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

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-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