Evaluation of atmospheric CO2 measurements from new flask air sampling of JAL airliner observations

Abstract

A new flask sampling system (Automatic Air Sampling Equipment (ASE)) was used to conduct atmospheric CO2 measurements at about 10km altitude over the western Pacific between Australia and Japan using a Japan Airlines (JAL) airliner from December 2005 to April 2007. The observed CO2 from the ASE agreed well with that determined by the in-situ CO2 measuring system (Continuous CO2 Measuring Equipment (CME)) during the same flights. The data from the ASE and CME exhibited similar mean CO2 for 12 latitudinal bands at an interval of 5° between 30°N and 30°S, although the discrete ASE data are sparse compared to the frequent measurements by the CME. The CO2 standard scales of the Meteorological Research Institute and the National Institute for Environmental Studies were compared to provide a consistent data set for the first and second phases of the JAL project. The new ASE data clearly depicted a seasonal cycle and increasing trend, which were reproduced by the extrapolated variations deduced from the climatology of previous observations for the past 12 years. In particular, latitudinal changes of detrended seasonal cycles obtained from the new observation were quite similar to those derived from the climatology in the previous observation. These results indicated the consistency in the continuity of the CO2 record extended by the new JAL observations. © 2008 by the Japan Meteorological Agency/Meteorological Research Institute.