Development and Evaluation of a High Resolution Oceanic General
Circulation Model (OGCM)
Yongqiang YU, Hailong Liu, Pengfei Lin,
Xuehong Zhang, Huier Mo
LASG/IAP/CAS
Guilin, China, October 28th-31st , 2013
Outline
1. Introduction
2. Model Description
3. Numerical and Parallel Computing
Schemes
4. Large-scale Circulation
5. Marginal Sea Circulation near China
6. Summary
10.6% /10 years
Global Mean Surface Air Temperature Change (IPCC, 2013)
How to reduce the Model Uncertainties
Increase spatial resolution of climate
system models
Improve Numerical Methods
Improve the subgrid physical
parameterization schemes
Introduce new component models
Spectrum of Kinetic Energy in the ocean
Outline
1. Introduction
2. Model Description
3. Numerical and Parallel Computing
Schemes
4. Large-scale Circulation
5. Marginal Sea Circulation near China
6. Summary
Ocean Model Development Historyat LASG/IAP
4-Level (4X5) OGCM by Zhang et al. (1989) Convex-C120
20-Level (4X5) OGCM by Chen et al. (1997) Convex-C3210
30-Level (2X2) GCM by Jin et al. (1999) SGI workstation
LICOM1.0 (0.5X0.5) by Liu et al. (2003) SGI and IBM
LICOM2.0 (0.1X0.1) by Liu et al. (2012) and Yu et al. (2012)
(TH-1A)
Approximations and Equations
z
I
c
1F
td
Td
p0T
u0
Fx
p1vf
td
ud
pST ,,
0z
w
v
gz
p
SFtd
Sd
v0
Fy
p1uf
td
vd
Barotropical Equations
y
V
x
U
t
z0
Xdzx
p11Vf
x
zzHg
t
U 0z
H
C
0x,bx
0
00
Ydzy
p11Uf
y
zzHg
t
V 0z
H
C
0y,by
0
00
Sub-Grid Physical Parameterizations
Turbulent Mixing schemes (Canuto,
2003,2007)
Solar radiation penetration scheme
Bottom drag scheme
Bi-Harmonic diffusion/viscosity
Outline
1. Introduction
2. Model Description
3. Numerical and Parallel Computing
Schemes
4. Large-scale Circulation
5. Marginal Sea Circulation near China
6. Summary
Z-Coordinate and Latitude-Longitude
grid
Leap-frog time integration
Barotropic and Baroclinic Split
Technology
2-order central difference for
momentum advection
Two-step shape-preserving scheme
for temperature and salinity
advection
Implicit scheme for vertical
diffusion/viscosity
2-D MPI Parallel Computing
14
Speed-up in TianHe-1A
Zonal filter in high latitudes lead to imbalance
Serial IO becomes key bottleneck
Experiment Design of LICOM2.0
12-year spin-up forced NCEP climatological flux
2000-2007 simulation by daily forcing form
NCEP Heat Flux and QuickSCAT wind stress
A 60-year integration with NCEP reanalysis.
1 model year/ 2 days
Outline
1. Introduction
2. Model Description
3. Numerical and Parallel Computing
Schemes
4. Large-scale Circulation
5. Marginal Sea Circulation near China
6. Summary
Standard Deviation of Sea Level Height
SST Snapshot near Western Boundary
Observed and Simulated zonal cuurent in the tropic Pacific
Kuroshio Path from 2000 to 2007
MOC FC Ek MO
mean std mean std mean std mean Std
RAPID/MOCHA 18.7 4.7 31.7 2.8 3.5 3.2 -16.5 3.15
LICOM 16.6 6.3 26.3 3.5 3.6 3.5 -13.2 5.7
5-daily mean integrated transports
MOC=FC+EK+MO
MOC , r=0.62
FC : Florida Current transport , r=0.43
EK : Ekman transport r=0.96
MO : upper mid-ocean transport , r=0.3
RAPID (dash line) model (solid line)
CMIP3 models (from Sarojini et al.
2011) the black line is OBS
Power Spectrum of 5-daily mean transports
LICOM
hardly reproduce the 30 to 40 days period
LICOM successfully represent this feature
Velocity profile of ITF (m/s) .
Makassar
Lombok
Ombai
TimorLifatomola
Strait or passage
LICOM2.0 (Sv)
Mean
INSTANT (Sv)
Mean
Makassar Strait
-10.8 (77%) -11.6 (82%)
Lifamatola Passage
-3.2 (23%) -2.5 (18%)
Lombok Strait -2.7 (18%) -2.6 (17%)
Ombai
Strait
-3.1 (21%) -4.9(33%)
Timor Passage -9.2 (61%) -7.5 (50%)
In/out -14/-15 (-1) -14.1/-15 (-0.9)
LICOM1.0 (Sv)
Mean
HYCOM (Sv)
Mean
-8.0 -7.3 (78%)
- -2.0 (22%)
-5.6 (44%) -2.4 (18%)
-6.5 (51%) -5.1 (38%)
-0.7 (5%) -5.9 (44%)
-/12.8 -9.3/-13.4 (-4.1)
Annual mean volume transport
Time series of Volume transport
Outline
1. Introduction
2. Model Description
3. Numerical and Parallel Computing
Schemes
4. Large-scale Circulation
5. Marginal Sea Circulation near China
6. Summary
Depth-Longitude section of observed and simulated temperature along 35N
Jan Apr
Jul Oct
Luzon transport in upper(0-500), middle (500-1500) and deep layers (<1500).
Summary
Compared with coarse resolution of the ocean model LICOM, the eddy-resolving version well reproduces the meso-scale eddies as observed.
The model doesn’t only reproduce equatorial current system such as EUC, ETC etc, but also oceanic circulation in the North Pacific.
The model can simulate the large meander of Kuroshio, as well as its interannaul variability.
The marginal sea circulation near China are also reproduced by the eddy-resolving model.
The mass transport along 26.5N and Indonesian straits are well reproduced.
Ongoing Work
Sub-grid Parameterizations: Tidal mixing,
wave mixing, internal wave mixing etc.
Dynamical Core: Time integration scheme
Tripole Coordinate: reduce load imbalance
Parallel Optimization : MPI + Open MP
High resolution coupled Ocean-Atmosphere
Model
Next Step
在 LICOM 模式中引进三极坐标 改进湍流混合方案 引进潮汐混合、波浪混合、底边界层混合方
案等 进行高分辨率耦合试验 .
Time mean temperature transects at 26.5ºN
LICOM can’t resolve the Bahamas at the western boundary, and the depth of Florida Straits is too shallow compared to the real topography.
WOA09
LICOM
LICOM-WOA09
LICOM can reproduce the observational temperature structure
Schematic of MOC monitoring array at 26ºN
Observational Strategy Modeled Strategy
Meridional overturning circulation (MOC)
MOC=FC+EK+MO zonally and vertically integrated meridional volume transport above 1000m
Florida Current transport (FC)
Cables, velocity profile hori : west boundary to 78.8W
vert : surface to the depth of model topography
Ekman transport (EK)
Mid-ocean transport (MO) Density difference between the profiles at the boundaries
MO=MOC-EK-FC
from Rayner et al. , 2011
QuickScat
meridional heat transport
pQ c v dxdz
observation model
mean 1.34PW 1.14PW
std 0.39PW 0.44PW
R=0.68
Underestimated by 0.2PW
Purpose: evaluate the ability of the eddy-resolving ocean circulation model LICOM to reproduce the variabilities of AMOC on the time mean scale and the time scales less than one year against the high frequency observational data (RAPID data) along 26.5 ºN in Atlantic.
Mass and Heat Transport along 26.5N in North Atlantic
Qu(2000)
Fang(2003)
Lan(2004)
Cai(2005)
Zhao(2007)
Chen(2009)
Wang(2009)
High resolution LICOM
Jan. -6.1 -11.27 -5.53 ≈-5.6 -9.5 -21.03 ≈-6.8 -7.97
Apr. -4.11 -2.5 ≈-3.0 -3.1 -2.01 ≈-3.0 -0.18
Jul. -0.9 -2.4 -0.29 ≈-3.1 -1.6 -9.08 ≈-2.4 -0.47
Oct. -7.65 -2.24 ≈-5.2 -9.2 -17.96 ≈-5.2 -5.97
Ann. -2.4 -6.40 -2.69 -4.27 -5.7 -13.05 -4.5 -3.76
Volume Transport across Luzon Strait ( Unit : Sv)
Observed and Simulated SSH Anomaly in 2005 and 2007
OBS (2005)OBS (2007)
Model (2005) Model (2007)
Zonal Current along 160E
Dec Mar
SepJun
Deep layer transport across Luzon strait
LICOM
SODA
Zonal Jets in the subtropics
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