summer school rio de janeiro march 2009 5. modeling maritime pbl amauri pereira de oliveira group of...
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Summer SchoolRio de JaneiroMarch 2009
5. MODELING MARITIME PBL
Amauri Pereira de Oliveira
Group of Micrometeorology
2
Topics
1. Micrometeorology
2. PBL properties
3. PBL modeling
4. Modeling surface-biosphere interaction
5. Modeling Maritime PBL
6. Modeling Convective PBL
3
Modeling Maritime PBL
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Maritime PBL
Sjöblom, A. and Smedam, A.S., 2003: Vertical structure in the marine atmospheric boundary layer and its implication for the inertial dissipation method, Boundary-Layer Meteorology, 109, 1-25
•Inertial layer;•Roughness layer.
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What is going on beneath the ocean surface
Thorpe, S.A., 2004: Recent developments in the study of ocean turbulence. Ann. Rew. Earth Planet. Science., 32, 91-102.
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Oceanic mixed layer
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Air-Sea Interaction
Edson et al., 1999: Coupled Marine Boundary Layers and Air-Sea Interaction Initiative: Combining Process Studies, Simulations, and Numerical Models.
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Some important discrepancies
Wainer, et al., 2003: Intercomparison of Heat Fluxes in the South Atlantic. Part I: The Seasonal Cycle. Journal of Climate.
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Convective PBL over Cabo Frio
• Cabo Frio – upwelling area• Upwelling - Stable PBL• Cold Front passage disrupt upwelling • Upwelling give place to a downwelling• Dowelling - Convective PBL
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References
Dourado, M.S. and Oliveira, A.P., 2008: A numerical investigation of the atmosphere-ocean thermal contrast over the coastal upwelling region of Cabo Frio , Brazil, Atmosfera , 21(1) ,13-34.
Dourado, M., and Oliveira, A.P., 2001: Observational description of the atmospheric and oceanic boundary layers over the Atlantic Ocean. Revista Brasileira de Oceanografia, 49, 49-64.
Available at:
http://www.iag.usp.br/meteo/labmicro
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Cabo Frio upwelling
SST
AVHRR NOAA(Dutra et al. 2006, XV CBMET)
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Upwelling Downwelling
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Cold Front July 6, 21GMT
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Cold Front
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upwellingdownwellin
g
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Second Order Closure Model
Oceanic mixed layer model
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Mean equations
z
´w´u)vV(f
t
uG
z
´w´v)uU(f
t
vG
z
R
cρ
1
z
´w'θ
t
θ N
P
vV
z
´w´q
t
q
Momentum
Thermodynamic
Specific Humidity
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Second Order Closure Model
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Oceanic Mixed Layer Model
(i) The turbulent mixing is strong enough so that upper ocean is characterized by a mixed layer where the temperature does not vary in the vertical direction;
(ii) Transition layer between the mixed layer and the stratified non turbulent ocean bellow is much smaller than the mixed layer so that the vertical variation of temperature can be indicated by a temperature jump;
(iii) The energy required to sustain turbulent mixing is provided by convergence of the vertical flux of TKE.
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Oceanic Mixed Layer Model
Mixed layer
ocean
atmosphere
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Oceanic Mixed Layer ModelTemperature (To)
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Derivation of OML Temperature equation
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Oceanic Mixed Layer Modeldepth (h) and temperature jump
(ΔT)
BT
0T13*1
Tαg
´w´TαgBhνA
h
1
td
hd
h
1´w´TII
cρ
1
td
hd
h
T
td
)T(d0Nh0N
ww
BB
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Turbulent heat flux effects
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Boundary (coupling) conditions
ww
000N0N0
c
LEHIR´w´T
Energy
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Oceanic Mixed Layer
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**P00 θucρH
**e00 quLρLE
Atmospheric turbulent fluxes
CH, CE and CD are transfer coefficient of sensible, latent and momentum (drag coefficient).
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Atmospheric turbulent fluxes
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Radiation balance at the surface
00000N LWULWDSWUSWDR
ZcosISWD 00
00 SWDSWU
Short wave down
Short wave up
Zcos2.06.0
rZtan
rZtan
rZsin
rZsin50.0
2
2
2
2
Broadband transmissivity
Albedo
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Radiation balance at the surface
Long wave contribution
Long wave up
Long wave down
ε = 0.98 Surface emissivity
a = 0.52 and b = 0.064
4000 TσεLWU
4RR0 Tσ)eba(LWD
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Boundary and coupling conditions
w0** u Stress
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MIXING LAYER MODEL CLOSURE
w
pe
zw
g
zd
vdwv
zd
udwu
t
e
00
Applying TKE equation to transition layer
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MIXING LAYER MODEL CLOSURE
i
0i0
wp
ez
wg
0
In the interface
Dimensional analysis
hw
pe
z
3
w
i0
hg
1w
3
w
0
i
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MIXING LAYER MODEL CLOSURE
1. Stationary:
2. Shear production, molecular dissipation and pressure term are neglected in transition layer is neglected because:
0t
e
0zd
udwu
zd
udwu
0
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Mixing Layer Model
TransitionLayer
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i)w(t
h
hh
h
h
)w()w(zdt
Thermodynamic Equation
Limit 0
z
)w(
t
ewt
h
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MIXING LAYER MODEL CLOSURE
hg
1w
3
w
0
i
2.0w
3
*
3
w
Thermal mixing Mechanical Mixing
3*
3w uA
hwg
w 0
0
3
*
gh
uAw 0*
i
0i w2.0w
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Stable and Convective Run
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Upwelling – Stable PBL
Downwelling - Convective PBL
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Upwelling – Stable PBL
Downwelling - Convective PBL
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Upwelling – Stable PBL
Downwelling - Convective PBL
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Upwelling – Stable PBL
Downwelling - Convective PBL
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PBL Time Evolution
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Fluxes and Variances
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46
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Observations
• FluTuA– Campaign May 2002– Campaign December 2008
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FluTuAObservational campaign May
2002
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Bacellar, S., Oliveira, A. P., Soares, J., and Servain, J., 2009:
Assessing the diurnal evolution surface radiation balance over the
Tropical Atlantic Ocean using in situ measurements carried out
during the FluTuA Project. Meteorological Application.
http://dx.doi.org/10.1002/met.111
Available at:
http://www.iag.usp.br/meteo/labmicro/index_arquivos/Page779.htm
References
50
Surface Emissivity
ε = 0.97 Surface emissivity
ε = 0.97
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Broadband atmospheric transmissivity
Zcos3.05.0
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Surface albedo
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Net radiation
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Comparison with satellite estimate (SRB/NASA project)
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Conclusion
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Flutua 2008
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Archipelago St Peter and St Paul
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Air Temperature and SST
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Turbulence – Nighttime conditions (20 Hz)
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Turbulence – Daytime Conditions (20 Hz)
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http://www.iag.usp.br/meteo/labmicro
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