OBS-3A Turbidity and Temperature Monitoring System
•
Water Density
Specify the water temperature and salinity. The specified temperature and
salinity only affect the depth calculation. They do not influence
temperature or salinity measurements.
•
Wave Setup
Wave Setup fields are only enabled when Depth is selected under
Sensor Measurements and the Depth Statistics is set to Depth,
Hs, Ts.
NOTE
o
Record Length
When wave measurements are selected, this sets the time in seconds
for which depth measurements are made for the wave-spectral
computations.
Use a record length of 512 seconds for inshore waters (lakes and
rivers), protected bays and estuaries. For coastal waters with
intermediate periods (6 to 9 seconds) use 1024 seconds. For the open
ocean select a record length of 2048 seconds to record long period
waves (Ts > 10 seconds).
o
Record Rate
Rate is the frequency of sampling for the duration of measurements.
All sensors are sampled at the same rate, typically 2, 5, 10, or 25 times
per second (Hz). For example, a rate of 25 Hz for a 60-second
duration will produce a sample with 1500 measurements for each
sensor.
o
Depth
This is the user’s best estimate of the water depth when the OBS-3A
is deployed. It is an initial value needed by the unit to compute wave
heights and correct for the attenuation of dynamic pressure with
depth. When depth is specified in the Wave Setup box, the OBS-3A
automatically measures height above bottom after reaching the
deployment depth.
o
Height Above Bottom
This is distance above the bottom in meters or feet where the OBS-3A
will come to rest after it is deployed. It is an alternative initial value
used by the unit to correct for pressure attenuation. When height
above bottom is selected, depth is automatically computed once the
unit has come to rest.
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