摘要
以2005年6月23日南京多普勒雷达探测的晴空回波演变为例,分析了回波反射率与径向速度从夜间至上午的演变规律,利用实际的气象观测资料,对比了折射指数、地面温度、露点温度、水汽压和气压与回波强度的相关性,进一步探讨了边界层晴空回波与湍流混合特性之间的关系。研究表明:夜间大气的温、压、湿梯度使湍流出现,但湍流未充分混合使梯度维持,并导致折射指数的梯度增加,出现晴空回波;白天升温后湍流的增强使近地层大气充分混合,温、压、湿梯度减弱导致折射指数梯度减小,回波减弱消失。
The diumal evolution of clear air echo （CAE） and its association with turbulent mixing in the boundary layer are investigated using the CAE data observed by Nanjing Doppler radar on 23 June, 2005 and the surface meteorological observations of the same time period. The temporal evolution of the reflectivity of CAE is analyzed against the evolution of refractive index ,N,surface temperature, T, dew point, td, vapor pressure, e, surface pressure ,p. The results show that at night turbulences occured when gradients of T,p, e were moderate,but they were not strong enough to completely mix airs of the surface layer. Along with the inerease in the fluctuation of refrative index △N, the CAE appeared. Temperature rising after sunrise gradually strengthened turbulances, which resulted in fully mixing of air and the reduction of T,p,e gradients and △N in the surface layer,then ,the weakening and vanish of CAE.
出处
《南京气象学院学报》
CSCD
北大核心
2007年第6期736-744,共9页
Journal of Nanjing Institute of Meteorology
基金
国家自然科学基金重点资助项目(40333027)
国家自然科学基金资助项目(60674074)
江苏省气象灾害重点实验室项目(KLME05011)
南京信息工程大学科研基金项目(QD62)
关键词
多普勒雷达
晴空回波
边界层
折射指数
湍流
Doppler radar
clear air echo
atmosphere boundary layer
refractive index
turbulence
