Long-term greenhouse gas measurements from aircraft
Long-term greenhouse gas measurements from aircraft
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DOI：
10.5194/amt-6-511-2013
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发表时间：
2013-01-01
影响因子：
3.8
通讯作者：
Tans, P.
中科院分区：
文献类型：
--
作者：
Karion, A.;Sweeney, C.;Tans, P.
2009年3月，NOAA/ESRL/GMD碳循环和温室气体小组与美国海岸警卫队（USCG）合作建立了阿拉斯加海岸警卫队（ACG）采样站，这是NOAA大气监测网络的一个独特补充。这项合作利用了USCG每两周一次的北极区域意识（ADA）飞行，每年3月至11月使用大力神C-130飞机进行。航班通常持续8小时，覆盖面积很大，从科迪亚克到阿拉斯加的巴罗，海拔高度分布在海岸附近和内陆。NOAA每次飞行的仪器包括一个烧瓶取样系统、一个连续光腔衰荡光谱（CRDS）二氧化碳（CO2）/甲烷（CH 4）/一氧化碳（CO）/水蒸气（H2O）分析仪、一个连续臭氧分析仪以及一个环境温度和湿度传感器。在飞行中收集的空气样品进行分析，在NOAA/ESRL的主要温室气体和各种卤代烃和碳氢化合物的影响气候，平流层臭氧和空气quality.We描述了整个系统，使准确的温室气体测量使用CRDS分析仪在飞机上，最小的操作员的相互作用，并提出了一个评估分析仪的性能超过三年的时间。考虑到短期精度、校准不确定性和水蒸气校正不确定性，2011年CRDS测量的总体分析不确定性估计为CO2、CH 4和CO分别为0.15 ppm、1.4 ppb和5 ppb。CRDS分析仪在7个月的部署期内的稳定性优于0.15 ppm，2 ppb，和4 ppb的CO2，CH 4和CO，分别基于从部署前进行的实验室校准的板载参考罐测量的差异。这种稳定性不受飞行过程中压力或温度变化的影响。我们的结论是，我们的测量报告的不确定性不会受到显着影响，如果测量没有在飞行中校准，提供地面校准和测试定期进行。原位CRDS测量和烧瓶测量之间的比较是一致的，预期的测量不确定性的CH 4和CO，但差异大于预期的CO2。与烧瓶样品比较的偏差和标准差表明，大气变化，烧瓶间的变化，以及可能的烧瓶采样偏差可能会驱动观察到的烧瓶与原位CO2的差异，而不是CRDS测量。
In March 2009 the NOAA/ESRL/GMD Carbon Cycle and Greenhouse Gases Group collaborated with the US Coast Guard (USCG) to establish the Alaska Coast Guard (ACG) sampling site, a unique addition to NOAA's atmospheric monitoring network. This collaboration takes advantage of USCG bi-weekly Arctic Domain Awareness (ADA) flights, conducted with Hercules C-130 aircraft from March to November each year. Flights typically last 8 h and cover a large area, traveling from Kodiak up to Barrow, Alaska, with altitude profiles near the coast and in the interior. NOAA instrumentation on each flight includes a flask sampling system, a continuous cavity ring-down spectroscopy (CRDS) carbon dioxide (CO2)/methane (CH4)/carbon monoxide (CO)/water vapor (H2O) analyzer, a continuous ozone analyzer, and an ambient temperature and humidity sensor. Air samples collected in flight are analyzed at NOAA/ESRL for the major greenhouse gases and a variety of halocarbons and hydrocarbons that influence climate, stratospheric ozone, and air quality.We describe the overall system for making accurate greenhouse gas measurements using a CRDS analyzer on an aircraft with minimal operator interaction and present an assessment of analyzer performance over a three-year period. Overall analytical uncertainty of CRDS measurements in 2011 is estimated to be 0.15 ppm, 1.4 ppb, and 5 ppb for CO2, CH4, and CO, respectively, considering short-term precision, calibration uncertainties, and water vapor correction uncertainty. The stability of the CRDS analyzer over a seven-month deployment period is better than 0.15 ppm, 2 ppb, and 4 ppb for CO2, CH4, and CO, respectively, based on differences of on-board reference tank measurements from a laboratory calibration performed prior to deployment. This stability is not affected by variation in pressure or temperature during flight. We conclude that the uncertainty reported for our measurements would not be significantly affected if the measurements were made without in-flight calibrations, provided ground calibrations and testing were performed regularly. Comparisons between in situ CRDS measurements and flask measurements are consistent with expected measurement uncertainties for CH4 and CO, but differences are larger than expected for CO2. Biases and standard deviations of comparisons with flask samples suggest that atmospheric variability, flask-to-flask variability, and possible flask sampling biases may be driving the observed flask versus in situ CO2 differences rather than the CRDS measurements.