RAWS-H Remote Automated Weather Station
station. More difficult maintenance, such as sensor calibration, sensor
performance testing (i.e., bearing torque), and sensor component replacement,
generally requires a skilled technician, or send the instrument to Campbell
Scientific. A station log should be maintained for each weather station that
includes equipment model and serial numbers and maintenance that was
performed.
Consult the equipment manual for routine maintenance
procedures.
NOTE
Contact Campbell Scientific, Inc., phone (435) 227-9000, for a
RMA number before returning sensor or equipment for service.
NOTE
8. References
8.1 RAWS Orientation
8.1.1 Determining True North and Sensor Orientation
Orientation of the wind direction sensor is done after the datalogger has been
programmed and the location of True North has been determined. True North
is usually found by reading a magnetic compass and applying the site-specific
correction for magnetic declination; where the magnetic declination is the
number of degrees between True North and Magnetic North. Magnetic
declination for a specific site can be obtained from a USGS map, local airport,
or through the web calculator offered by the USGS (Section 8.1.2). A general
map showing magnetic declination for the contiguous United States is shown
in Figure 8.1-1.
Declination angles are always subtracted from the compass reading to find
True North. A declination angle East of True North is reported as positive a
value and is subtracted from 360 (0) degrees to find True North as shown
Figure 8.1-2. A declination angle West of True North is reported as a negative
value and is also subtracted from 0 (360) degrees to find True North as shown
in Figure 8.1-3. Note that when a negative number is subtracted from a
positive number, the resulting arithmetic operation is addition.
For example, the declination for Longmont, CO is 10.1
°
, thus True North is
360
°
- 10.1
°
, or 349.9
°
as read on a compass. Likewise, the declination for Mc
Henry, IL is -2.6
°
, and True North is 0
°
- (-2.6
°
), or 2.6
°
as read on a compass.
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