19
To set the
Strike Reject Lvl
follow the steps below:
1. Press
Enter to begin changing the
Strike Reject Lvl
.
2. Press the
UP and DOWN arrows to select the new level.
3. Press
Enter or SAVE to save the new
Strike Reject Lvl
to the sensor.
4. Check the settings.
5. Follow the directions on the screen.
a. Change screens.
b. Recheck the saved settings.
3.10 BAROMETRIC SENSOR
The barometric pressure sensor is located behind the teflon screen next to the relative
humidity sensor. It measures the atmospheric pressure of the environment in which the
ATMOS 41 is deployed. With a range from 50 to 101 kPa, it is suitable for measurement
across a wide range of elevations, but keep in mind that the magnitude of sensor output will
depend chiefly on the installation altitude with subtle changes caused by weather.
3.11 TILT SENSOR
The ATMOS 41 is also equipped with a tilt sensor similar to those found in smartphones.
Although this sensor may be used to level the instrument, it is much easier to use the small
bubble level on the bottom of the anemometer plate. The primary use of the tilt sensor data
will be to ensure the ATMOS 41 remains level at all times. Regularly check x and y tilt data
to ensure the ATMOS 41 is level; if it has tilted, return to the site and level again. Even a few
degrees off level can cause errors in the rain and solar radiation measurements.
3.12 THEORY
The following sections explain the theory of wind speed, wind direction, and air
temperature measurements.
3.12.1 WIND SPEED AND DIRECTION
The theory behind the anemometer comes from Campbell and Unsworth (1979). The speed
c
(m/s) of sound in still air depends on air temperature
T
(K), vapor pressure
e
(kPa), and
atmospheric pressure,
p
(kPa), as shown in
.
Equation 3
.
.
c
T
P
e
20 067
1
0 32
=
+
c
m
