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Topics in 2015




CONTRAIL Team was awarded at the Special Prize in the Grand Prize for the Global Environment Award

We were awarded at the Special Prize in the Grand Prize for the Global Environment Award sponsored by the Fujisankei Communications Group.

Yoshiharu Ueki, the president of JAL, (left) recieved the trophy at the ceremony,
in the presence of their Imperial Highnesses Prince and Princess Akishino.


A group photo of CONTRAIL Team taken at the ceremony. Yoshiharu Ueki, the president of JAL,
holds the award certificate and Akimasa Sumi, the president of NIES, holds the trophy.


Long-term change of CO2 latitudinal distribution in the UT

An edited version of this paper was published by AGU. Copyright (2015) American Geophysical Union.

We analyzed temporal variations in the annual mean latitudinal distribution of upper tropospheric CO2 using the aircraft measurements taken between Japan and Australia over the period 1993–2013, plus earlier data from 1984 and 1985. The observed CO2 latitudinal gradient between 30°N and 30°S showed large interannual variations that are clearly associated with El Niño–Southern Oscillation events. We also found long-term increasing trends of the CO2 gradients in the most northern latitudes that are proportionally associated with increasing fossil fuel emissions, while decreasing trends were found around the tropical regions. Extrapolation of the changes in the CO2 gradient back to zero fossil fuel emissions showed a negative north-south gradient with lower CO2 in the Northern Hemisphere than in the Southern Hemisphere, as well as a regional CO2 elevation in the tropical regions. These features provide a useful constraint on model estimates of CO2 fluxes from the ocean and the land biosphere.


(upper) Temporal variations of CO2 at about 10 km altitude for 12 latitudinal bands between 30°N and 30°S from April 1993 to December 2013. The red, blue, and green plots represent the data collected from the instrumentations of old ASE, new ASE, and CME, respectively.


(left) The latitudinal CO2 gradients (relative to 20°S–25°S band) extrapolated to zero fossil fuel (FF) emissions (blue line) and mean gradients observed during the periods 1984–1985 (black dashed line) and 1995–2011 (red line).

Reference



Seasonal changes of CO2, CH4, N2O, and SF6 in the UT/LS

An edited version of this paper was published by AGU. Copyright (2015) American Geophysical Union.

The seasonal variations of greenhouse gases at about 11 km altitude were analyzed from monthly air samples collected aboard a commercial airliner flying between Europe and Japan from April 2012 to March 2014. Compared to lower latitudes, the upper troposphere between 50 and 70°N showed higher CH4 and SF6 and an earlier seasonal phase of CO2. However, N2O values were similar to those in the subtropics. CH4, N2O, and SF6 in the lower stratosphere with potential temperature of up to 50 K above the tropopause showed seasonal variations with maxima in November/December and minima in April/May. At potential temperatures of 37.5–50 K above the tropopause, SF6 age was estimated to be about 22 months in May and 9 months in November. This strong seasonal variation is explained by the subsidence of high-stratospheric air in spring and the effective flushing of the lowermost stratospheric air with tropospheric air in autumn.

Monthly means and standard deviations for CH4 since April 2012. Blue color represents the mole fractions observed over the Eurasian continent in the 50–70°N latitudinal band. Red, orange, and green colors represent those observed over the western North Pacific in the 0-10°N, 10-20°N, and 20-30°N latitudinal bands, respectively.
Monthly means and standard deviations for SF6 between April 2012 and March 2014. The colors represent the mole fractions observed at every 12.5 K bin from the local tropopause along the flight route over the Eurasian continent.

Reference