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| Titel |
Interannual to decadal variability in a control experiment using MIROC4 - a high-resolution AOGCM for the near-term climate prediction |
| VerfasserIn |
Takashi T. Sakamoto, Yoshiki Komuro, Masayoshi Ishii, Hiroaki Tatebe, Akira Hasegawa, Hideo Shiogama, Takahiro Toyoda, Masato Mori, Masahide Kimoto |
| Konferenz |
EGU General Assembly 2010
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| Medientyp |
Artikel
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| Sprache |
Englisch
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| Digitales Dokument |
PDF |
| Erschienen |
In: GRA - Volume 12 (2010) |
| Datensatznummer |
250039352
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| Zusammenfassung |
| Preliminary results, especially mean climate and interannual to decadal variability,
in a general circulation climate model, Model for Interdisciplinary Research on
Climate (MIROC) version 4, are presented. The model is developed by the Center for
Climate System Research (CCSR), the University of Tokyo; National Institute for
Environmental Studies (NIES); and Japan Agency for Marine-Earth Science and Technology
(JAMSTEC). MIROC4 is an updated model from the previous version MIROC3_hires,
which was used to contribute to the IPCC AR4. Most of the model components are
the same as MIROC3_hires, but the atmospheric component is changed to T213
spectrum model from T106 one to inform adaptation policies for near-term climate
changes. The ocean component is the same as that used in MIROC3_hires, whose
horizontal resolution is 0.28125Ë zonally and 0.1875Ë meridionally, while the
latitudinal range where the Gent-McWilliams (GM) parameterization is applied
is changed in order to improve the climatological distribution of SST. The other
components, sea ice, land surface process, and river routing models, are also same as
the previous model. To obtain the radiative balance, parameters associated with
radiation, clouds, and aerosols are tuned. Using this model, spin-up and control
experiments (120 years) under the condition of year 1950 without flux adjustment were
conducted.
Globally averaged 2-m temperature (T2) and SST are not drifted, and biases in the SST
field, typically warm bias in the high-latitudes and cold bias in the low- and mid-latitudes, are
reduced in MIROC4, especially in the Northern Hemisphere. Associated with the reduction
of the warm SST bias in the high-latitudes, sea ice in the Northern Hemisphere becomes
thicker in MIROC4 than MIROC3_hires.
The Atlantic meridional overturning circulation (AMOC) is relatively weak in MIROC4,
and mean volume transport of the North Atlantic Deep Water (NADW) is 12–13 Sv (Sv -¡106
m3/s), which is 1–2 Sv weaker than that obtained by MIROC3_hires. However, the 120-year
integration is not enough to spin-up AMOC, and the NADW transport will be greater in the
end of the control experiment.
Simulated ENSO signal in MIROC4 is improved. The standard deviation of the Niño-3
index in MIROC3_hires was 0.33, but that in MIROC4 it is 0.57 (observation ~ 0.8). Not
only the Niño indices, but also distribution of ENSO related fields, e.g. PNA pattern, are
better simulated than MIROC3_hires.
The time series of PDO obtained as the EOF1 of low-pass filtered (7 years) SST over the
Pacific shows that a 20-year variation is dominant, and explains 37% of the total
variance in the MIROC4. Its spatial distribution becomes more realistic than that in
MIROC3_hires.
Currently, only the spin-up and control experiments are finished using MIROC4. We will
conduct near-term climate prediction experiments for the coming decades to contribute for
CMIP5/IPCC AR5. |
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