Long-term greenhouse gas measurements from aircraft

摘要: Abstract. In March 2009 the NOAA/ESRL/GMD Carbon Cycle and Greenhouse Gases Group collaborated with US Coast Guard (USCG) to establish Alaska (ACG) sampling site, a unique addition NOAA's atmospheric monitoring network. This collaboration takes advantage of USCG bi-weekly Arctic Domain Awareness (ADA) flights, conducted Hercules C-130 aircraft from November each year. Flights typically last 8 h cover large area, traveling Kodiak up Barrow, Alaska, altitude profiles near coast in interior. NOAA instrumentation on flight includes flask system, continuous cavity ring-down spectroscopy (CRDS) carbon dioxide (CO2)/methane (CH4)/carbon monoxide (CO)/water vapor (H2O) analyzer, ozone an ambient temperature humidity sensor. Air samples collected are analyzed at NOAA/ESRL for major greenhouse gases variety halocarbons hydrocarbons that influence climate, stratospheric ozone, air quality. We describe overall system making accurate gas measurements using CRDS analyzer minimal operator interaction present assessment performance over three-year period. Overall analytical uncertainty 2011 is estimated be 0.15 ppm, 1.4 ppb, 5 ppb CO2, CH4, CO, respectively, considering short-term precision, calibration uncertainties, water correction uncertainty. The stability seven-month deployment period better than 2 4 based differences on-board reference tank laboratory performed prior deployment. not affected by variation pressure or during flight. conclude reported our would significantly if were made without in-flight calibrations, provided ground calibrations testing regularly. Comparisons between situ consistent expected measurement uncertainties CH4 but larger CO2. Biases standard deviations comparisons suggest variability, flask-to-flask possible biases may driving observed versus CO2 rather measurements.