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3
The water column (WC) above the CTD-Diver can be expressed as:
WC = 9806.65
p
Diver
−p
baro
ρ∙g
(1)
where p is the pressure in cmH
2
O, g is the acceleration due to gravity (9.80665 m/s
2
) and
ρ
is the
density of the water (1,000 kg/m
3
).
The water level (WL) in relation to the vertical reference datum can be calculated as follows:
WL = TOC − CL + WC
(2)
By substituting WC from equation (1) in equation (2) we obtain:
WL = TOC − CL + 9806.65
p
Diver
−p
baro
ρ∙g
(3)
1.3.2
Calculating the Cable Length from a Manual Measurement
If the cable length is not exactly known, it can be determined using a manual measurement, see the
figure below. The manual measurement (MM) is taken from the top of casing to the water level. The
value of the water level is positive unless, in exceptional circumstances, the water level is situated
above the top of casing.
The cable length can now be calculated as follows:
CL = MM + WC
(4)
where the water column (WC) is calculated based on the measurements taken by the CTD-Diver and
the Baro-Diver.
Notes:
•
If the pressure measured by the CTD-Diver and the Baro-Diver is measured at different points
in time, it is necessary to interpolate. The Diver-Office software automatically performs this
interpolation.
•
It is possible to enter manual measurements into the Diver-Office software. The software
subsequently automatically calculates the cable length.
Example
The top of casing is measured to be 150 cm above the Mean Seal Level (MSL): TOC = 150 cm.
The cable length is not exactly known and therefore a manual measurement is taken. It turns
out to be 120 cm: MM = 120 cm.
Summary of Contents for CTD-Diver DI28 Series
Page 1: ...CTD Diver DI28x Series...
