Campbell Scientific CNR2 Radiometer - Manual (Page 12)

CNR2 Net Radiometer
can be determined by simply comparing the results of single-ended and
differential measurements made under the same conditions.
6.1 Calibration Factor
Each CNR2 is shipped with a ‘Certificate of Calibration’ by the manufacturer
that shows the sensor serial number and ‘sensitivity’, or calibration factor.
The serial number and sensitivity are also shown on a label attached to the
sensor.
The calibration factor is in units of μV/(W m -2 ), which needs to be converted
to units of (W m -2 )/mV for the multiplier parameter in the datalogger program.
To determine the multiplier, divide the calibration factor into 1000. For
example, if the calibration factor is 22.0 for short-wave radiation and 11.6 for
long-wave radiation, the multipliers are:
Short Wave: 1000/22.0 μV/(W m -2 ) = 45.46 (W m -2 )/mV
Long Wave: 1000/11.6 μV/(W m -2 ) = 86.21 (W m -2 )/mV
6.2 Example Programs
6.2.1 Example Program for CR1000 Datalogger
'CNR2 Net Radiometer program for CR1000 datalogger
'*** Wiring ***
'1H Short wave signal (white)
'1L Short wave signal reference (blue)
'2H Long wave signal (brown)
'2L Long wave signal reference (black)
'gnd Shield (clear)
‘Declare Constants
Const CNR2_SW_CAL = 45.46
'Unique multiplier for CNR 2 net SW radiation (1000/sensitivity).
Const CNR2_LW_CAL = 86.21 'Unique multiplier for CNR 2 net LW radiation (1000/sensitivity).
'Declare Variables and Units
Public Net_Shortwave
Public Net_Longwave
Public Net_Rad
Units Net_Shortwave=Wm-2
Units Net_Longwave=Wm-2
Units Net_Rad=Wm-2
'Define Data Tables
DataTable(Table1,True,-1)
DataInterval(0,60,Min,10)
Minimum(1,Net_Shortwave,IEEE4,False,True)
Maximum(1,Net_Shortwave,
IEEE4,False,True)
Average(1,Net_Shortwave, IEEE4,False)
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