Development of Cloud Detection Methods Using CFH, GTS1, and RS80 Radiosondes

The accuracies of three instruments in measuring atmospheric column humidity were assessed during an upper troposphere and lower stratosphere observation campaign conducted from 7 to 13 August 2009 in Kunming, China. The three instruments are a cryogenic frost-point hygrometer （CFH）, a Vaisala RS80 radiosonde （RS80）, and a GTS1 radiosonde （GTS1）. The accuracy of relative humidity （RH） measurements made by the CFH, GTS1, and RS80 was similar between the surface and 500 hPa （～5.5 km above sea level）. However, above 500 hPa, the errors in RH measurements made by the RS80, relative to measurements made by the CFH, are much less than those detected with the GTS1. Three different retrieval methods for determining cloud boundaries from CFH, RS80, and GTS1 measurements were developed and take into account the differences in accuracy among the three instruments. The method for the CFH is based on RH thresholds at all levels, which demands high accuracy. Given that the accuracy of RH measurements decreases at higher altitudes, the cloud detection methods for RS80 and GTS1 are different for different altitude ranges. Below 5 km, the methods for the RS80 and the GTS1 are similar to that of the CFH; above 5 km, the methods for the RS80 and the GTS1 are both developed based on the second-order derivatives of temperature and RH with respect to height, but with different criteria applied. Comparisons of cloud-layer retrievals derived from the three measurements are also made.

两种探空仪观测湿度垂直分布及其应用比较

对2010年8月在云南腾冲利用芬兰Vaisala RS80和低温霜点仪(Cryogenic Frostpomt Hygrometer,CFH)两种探空仪测量大气湿度的垂直分布进行对比分析,同时比较它们白天和夜间测量误差的差别,并对国产GTS1,RS80和CFH共3种探空仪测量水汽总量与地基GPS遥测结果进行比较。结果表明:RS80湿度测值在整个对流层比CFH测值偏干(23.7±18.5)%;因太阳辐射白天RS80偏干较夜间更明显,比夜间偏干(13.5±14.8)%。而在对流层上层向平流层过渡区域内RS80湿度数据基本无效。CFH在低温、低湿环境下对湿度能有效测量,但在湿度较高的对流层低层测值偏高,导致比较中CFH水汽总量平均比G.PS遥测的水汽总量偏高(4.3±2.0)mm(样本数为11),而RS80,GTS1与GPS的水汽总量差别分别是(0.2±1.4)mm(样本数为12),(-0.2±2.2)mm(样本数为43)。地基GPS遥测的水汽总量对对流层上层至平流层的水汽变化不敏感。由于RS80测量相对湿度在高空偏低,通过RS80相对湿度测值来确定中、高云结果是偏低的,特别是对6000 m以上的高云判别上,RS80相对湿度的探测几乎很难甄别到云的存在。

彩超诊断仪典型故障芯片级维修二例

彩超诊断仪是医院中应用较多的辅助诊断设备,大多从国外进口,维修与保养费用较高,因此,维修人员应主动了解设备的工作原理及内部结构,并且通过与厂家工程师沟通或学习相关维修手册的方式来提高维修技能,深入分析故障发生原因,积极累积维修经验,以便及时发现并维修故障,从而提高设备利用率,为医院节约维修时间及成本[1-3]。本研究介绍了我院两个品牌彩超诊断仪的典型故障芯片级维修二例,并提供了故障分析及排除方法,以供参考。