Marine Ecosystems Research Department - jamstec japan agency ...

JAMSTEC 2002 Annual Report
Frontier Research System for Global Change
GAME-Reanalysis and ECMWF data, are used to make
initial and boundary conditions. The data at UTC on
July were used for the initial condition and hours
integration was performed. The disturbance of the
GAME-Reanalysis run is too strong and moves too fast
to the northeastward, and after its movement there is no
intense convection. On the other hand, in the ECMWF
run, many convection systems develop around the front
and the persistent heavy rainfall area is properly reproduced.
We preformed several sensitivity experiments
which show that the surface condition does not play an
important role in this heavy rainfall event.
c-. GEWEX Cloud System Study (GCSS) Model
Inter-comparison
We proposed the snow cloud system associated
with the winter monsoon as a case suitable for international
model intercomparison.
3. Global Warming Research Program
The main goal of the Global Warming Research
Program is the projection and predictive understanding
of global warming. The program consists of three
research group projects, which conduct research on
global warming, carbon cycle and paleoclimate. The
th assessment report of the Intergovernmental Panel
on Climate Change (IPCC) is to be prepared in .
This program aims to contribute to the report on the
projection of future climate change. Here, selected
research accomplishments during the last fiscal year
are briefly described.
reduction of the global warming through negative
water vapor feedback using a cumulus chimney model
(left panel in Figure. ). This point was examined with
the use of two-dimensional radiative-convective models
without cumulus parameterization. The circulation
obtained is schematically illustrated in the right panel
of Fig. and is different from a chimney model. The
detrainment from the cumulus especially at low levels
effectively humidifies the surrounding atmosphere.
This is contrasted to the chimney type circulation
hypothesized by Lindzen.
Global warming impacts on tropical cyclone climatology,
was investigated using a high-resolution
atmospheric general circulation model. The frequency
of tropical cyclone formation decreases significantly
in response to CO increase through radiation processes
of the model, even without changing sea surface
temperature. During FY, further investigation of
the effect of CO increase was made by analyzing the
output of CO and CO experiments with the
model of JMA-GSM, T L. It is shown that,
in response to CO increase, vorticities tends to be
weaker in the tropics.
As one of the methods to validate radiative feedback
in atmospheric GCMs, this study estimated how the
radiative damping of the annually varying, global mean
surface temperature anomaly is altered by the net effect
a. Global Warming Research Group
The Cumulus Convection and Water Vapor
Feedback in Global Warming was investigated. Many
studies of global warming have commonly reported
positive water vapor feedback. However, this is not
self-evident, since water vapor content in the atmosphere
may be significantly affected by cumulus convection
which involves strong vertical motions. For
example, Lindzen () claimed a possibility of
Fig. 9 Schematic figures for circulations around cumulus
assumed in the cumulus chimney model (left), and those
obtained from this study (right). Orange and blue arrows
show those convectively forced and those responsible for
the net transport, respectively.
126