nrl post stratocumulus cloud modeling efforts
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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 - PowerPoint PPT PresentationTRANSCRIPT
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.
Surface heat, moisture, and momentum fluxes
Height
0 m
vθ
vθ
ilθ
vθ
Long wavecooling
Entrainment
Subsidence
Wind ShearDrizzle
Short waveheating
zi
Sea Spray/aerosols
Turbulence
Stratocumulus-toppedMarine Boundary Layer
''
''''''
lT
llwwv
w
qwqww
A is the total water fluxB is the liquid water fluxC is the liquid water potential temperature flux A, B, and C sum to D (the buoyancy flux 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.
CD
B
B DC
Hei
ght
(m)
D A B
C
Vertical Profiles of Thermodynamic Fluxes In a Stratocumulus-topped, Entraining Boundary Layer
The Wind Shear Impact on the Entrainment and Cloud Structure
Temperature Total water mixing ratio
Cloud Water
Aircraft observations on 8 July 1999 in Monterey Bay area in DECS (from Qing Wang)
u v Ltq
• 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?
The Wind Shear Impact on the Entrainment and Cloud Structure
e f g h
j k li
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)
COAMPS-LES Simulation
X=30m; Z=5-20m
• The intense wind shear enhances the TKE buoyancy consumption, decreases the liquid water content, and reduces the radiative cooling near the cloud top.
Strong ShearWeak ShearNo Shear
High-Resolution X=10m; Z=5m
Strong Shear
Wind Shear Impact on the Entrainment and Cloud Structure
No Shear Weak Shear Strong Shear
Inversion top Inversion base Cloud top
• 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.
Wind shear across the inversion significantly change the inversion layer characteristics
Inversion top and base are defined by
Cloud-top is defined by the level of the highest cloudy grid point.
2l
COAMPS-LES Simulations:
07Z29-07Z30
Diurnal Variation
7:00 AM Jul 29 – 7:00 AM Jul 30, 2007 (PDT)
Monterey Bay
Salinas Valley
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.
Bay Area Averaged Vertical MotionBay Area Averaged Potential
Temperature and Liquid Water
Diurnal Variation of Stratocumulus in Monterey Bay: COAMPS Simulation
Diurnal Variation
• 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 (http://www.cencoos.org)
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
Evaluation and Improvement of COAMPS Stratocumulus Simulation
COAMPS AOSN Real-Time Forecast
• http://www.nrlmry.navy.mil/coamps-web/web/mbay
• Grid 3 (3km) output are shown
• Surface, 3D fields and cross section
• Meteograms from 12 locations
Liquid water mixing ratio
Topography and Vertical Cross Sections
10 m Wind Vectors