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| Titel |
High-frequency and long-range observations of atmospheric CO2 by CONTRAIL project |
| VerfasserIn |
Toshinobu Machida, Hidekazu Matsueda, Yousuke Sawa |
| Konferenz |
EGU General Assembly 2011
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| Medientyp |
Artikel
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| Sprache |
Englisch
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| Digitales Dokument |
PDF |
| Erschienen |
In: GRA - Volume 13 (2011) |
| Datensatznummer |
250051310
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| Zusammenfassung |
| Regular air sampling using Boeing 747 commercial airliner had been carried out since 1993 to observe CO2, CH4 and CO mixing ratios between Japan and Australia. The observation was improved to add the in-situ CO2 measurement onboard the aircraft. The advanced research project “Comprehensive Observation Network for TRace gases by AIrLiner (CONTRAIL)” has started in 2005 using newly developed Continuous CO2 Measuring Equipment (CME) and improved Automatic Air Sampling Equipment (ASE) onboard two Boeing 747-400 aircraft and three 777-200 aircraft operated by Japan Airlines (JAL). In October 2010, two 747-400 aircraft retired for operation. We are planning to modify additional two 777-200 aircraft to install CME in 2011-2012.
Long-term CO2 data from 1993 to 2009 obtained by ASE show clear seasonal variation and increasing trend in the upper troposphere over the western Pacific. During five-years CME observation, more than 9,000 vertical profiles over 43 sites as well as the horizontal distribution in the upper troposphere and lower stratosphere are obtained and the CO2 seasonal cycles were well defined over 25 sites. Seasonal amplitudes in CO2 mixing ratio are different both in altitude and latitude. CO2 amplitudes at 2 km are 10.5 ppm over north Europe, 7.6 ppm over Honolulu and 1.5 ppm over Australia. Seasonal variations over the sites in northern mid-high latitudes largely decayed with altitude, while CO2 amplitudes at upper troposphere over Australia are slightly larger than those in lower altitudes. Transport of northern air with high CO2 mixing ratio into southern upper troposphere from April to July contributes to enhance CO2 seasonality at higher altitudes over Australia.
Annual mean CO2 in the free troposphere shows latitudinal gradient from southern mid-latitude to tropics, but the gradient within northern hemisphere is rather small. Higher values are observed over Japanese airports, while rather low CO2 are found over Deli, India. CO2 difference between northern and southern hemisphere in the free troposphere is smaller than that observed near the surface.
By analyzing dense observation data in free troposphere, short-term (synoptic) variabilities in CO2 mixing ratio are found. Almost daily change of CO2 in the free troposphere was observed over Narita, Japan, because most of the aircraft onboard the CME return to Narita international airport. The short-term variability at 2km over Europe is 1.5ppm (1 standard deviation), which is more than 2 times larger than that observed over Honolulu, being 0.6ppm. This difference implies that the difference in heterogeneity of CO2 flux bring a substantial influence in CO2 variation in free troposphere. |
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