Implementation of IPHOC in VVCM:

Tests of GCSS Cases

Anning Cheng1,2 and Kuan-Man Xu 2

1. AS&M, Inc.

2. Science Directorate, NASA Langley Research Center

Intermediately Prognostic Higher-Order Closure Model

• Double-Gaussian distribution of liquid-water potential temperature, total water mixing ratio and vertical velocity

• Skewnesses of these three third-order moments predicted

• All first-, second-, third- and fourth-order moments, subgrid-scale condensation and buoyancy based on the same probability distribution function

• A bulk microphysics scheme considering subgrid-scale variabilities has been developed and tested (Cheng and Xu 2008; in preparation)

Experiment Design

• Standard initial condition and forcing for GCSS ARM (continental shallow cumulus), BOMEX (shallow cumulus), ATEX (intermediate cloud regime) and ASTEX (stratocumulus) cases

• 2-D Domain; 256 km in horizontal direction; 4.5 km for ARM; 3 km for ATEX and BOMEX, and 1.5 km for ASTEX in vertical direction

• Resolution: 4 km in horizontal direction; 40 m for ARM, BOMEX and ATEX, and 25 m for ASTEX in vertical direction

• Momentum fluxes from IPHOC are not used

Cloud Evolution for BOMEX

(%)

Cloud Evolution for ARM

(%)

Mean Profile Averaged from 10h - 12h

Fluxes Averaged from 10h - 12h

Moments of w Averaged from 10h - 12h

Cloud Evolution for ATEX

(%)

Mean Profile Averaged over Last Hour

Fluxes Averaged Over Last Hour

Moments of w Averaged Over Last Hour

Cloud Evolution for ASTEX

(%)

Summary and Discussion

• An IPHOC has been implemented in VVCM and tested with major GCSS cases

• IPHOC is capable of simulating various PBL clouds with variable large-scale and radiative forcings using 4 km horizontal grid spacing

• Further improvement of the IPHOC is needed to capture the fine structure of the cloud fields simulated from benchmark LESs

• The LBA shallow-to-deep convective cloud transition case is under testing

Thank You!

Shallow Cumulus Clouds from the Focring of SP-CAM

Mean Profile Averaged over Last 40 Hour

Cloud Radiation Forcing