Development of calibration instrument for precise stratospheric and tropospheric ozone measurement

为了研究平流层下层臭氧减少和对流层上层臭氧增加的情况，需要显著提高测量精度。在类似于对流层上层/平流层下层的低压条件下，校准臭氧测量仪器是至关重要的。为此，我们研制了一种在低压条件下校准臭氧监测仪的仪器。首先，我们使用商用标准臭氧发生器作为臭氧源，并制作一个带反压控制器的聚四氟乙烯室，以降低臭氧发生器产生的臭氧压力。然而，虽然减压是成功的，但腔室压力的调整是困难和关键的。为此，我们对该系统进行了改进：1)对臭氧发生器的进排气口进行稳压，2)对臭氧发生器的流量进行监测，3)在臭氧发生器与特氟龙腔之间用毛细管代替针阀进行压降，等等。经过这些改进，所研制的标定系统工作稳定。通过与精密臭氧监测仪的比较，该臭氧校准系统对臭氧测量仪器的校准精度可达3%。但为了便于在观测现场使用，该系统应实现自动化操作。

To investigate the ozone decrease in the lower stratosphere and ozone increase in the upper troposphere, the precision of the measurement should be improved significantly. It is crucial to calibrate instruments for ozone measurement under the low-pressure condition similar to the upper troposphere/lower stratosphere. For this purpose, we have developed an instrument for calibration of ozone monitor under low-pressure condition. At first, we used a commercial standard ozone generator as the ozone source and made a Teflon chamber with backward pressure controller to reduce the pressure of ozone from the ozone generator. However, the adjustment of the pressure of the chamber was difficult and critical although the pressure reduction was successful. Thus we have improved this system : 1) pressure-stabilize the inlet and exhaust ports of the ozone generator, 2) flow monitor from ozone generator, 3) some capillaries (instead of needle valve) are used to make pressure drop between ozone generator and the Teflon chamber, and so on. After these improvements, the developed calibration system worked stably. By comparing a precise ozone monitor, this ozone calibration system can calibrate a ozone measurement instrument with an accuracy of 3%. However, for using this system easily in the observation field, the operation should be automated.