model validation: flux sites
DESCRIPTION
Model validation: flux sites. - NOAA/ATDD-Tilden Meyers flux data sets - Components of the surface energy budget: ( incoming/outgoing short/longwave radiation , latent , sensible , ground heat flux), plus meteorological observations and sub-surface temperature and soil mositure - PowerPoint PPT PresentationTRANSCRIPT
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Model validation: flux sites- NOAA/ATDD-Tilden Meyers flux data sets
- Components of the surface energy budget:(incoming/outgoing short/longwave radiation,latent, sensible, ground heat flux), plusmeteorological observations and sub-surfacetemperature and soil mositure
- 11 measurement sites across CONUS
- 2+ years of data available (at NCEP)
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NOAA/ATDD Surface Flux Network
FP
BV,BP
AZWB,CH
SFBH
MO
GC
CV
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NCEP model vs obsMAY 2007
average fluxes
Ft. Peck, MT
H LE
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MAY 2007 avg. H, NCEP model vs obs
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MAY 2007 avg. LE, NCEP model vs obs
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LST verification 07May2006
300
310
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LST verification May2006 Mean
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For a fully-vegetated surface:
Ch = exchange coefficient (=1/ra)
rs = canopy resistance (inverse canopy cond.)
Using surface fluxes to evaluateland-surface physics formulations
and parametersSensible heat flux (bulk aerodynamic form):
H = cpCh(Tsfc - Tair)Latent heat flux (i.e. Penman-Monteith form):
_______________________LE = (Rn-G) + cp(esfc - eair)/ra
+ (1+rs/ra)
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Transpiration processes/parameters:
...e.g., effect of vapor pressure deficit on canopy conductance:
· Better NLDAS results with new VPD option (next pages)
cano
py c
ondu
ctan
ce (
cm/s
)
Vapor pressure deficit (mb)
soy beans(C3)
corn (C4)
Bondville, Ill. flux siteJULY 2006
T>20C,SWDN>600W/m2
current Noah
test Noah
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From Chen et al. 1996
Using a narrow range of this tends to overestimate the evaporation during wet periods (spring) and underestimate the evaporation during dry periods (summer).
SMHIGH and SMLOW
BXEXP
To reduce low LH biases during the SummerVapor pressure deficit function
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Experimental Design ARM/CART sites • Oklahoma Mesonet sites
• CONTROL• TEST:Seasonal LAI
Root Fraction
Vapor Pressure Deficit Function
SIMULATION PERIOD: OCT 1996 - SEP 1999
ARM/CART
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Averaged over 24 ARM/CART sites CONTROL
TEST