Development of airborne instrument for CO measurement

利用真空紫外(VUV)共振荧光技术研制了一种快速响应、高精度测量对流层一氧化碳(CO)的机载仪器。激发辐射由直流放电CO谐振灯和滤光片相结合，获得150 nm附近的CO4正带发射。滤光片由真空紫外单色仪和晶体石英窗口(147 nm截止波长)组成。水晶石英窗口确保了对135.7 nm以下波长的清晰识别，这会产生水蒸气的积极干扰。实验室测试表明，在CO浓度为100ppbv、积分时间为1秒的条件下，该光学系统的测量精度为十亿分之一(Ppbv)，Flow系统的响应时间(1/e时间常数)约为2秒。飞机测量活动生物质燃烧和闪电实验B阶段于1999年8月至9月在澳大利亚上空进行。在这次战役中获得的飞行数据被用来证明该仪器的高精度和快速响应。在BASIC-B期间进行了VUV CO测量和气相色谱CO测量的相互比较。总体而言，这两个独立的测量结果在实验不确定度范围内显示出良好的一致性。

An airborne instrument for fast-response, high-precision measurement of tropospheric carbon monoxide (CO) was developed using a vacuum ultraviolet (VUV) resonance fluorescence technique. The excitation radiation is obtained by a DC discharge CO resonance lamp combined with an optical filter for the CO 4^<th> positive band emission around 150nm. The optical filter consists of a VUV monochromator and a crystalline quartz window (<147nm cutoff). The crystalline quartz window ensures sharp discrimination against wavelengths below 135.7nm, which yields a positive interference from water vapor. Laboratory tests showed that the optical system achieves a precision of 1.1 parts per billion by volume(ppbv) at a CO concentration of 100ppbv for a 1-seconds intergration period, and flow system provides a response time(1/e time constant) of about 2 seconds. The aircraft measurement campaign Biomass Burning and Lightning Experiment-phase B (BIBLE-B ) took place between August and September 1999 over Australia. The flight data obtained during this campaign are used to demonstrate the high precision and fast response of the instrument. An intercomarison of the VUV CO measurement and a gas chromatographic CO measurement was conducted during BIBLE-B. Overall, these two independent measurements showed good agreement, within the experimental uncertainties.