ontario sugar beet growers - Atrium - University of Guelph
ontario sugar beet growers - Atrium - University of Guelph
ontario sugar beet growers - Atrium - University of Guelph
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EVAPOTRANSPIRATION VALUES<br />
A comparison <strong>of</strong> calculated and measured reference evapotranspiration was made. A<br />
calculated reference evapotranspiration (ETo) was determined at each <strong>of</strong> the two research<br />
test sites, Location A and B using the standard meteorological weather information from<br />
the three closest MAWN (Michigan Automated Weather Network) sites at Fairgrove,<br />
Munger and Saginaw, (Fig. 1). The formulae used to calculate ETo was from the Priestly-<br />
Taylor model. These daily calculated ETo values were compared to the measured values<br />
using an Atmometer sensor located at the test sites. An Atmometer is an instrument with<br />
a porous membrane connected to a reservoir <strong>of</strong> water by a wicking mechanism that<br />
allows water to difhse to the atmosphere. By monitoring the volume <strong>of</strong> water lost, the<br />
user can obtain a measure <strong>of</strong> the evapotranspiration.<br />
Fig. 12 Atmometer to measure reference evapotranspiration @To). Photograph<br />
from Manufacture's web.<br />
Fig 13. ETo comparisons between the calculated values using weather station data<br />
and a direct measurement using an Atmometer Gauge.<br />
ET Comparison (Gauge vs. Calculated)<br />
I - ET Gauge - - - - Reif (MAWN) -- -- - Sylvester (MAWN) I<br />
C C C<br />
3 3 3<br />
777<br />
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