基于欧洲气象计量研究计划(MetroMet),继WMO RA VI实验室比对(ILC)后,世界气象组织RAⅡ,Ⅴ和Ⅵ的区域仪器中心(RIC)参加了温度、湿度和气压量值的实验室比对。比对采用圆环形传递路线,主导实验室依次完成测试后,参比实验室相继测试,然后主导实验室再次测试,直至闭环。比对协议指出参考值取主导实验室的两次量值的加权平均值;本文指出参考值取全部实验室的单次量值的加权平均值,然后利用各实验室报告的比对结果,分别采用不同算法确定2个参考值,用归一化偏差E值作为比对判据评价各实验室的测量结果。比较两个不同参考值的结果评价情况,验证参比实验室在比对评价不满意的测量点与每个主导实验室的数据兼容性,说明采用全部实验室的单次量值计算参考值的算法更合理。
Moisture measurement is of great needs in semiconductor industry, combustion diagnosis, meteorology, and atmospheric studies. We present an optical hygrometer based on cavity ring-down spectroscopy （CRDS）. By using different absorption lines of H20 in the 1.56 and 1.36 gm regions, we are able to determine the relative concentration （mole fraction） of water vapor from a few percent down to the 10-12 level. The quantitative accuracy is examined by comparing the CRDS hygrometer with a commercial chilled-mirror dew-point meter. The high sensitivity of the CRDS instrument allows a water detection limit of 8 pptv.
