Tracer transport simulation by an icosahedral grid model
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Tracer transport simulation by an icosahedral grid model
Center for Climate System Research, Univ. of Tokyo
Yosuke Niwa
R. Imasu, M. Satoh, S. Maksyutov,
T. Machida, H. Matsueda
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NICAM Nonhydrostatic ICosahedral Atmospheric Model NICAM was first developed by Satoh (CCSR/FRCGC) and
H. Tomita (FRCGC).(H. Tomita and M. Satoh, 2004, M. Satoh et al., 2007)
Developed as a global cloud resolving model (GCRM).The max resolution… dx~3.5km
NICAM is also used as a low-resolution Atmospheric Circulation Model (AGCM) and as a regional model (Stretch-NICAM).I used NICAM as a AGCM and modified it an on-line tracer transport model.
I added new tracers and developed nudging moduleresolution…dx~240km
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Realistic experiment by NICAM
OLR (by H. Miura) http://www.ccsr.u-tokyo.ac.jp/~satoh/nicam/index.html
dx~3.5km
A 3.5km-mesh global simulation was performed using the Earth Simulator. (H. Miura et al., 2007)
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Grids of NICAM
sT
sT
zz
zzzz
)(
*
recursively divided
Horizontal grid:
Vertical grid:
Terrain-following coordinate: *z
level sea aboveheight :
location) horizontalon (dependsheight surface :
domain model of top:
z
z
z
s
T
It looks like σ coordinate, but doesn’t depends on pressures and is not time-variable.
Regional model version:
stretched gridicosahedral grid
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Advantages of NICAM for tracer transport simulations High-resolution
if I could use the Earth Simulator Tracer masses are completely conserved without a mass fixer
Tracer advection is consistent with continuity Easy to develop adjoint code
no limiters or fixers, not semi-Lagrangian scheme
→ good properties for high-resolving inverse method.
Since NICAM is a new model, evaluation of the model performance is needed.
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The setting of NICAM Horizontal resolution: dx~240km The number of vertical layers: 54 Time step: 20 min Advection scheme : Miura2004 scheme (horizontal)
2nd order difference (vertical) Cumulus convection : simplified prognostic Arakawa- Schubert Vertical diffusion : Mellor-Yamada 2 with modification by Smith (Smith, 1990)
Analysed fields used for nudging: NCEP, JRA (not submitted to TC cont.) Meteorological variables used for nudging: U , V (τ=0.7day), T (τ=3day)
Nudged only for the free troposphere (12th layer ~)
not nudged in boundary layers
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Evaluation of meridional transport comparison with TransCom 3 models ①
The North-South gradient simulated by NICAM is smaller than other models.
Surface 500hPa
tracer : fossil fuel 1990
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Evaluation of meridional transport comparison with TransCom 3 models ②
stronger inter-hemispheric transport
TransCom 3 models
NICAM
tracer : fossil fuel 1990
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CTL
Nudged
sub-grid transport by cumulus convection was reduced by half
½ cumulus effect
dynamical field simulated by NICAM is not problem
cumulus convection hardly affect!
Large scale advection is the cause of inter-hemispheric transportDue to the advection scheme of NICAM ?
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SF6 simulationTransCom 2 experiment
S. Denning et al., 1999NICAM
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Comparison with TransCom continuous data experiment models
fossil98 SF6
SF6 observation data were downloaded from WDCGG site
Inter-hemispheric transport of NICAM is still seemed to be stronger
NICAM
observation
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Vertical transport: 222Rn simulationComparison with Jacob, et al., 1997
Green: other models, Blue: NICAM (V: not nudged, X: JRA, Y: NCEP)
Although there is an uncertainty of radon fluxes, the vertical transport simulated by NICAM is seemed to be a little stronger than others in summer.
summer winter
PBL
upper airobs.
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Comparison with continuous data at Hateruma
)]2cos( )2sin([ 2
3
1210 ixaixaxaay ii
i + R
Observation data were downloaded from WDCGG site
DJF JJA
Except in summer, high CO2 air from continental PBL was captured well.
SiB CASA
blue:SiB, green:CASA, red:observation
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Comparison with aircraft dataVertical profile @ Novosibirsk (West Siberia)
Upper air by JAL airplane (Tokyo-Sydney)Boundary layer was simulated well
z
S ← latitude → N
convected high CO2 air
OLR
Siberia data were provide by T. Machida (NIES)JAL data were provided by H. Matsueda (MRI)
NICAM observation
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Summary and Perspective Introduction of NICAM
NICAM is a new model developed as a global cloud resolving model.
The grids of NICAM are very different. Comparison with TransCom models
Inter-hemispheric transport simulated by NICAM is stronger than other models
The model results are in the range of other model results and in good agreement with observations.
Comparison with observations Synoptic scale variations were captured well. Small scale variation of atmospheric CO2 were reproduced.
Perspective Development of high-resolving inverse model
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Thank you!
AcknowledgementThe datasets used for this study are provided from the cooperative research project of the JRA-25 long-term reanalysis by Japan Meteorological Agency (J MA) and Central Research Institute of Electric Power Industry (CRIEPI). NCEP Reanalysis data were provided by the NOAA/OAR/ESRL PSD, Boulder, Colorado, USA, from their Web site at http://www.cdc.noaa.gov/. Aircrafts observation data at Siberia sites were offered from T. Machida (NIES) and JAL observation data were offered from H. Matsueda (MRI).