Agriculture Reference
In-Depth Information
100
Paragominas (Brasil), 2007
DOY - 95
80
DOY - 99
60
40
20
0
(c)
-20
0
4
8
12
16
20
24
Local time (hours)
Figure 9. Daily variation of latent heat flux for DOY 65, 69, 79, 83, 87, 91, 95 and 99 obtained by the
LAPS scheme over a soybean field in Paragominas (Brasil) during its growing season in 2007.
Figure 9 depicts diurnal variation of the latent heat flux for DOY 65, 69, 79, 83, 87, 91,
95 and 99 in Paragominas (Brasil). The evaporation during these days usually comes from the
bare soil fraction since the fractional cover was still not so large. Also the humidity was very
high. Therefore, the maximum amount of total evaporation is small not exceeding value of
100 Wm
-2
.
The forcing data for simulation of latent heat flux, over a soybean during its growing
season, were taken from the micrometeorological measurement program over a soybean field,
that was located in Marchfeld plain, an area of intensive arable agricultural production north-
east of Vienna. The soil is loamy sand and sandy silt loam, which is typical for the Marchfeld
region. The soybean was grown at the experimental site on a 100 x 50 m plot with rows
oriented north to south. The plant population was sown with 0.5 m row spacing and 0.07
spacing in the row (50 plants per m²). More details of the experimental setup can be found in
[47]. We run the LAPS for the DOY 150-240. For that period the canopy height
H
, and leaf
area index were derived from the measurements using the cubic spline interpolation. The
fractional vegetation cover
σ
f
was derived from
LAI
using the relationship,
σ
f
= 1-e
-cLAI
where
the coefficient
c
is set to 0.6 which is appropriate for soybean crops. All other aerodynamic
parameters are derived accordingly. Temporal variation of latent heat flux for DOY 150-240
obtained by the LAPS scheme compared with the observations over a soybean field at
Marchfeld (Austria) during its growing season in 1995 is given in Figure 10.
Figure 11 depicts the soil moisture simulation of the top 0.1 m, 0.5 m and 1.6 m,
respectively over the year obtained by the LAPS scheme It is seen that the during growing
season the variations of the soil moisture in the top 0.1 m are less smoother than in two other
top layers. This is because the first, the thin layer (0.1 m thin) has more instantaneous
response on the input/output water comparing with two other layers.
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