MONITORING STATION INSTRUMENTATION AND MEASUREMENTS - Wind Resource Assessment: A Practical Guide to Developing a Wind Project - page 48

Table 4-5. Derived statistics for basic and additional parameters

Measurement parameters Recorded values

Wind speed, m/s Average, standard deviation, min/max

Wind direction, degrees Average, standard deviation, max gust direction

Temperature, ◦ C Average, min/max

Solar radiation, W/m 2 Average, min/max

Vertical wind speed, m/s Average, standard deviation, min/max

Barometric pressure, kPa Average, min/max

Delta temperature, ◦ C

Average, min/max

Relative humidity, % Average, min/max

speeds. Averages are used in reporting wind speed variability, as well as wind speed
and direction frequency distributions.

4.3.2 Standard Deviation
The standard deviation should be determined for both wind speed and wind direction
and is defined as the population standard deviation ( ) for all 1- or 2-s samples within

each 10-min interval. The standard deviations of wind speed and wind direction are
indicators of turbulence. They are also useful for detecting suspect or erroneous data.

σ

4.3.3 Maximum and Minimum
The maximum and minimum values observed during each interval should be recorded
for all parameters. This is especially important for the maximum 3-s gust (speed),
which can affect whether a particular turbine model is deemed suitable for the site. If
possible, the coincident directions corresponding to the maximum and minimum wind
speeds should also be recorded.

4.4 DATA LOGGERS

Data loggers (or data recorders) have evolved from dials and strip charts read by
a person to a variety of digital stand-alone devices. Many manufacturers now offer
complete data-logging systems that include integrated data storage and transfer options
(Fig. 4-8).
All data loggers store data locally, and many can transfer the data to another location
through cellular telephone, radio frequency (RF) telemetry, or satellite link. Remote
data transfer allows the user to obtain and inspect data without making frequent site
visits and also to verify that the logger is operating correctly. Section 4.6 provides
detailed information on data transfer equipment options.
The data logger must be compatible with the sensor types employed and must be
able to support the desired number of sensors, measurement parameters, and sampling