A cloud schemeincluding indirect aerosol effects on

ice and liquid cloud particlesin the MRI Earth System Model

SAKAMI, T., T.OSE and S. YUKIMOTOwith the MRI Earth System Modeling Group

(Meteorological Research Institute, Tsukuba, JAPAN)Today’s speaker is T.OSE.

OUTLINE

• MRI-ESM and cloud models

• Performance of cloud models

• Sensitivity experiments for 2×CO2

• Summary 　

Development of Earth System Model for Global Warming Projection (FY2005-2009: S. YUKIMOTO)

Tanaka, T. Y., and M. Chiba, 2005

2-moment cloud microphysics schemes are incorporated in the MRI-ESM.

NEW Cloud (qc,qi,Nc,Ni) OLD Cloud (qc)

Arakawa-Schubert

Tiedtke cloud

Tiedtke cloud

Arakawa-Schubert

Incorporated microphysical schemes for cloud phase change processes

Murakami(1994) for sublimationMurakami(1999) for depositionRutldge(1983) for depositional growth

Bigg(1953) for immersion freezingLohman(2006) for contact freezing

Detrained ice/liquid depending on T

Levkov (1992) for accretion

Rotstayn(2000) for autoconversion and collection

Melting occurs at 273.15K

Incorporated microphysical schemesfor cloud particle numbers

Abdul-Razzak (2000,2002) for activation to cloud droplets

Karcher(2006) for activation to ice crystals

Ming(2007) for Detrained number of cloud droplet and ice crystal from cumulus cloud

Martin(1994),Liu(2006) for effective radius of cloud droplets

Lohmann(2002) for volume radius to get effective radius of ice crystals

OUTLINE

• MRI-ESM and cloud models

• Performance of cloud models

• Sensitivity experiments for 2×CO2

• Summary 　

Preliminary experiments

Experiments

• 3 years run • MRI-AGCM (TL159L46)• Climatological SST• Climatological aerosol mass • No aerosol transport model• No direct effect of aerosol

Comparisons with

• ECHAM5-HAM and OBS in • U. Lohmann et al. (2007)

• NCAR CAM3 and OBS in • X.Liu et al. (2007)

• GFDL AM2 in • Ming et al. (2007)

Aerosol number concentration (#/cm3) arediagnosed from a given aerosol mass in the model.

Sulfate

BC

OC

SeasaltDust

Cloud Cover in comparison with ECHAM5-RH in U. Lohmann et al. (2007)

ECHAM5-RH

MRISCdetrainment

MRI

MRIASdetrainment

Grid-averaged Cloud Liquid Waterin comparison with ECHAM5-RH in U. Lohmann et al. (2007)

ParticleNumber1/cm3

Massmg/kg

ECHAM5-RH

MRI

In-cloud particle concentration (#/cm3) at 850-950hPain comparison with GFDL_AM2 in Ming (2007)

GFDLPrognostic

GFDLDiagnostic

MRI

MRIAerosol

Grid-averaged Cloud Ice Water in comparison with ECHAM5-RH in U. Lohmann et al. (2007)

ECHAM5-RH

MRI

Number1/cm3

Massmg/kg

Grid-averaged Cloud Ice Water (mg/m3) in comparison with CAM in Liu et al. (2007)

CAMICE

CAMREF

OBSMRI

Cloud radiative effects tend to be overestimated probably due to small cloud effective radius.

ERBEDSW

ERBEULW

MRIDSW

MRIULW

OUTLINE

• MRI-ESM and cloud models

• Performance of cloud models

• Sensitivity experiments for 2×CO2

• Summary 　

Radiative forcing for 2xCO2in comparison with Fig.3 in Gregory and Webb (2008)

• Hansen et al. (2002) type approach

• (4xCO2-1xCO2)*0.5

• Fixed SSTs • 3 years runs

0.58

-1.15

3.75

0.50

3.68

CLRLW

CLRSW

CLDLW

CLDSW

NET

Cloud forcing seems to be well related to cloud cover changes.

CLOUDChange

DSW

DLW

WARMING

COOLING

CuDetrainmentChange

SCDetrainmentchange

950-1000hPa clouds increase over their climatologically abundant region .

950-1000hPa Climatological Cloud Cover

950-1000hPa Cloud Cover Change

950-1000hPa cloud increase tend to contribute SW radiative cooling. Strong SW radiative warming due to suppressed cumulus is more clear.

Negative DSW TOAChange

950-1000hPa Cloud Cover Increase

Shallow Cumulus detrainment change contributes to 800-950hPa cloud changes to some extent, but small impact on cloud forcing in the model.

SCClimate

SCChange

800-950hPaClimateCloud

800-950hPaCloudChange

SUMMARY• The 2-moment liquid and ice cloud models including

cumulus-related activation and detrainment processes are incorporated in the MRI-ESM.

• Those cloud models basically seem to show good performance.

• Suppressed deep cumulus detrainments and enhanced low-level clouds seem to be significant for radiative forcing change in a sensitivity experiment.

• Indirect effects of the model need to be examined in different aerosol environments.