Marine Ecosystems Research Department - jamstec japan agency ...

JAMSTEC 2002 Annual Report
Frontier Research System for Global Change
Ozone, a greenhouse gas as well as carbon dioxide
and methane, is the most important chemical species
for tropospheric photochemistry to control the lifetime
of other chemical species. The principal objective of
our study is to evaluate the influence of tropospheric
and stratospheric ozone on climate change by using a
photochemically coupled global circulation model.
Additionally, our model will be used as a sub-component
of the integrated model, and the interaction with
other sub-component such as vegetation and ocean
chemistry will be considered. In this year, a new
advection scheme was introduced into the model. After
-years' integration, it is found that the new advection
scheme improves the humidity in the upper troposphere.
Next, the model, which is fully coupled with
tropospheric photochemistry, is used for the simulation
to evaluate impacts of emission change and climate
change independently (Figure ). Global mean
methane concentration increased to about ppmv in
with emission change only, but to . ppmv with
climate change, reflecting the impact of temperature
and water vapor increases on the methane lifetime
(Figure (b)).
b-. Accurate Estimate of Feedbacks on the Global
Warming through Interactions in the Cloud –
aerosol – radiation System
The purpose of our sub-group is to develop the parameterization
for GCM to estimate the effect of tropospheric
aerosol on the optical properties of clouds i.e.
the indirect radiative forcing of aerosol.
First, we investigated the parameterization to estimate
the indirect radiative forcing of aerosol in
CCSR/NIES-GCM and ECHAM-GCM (Max Plank
Institute). Second, we developed the parameterization
to estimate the effect of cloud condensation nuclei
(CCN) on the microstructure of cloud (Kuba et al.,
, Kuba and Iwabuchi, ). Third, we examined
the treatment the output of SPRINTARS (aerosol
transportation model: Takemura et al., ) to make
this parameterization effective.
The scale gap between cloud microphysical model
and GCM is remarkable. To bridge this scale gap we
are planning to install the cloud microphysical model
in NICAM (New ICosahedral Atmospheric Model:
Satoh, , Tomita, ) and MRI/NPD-NHM
(Saito and Kato, ). We conducted many numerical
experiments using our cloud microphysical model with
particle method to develop the parameterization to estimate
the relationship between CCN and cloud
microstructure. Due to the scale gap between microphysical
model and GCM, there are many problems to
install this parameterization to GCM, such as how to
estimate the updraft velocity in the cloud from grid
mean updraft velocity, and how to estimate LWP of the
cloud from the grid mean LWP. Therefore, we are trying
to compare the simulated results between GCM
(grid scale is a few hundred km), NICAM ( km) coupled
with cloud microphysical model with base function
expansion method and NHM ( m) coupled with
cloud microphysical model with bin method.
Trp. O3 Burden [TgO3]
500
450
400
350
Tropospheric Ozone Burden: Global
A2: Exp2
A2: Exp1
4.0
Global CH4 concentration
A2: Exp2
A2: Exp1
1.1
a)
3.5
3.0
b)
1
0.9
0.8
c)
2.5
0.7
2.0
0.6
CH4 mixing ratio [ppmv]
Sulfate burden [TgS]
1.2
Sulfate burden
A2: Exp2
A2: Exp1
300
2000 2020 2040 2060 2080 2100
year
1.5
2000 2020 2040 2060 2080 2100
year
0.5
2000 2020 2040 2060 2080 2100
year
Fig.32 Time evolution of (a) tropospheric ozone inventory, (b) global mean methane, and (c) sulphate
aerosol inventory simulated by the model using the SRES-A2 scenario. Solid lines represent experiments
that consider the effects of climatic changes, and dashed lines represent those that do not.
152