Section 7. Installation
191
often included to zero the measurement when it equals the offset so that
WindVector()
can reject measurements when wind speed is zero.
Standard deviation can be processed one of two ways: 1) using every sample
taken during the data storage interval (enter
0
for the
Subinterval
parameter), or 2)
by averaging standard deviations processed from shorter sub-intervals of the data-
storage interval. Averaging sub-interval standard deviations minimizes the effects
of meander under light wind conditions, and it provides more complete
information for periods of transition (see EPA publication "On-site
Meteorological Program Guidance for Regulatory Modeling Applications").
Standard deviation of horizontal wind fluctuations from sub-intervals is calculated
as follows:
where:
is the standard deviation over the data-storage interval, and
are sub-interval standard deviations. A sub-interval is
specified as a number of scans. The number of scans for a sub-interval is given
by:
Desired
sub
‐
interval
(secs)
/
scan
rate
(secs)
For example, if the scan rate is 1 second and the data interval is 60 minutes, the
standard deviation is calculated from all 3600 scans when the sub-interval is 0.
With a sub-interval of 900 scans (15 minutes) the standard deviation is the
average of the four sub-interval standard deviations. The last sub-interval is
weighted if it does not contain the specified number of scans.
The EPA recommends hourly standard deviation of horizontal wind direction
(sigma theta) be computed from four fifteen-minute sub-intervals.
7.8.5.2.1 Measured Raw Data
•
S
i
: horizontal wind speed
•
Θ
i
: horizontal wind direction
•
Ue
i
: east-west component of wind
•
Un
i
: north-south component of wind
•
N: number of samples
7.8.5.2.2 Calculations
Mean Wind Vector
Resultant
mean
horizontal
wind
speed,
Ū
:
Содержание CR850
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Страница 26: ...Table of Contents 26...
Страница 30: ...Section 2 Cautionary Statements 30...
Страница 32: ...Section 3 Initial Inspection 32...
Страница 35: ...Section 4 Quickstart Tutorial 35 Figure 2 Wiring panel...
Страница 55: ...Section 4 Quickstart Tutorial 55 Figure 24 PC200W View data utility...
Страница 78: ...Section 5 System Overview 78...
Страница 80: ...Section 6 CR800 Specifications 80...
Страница 95: ...Section 7 Installation 95 Figure 35 DevConfig OS download window Figure 36 Dialog box confirming OS download...
Страница 104: ...Section 7 Installation 104 Figure 43 Include File settings via DevConfig Figure 44 Include File settings via PakBusGraph...
Страница 267: ...Section 7 Installation 267 Figure 84 Running average signal attenuation...
Страница 268: ...Section 7 Installation 268...
Страница 384: ...Section 8 Operation 384 Figure 113 Using the keyboard display...
Страница 385: ...Section 8 Operation 385 8 8 1 Data Display Figure 114 Displaying data with the keyboard display...
Страница 387: ...Section 8 Operation 387 Figure 116 Real time custom...
Страница 388: ...Section 8 Operation 388 8 8 1 3 Final Storage Tables Figure 117 Final storage tables...
Страница 389: ...Section 8 Operation 389 8 8 2 Run Stop Program Figure 118 Run Stop Program...
Страница 390: ...Section 8 Operation 390 8 8 3 File Display Figure 119 File display...
Страница 396: ...Section 8 Operation 396...
Страница 402: ...Section 9 Maintenance 402...
Страница 450: ...Section 11 Glossary 450...
Страница 504: ...Appendix A CRBasic Programming Instructions 504...
Страница 526: ...Appendix B Status Table and Settings 526...
Страница 530: ...Appendix C Serial Port Pinouts 530...
Страница 536: ...Appendix E FP2 Data Format 536...
Страница 550: ...Appendix F Other Campbell Scientific Products 550...
Страница 564: ...Index 564 WriteIO 464 Writing Program 108 X XML 448 XOR 473 Y Y intercept 141 142 Z Zero 155 166 Zero Basis 151...
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