L波段与59-701探空系统相对湿度对比分析

Comparison of Relative Humidity Data Between L-band and 59-701 Sounding System

通过统计全国探空系统早期换型时获取的59个高空站L波段雷达-GTS1型电子探空仪系统相对于59-701探空系统在1000 hPa到200 hPa之间各规定等压面相对湿度的差值,分析探空系统换型对于相对湿度一致性的影响。结果表明:GTS1型探空仪测得的相对湿度明显比59型探空仪低,且差值随高度增加而增大,近地层二者相对湿度差值低于5%,200 hPa高度二者差值达到20%以上;冬季两套探空系统相对湿度的差值明显大于夏季,且差值随高度分布情况不尽相同。分析表明:相对湿度差值的变化除了与探空仪施放过程中外界温度变化相关,还与湿度变化趋势和变化幅度密切相关,湿度传感器存在湿滞回线和滞后现象。分析还发现,太原无线电一厂与上海长望气象科技有限公司制造的59型探空仪的性能差异不明显,且GTS1型探空仪与59型探空仪的两种湿度传感器在白天受太阳辐射的残余影响差异也不明显。

The importance of consistency of upper-air observation reports in serial of space and time is well recognized by users and upper-air observation operators.It is the most effective way that the systematic differences between observations of pre and post updating radiosondes can be obtained using the method of direct intercomparison.To achieve that,two datasets are used to analyze effects of pre and post radiosondes updating on the relative humidity（RH） observed by 59-701 sounding system and L-band sounding system.The sensor for humidity measurement changes from goldbeaters skin to a carbon hygristor.Onemonth RH data of these two different sounding systems are compared directly to analyze the consistency of pre and post updating.Average RH biases between 59-701 and L-band sounding system from 1000 hPa to 200 hPa specified isobaric surface are analyzed.Results reveal that without considering the radiosonde errors upon the place,the season of the year,the time of the day,the RH of L-band is obviously lower than that of 59-701 sounding system in China,and differences are increased with altitudes.The RH bias of two sounding systems is less than 5%near the surface,but the value reaches more than 20%at 200 hPa.It shows that the RH bias of two sounding systems in winter is greater than that in summer,but differences with height are not the same in detail.Whether winter or summer,several stations reflect the problem that differences of average RH bias are much larger than the overall average RH bias,which shows that the difference change of average RH bias is not only related with the ambient temperature change,but also related to the change of RH.This phenomenon reflect possible ＂wet hysteresis loop＂ effect of humidity sensors.The difference of humidity components performance is not obvious between the type 59 radiosondes from Taiyuan and Shanghai.The effect of solar radiation on humidity components of these two types of radiosondes is also not obvious.Integrating comparison results,it shows that the RH bias between 59-701 and L-band sounding systems isn＇t affected by the type 59 radiosonde manufacturers,and RH observations are all affected by the ambient temperature,lag and wet hysteresis.But the influence details in different situations should be study further,and these results can be used as reference of correction by related departments.