High-resolution AGCM Modeling and Application for

High-resolution AGCM Modeling and
Application for AMIP-type Future Projection
Tomoaki Ose1), Ryo Mizuta1), Hiroyuki Murakami2), Shoji Kusunoki1) , Akio Kitoh3) and Izuru Takayabu1)
1) Meteorological Research Institute (MRI in Tsukuba, Japan)
2) Geophysical Fluid Dynamics Laboratory (GFDL in Princeton, USA)
3) University of Tsukuba (in Tsukuba, Japan)
Key words: high resolution, downscaling, climate projection, ensemble, tropical cyclone. Presentation is given by Tomoaki OSE: e-mail address is [email protected],
SUMMARY:
SUMMARY : AMIP-type future projection by high-resolution (20-60km) AGCMs has significant merits: (1) good
present-day climatology critical for regional climate change studies, (2) realistic extremes including fine topography
effects and realistic tropical cyclones, and (3) designed future SST ensemble projections and their understanding.
1. High-resolution AMIP-type Future Projection
A new project (SOUSEI-C) is started,
where the 20km-resolution MRI-AGCM3.2
is being integrated for a four-member
ensemble of RCP8.5-scenario future
projections using one CMIP5 ensemble
mean and three statistically classified SST
changes as well as the present-day
simulation.
High-resolution (20km
and 60km) AGCMs have
been
developed
at
MRI/JMA (e.g., Mizuta et
al., 2012) and applied to
future SST-given AMIPtype climate projections for
extreme weathers such as
tropical
cyclones
and
heavy precipitation, and
also to regional projections
for extreme precipitation
using
2
to
5
km
downscaling
in
the
research projects (Kitoh et
al., 2009).
The 20km AGCM outputs for further
downscaling in any regions will be
available as well as the outputs for
analysis.
Clustered future SSTs based on
CMIP5 experiments are featured as
follows; Cluster 2 (HadGEM2-type)
indicates ENSO-like and relatively warm
Northern Hemisphere (NH) SST change.
Cluster 1 (NCAR-type) is relatively La
Nina-like and warm Southern Hemisphere
SST change. Cluster 3 (GFDL-type)
shows warmer NH SST change than
Clusters 1 and 2.
(http://www.jamstec.go.jp/kakushin21/eng/brochure.html).
The state of the art AGCMs such
as
high-resolution
numerical
weather prediction models or even
non-hydrostatic global models can
be applied to the AMIP-type
projections. When common future
SSTs are used, the results can be
compared about future changes in
extreme events, tropical cyclones
and regional climatology.
2. Merits (1)(2)
4. Clustered CMIP5 SST Ensemble Projection Plan
Downscaling and Extremes
Use of high resolution AGCMs provides significant merits; (1) simulated presentday climatology is much better than those of coupled models because of real sea
surface temperatures specified in AGCMs. This is critical for studying regional
climate change (Kusunoki and Mizuta, 2008) and downscaling (Kanada et al.
2010), (2) high resolution models are able to represent the effect of fine
topography and realistic tropical cyclones (Murakami et al. 2008).
Clustered CMIP5 experiments share
common characteristics about future
projections among the group models in
terms of the changes in surface air
temperature,
precipitation
and
atmospheric circulation, associated with
summer and winter monsoons not only
over the tropical oceans but also over the
tropical lands and the extra-tropics
(Mizuta et al., 2014, submitted).
3. Merits (3)
Multi- Cumulus and SST Ensemble
(3) variously controlled future projections are possible in AGCMs. Actually, a
CMIP3-ensemble-mean SST change could be considered as the ‘most reliable’
future projection. Besides, uncertainty of projections was estimated by comparing
the impact of different SST future changes and cumulus schemes in the ensemble
projections (Endo et al. 2012).
(Right) The average precipitation is simulated well over Japan, but the number of
Wetday is overestimated and the strength of precipitation is underestimated by
20km AGCM. The 2~5km downscaling improves them.
(Left) Projection for future precipitation is consistent with the observed trend.
The simulated heavy precipitation is
strongly dependent on cumulus
schemes.
Uncertainty due to future SST change is
relatively large over the Pacific, but small
over the lands and the Indian Ocean.
References
The 20km JMA model is able to predict
more realistic development of tropical
cyclones than the 60km model.
The 20km model allows to estimate
regional future change in tropical
cyclones as well as their global change.
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This work was supported by the SOUSEI Program of the Japanese Ministry of Education, Culture, Sports, Science, and Technology.

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