Marine Ecosystems Research Department - jamstec japan agency ...

JAMSTEC 2002 Annual Report
Frontier Research System for Global Change
strength of the North Atlantic Deep Water formation
reaches a realistic value, ranging from to Sv.
A new analysis of paleo-climate data was made,
using wavelet methods to determine the timings and
characteristics of the ice-age terminations. One novel
aspect was the use of an antisymmetric wavelet which
detects locations in the time series where there are large
changes. The results are consistent with previous ones
but it was, for the first time, possible to explore the features
of the individual terminations in an objective way.
It was found that, at the terminations, the interval
between atmospheric carbon dioxide changes and sealevel
is about ~kyr, compared with ~kyr obtained
using Fourier methods which estimate the phase over
the whole ~kyr signal. The sea level change is the
fastest but occurs after the other three components.
The stability of climate and the extent of partial ice
cover due to carbon cycle feedback was investigated. A
global carbon cycle which accounts for atmospheric carbon
dioxide concentrations and the terrestrial and oceanic
storage of carbon was introduced into a zonally averaged
energy balance model. It was found that inclusion
of a closed carbon cycle reduces the range of insolation
over which stable partial ice solutions may occur.
In order to understand the role of oceans in paleoclimate,
we have performed several sensitivity experiments
with the use of GFDL CGCM. In the control
run, they found a pronounced variability of a -year
period in the Southern Ocean (see Fig.). The
sensitivity experiments of quadrupled atmospheric
CO concentration without Greenland and Antarctic
ice sheets are carried out to investigate both the surface
climate and response of the thermohaline circulation
(THC). Sensitivity experiments to study the
effects of opening and closing the Gibraltar, Drake
Passage and the Panama Isthmus on the global climate
and THC are currently in progress. Results from a run
whereby the Mediterranean outflow is not simulated
(NMOW) shows general decreases in sea surface
salinity (SSS) and temperature (SST) in the North
Atlantic accompanied by a decrease in average THC
by . Sv below that of the control run.
4. Atmospheric Composition Research Program
The target of this program is the prediction of the air
quality change and climate change as well as the elucidation
of the link between them. Three categories of
atmospheric species studied in this program are long-
a
b
2.0
0.0
-2.0
SST
2.0
0.0
-2.0
8000 8100 8200 8300 8400 8500
1 3 5 7 9 11
Fig.10 (a) Distribution of mean (line-contoured) and standard deviation (colorshaded)
of sea surface temperature (unit in centigrade). The enclosed
area indicates the southern limb. (b) Time series of sea surface temperature
in the southern limb over the sample period from model year
8000 to 8500.
2 4 6 8 10
SST (x10)
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