利用微波辐射计观测计算云衰减

A Method of Radiometric Measurements of Cloud Attenuation

  • 摘要: 在地-空路径传播过程中,云衰减对无线电卫星通信系统的高频率信号有着不可忽略的影响。利用HATPRO型微波辐射计观测反演获得的云中液态水密度廓线等信息,提出了一种适用于中纬度地区的精确计算云衰减的方法,得出了地-空路径信号传播过程中,云衰减对信号的影响随着频率增大急剧扩大的结论;具体表现为,在高频波段,99.99%的链路可用时间内云衰减超过10 dB。将微波辐射计计算所得的云衰减与云中液态水总量建立“线性关系”,与ITU-R(国际电联无线电通信部门)模型结果对比。结果表明:由于ITU-R模型低估了武汉地区的云中液态水总量,导致该模型低估了武汉地区的云衰减影响。

     

    Abstract: Cloud attenuation has a non-negligible impact on radio waves propagating over an earth-space path, especially in high frequency signals of the satellite communication system. A precise cloud attenuation method that has mid-latitude regions applicability is presented in this paper, using the HATPRO microwave radiometer's data particularly cloud liquid water density profiles. The result indicates that the effect of cloud attenuation enlarges rapidly as the frequency increases. More than 10 dB is caused due to cloud for 99.99% link availability at high bands. It is useful to relate the calculated cloud attenuation to integrated liquid water content,and the relationship is modeled by solid line. Predictions made with the method are compared with cloud attenuation data calculated by ITU-R (The ITU Radio communication sector) model, suggesting that the ITU-R model underestimates the effect of cloud attenuation in Wuhan area, resulting from the model's underestimation of integrated liquid water content.

     

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