Aircraft observation of carbon dioxide at 8–13 km altitude over the western Pacific from 1993 to 1999 |
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| Authors: | HIDEKAZU MATSUEDA HISAYUKI YOSHIKAWA INOUE MASAO ISHII |
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| Institution: | Geochemical Research Department, Meteorological Research Institute, 1-1 Nagamine, Tsukuba-shi, Ibaraki-ken 305-0052, Japan |
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| Abstract: | Abstract The spatial and temporal variations of atmospheric CO2 at 8–13 km from April 1993 to April 1999 were observed by measuring CO2 mixing ratios in samples collected biweekly from a commercial airliner between Australia and Japan. The CO2 growth rate showed a considerable interannual variation, with a maximum of about 3 ppm yr?1 during late 1997. This variation is related to the El Niño/Southern Oscillation (ENSO) events. A year-to-year change related to the ENSO events was also found in the latitudinal distribution pattern of the CO2 annual mean between 30°N and 30°S. The averaged CO2 seasonal cycle in the Northern Hemisphere gradually decayed toward the equator, and a relatively complicated variation with a double seasonal maximum appeared in the Southern Hemisphere. A significant yearly change of the seasonal cycle pattern was observed in the Southern Hemisphere. The impact of a tropical biomass-burning injection on the upper tropospheric CO2 was estimated on the basis of the CO data from the same airliner observation. |
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