1. NRL POST Stratocumulus Cloud Modeling Efforts
Shouping Wang, William Thompson, Tracy Hack and Yi Jin
Research issues
Wind shear impact on the entrainment and cloud structure
Stratocumulus diurnal variation in Monterey Bay area
Evaluation and improvement of stratocumulus simulation of COAMPS
Evaluation of thermodynamic fluxes in stratocumulus
Approaches
COAMPS-LES and COAMPS mesoscale modeling
Data analysis and comparison with model output
COAMPS real time forecast
Close collaboration with other PIs.

2. Stratocumulus-topped Marine Boundary Layer
Surface heat, moisture,
and momentum fluxes
Height
0 m
Long wave
cooling
Entrainment
Subsidence
Wind Shear
Drizzle
Short wave
heating zi
Sea Spray/aerosols
Turbulence

3. Vertical Profiles of Thermodynamic Fluxes In a
Stratocumulus-topped, Entraining Boundary Layer D A B
100
200
300
400
500
600
700
800
900
1000
-.050
0.0
.050
-.025
.025
12 h forecast profiles of buoyancy flux components for point2. C D B
Height (m) C
A is the total water flux
B is the liquid water flux
C is the liquid water
potential temperature
flux
A, B, and C sum
to D (the buoyancy flux

4. The Wind Shear Impact on the Entrainment and Cloud Structure
Aircraft observations on 8 July 1999 in Monterey Bay area in DECS (from Qing Wang)
Temperature
Total water mixing ratio
Cloud Water
Strong wind shear exists at the top of clouds due to topography and land-sea contrast
What is the effect of the intense wind shear on the entrainment?
How does the wind shear affect the inversion structure?
what is the response of turbulence and cloud structure to the wind shear?

5. The Wind Shear Impact on the Entrainment and Cloud Structurej k l i
Buoyancy Production (m2 s-3)
Shear Production
(m2 s-3)
Radiative Heating
(K h-1)
Qc (g kg-1)
Theta-L (K)
Qt (g kg-1)
U (m s-1)
V (m s-1) e f g h
COAMPS-LES Simulation
X=30m; Z=5-20m
Strong Shear
Weak Shear
No Shear
High-Resolution X=10m; Z=5m
Strong Shear
The intense wind shear enhances the TKE buoyancy consumption, decreases the liquid water content, and reduces the radiative cooling near the cloud top.

6. Wind Shear Impact on the Entrainment and Cloud Structure
Wind shear across the inversion significantly change the inversion layer characteristics
No Shear
Weak Shear
Strong Shear
COAMPS-LES Simulations:
Inversion top
Inversion base
Cloud top
Inversion top and base are defined by
Cloud-top is defined by the level of the highest cloudy grid point.
The entrainment mixing is enhanced by the wind shear;
A separation between the cloud top and inversion top is produced;
This separation layer thickness is proportional to the intensity of the wind shear.
Data need: soundings, entrainment zone, surface and cloud layer turbulence and cloud microphysics.

7. 07Z29-07Z30
7:00 AM Jul 29 – 7:00 AM Jul 30, 2007 (PDT)
Diurnal Variation
Monterey Bay
Salinas Valley

8. Bay Area Averaged Potential Temperature and Liquid Water
Diurnal Variation of Stratocumulus in Monterey Bay: COAMPS Simulation
Bay Area Averaged Potential Temperature and Liquid Water
Bay Area Averaged Vertical Motion
Diurnal Variation
The cloud diurnal variation is caused by the diurnal change in mesoscale vertical motion, which is produced by the topography and the land surface diurnal heating.
Data need: Soundings (above and within PBL), surface and cloud layer turbulence and cloud microphysics during day and night if possible.

9. Evaluation and Improvement of COAMPS Stratocumulus Simulation
Focus
 Entrainment, PBL height, cloud water, mesoscale variability.
Data need: Soundings (above and within PBL), surface and cloud layer turbulence and cloud microphysics
Turbulent fluxes, variances at various levels
Liquid water content, droplet number concentration, drizzle rate, SST, LW and SW fluxes
COAMPS real time forecast (James Doyle)
originally performed for AOSN (Adaptive Ocean Sampling Network) field campaign in the vicinity of Monterey Bay; now supported by CeNCOOS (
can be used for POST field program;
has three grids (27, 9, 3km) and 40 levels;
produces 48 hours forecast output presented in a NRL website
Diurnal Variation

10. COAMPS AOSN Real-Time Forecast
Liquid water mixing ratio
Topography and Vertical Cross Sections
10 m Wind Vectors
Grid 3 (3km) output are shown
Surface, 3D fields and cross section
Meteograms from 12 locations