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Thermal Radiation and Energy Closure Assessment
Figure 5.6a and b shows for the same day and time period raw 20-Hz time series
for air temperature, and water vapor concentration, respectively. Here, we can observe
that under, stable conditions, the temperature and water vapor concentrations are
inversely related. Decreasing temperature with time can be observed with increasing
water vapor concentration from the IRGA (see highlighted sections in Figure 5.6). At
1900 h, the available energy is minimal, but the advection of saturation deficit or H is
still considerable (–71 W m –2 ) and is driving the humidification of the air above the
cotton canopy (decreasing temperature while increasing water vapor concentration).
Energy extracted from the overlying advected air evaporates water at the surface,
(a)
(b)
1 31 61 91 121 151 181 211 241 271 301 331 361 391 421 451 481
Time: 0.05 s
1 31 61 91 121 151 181 211 241 271 301 331 361 391 421 451 481
Time: 0.05 s
Temp (°C)
ρ
v (kg m –3
)
30.0
30.5
31.0
31.5
32.0
32.5
33.0
13.8
14.3
14.8
15.3
15.8
16.3
16.8
17.3
17.8
FIGURE  5.7  July 27, 2008, 1300 hours (unstable conditions), 25 s of instantaneous raw
20-Hz air temperature (a) and water vapor concentration (b) data.