Simulation of crop evapotranspiration for an almond orchard using

27 Pages·2012·1.72 MB·English

Simulation of crop
evapotranspiration for an almond
orchard using the ACASA model
Matthias Falk
CSTARS, LAWR, UC Davis
Introduction
Advanced Canopy-Atmosphere-Soil Algorithm (ACASA)
ACASA uses fully diabatic, turbulent steady-state equations closed at the third order for
estimating energy and mass fluxes and profiles for each layer, placing it among the most
complex SVAT models.
GOALS
1. Test ACASA for an irrigated agricultural crop canopy such as almonds
2. Evaluate model performance by comparing simulated energy and mass exchanges
(flux densities) with long-term Eddy Covariance flux measurements
3. Validate the use of ACASA to show suitability as a surface layer scheme in WRF-
ACASA to provide more accurate estimates of spatial crop evapotranspiration (ETc)
QUESTION:
WHY DO WE NEED SO MUCH PHYSICS?

Location overview: (A) CIMIS Belridge and (B) Belridge Kc-testing EC tower site
Eddy-Covariance Tower at Belridge BE_004
Almonds, z = 5.5 meters, LAI ~ 1.5 m2m-2
c
Climate
ANNUAL CLIMATE DIAGRAMS FOR BELRIDGE CIMIS STATION (#146) FOR 2008 AND 2009
Monthly Values for Average Air Temperature (T ), Total Precipitation (Precip),
air
Average Incoming Solar Radiation (R ) and Total Reference Evapotranspiration (ET )
s o
CIMIS Belridge (# 146)
CIMIS Belridge (# 146)
50
50
ET Precip T R
750 o air solar 35 750 ETo Precip Tair Rsolar
35
30
30
25
C] 40 500 C] 40 500 25 mm]
oT [air Day] 20 mm] oT [air Day] 20 Pcp [
[Ly/ 15 [ R [Ly/s 15 ET, o
10
30 250 10
30 250
5
5
0
0
Jan 2009Feb 2009Mar 2009Apr 2009May 2009Jun 2009Jul 2009Aug 2009Sep 2009Oct 2009Nov 2009Dec 2009 Jan 2008Feb 2008Mar 2008Apr 2008May 2008Jun 2008Jul 2008Aug 2008Sep 2008Oct 2008Nov 2008Dec 2008
Month Year
Month Year
Climate
Belridge CIMIS Station (CIMIS #146)
Climate: Hot Semi-arid climate or Hot-Summer Mediterranean climate
Averages calculated for data from 1998 through 2010:
Annual Average Temperature: 17.26 oC
Average Annual Total Precipitation: 133.62 mm or 5.26 inches
Average Annual Total CIMIS ETo: 1495.98 mm or 58.9 inches
Annual Irrigation: 50+ in; so about 10x Precipitation
ACASA Description
10 Leaf Classes:
• 9 different leaf angles
• 1 shaded leaf
(not angle dependent)
ACASA Input
METEOROLOGY (hourly)
Temperature (T ),
air
Relative Humidty (RH),
Wind Speed (u),
Solar Radiation (R )
s
Precipitation (pcp)
Pressure (p) ~ const.
CO -Concentration (CO ) ~ const.
2 2
Downwelling Longwave Radiation (L ) – modeled
d
NEW: Leaf Area Index (LAI(t))
ACASA Input
Morphology
3600.0 !deltat1 REAL time step length (s) [900,7200]
35.509 !zlatude REAL latitude (oN) [-90,90]
8760 !ntimesteps INTEGER total number of time steps in forcing dataset [any]
1 !needtinf INTEGER ?need input downward LW radiation?(1='yes',0='no') [0,1]
1 !ihumid INTEGER ?is input humidity relative(RH%)?,1='yes', RH(%)-->(g kg-1); 0='units (g kg-1) already' [0,1]
1 !iprint7 INTEGER ?extra output? 1='yes', 0='no'
8 !isoi3 INTEGER soil type (USDA 16 classification) [1,16]
4 !nsoil0 INTEGER total number of soil layers [4,20]
3 !nroot INTEGER total number of active root layers (KEEP <= nsoil !!!)
0.25 !zs19 REAL soil layer width (m) [0.1,0.5]
0.1 !zmoi REAL wilting point soil moisture (m3 m-3) [0.10,0.25]
277 !tsinit REAL initial soil temperature (K) /all layers [earth-normal 150,350]
0.2 !qsinit REAL intial soil moisture (m3 m-3) /all layers [0.05, 0.50]
1.5 !xlai7 REAL total Leaf Area Index (LAIgreen) (m2 m-2 1-sided) [0,15]
3 !lveg INTEGER canopy architecture index:1=coniferous,2=grass;3=temperate-deciduous,4=tropical-primary,5=disturbed/mixed --,[1,5] sets
170. !xrsmn9 REAL Vcmax_25 (maximum RuBisCO) (umol m-2 s-1) [10, 100]
0.01 !drx9 REAL mean leaf/canopy element drag coefficient [0.01-dense_urban,0.15-furry_vegetation]
0.05 !pv09 REAL leaf PAR reflectivity (0.3-0.7 micron wavelength) [0.05, 0.5]
0.30 !pr09 REAL leaf NIR reflectivity (0.7-2.0 micron wavelength) [0.05, 0.5]
0.35 !pv09g REAL ground bkg. PAR reflectivity (0.3-0.7 micron wavelength) [0.05, 0.5]
0.35 !pr09g REAL ground bkg. NIR reflectivity (0.7-2.0 micron wavelength) [0.05, 0.5]
6.5 !standage REAL canopy height, 90%ile, (m) [0.5, 300.0]
0.00 !popdens REAL human population density (people/m2) [0-.02]