Hajime Akimoto (Director of Atmospheric Composition Research Program),
Masaaki Takahashi (Group Leader, joint appointment of professor at
Center for Climate System Research, University of Tokyo), and Kengo
Sudo (Research Fellow) at Frontier Research System for Global Change
(FRSGC: joint project of JAMSTEC and JAXA), has found that ozone transport
from the stratosphere (Note 1) to the troposphere will be enhanced
by global warming as studied by chemical/climate model experiment
(Figure 1 and 2).
It is suggested that the enhanced intrusion of ozone to the troposphere
will further accelerates global warming.
This research outcome was published in Geophysical Research Letter
(Vol. 30, No. 24), by American Geophysical Union, and distributed
in Japan at the end of February.
Impact of climate change induced by global warming, on chemical species
formed in the atmosphere such as ozone, and its feedback of the chemistry
change to the climate is called chemistry-climate interaction, which
is becoming one of the major concerns in various sectors. Particularly,
tropsopheric ozone (Note 2) is recognized as the third most important
greenhouse gas in the IPCC Third Assessment Report, and its relevance
to global warming/climate change attracts much attention.
In order to study climate change accompanied by the increase of
greenhouse gasses, FRSGC has developed a chemical climate model,
"CHASER" (Note 3), jointly with Center for Climate System
Research, University of Tokyo (CCSR), and National Institute for
Environmental Studies (NIES), which can calculate chemical processes
in the troposphere and its impact on climate on a global scale.
So far, future change of distribution of air pollutants such as
ozone, and their climate effect have been predicted.
Using the A2 Scenario of IPCC (Reference
1), increase of tropopsheric ozone has been calculated, and
it was elucidated that there will be a big difference in vertical
distribution of ozone between the cases with and without considering
global warming. Result of experiment considering warming shows great
enhancement of ozone in the upper troposphere at mid and low latitude.
The reason was found to be due to the enhancement of atmospheric
circulation both in the stratosphere and troposphere, resulting
the increase of stratospheric intrusion of ozone to the troposphere
It is known that ozone in the upper troposphere has a strong greenhouse
effect and its increase has marked effect on the increase of earth
surface temperature (Reference
3). Therefore, the present result implies that global warming
enhances ozone in the upper troposphere, the ozone enhancement possibly
further accelerates warming.
Frontier Research System for Global Change
Contact: Ms. Ota
Tel: +81 (0)45-778-5687 (direct)
NASDA, Public Relations Office
Tel: +81 (0)3-3438-6107, -6108, or -6109
JAMSTEC, Public Relations Office, General Affairs Department
Tel: +81 (0)46-867-9066
||Stratospheric ozone: In the stratosphere oxygen atom (O) formed
in the photolysis of oxygen (O2) by
ultraviolet (UV) light in the sun radiation produces ozone (O3).
Ozone is in turn photolyzed to regenerate O an O2
by absorbing UV light, which is harmful to living thing on the
||Tropospheric (surface) ozone: In the troposphere ozone is
produced from oxygen atoms formed in the photolysis of nitrogen
dioxide (NO2) emitted from automobiles
and factories. Ozone is a major component of photochemical smog
and toxic air pollutants to living things. According to IPCC
Third Assessment Report, ozone is recognized as the third most
important greenhouse gases following to carbon dioxide and methane.
||CHASER (Chemical AGCM for Study of Atmospheric Environment
and Radiative Forcing) : Chemical-climate model in which photochemistry
is incorporated CCSR/NIES/ FRSGC atmospheric general circulation
model (AGCM). It can calculate emission, atmospheric transport,
chemical reaction wet removal etc. of precursor pollutants such
as nitrogen oxides (NOx), carbon monoxide (CO), sulfur dioxide
(SO2), and simulate formation and global
distribution of ozone, sulfate aerosol, etc.
||Hadley Circulation: Atmospheric circulation which rises near
equator and descend near 30 degree north and south.