基于相对湿度阈值法的沈阳地区云垂直分布特征

Characteristics of Cloud Vertical Structure Based on Threshold Method of Relative Humidity in Shenyang

利用2006—2015年辽宁沈阳站的L波段探空数据,探讨了相对湿度阈值法对沈阳地区云识别的可靠性,并基于该方法对云的垂直结构进行定量分析。结果表明:相对湿度阈值法识别沈阳地区云的正确率可达75%以上,与地面观测有较好的一致性。60.7%的探空曲线识别到云的存在,云的出现频率夏季最高,为75.7%,秋季最低,为52.6%。有云条件下,沈阳地区以单层云为主,只有夏季多层云的出现频率较单层云高,多层云的出现频率随层数增加而减小。云层的垂直分布随云层数目及季节变化差异显著。云层及云夹层的厚度主要在2 km以下,且随云层数目的增加而减小。

Based on L-band sounding data and cloud ground observation data at Shenyang station from 2006 to 2015,the reliability of using threshold method of relative humidity to recognize cloud in Shenyang region was discussed,and then the vertical structure of cloud parameters including the location and thickness of cloud layers,cloud-top height,cloud-base height,etc,was quantitatively analyzed based on this method. The results show that the accuracy of cloud identification in Shenyang region based on the threshold method of relative humidity was above 75%,which was consistent well with the observation. About 60. 7% sounding profiles could identify the cloud in Shenyang,and the frequency of cloud occurrence was the highest in summer（75. 7%） and the lowest in autumn（52. 6%）. In general,the single-layer clouds were dominant under the cloudy condition,but the occurrence frequency of multi-layer clouds was higher than that of single-layer clouds in summer,and the frequency of multi-layer clouds decreased with the increase of cloud layer number. The differences of cloud vertical structure were significant with the change of seasons and number of cloud layers. Moreover,the thickness of clouds and their interlayer was below 2 km,which decreased with the increase of cloud layers number.