cgils updated results gcss-blcwg meeting, september 29-30, 2010 knmi minghua zhang (stony brook...
DESCRIPTION
Purpose: To understand the causes of cloud feedbacks, and thus climate sensitivities of climate models. Objectives: 1.To understand the physical mechanisms of cloud feedbacks in SCMs 2.To interpret GCM cloud feedbacks by using SCM results 3.To Evaluate the SCM cloud feedbacks using LES simulationsTRANSCRIPT
CGILS Updated Results
GCSS-BLCWG Meeting, September 29-30, 2010 KNMI
Minghua Zhang (Stony Brook University)
Julio Bacmeister, Sandrine Bony, Chris Bretherton, Florent Brient,
Anning Cheng, Stephan de Roode,Tony Del Genio, Charmaine
Franklin, Chris Golaz, Cecile Hanny, Francesco Isotta, In-Sik Kang,
Hideaki Kawai, Martin Koehler, Suvarchal Kumar, Vince Larson,
Adrian Lock, Ulrike Lohman, Marat Khairoutdinov, Andrea Molod, Roel
Neggers, Sing-Bin Park, Ryan Senkbeil, Pier Siebesma, Colombe
Siegenthaler-Le Drian, Bjorn Stevens, Max Suarez, Kuan-man Xu, Mark
Webb, Audrey Wolfe, Ming Zhao,
GPCI
S6
S11 s12
Purpose:
To understand the causes of cloud feedbacks, and thus climate
sensitivities of climate models.
Objectives:
1. To understand the physical mechanisms of cloud feedbacks
in SCMs
2. To interpret GCM cloud feedbacks by using SCM results
3. To Evaluate the SCM cloud feedbacks using LES
simulations
(moist adiabat)
T(z)
RH Fixed
Warm Pool Cold Tongue
T(z)
(Zhang and Bretherton, 2008)
CGILS (CFMIP-GCSS Intercomparison of Large-Eddy and Single-Column Models)
Need to be relevant to observations and GCMs
SCM (16)
CAM4*CAM5*CCC*CSIRO*ECHAM5*ECHAM6*ECMWF*GFDLGISS*GSFC*JMA*KNMI-RACMO*LMD*SNUUKMO*UWM*
LES (5)
DALESSAMUCLAUCLA/LaRCUKMO
* Indicates SCMs that completed the revised runs
The second round of SCM simulations
Forcing revised to be the same as in LES
Control case temperature and relative humidity are now
directly from ECMWF Interim Analysis for July 2003 from
Martin Koehler.
1. Lower troposphere above the boundary layer is warmer,
with more realistic inversion height and strength.
2. More moisture in the boundary layer for LES to start with.
3. Subsidence extended to below 1000 mb, thus slightly
stronger than before below 900 mb.
Cloud feedbacks at S6
-20
-10
0
10
20
cam
3ca
m4
csiro
csiro
2
ecm
wf
gfdl
giss
giss
2gs
fc
knm
i
larc
lmd
sam
snu
ukm
o
ukm
o38
ukm
o63
uwm
CRF (W/m2)
s6
CR
F (W
/m2)
Cloud feedbacks at S6Round 1 versus Round 2
CRF at S6
CRF at S11
CRF at S12
S6
S11
S12
Points to Note
Some models maintain the same sign of feedbacks or negligible feedback at all three locations
Negative feedback: CAM4, ECMWF, JMA, UWM
Positive feedback: CAM5, CCC, CSIRO, ECHAM6, LMD, UKMO
Flipped: GISS, GSFC, RACMO (in the same direction: positive at s6, negative at s12).
Feedbacks at the two locations of S11 and S12 mostly show the same sign in the models
CRF at S6
CRF at S11
CRF at S12
S6
S11
S12
Points to Note
At S6, Two models show little feedback (CSIRO and UKMOL38) The small group show negative feedback (CAM4, ECMWF, JMA
UWM)The majority show positive feedback (CAM5, CCC, ECHAM6, GISS,
GSFC, LMD, RACMO)
At S11, Two models show little feedback (ECHAM6 and LMD)About half of the models show positive feedback (CAM5, CCC,
CSIRO, RACMO, UKMO)Half of the models show negative feedback (CAM4, ECMWF, GISS,
GSFC, JMA, UWM)
At S12, Two models show little feedback (ECHAM6 and LMD)Three models show positive feedback (CCC, CSIRO, UKMO)The majority show negative feedback (CAM4, CAM5, ECMWF,
GISS, GSFC, JMA, RACOM,UWM)
Instead of discussing clouds at one location at a time (the GCSS perspective), in the following, we will show all cloud types for one model at a time (the GCM perspective)
CRF at S6
CRF at S11
CRF at S12
S6
S11
S12
CAM4
CAM4 s6 ctl CAM4 s6 p2k
CAM4 s11 ctl CAM4 s11 p2k
CAM4 s12 ctl CAM4 s12 p2k
CAM4 ql s6 CAM4 ql s11 CAM4 ql s12
CRF at S6
CRF at S11
CRF at S12
S6
S11
S12
CAM5
CAM5 s6 ctl s6 p2k
s11 ctl s11 p2k
CAM5 s12 ctl s12 p2k
ql at s6 ql at s11 ql at s12
CRF at S6
CRF at S11
CRF at S12
S6
S11
S12
ECHAM6
ECHAM6 s6 ctl s6 p2k
s11 ctl s11 p2k
ECHAM6 s12 ctl s12 p2k
ql at s6 ql at s11 ql at s12
CRF at S6
CRF at S11
CRF at S12
S6
S11
S12
ECMWF
ECMWF s6 ctl s6 p2k
s11 ctl s11 p2k
ECMWF s12 ctl s12 p2k
ql at s6 ql at s11 ql at s12
CRF at S6
CRF at S11
CRF at S12
S6
S11
S12
ECMWF2
ECMWF2 s6 ctl s6 p2k
s11 ctl s11 p2k
ECMWF2 s12 ctl s12 p2k
ql at s6 ql at s11 ql at s12
CRF at S6
CRF at S11
CRF at S12
S6
S11
S12
LMD
LMD s6 ctl s6 p2k
s11 ctl s11 p2k
LMD s12 ctl s12 p2k
ql at s6 ql at s11 ql at s12
CRF at S6
CRF at S11
CRF at S12
S6
S11
S12
RACMO
RACMO s6 ctl s6 p2k
s11 ctl s11 p2k
RACMO s12 ctl s12 p2k
ql at s6 ql at s11 ql at s12
CRF at S6
CRF at S11
CRF at S12
S6
S11
S12
UKMOL38
UKMOL38 s6 ctl s6 p2k
s11 ctl s11 p2k
UKMOL38 s12 ctl s12 p2k
ql at s6 ql at s11 ql at s12
CRF at S6
CRF at S11
CRF at S12
S6
S11
S12
UWM
UWM s6 ctl UWM s6 p2k
UWM s11 ctl UWM s11 p2k
UWM s12 ctl s12 p2k
ql at s6 ql at s11 ql at s12
Negative feedbacks
Deepened mixed layer without much dilution at the cloud top:
1. no explicit cloud-top entrainment and no shallow convection
2. weak cloud-top entrainment and small moisture effect of shallow convection
1000mb
900mb
950mb
800mb
1010mb
Negative feedbacks
Deepened mixed layer without much dilution at the cloud top:
1. no explicit cloud-top entrainment and no shallow convection
2. weak cloud-top entrainment and small moisture effect of shallow convection
1000mb
900mb
950mb
800mb
1010mb
1000mb
900mb
950mb
800mb
1010mb
Positive feedbacks
1. More intermittent clouds due to cloud-top entrainment or shallow convection
2. Less cloud water due to cloud-top mixing
Summary
1. Evidences suggest that the CGILS results from some models can be used to interpret GCM cloud feedbacks. For other models, especially those displaying multiple equilibrium behavior, alternative configuration of running the SCMs may be insightful. This was demonstrated by the LMD group who added transient forcing to break up the multiple equilibriums.
2. Two groups of models have been identified to show the same sign or negligible cloud feedbacks at all three locations, displaying positive and negative feedbacks. It would be interesting to see if the corresponding GCMs show the same sign of cloud feedbacks.
3. The deciding physical process appears to be the mixing at the cloud top, carried out either by explicit cloud-top entrainment or shallow convection.
Summary
4. Comparisons with LES and with GCMs are yet to be carried out. SCMers are waiting for LES and CFMIP results.
-40
-20
0
20
40
cam
3ca
m4
csiro
csiro
2ec
ham
echa
m2
ecm
wf
gfdl
giss
giss
2gs
fckn
mi
knm
iBla
rcla
rcB
lmd
sam
sam
Bsn
uuk
mo
ukm
o38
ukm
o63
ukm
oBuk
moC
uwm
CRF (W/m2)
s11
CR
F (W
/m2) Opposite:
CSIROECMWFGISSKNMI
Cloud feedbacks at S11Round 1 versus Round 2
-40
-20
0
20
40
cam
3ca
m4
csiro
csiro
2ec
mw
fgf
dlgi
ssgi
ss2
gsfc
knm
ila
rcla
rcB
lmd
sam
snu
ukm
ouk
mo3
8uk
mo6
3uw
m
CRF (W/m2)
s12
CR
F (W
/m2) Opposite:
ECMWFGISS
Cloud feedbacks at S12Round 1 versus Round 2
CGILS SCM Next Steps:
1. Understanding of processes in each model.
2. Re-configure simulations, such as adding transience, if results are suspicious.
3. Linking with GCMs
4. Use LES models to say something about the SCMs
CGILS LES Next Steps
1. At s11, reduce vertical resolution to 5 m for all models to seek consistent LES results
2. At s12, either the forcing data or the simulation setup will be revised to enable the LES models maintain stable cloud layer.
CGILS Future Plan
1. Use seasonal, interannual, and decadal variations to evaluate the models
2. Close coordination with CFMIP to conduct SCM&GCM sensitivity experiments
3. Use LES results to constrain the SCM parameterizations
CGILS Paper Options
Wait for LES resultsWait for some CFMIP resultsSCM results written up first
Next meeting: A telecon before the end of 2010A CGILS session at the next EUCLIPSE general meeting