factor.展开更多
高频地波雷达海洋回波谱的Bragg峰和二次谐波峰中,均蕴含着浪高信息,因此发展出了基于Bragg峰功率(Power of Bragg Peak,PB)、二次谐波峰与Bragg功率比(Power Ratio of Second Harmonic Peak to Bragg Peak,RSB)、双频Bragg峰功率比(Pow...高频地波雷达海洋回波谱的Bragg峰和二次谐波峰中,均蕴含着浪高信息,因此发展出了基于Bragg峰功率(Power of Bragg Peak,PB)、二次谐波峰与Bragg功率比(Power Ratio of Second Harmonic Peak to Bragg Peak,RSB)、双频Bragg峰功率比(Power Ratio of Dual Frequency Bragg Peak,RDB)等浪高反演算法。然而,三种算法均无法实现不同海况、不同距离下浪高的精确反演。本文研究发现,PB算法适用于低海况,RSB算法在近距离高海况下表现良好,而RDB算法适用于远距离测量,即三种算法高性能测量区间存在强互补性。在此基础上,本文提出了一种基于多特征(PB、RSB和RDB)融合的浪高反演算法,其中采用反向传播(Back Propagation,BP)神经网络作为特征融合器。实验表明:本文算法在测量精度、波高适应范围、距离适应范围上均优于现有波高反演算法。展开更多
基金Supported by China Meteorological Administration Special Public Welfare Research Fund(GYHY201206038,GYHY200906053,and GYHY201306040)National(Key)Basic Research and Development(973)Program of China(2013CB430102)+8 种基金National High Technology Research and Development Program(863)of China(2007AA061901)Natural Science Foundation of the Jiangsu Higher Education Institutions of China(10KJA170030)State Key Laboratory Program(2013LASW-B16)Nanjing Weather Radar Open Laboratory Research Fund(BJG201208)Key Technology Projects of China Meteorological Bureau(CMAGJ2014M21)Young Scientists Fund of the Natural Science Foundation of Jiangsu Province(BK2012466)Postgraduate Science and Technology Innovation Project of Jiangsu Province(CXZZ13-0513)Non-Profit Industry Fund by Ministry of Science and Technology of China and Ministry of Water Resources(201201063)Young Scientists Fund of the National Natural Science Foundation of China(41305031)
文摘By using the cloud echoes fi rst successfully observed by China’s indigenous 94-GHz SKY cloud radar, the macrostructure and microphysical properties of drizzling stratocumulus clouds in Anhui Province on 8 June 2013 are analyzed, and the detection capability of this cloud radar is discussed. The results are as follows. （1） The cloud radar is able to observe the time-varying macroscopic and microphysical parameters of clouds, and it can reveal the microscopic structure and small-scale changes of clouds. （2） The velocity spectral width of cloud droplets is small, but the spectral width of the cloud containing both cloud droplets and drizzle is large. When the spectral width is more than 0.4 m s-1, the radar refl ectivity factor is larger （over-10 dBZ）. （3） The radar’s sensitivity is comparatively higher because the minimum radar refl ectivity factor is about-35 dBZ in this experiment, which exceeds the threshold for detecting the linear depolarized ratio （LDR） of stratocumulus （commonly -11 to -14 dBZ; decreases with increasing turbulence）. （4） After distinguishing of cloud droplets from drizzle, cloud liquid water content and particle eff ective radius are retrieved. The liquid water content of drizzle is lower than that of cloud droplets at the same radar refl ectivity factor.
文摘高频地波雷达海洋回波谱的Bragg峰和二次谐波峰中,均蕴含着浪高信息,因此发展出了基于Bragg峰功率(Power of Bragg Peak,PB)、二次谐波峰与Bragg功率比(Power Ratio of Second Harmonic Peak to Bragg Peak,RSB)、双频Bragg峰功率比(Power Ratio of Dual Frequency Bragg Peak,RDB)等浪高反演算法。然而,三种算法均无法实现不同海况、不同距离下浪高的精确反演。本文研究发现,PB算法适用于低海况,RSB算法在近距离高海况下表现良好,而RDB算法适用于远距离测量,即三种算法高性能测量区间存在强互补性。在此基础上,本文提出了一种基于多特征(PB、RSB和RDB)融合的浪高反演算法,其中采用反向传播(Back Propagation,BP)神经网络作为特征融合器。实验表明:本文算法在测量精度、波高适应范围、距离适应范围上均优于现有波高反演算法。
