CR200/CR200X Series Dataloggers - Campbell Scientific
CR200/CR200X Series Dataloggers - Campbell Scientific
CR200/CR200X Series Dataloggers - Campbell Scientific
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Section 11. Programming Resource Library<br />
For most applications, total power usage of 318 mA for 15 seconds is not<br />
excessive, but if 16 probes were wired to the same SDI-12 port, the resulting<br />
power draw would be excessive. Spreading sensors over several SDI-12<br />
terminals will help reduce power consumption.<br />
11.5 Wind Vector<br />
11.5.1 OutputOpt Parameters<br />
In the <strong>CR200</strong>(X) WindVector () instruction, the OutputOpt parameter is used to<br />
define the values which are stored. All output options result in an array of<br />
values, the elements of which have "_WVc(n)" as a suffix, where n is the<br />
element number. The array uses the name of the Speed/East variable as its base.<br />
TABLE. OutputOpt Options (p. 120) lists and describes OutputOpt options.<br />
Table 16. OutputOpt Options<br />
Option<br />
0<br />
Description (WVc() is the Output Array)<br />
WVc(1): Mean horizontal wind speed (S)<br />
WVc(2): Unit vector mean wind direction (Θ1)<br />
WVc(3): Standard deviation of wind direction σ(Θ1). Standard deviation is calculated using the Yamartino<br />
algorithm. This option complies with EPA guidelines for use with straight-line Gaussian dispersion models<br />
to model plume transport.<br />
1 WVc(1): Mean horizontal wind speed (S)<br />
WVc(2): Unit vector mean wind direction (Θ1)<br />
2 WVc(1):Resultant Mean horizontal wind speed (Ū)<br />
WVc(2): Resultant mean wind direction (Θu)<br />
WVc(3): Standard deviation of wind direction σ(Θu). This standard deviation is calculated using <strong>Campbell</strong><br />
<strong>Scientific</strong>'s wind speed weighted algorithm. Use of the resultant mean horizontal wind direction is not<br />
recommended for straight-line Gaussian dispersion models, but may be used to model transport direction in<br />
a variable-trajectory model.<br />
11.5.2 Wind Vector Processing<br />
WindVector () processes wind speed and direction measurements to calculate<br />
mean speed, mean vector magnitude, and mean vector direction over a data<br />
storage interval. Measurements from polar (wind speed and direction) or<br />
orthogonal (fixed East and North propellers) sensors are accommodated. Vector<br />
direction and standard deviation of vector direction can be calculated weighted<br />
or unweighted for wind speed.<br />
When a wind speed measurement is zero, WindVector () uses the measurement<br />
to process scalar or resultant vector wind speed and standard deviation, but not<br />
the computation of wind direction.<br />
120