2007 Annual Report - jamstec japan agency for marine-earth ...

and tropical forest was surveyed by satellite data, and its impact
on the carbon cycle was investigated. Long term snow cover
change, which influences vegetation phenology was also investigated.
The study of the global relationships of vegetation-air
temperature, vegetation-precipitation, and vegetation-PAR was
developed
AGCM. Main differences of this scheme from the past scheme
are 1improved treatment of mixing length and 2pressure
correlation terms, 3updated closure constants based on
LES results and 4higher level in the hierarchy of the
scheme. Main Improvements are seen in vertical distribution of
water vapor and cloud water in the lower troposphere
5Global Warming Research Program
The principal goal of the Global Warming Research
Program is projection and understanding of global warming.
Working towards this goal, three groups, Global Warming
Research Group, Coupled Model Development Group and
Paleoclimate Research Group, are involved in numerical experiments
for present day, future global warming and paleoclimate
using the Earth Simulator, and in climate model development.
As the IPCC AR4 process was over in FY2006, all groups
have slightly adjusted their research plan with AR5 in mind.
Members of the Global Warming Research Group are engaged
in critical analyses of model outputs presented to AR4 in order
to understand model performance better.
The Coupled Model Development Group is engaged in
studies to improve model physics in the CCSR/NIES/FRCGC
Fig.1. Large dry biases around 850hPa are almost eliminated
with this scheme. Low level clouds tend to be lifted up making
the result closer to observations.
A new cumulus parameterization is developed. Its main
characteristics are 1 lateral entrainment rate changes vertically
depending on buoyancy and vertical velocity of cloud air
parcel, 2 updraft ensemble is spectrally represented according
to updraft velocity at cloud base and 3 cloud base mass
flux is determined by the same method as the prognostic
Arakawa-Schubert scheme. The result shows great improvements
such as 1equatorial moist Kelvin waves and MJOlike
waves are represented without any empirical triggering
schemes, 2double Inter Tropical Convergence Zone
ITCZ disappearsFig.2in the eastern Pacific and 3
South Pacific Convergence Zone SPCZ is well represented.
Atmosphere Ocean Coupled General Circulation Model
henceforce, this model is called MIROC, and the atmospheric
part of it MIROC AGCM and to clarify characteristics of
model biases. This group is a core group of the coupled model
development at FRCGC, and members of the other groups of
GWRP as well as other programs at FRCGC have joined in the
activities.
The Paleoclimate Research Group is engaged in various
numerical experiments, on the onehand, to understand the
mechanisms of paleoclimate changes and on the other, to verify
b. Change in climate sensitivity by the improvement of atmospheric
boundary layer in MIROC
Since we plan to use MIROC, described above, for the
comprehensive global warming research, we have examined the
climate sensitivity the equilibrium change in global mean
surface temperature following a doubling of the atmospheric
CO 2 concentration which is a useful measure to identify and
characterize a GCM. We have found that the higher-order closure
scheme has a large influence on the climate sensitivity
MIROC, strengthening cooperation with other related research
groups.
Research Results
a. Improvement of boundary layer and cumulus parameterization
An improved version of Mellor-Yamada scheme based on
Nakanishi and Niino 2004 is implemented in MIROC
Fig.1 Zonally averaged annual mean specific humidity bias in the
experiment with old left and new right scheme.