对流层晴空湍流耗散率的风廓线雷达测量及特征

Variability of clear-air turbulent dissipation rate in troposphere measured by wind profiler

从Airda16000低平流层风廓线雷达的谱宽出发,扣除非湍流因素引起的谱宽加宽,得到湍流对谱宽的贡献,并计算出湍流耗散率。对对流层湍流耗散率的变化特征进行了分析,得出结论：对流层以下耗散率的量级在10-6~10-2m2.s-3之间,并且随高度增加而减小。在3 km以下,晴空湍流耗散率具有明显的日变化特征,中午逐渐增大,在夜间和清晨偏小,并且随着高度增加,日变化规律随时间向后延迟;3 km以上则不具有明显的日变化规律。耗散率的季节变化很突出,不同季节耗散率随高度递减的程度有差异,2008年夏季耗散率随高度的递减率为5.67%;冬季耗散率随高度递减率为14.7%;秋季分别为12.5%;而09年春季递减率为11.5%。耗散率的变化可以反映出雷达的探测高度,夏季雷达探测高度可达12 km;冬季雷达探测高度很低,仅为7 km;春秋两季探测高度为8~10 km。

Using the spectral width from the Airda16000 low stratospheric wind profiler radar,removing the non-turbulent contaminations,then obtaining the spectral width contributed by turbulence,the turbulent dissipation rate could be estimated.The height profiler,diurnal and seasonal variability of turbulent dissipation rate in the troposphere were studied.Results show that： First,the turbulent dissipation rate distributed between 10-6 m2·s-3 and 10-2 m2·s-3 on clear air days,and decreased with the increase of height.Second,it had remarkable diurnal variability below 3 km,which increased in the midday and decreased in the evening and morning,also,there was a delay of diurnal variability with time,the dissipation rate did not display the tendency of diurnal variability over 3 km.Third,the seasonal variability of dissipation rate was also obvious,the lapse rate with height was only 5.67% in the summer of 2008,while in the winter it was 14.7% and in the autumn it was 12.5%,respectively,but it was 11.5% in the spring of 2009.Fourth,the variability of dissipation rate could reflect the detective height,which could reach 12 km in the summer,while it was only 7 km in the winter,and in the autumn and spring the detective height was 8~10 km.