Plausible Improvement of AGCM focused on MJO (ISO)

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Lecture 1 Current status of climate models
Plausible Improvement of AGCM focused on MJO
(ISO) In-Sik Kang

• Current Status of ISO simulation AGCM
  Intercomparison
• Modification of Minimum Entrainment Rate in RAS
  Scheme
• Layer Cloud Characteristic Precipitation Time
  Scale
• Relative Humidity Criteria in RAS Scheme

Climate Environment System Research Center
2
? A-A Monsoon AGCM Intercomparison project

• Global Atmospheric Anomalies during 97/98 El Niño
  
• Kang et al., Journal of Climate (2002), Vol. 15,
  No. 19, pp. 27912805
• Climatological Variations of Asian Summer Monsoon
• Kang et al., 2002, Climate Dynamics (2002), Vol.
  19, pp.383-395.
• Asian-Australian Monsoon Anomalies during 97/98
  El Niño
• Wang et al., Journal of
  Climate (2004)
• Forced and Free Intraseasonal Variability over
  the South Asia Monsoon Region
• Wu et al., Journal of Climate (2002), Vol. 15,
  No. 20, pp. 28622880
• Intraseasonal Variability Associated with Asian
  Summer Monsoon
• Waliser et al., Climate Dynamics (2004)

Lee, M.-I., I.-S. Kang, B.E.Mapes, 2001,
Influence of cloud-radiation interaction on
simulating tropical intraseasonal oscillation
with an atmospheric general circulation model. J.
Geophys. Res., 106, D13, 14, 219-14, 233. Lee,
M-I, I.-S. Kang, B.-E. Maps, 2003 Impact of
Cumulus Convection Parameterization on
Aqua-planet AGCM Simulations of Tropical
Intraseasonal Variability. J. Meteor. Soc. Japan,
81,963-992.
CES/SNU
A-A Monsoon AGCM Intercomparison Project
3
Current Status of ISO Predictability MJJAS
Variability of ISO
CMAP observed standard deviation of the 20-90 day
filtered MJJAS precipitation during 1979-1998
MJJAS
Simulated standard deviation of the 20-90 day
filtered MJJAS precipitation during 1997-98 of 10
ensemble members
   
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Current Status of ISO Predictability Eastward
Propagation
10oS-10oN Time-longitude Cross Section of
Precipitation during 1997
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Current Status of ISO Predictability Northward
Propagation
Composite ISO events of rainfall based on the
extended EEOF
CMAP 20-90 day filtered MJJAS precipitation
during 1979-1998 MJJAS
20-90 day filtered MJJAS precipitation during
1997-98 of 10 ensemble members
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Possible Improvement of ISO Simulation in AGCMs

• How the ISO simulation can be improved?

Numerics

• Need of high horizontal resolution of the model
  (Hayashi and Golder, 1986)

Boundary Condition

• High-frequency interaction with SST (Lau and
  Shen, 1988 Sperber et al., 1996 Lau and Sui,
  1997)

Physical Parameterization

• Improvement of cumulus parameterization (Lau and
  Peng, 1997 Chao and Deng, 1998 Wang and
  Schlesinger, 1999)

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Current Status of ISO Predictability CES/SNU AGCM
10oS-10oN Time-longitude Cross Section of
Precipitation during 1997
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ISO Dependence on Convection Scheme Problem in
RAS Scheme

• Precipitation rate in each convection scheme
  (2oS-2oN)

• Idealized Aqua-Planet Experiment
• Resolution T31 (3.75x3.75) L20
• Prescribed zonally uniform SST
• Equinox perpetual 120 day run
• Cumulus Convection Parameterization
• Relaxed Arakawa-Schubert
• (Moorthi and Suarez, 1992)
• Kuo (1974)
• Moist Convective Adjustment
• (Manabe et al. 1965)

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ISO Dependence on Convection Scheme Problem in
RAS Scheme

• Vertical distribution of total diabatic heating
  rate

Loose convection criteria than other schemes
Composite over the rainy area more than 2 mm
day-1 between 2oS-2oN latitude belt.
Respond to small-scale moisture convergence
perturbations
Kday-1

• Mosit static energy in rainy and dray region

Suppress the well developed large-scale eastward
waves
Red Rainy area composite Black dry area
composite
KJ kg-1
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Strategy for Improving the ISO Simulation in
CES/SNU AGCM

• Improvement of Physical Parameterization

Problem
Solution
Problem
Solution
Loose convection criteria suppress the well
developed large-scale eastward waves
Unrealistic precipitation occurs over the warm
but dry region
Minimum entrainment constraint
Relative Humidity Criterion
Cloud-radiation interaction suppress the eastward
waves
Layer-cloud precipitation time scale
Better Simulation of ISO
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Modification1 Cumulus Entrainment Constraint

• Minimum cumulus entrainment rate in RAS (Tokioka
  et al. 1998)

D PBL depth ? non-negative constant
Convection can be triggered in case of ? ? ?min
Equatorial transients

• Minimum cumulus entrainment rate condition
  dependent on PBL depth (D)
• Cumulus entrainment characterizes the degree of
  lateral mixing and cloud top altitudes
• Lower- µ less entraining deep clouds
• Higher- µ more entraining shallow clouds

?0.0
?0.15
?0.05
?0.25
ITCZ structure

• Increased ? makes
• more enhanced ISO variability
• single ITCZ from double

Constant ? 0 (original scheme) ? ? 0.1
(modified)
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Modification1 Cumulus Entrainment Constraint
?0.0 (control)
?0.1 (modified)
(a) PRCP
(b) VP200
(a) PRCP
(b) VP200
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ISO with turning on Cloud-Radiation Interaction
Time-longitude Diagram of Rainfall

• Two Experiments in Aqua-Planet

(a) Fixed
(b) Interactive
Experiment Description
Fixed Prescribed zonally uniform radiative heating rate
Interactive Fully interactive radiation

• Cloud-radiation interaction simulated in the
  model (in particular, RAS scheme) prevents the
  eastward propagation of large-scale waves and
  make westward moving transients more prominent.

Space-time Power Spectra of Rainfall

• The power of the moist Kelvin wave is
  significantly reduced and the westward transients
  are more prevalent

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ISO with turning on Cloud-Radiation Interaction

• Atmospheric Cloud-Radiative Forcing Positive
  Feedback

• Why the small-scale disturbances are
  persistently excited and advected westward in the
  cloud-radiation interactive case?

? Thecumulus anvil type high cloud induced
positive ACRF feedback suppresses the wavenumber
1-2 Kelvin waves propagation eastward .

• Vertical Distribution of Diabatic Heating

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ISO with turning on Cloud-Radiation Interaction
2oS-2oN Time-longitude Cross Section of
Precipitation

• Cloud-radiation feedback mechanism is largely
  subjected to the cumulus parameterization scheme
  (RAS), which has cumulus anvil cloud detrained.

• In particular, the longwave ACRF feedback is
  more crucial for this feature in RAS scheme.

Day
Day
without shortwave cloud radiative forcing
without longwave cloud radiative forcing
Kuo scheme in fully interactive case
Moist convective adjustment scheme in fully
interactive case
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Modification2 Layer-cloud Precipitation time
Scale

• Strategy

• Characteristic precipitation timescale, ?p

For the reduction of longwave ACRF
(Sundqvist, 1978)
Modulation of model cloudiness
lc critical cloud liquid water content to
characteristic timescale for conversion of cloud
droplets into rain drops
Reduction of precipitation time scale for
reducing longwave heating induced by ACRF

• Precipitation rate

P precipitation rate l cloud liquid water
content ?p characteristic precipitation timescale

• Observational evidence Autoconversion
  precipitation timescale over the tropics is
  200800 sec (Lau et al. 2003)

Warm rain
Cold rain

• ? The reduction of ?p means fast autoconversion
  from cloud liquid water to precipitable raindrops
  
• ? Reducing Cloud Lifetime
• Longwave ACRF (atmosphere cloud radiative
  forcing) heating reduced

Constant ?p 9600 sec (original) ? smaller
value up to 900 sec
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Modification2 Layer-cloud Precipitation time
Scale
Sensitivity to Precipitation Timescale
Time-longitude Diagram
Precipitation
200 hPa Velocity Potential
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Modification Results in Real Surface Condition

• Experiments in Real Surface

Tokioka effect Layer-cloud precipitation timescale Layer-cloud precipitation timescale
RAS cumulus entrainment minimum Reduced region LSC time scale ?0
Control Off No 9600 sec
Modified ?0.1 20oS20oN 9600900 sine curve
10oS-10oN Time-longitude Cross Section of 200 hPa
Velocity Potential during 1997
Zonal Mean OLR during Sep1996 Aug1998
By the modulation of cumulus entrainment
constraint in RAS and layer-cloud precipitation
time scale in cumulus convection scheme, the
simulated MJO is improved and mean state is also
conserved.
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Modification3 Relative Humidity Criteria

• Relative Humidity Criteria for Cumulus
  Suppression in RAS

Cloud work function A controls the flux of
cumulus convection.
A
Precipitation is influenced by temperature and
humidity. For warm but dry region, model might
simulate unrealistic precipitation.
No RHc criteria (original scheme) ? RHc 80
(modified)
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Modification3 Relative Humidity Criteria -
Results

• 10oS-10oN Time-longitude Cross Section of
  Precipitation

(a) Control
(b) Modified

• Perpetual Experiment
• Resolution T31 (3.75x3.75) L20
• 4 months simulation with June condition
• For modified case, RHc is 80

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Unified Cumulus Parameterization

• Multi-model superensemble reduces the systematic
  errors, although there are not seem to have any
  essential physical insights.
• Following concept of Unified cumulus
  parameterization contains KUO, RAS, and MCA
  scheme.
• The unified cumulus parameterization has more
  physical meaning than the multi-model
  superensemble in respect of merely reducing the
  forecast errors.

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Unified Cumulus parameterization Result
precipitation
Observation (CMAP)
CESGCM Control
Identical weighting unified simulation (UCP)
Simple Ensemble mean (ENS)
Unified simulation weighted by correlation
between observation and each scheme (UCP1)
Same with UCP1 except different combination
(MCARAS) (UCP2)
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Strategy using Coupled System AGCM vs. CGCM
RMS of 20-90 day filtered rainfall
CMAP
ISO Variability (100E-150E/0-25N)
CMAP
SMIP
10 member
AGCM(SMIP)
ENS
Using coupled system, the intraseasonal
variability is increased in CGCM
CGCM
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Strategy using Coupled System CISO in AGCM vs.
CGCM
CMAP
Using coupled system, the climatological
intraseasonal mode (CISO, Kang et al., 1999)
associated with Chang-ma is improved
AGCM(SMIP)
CGCM
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Lecture 1 Current status of climate models
Future Perspective on the Climate Model
Climate Environment System Research Center
26
Modification including Direct Effect of Aerosol

• Plausible Direct Effect of Aerosol

Interception of solar radiation
Reduction of land-sea temperature gradient
Reduction of land-sea breeze (Reduction of
monsoon circulation)
Incoming solar radiation Temperature
gradient Land-sea breeze
Surface evaporation and convergence over the
ocean is decreased

• Overestimated precipitation and monsoon
  circulation in the Bay of Bengal and western
  Pacific are reduced in boreal summer.

Convection and precipitation are reduced
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Modification including Direct Effect of Aerosol
Results

• 10-year run with climatologial SST in T42L20

Initial Data of Aerosol
Aerosol optical depth
Aerosol optical depth AERONET
Assumed vertical aerosol concentration profile
Tropopause concentration is 100 times than
surface (Wallace,1977)
Determining the constant C
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Development of Integrated Climate and
Environmental Model
Aerosol Transport Model
Land Surface Model
Land Surface Model
Gas chemical reaction process model
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Integrated Climate and Environmental Model in
CES/SNU
Future status of Integrated Modeling System
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References

• Kang I.-S., K. Jin, B. Wang, K.-M. Lau, J.
  Shukla, V. Krishnamurthy , S.D.Schubert,
  D.E.Waliser, W.F.Stern, A.Kitoh, G.A.Meehl,
  M.Kanamitsu, V.Ya.Galin, V.Satyan, C.-K.Park, and
  Y.Liu, 2002 Intercomparion of atmospheric GCM
  simulated anomalies associated with the 1997-98
  El Nino. Journal of Climate, 15(19), 2791-2805.
• Kang I.-S., K. Jin, B. Wang, K.-M. Lau, J.
  Shukla, V. Krishnamurthy , S. D. Schubert, D. E.
  Waliser, W. F. Stern, A. Kitoh , G. A. Meehl , M.
  Kanamitsu,  V. Ya. Galin, V. Satyan, C.-K. Park,
  and Y. Liu, 2002 Intercomparison of the
  climatological variations of Asian summer monsoon
  precipitation simulated by 10 GCMs. Climate
  Dynamics. 19, 383-395.
• Wang, Bin, Kang, In-Sik, Lee, June-Yi. 2004
  Ensemble Simulations of Asian-Australian Monsoon
  Variability by 11 AGCMs. Journal of Climate, Vol.
  17, No. 4, 803-818.
• Waliser, D. E., K. Jin, I.-S. Kang, W. F. Stern,
  S. D. Schubert, M. L. C. Wu, K.-M. Lau, M.-I.
  Lee, V. Krishnamurthy, A. Kitoh, G. A. Meehl, V.
  Y. Galin, V. Satyan, S. K. Mandke, G. Wu, Y. Liu,
  C.-K. Park, 2003 AGCM simulations of
  intraseasonal variability associated with the
  Asian summer monsoon, Climate Dynamics, 21,
  423-446.
• Lee, M.-I.,I.-S. Kang, J.-K. Kim, and B.E.Mapes,
  2001, Influence of cloud-radiation interaction on
  simulating tropical intraseasonal oscillation
  with an atmospheric general circulation model. J.
  Geophys. Res., 106, D13, 14, 219-14, 233.
• Lee, Myong-In, I.-S. Kang, B.-E. Maps, 2003
  Impact of Cumulus Convection Parameterization on
  Aqua-planet AGCM Simulations of Tropical
  Intraseasonal Variability. J. Meteor. Soc. Japan,
  vol.81,no.5, 963-992.