Campbell CNR1 User manual

CNR1 Net Radiometer
Revision: 5/11
Copyright © 2000-2011
Campbell Scientific, Inc.

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CNR1 Table of Contents
PDF viewers note: These page numbers refer to the printed version of this document. Use
the Adobe Acrobat® bookmarks tab for links to specific sections.
1. General Description.....................................................1
2. Sensor Specifications .................................................1
2.1 CNR1 Specifications ................................................................................1
2.2 CM3 Specifications ..................................................................................2
2.3 CG3 Specifications ...................................................................................3
3. Installation....................................................................3
3.1 Connecting and Using the Heater .............................................................5
4. Using the CNR1 in the Four Separate
Components Mode (4SCM).................................... 5
4.1 Measuring Solar Radiation with the CM3 ................................................5
4.2 Measuring Far Infrared Radiation with the CG3 ......................................6
4.3 Measuring the CNR1’s Temperature with the Pt-100 ..............................6
4.4 Calculation of the Albedo for Solar Radiation .........................................7
4.5 Calculation of the Net Solar Radiation (Net Short-Wave) .......................7
4.6 Calculation of the Net Infrared Radiation (Net Long-Wave) ...................7
4.7 Calculation of the Net (total) Radiation....................................................8
5. Wiring............................................................................ 8
6. Datalogger Programming..........................................11
6.1 Calibration Factor ...................................................................................12
6.2 Example Programs..................................................................................12
6.2.1 Example 1, CR1000 Using Differential Channels ........................12
6.2.2 Example 2, CR5000 Using Differential Channels (no 4WPB100)14
6.2.3 Example 3, CR23X Program Using Differential Channels...........17
6.2.4 Example 4, CR23X Program Using Single-Ended Channels .......20
7. Calibration ..................................................................22
8. Troubleshooting ........................................................23
8.1 Testing the CM3 .....................................................................................23
8.2 Testing of the CG3 .................................................................................24
8.3 Testing the Pt-100...................................................................................24
i

CNR1 Table of Contents
ii
A. CNR1 Performance and Measurements under
Different Conditions ........................................... A-1
B. Using the Heater...................................................... B-1
B.1 General Information ............................................................................ B-1
C. CR3000/CR5000 Program that Controls
the Heater............................................................C-1
Figures
2-1. The Dimensions of the CNR1................................................................. 2
3-1. CNR1 Mounting Options........................................................................ 4
5-1. CNR1 Schematic. ................................................................................... 9
5-2. Interfacing the Pt-100 Using the 4WPB100 Module.............................. 9
6-1. 4WPB100 Module ................................................................................ 12
Tables
5-1. Datalogger Connections for Differential Measurement, When Using
a 4WPB100 ....................................................................................... 10
5-2. Datalogger Connections for Single-Ended Measurement, When Using
a 4WPB100 ....................................................................................... 10
5-3. CR3000 and CR5000 Connections for Differential Measurement ....... 11
A-1. Typical output signals of the CNR1 under different meteorological
conditions ........................................................................................ A-2

CNR1 Net Radiometer
1. General Description
The CNR1 Net Radiometer is intended for the analysis of the radiation balance
of Solar and Far Infrared radiation. The most common application is the
measurement of Net (total) Radiation at the earth's surface.
The CNR1 design is such that both the upward-facing and the downward-
facing instruments measure the energy that is received from the whole
hemisphere (180 degrees field of view). The output is expressed in Watts per
square meter. The total spectral range that is measured is roughly from 0.3 to
50 micrometers. This spectral range covers both the Solar Radiation, 0.3 to 3
micrometers, and the Far Infrared radiation, 5 to 50 micrometers.
The design of CNR1 is such that Solar radiation and Far Infrared radiation are
measured separately. Solar radiation is measured by two CM3 pyranometers,
one for measuring incoming solar radiation from the sky, and the other, which
faces downward, for measuring the reflected Solar radiation. From these two
pyranometers, albedo, the ratio of reflected and incoming radiation, can also be
determined. Far Infrared radiation is measured by two CG3 pyrgeometers, one
for measuring the Far Infrared radiation from the sky, the other from the soil
surface.
An incorporated heater allows the CNR1 to be heated to prevent dew or frost
accumulation on the sensors.
Additional information on the CNR1 sensor can be found in the Kipp & Zonen
CNR1 Manual. The primary intent of this manual is to provide information on
interfacing the CNR1 to Campbell Scientific dataloggers.
2. Sensor Specifications
2.1 CNR1 Specifications
See the Kipp & Zonen manual for additional specifications.
Sensor sensitivities: All four sensors have equal sensitivity
Pt-100 sensor temperature
measurement:
DIN class A
Expected accuracy of the
temperature measurement:
±2 K, under non-stable conditions
with solar heating or heating by using
the heating resistor.
Operating temperature: -40 to +70 degrees Celsius
Requirements for data acquisition:
Radiation components: 4 differential or 4 single-ended analog
channels
Pt-100 temperature: 1 excitation and 2 differential analog
channels
Expected accuracy for daily totals: ±10 %
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CNR1 Net Radiometer
Cable length: 15 m (each cable)
Weight: 4 kg
Mounting arm attached to CNR1: 14.5” (37 cm) long
5/8” (1.6 cm) diameter
FIGURE 2-1. The Dimensions of the CNR1
2.2 CM3 Specifications
Specifications that are part of the ISO classification:
Response time 95%: 18 s
Non-stability: < 1% change per year
Non-linearity: Max. dev. 2.5% (0-1000 W m-2)
Directional error: Max. 25 W m-2 at 1000 W m-2
Spectral selectivity: Max. dev. 5% (350-1500 nm)
Temperature dependence of
sensitivity:
6% (-10 to +40oC)
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CNR1 Net Radiometer
Tilt response: Max. dev. 2%
Overall ISO classification: second class
Sensitivity: 10 - 35 µV/(W m-2)
Impedance: 125 Ohm nominal
Operating temperature: -40°C to +80°C
Spectral range: 305-2800 nm (50% points)
Expected signal range for
atmospheric application:
0 - 15 mV typical
Expected accuracy for daily sums: ±10%
Window heating offset: Max. 25 W m-2 at 1000 W m-2 normal
incidence solar radiation
2.3 CG3 Specifications
Response time 95%: 18 s
Non-stability: < 1% change per year
Non-linearity: Max. dev. 2.5% (0-1000 W m-2)
Temperature dependence of
sensitivity:
6% (-10°C to +40°C)
Tilt response: Max. 3% when facing downwards
Field of view: 150 degrees
Sensitivity: 5 - 35 µV/(W m-2)
Impedance: 125 Ohm nominal
Operating temperature: -40°C to +80°C
Temperature range for specified
behavior:
-10°C to +40°C
Measurement range: -250 to +250 W m-2
Spectral range: 5 to 50 µm
Expected signal range for
atmospheric application:
-4 to 4 mV
Expected accuracy for daily sums: ±10%
3. Installation
For measurement of the Net Radiation, it is most important that the instrument
is located in a place that is representative of the entire region that one wishes to
study.
When installed on a mast, the preferred orientation should be such that no
shadow is cast on the Net Radiometer at any time during the day. In the
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CNR1 Net Radiometer
Northern Hemisphere this implies that the Net Radiometer should be mounted
south of the mast.
It is suggested that the CNR1 is mounted at a height of at least 1.5 meters
above the surface to avoid shading effects of the instruments on the soil and to
promote spatial averaging of the measurement. If the instrument is H meters
above the surface, 99% of the input of the lower sensors comes from a circular
area with a radius of 10 H. Shadows or surface disturbances with radius
< 0.1 H will affect the measurement by less than 1%.
It is recommended that the CNR1 be mounted to a separate vertical pipe at
least 25’ from any other mounting structures. PN 14264 mounting bracket is
used to mount the CNR1 directly to a vertical pipe. Mount the sensor as
follows:
1. Attach PN 14264 mounting bracket to the vertical mounting pipe.
2. Insert the CNR1 mounting arm of the sensor into the 14264 mounting
block. Tighten the four set screws just enough to secure the mounting
arm position, but loose enough to allow the arm to be rotated.
Do not attempt to rotate the instrument using the sensor heads or
you may damage the sensors; use the mounting arm only.
NOTE
3. Loosen the vertical adjustment screws on the back of the 14264 mounting
bracket. Adjust the sensor mounting arm horizontally and vertically until
the bubble level on the sensor head shows level. Tighten the adjustment
screws to secure the position.
FIGURE 3-1. CNR1 Mounting Options
For installation in buildings or in solar energy applications, one will often have
to mount the CNR1 parallel to the surface that is being studied. This may be in
a tilted or a vertical position. The sensitivity of the radiometers will be
affected, but only in a minor way. This is specified as the so-called tilt effect.
From the specifications one can see that the tilt effect (this is a change in
sensitivity) remains within 3 %.
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CNR1 Net Radiometer
3.1 Connecting and Using the Heater
Only use the sensor’s heater when there is risk of dew forming on the sensors,
especially for low power installations. Furthermore, the heater should be
turned on and off infrequently because it may take some time for the sensor to
come to thermal equilibrium. No damage will result if the heater is powered
continuously, but as with all thermopile sensors, it is best if the sensor operates
at ambient temperatures and is not subject to rapid temperature changes.
The sensor power can be controlled using one of the 12V power switches built
into Campbell dataloggers or using an external solid state switch such as a
PSW12/SW12. The heater’s current drain is approximately 500 mA when
using a 12V battery. Connect the ground return from the heater either directly
to the battery or to a G terminal close the power input to the logger (i.e., not to
an analog ground near the measurement inputs).
The heater power can be controlled by adding instructions to the datalogger
program that turns on the heater only when the light level falls below 20 W m-2
or, if a measurement of air humidity is available, when the dew point of the air
falls to within 1ºC of the sensor body temperature. More details about using
the heater are provided in Appendix B. Appendix C provides an example
CR3000/CR5000 program that controls the CNR1 heater.
4. Using the CNR1 in the Four Separate Components
Mode (4SCM)
In the 4SCM configuration (measuring two Solar Radiation signals, two Far
Infrared signals and, for calculation purposes, one Pt-100 signal), all signals are
measured separately. Calculation of Net-Radiation and albedo can be done by
the datalogger, or later by the computer from the radiation and temperature
data.
The two CM3s will measure the solar radiation, both incoming and reflected.
The two CG3s will measure the Far Infrared radiation. For proper analysis of
the CG3 measurement results, they must be temperature corrected using the
temperature measurement performed by the Pt-100.
The following paragraphs describe how one should treat the instrument, and
how different parameters like net Solar radiation, net Far Infrared radiation,
soil temperature, sky temperature, and Net (total) radiation can be calculated.
4.1 Measuring Solar Radiation with the CM3
Measuring with the upward-facing CM3 the so-called global (solar) radiation is
measured. The downward-facing CM3 measures the reflected solar radiation.
When calculating the Net radiation, the Reflected radiation must be subtracted
from the global radiation. See Section 4.5.
The CM3 pyranometer generates a mV signal that is simply proportional to the
incoming Solar radiation. The conversion factor between voltage, V, and
Watts per square meter of solar irradiance E, is the so-called calibration
constant C (or sensitivity).
For the CM3 E = V/C (4.1)
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CNR1 Net Radiometer
4.2 Measuring Far Infrared Radiation with the CG3
The downward-facing CG3 measures the Far Infrared radiation that is emitted
by the ground. The upward-facing CG3 measures the Far Infrared radiation
from the sky. As the sky is typically colder than the instrument, one can expect
negative voltage signals from the upward-facing CG3. For this measurement,
the Pt-100 output is required. The Equation 4.2 is used to calculate the Far
Infrared irradiance of the sky and of the ground.
When using the CG3 pyrgeometer, one should realize that the signal that is
generated by the CG3 represents the exchange of Far Infrared (thermal)
radiation between the CG3 and the object that it is facing. This implies that the
CG3 will generate a positive voltage output, V, when it faces an object that is
hotter than its own sensor housing, and that it will give a negative voltage
signal when it faces an object that is colder. This means that for estimating the
Far Infrared radiation that is generated by the object that is faced by the
pyrgeometer, usually the sky or the soil, one will have to take the pyrgeometer
temperature, T, into account. This is why a Pt-100 is incorporated in the
CNR1's body. (This body is in very good thermal contact with the CG3 and
has the same temperature as the CG3 sensor surface.) The calculation of the
Far Infrared irradiance, E, is done according to the following equation:
For the CG3 only E = V/C + 5.67 ⋅10-8 ∗T4(4.2)
In this equation C is the sensitivity of the sensor. Please bear in mind that T is
in Kelvin, and not in Celsius or Fahrenheit.
4.3 Measuring the CNR1’s Temperature with the Pt-100
The Pt-100 temperature sensor is located in the CNR1 body. It will not
measure the exact temperature of the CG3 unless the whole instrument is in
thermal equilibrium. Errors, however, are minimized in the design by making
solid metal connections between the sensors and the temperature sensor. When
the sun is shining, the largest expected deviation between real sensor
temperature and Pt-100 reading is 2 degrees. This results in a worst-case error
for the CG3 of 10 Watts per square meter.
The Pt-100 will not give a good indication of ambient air temperature; at 1000
Watts per square meter Solar radiation, and no wind, the instrument
temperature will rise approximately 12 degrees above ambient temperature.
The offsets of both pyranometers and pyrgeometers might be larger than 10
Watts per square meter if large temperature gradients are forced on the
instrument (larger than 5 K/hr). This happens, for example, when rain hits the
instrument. The occurrence of this can be detected using the Pt-100 readout. It
can be used as a tool for quality assurance of your data.
The 4WPB100 module is used to interface the Pt-100 to the datalogger, and is
included with the CNR1 sensor purchased from CSI. The 4WPB100
configures the Pt-100 as a 4-wire half bridge circuit that requires one excitation
and two differential channels on the datalogger (Section 5).
6

CNR1 Net Radiometer
4.4 Calculation of the Albedo for Solar Radiation
The albedo is the ratio of incoming and reflected Solar radiation. It is a figure
somewhere between 0 and 1. Typical values are 0.9 for snow, and 0.3 for
grassland. To determine albedo, the measured values of the two CM3s can be
used. The CG3s are not involved, as they do not measure Solar radiation. Do
not use measured values when solar elevation is lower than 10 degrees above
the horizon. Errors in measurement at these elevations are likely and thus
yielding unreliable results. This is due to deviations in the directional response
of the CM3s.
Albedo = (E lower CM3) / (E upper CM3) (4.3)
In the above formula, E is calculated according to Equation 4.1.
Albedo will always be smaller than 1. Checking this can be used as a tool for
quality assurance of your data. If you know the approximate albedo at your
site, the calculation of albedo can also serve as a tool for quality control of your
measured data at this specific site.
4.5 Calculation of the Net Solar Radiation (Net Short-Wave)
Net Solar radiation is equal to the incoming solar radiation minus the reflected
solar radiation.
Net Solar radiation = (E upper CM3) - (E lower CM3) (4.4)
In this formula E is calculated according to Equation 4.1.
Net Solar radiation will always be positive. Checking this can be used as a tool
for quality assurance of your measured data.
4.6 Calculation of the Net Infrared Radiation (Net Long-Wave)
Net Far Infrared radiation is, like Net Solar radiation, the part that contributes
to heating or cooling of the earth's surface. In practice, most of the time Net
Far Infrared radiation will be negative.
Net Far Infrared radiation = (E upper CG3) - (E lower CG3) (4.5)
In this formula E is calculated according to Equation 4.2. From this equation
the term with T cancels.
The E measured with the CG3 actually represents the irradiance of the sky (for
the upward- facing CG3) or the ground (for the downward-facing CG3).
Assuming that these two, ground and sky, behave like perfect blackbodies
(actually this is only in theory), one can calculate an effective "Sky
temperature" and an effective "Ground temperature".
Sky temperature E upper CG3
=⋅
⎡
⎣
⎢⎤
⎦
⎥
−
567 10 8
14
.
/
(4.6)
Ground Temperature E lower CG3
=⋅
⎡
⎣
⎢⎤
⎦
⎥
−
567 10 8
14
.
/
(4.7)
7

CNR1 Net Radiometer
As a rule of thumb, for ambient temperatures of about 20 degrees Celsius, one
can say that one degree of temperature difference between two objects results
in a 5 Watts per square meter exchange of radiative energy (infinite objects):
1 degree of temperature difference = 5 Watts per square meter (rule of thumb)
4.7 Calculation of the Net (total) Radiation
In the 4 Separate Components Mode, Net radiation, NR, can be calculated
using the individual sensor measurement results:
NR =(E upper CM3) + (E upper CG3) -
(E lower CM3) - (E lower CG3) (4.8)
Where E is the irradiance that is calculated for the CM3 according to Equation
4.1, for the CG3 according to Equation 4.2, the terms with T cancel from this
equation.
5. Wiring
Figure 5-1 shows the CNR1 schematic with the four radiation outputs, Pt-100
temperature sensor, and the heater. The use of the heater is described in detail
in the Appendix B. All wiring schemes shown in this manual will show wiring
for both CNR1 and 4WPB100 modules. Wiring diagrams and Tables 5-1 and
5-2 are applicable only if you bought the CNR1 Net Radiometer from
Campbell Scientific, Inc.
Use of the CNR1 Net Radiometer, which you bought outside of Campbell
Scientific, is possible only on the CR3000 and CR5000 dataloggers. The
PT-100 can connect directly to the CR3000 and CR5000 because they have
current excitation inputs. Table 5-3 and Program Example 6.2.4 show wiring
and programming on the CR5000 datalogger without the 4WPB module.
All other CSI dataloggers require the 4WPB100 module to interface the
PT-100 to the datalogger.
8

CNR1 Net Radiometer
FIGURE 5-1. CNR1 Schematic
EX1
4WPB100
Red
CNR1
DATALOGGER
Yellow
Green
PT-100
Blue
H
L
G
10K
5H
5L
6H
6L
100
FIGURE 5-2. Interfacing the Pt-100 Using the 4WPB100 Module
9

CNR1 Net Radiometer
The four radiation outputs can be measured using Differential or Single-Ended
inputs on the datalogger. A differential voltage measurement (Instruction 2) is
recommended because it has better noise rejection than a single-ended
measurement. When differential inputs are used, jumper the low side of the
input to AG or to keep the signal in common mode range.
TABLE 5-1. Datalogger Connections for Differential Measurement, When Using a 4WPB100
Function Color CR10X
CR800, CR850,
CR1000 21X/CR7, CR23X
CM3 Up Signal Red Differential Input (H) Differential Input (H) Differential Input (H)
CM3 Up Reference *Blue Differential Input (L) Differential Input (L) Differential Input (L)
CM3 Down Signal White Differential Input (H) Differential Input (H) Differential Input (H)
CM3 Down Reference *Black Differential Input (L) Differential Input (L) Differential Input (L)
CG3 Up Signal Grey or
†Orange
Differential Input (H) Differential Input (H) Differential Input (H)
CG3 Up Reference *Yellow Differential Input (L) Differential Input (L) Differential Input (L)
CG3 Down Signal Brown Differential Input (H) Differential Input (H) Differential Input (H)
CG3 Down Reference *Green Differential Input (L) Differential Input (L) Differential Input (L)
Shield Shield G
*Jumper to AG or with user supplied wire.
†Cables extended > 48’have an orange wire.
Pt-100 Temperature Sensor Connections to 4WPB100 and Datalogger
Function Color 4WPB100 Datalogger
Black Wire Excitation
H Differential Input (H)
Pt-100 Excitation + Red L Differential Input (L)
Pt-100 Excitation - Blue G (AG CR10X/CR510)
Pt-100 Signal + Yellow Differential Input (H)
Pt-100 Signal – Green Differential Input (L)
TABLE 5-2. Datalogger Connections for Single-Ended Measurement, When Using a 4WPB100
Function Color CR10X CR23X, 21X, CR7
CR800, CR850,
CR1000
CM3 Up Signal Red Single-Ended Input Single-Ended Input Single-Ended Input
CM3 Up Reference Blue AG
CM3 Down Signal White Single-Ended Input Single-Ended Input Single-Ended Input
CM3 Down Reference Black AG
CG3 Up Signal Grey or Orange Single-Ended Input Single-Ended Input Single-Ended Input
CG3 Up Reference Yellow AG
CG3 Down Signal Brown Single-Ended Input Single-Ended Input Single-Ended Input
CG3 Down Reference Green AG
Shield Shield G
10

CNR1 Net Radiometer
TABLE 5-3. CR3000 and CR5000 Connections
for Differential Measurement
Function Color CR3000/CR5000
CM3 Up Signal Red Differential Input (H)
CM3 Up Reference Blue Differential Input (L)
CM3 Down Signal White Differential Input (H)
CM3 Down Reference Black Differential Input (L)
CG3 Up Signal Grey or Orange Differential Input (H)
CG3 Up Reference Yellow Differential Input (L)
CG3 Down Signal Brown Differential Input (H)
CG3 Down Reference Green Differential Input (L)
PT-100 Signal + Yellow Differential Input (H)
PT-100 Signal - Green Differential Input (L)
PT-100 Current Excitation + Red Current Excitation IX
PT-100 Current Excitation - Blue Current Excitation IXR
Shield Clear
6. Datalogger Programming
The CNR1 outputs four voltages that typically range from 0 to 15 mV for the
CM3 sensors, and ±5 mV for the CG3 sensors. A differential voltage
measurement (VoltDiff or Instruction 2) is recommended because it has better
noise rejection than a single-ended measurement. If differential channels are
not available, single-ended measurements (VoltSe or Instruction 1) can be
used. The acceptability of a single-ended measurement can be determined by
simply comparing the results of single-ended and differential measurements
made under the same conditions.
For the CR3000 and CR5000, one differential channel and a current excitation
channel are required to measure the PT-100.
For the other dataloggers, two differential channels and the 4WPB100 module
are required to measure the Pt-100 temperature sensor.
The 4WPB100 is included with the CNR1 sensor purchased from
CSI.
NOTE
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CNR1 Net Radiometer
FIGURE 6-1. 4WPB100 Module
6.1 Calibration Factor
Each CNR1 is provided 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 convert the units, divide the calibration factor into 1000. For example, if
the calibration factor is 7.30 μV/(W m-2), the multiplier is 1000/7.3 = 136.99
(W m-2)/mV.
6.2 Example Programs
6.2.1 Example 1, CR1000 Using Differential Channels
Program Example 1 requires six differential channels and the 4WPB100
module to measure the four radiation outputs and the Pt-100 temperature
sensor. The program measures the sensors every 2 seconds and calculates and
stores the following data to final storage every 60 minutes:
Year
Julian Day
Hour/Minute
Avg CM3 Up (shortwave radiation)
Avg CM3 Down (shortwave radiation)
Avg CG3 Up (longwave radiation)
Avg CG3 Down (longwave radiation)
Avg CNR1 temperature (degrees C)
Avg CNR1 temperature (degrees K)
Avg Net shortwave radiation
Avg Net longwave radiation
Avg Albedo
Avg Total Net radiation
Avg temperature corrected CG3 Up
Avg temperature corrected CG3 Down
12

CNR1 Net Radiometer
'CR1000
'Declare Variables and Units
Public Batt_Volt
Public CM3Up
Public CM3Dn
Public CG3Up
Public CG3Dn
Public CNR1TC
Public CNR1TK
Public NetRs
Public NetRl
Public Albedo
Public UpTot
Public DnTot
Public NetTot
Public CG3UpCo
Public CG3DnCo
Units Batt_Volt=Volts
Units CM3Up=W/meter²
Units CM3Dn=W/meter²
Units CG3Up=W/meter²
Units CG3Dn=W/meter²
Units CNR1TC=Deg C
Units CNR1TK=K
Units NetRs=W/meter²
Units NetRl=W/meter²
Units Albedo=W/meter²
Units UpTot=W/meter²
Units DnTot=W/meter²
Units NetTot=W/meter²
Units CG3UpCo=W/meter²
Units CG3DnCo=W/meter²
'Define Data Tables
DataTable(Table1,True,-1)
DataInterval(0,60,Min,10)
Average(1,CM3Up,FP2,False)
Average(1,CM3Dn,FP2,False)
Average(1,CG3Up,FP2,False)
Average(1,CG3Dn,FP2,False)
Average(1,CNR1TC,FP2,False)
Average(1,CNR1TK,FP2,False)
Average(1,NetRs,FP2,False)
Average(1,NetRl,FP2,False)
Average(1,Albedo,FP2,False)
Average(1,UpTot,FP2,False)
Average(1,DnTot,FP2,False)
Average(1,NetTot,FP2,False)
Average(1,CG3UpCo,FP2,False)
Average(1,CG3DnCo,FP2,False)
EndTable
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CNR1 Net Radiometer
'Main Program
BeginProg
Scan(2,Sec,1,0)
'Default Datalogger Battery Voltage measurement Batt_Volt:
Battery(Batt_Volt)
'CNR1 Net Radiometer measurements CM3Up, CM3Dn, CG3Up, CG3Dn, CNR1TC, CNR1TK,
'NetRs, NetRl, Albedo, UpTot, DnTot, NetTot, CG3UpCo, and CG3DnCo:
* VoltDiff(CM3Up,1,mV25,1,True,0,_60Hz,100.0,0)
* VoltDiff(CM3Dn,1,mV25,2,True,0,_60Hz,100.0,0)
* VoltDiff(CG3Up,1,mV7_5,3,True,0,_60Hz,100.0,0)
* VoltDiff(CG3Dn,1,mV7_5,4,True,0,_60Hz,100.0,0)
** BrHalf4W (CNR1TC,1,mV25,mV25,5,Vx1,1,2100,True ,True ,0,250,1.0,0)
PRT(CNR1TC,1,CNR1TC,1,0)
CNR1TK=CNR1TC+273.15
NetRs=CM3Up-CM3Dn
NetRl=CG3Up-CG3Dn
Albedo=CM3Dn/CM3Up
UpTot=CM3Up+CG3Up
DnTot=CM3Dn+CG3Dn
NetTot=UpTot-DnTot
CG3UpCo=CG3Up+5.67*10^-8*CNR1TK^4
CG3DnCo=CG3Dn+5.67*10^-8*CNR1TK^4
'Call Data Tables and Store Data
CallTable(Table1)
NextScan
EndProg
* mV20 range for the CR5000
** mV50 range (both) with 4200 mV excitation for CR5000
6.2.2 Example 2, CR5000 Using Differential Channels (no 4WPB100)
Program Example 2 requires five differential channels and one current
excitation channel to measure the four radiation outputs and the Pt-100
temperature sensor. The program measures the sensors every second and
calculates and stores the following data to final storage every 60 minutes:
Year
Julian Day
Hour/Minute
Avg CM3 Up (shortwave radiation)
Avg CM3 Down (shortwave radiation)
Avg CG3 Up (longwave radiation)
Avg CG3 Down (longwave radiation)
Avg CNR1 temperature (degrees C)
Avg CNR1 temperature (degrees K)
Avg Net shortwave radiation
Avg Net longwave radiation
Avg Albedo
Avg Total Net radiation
Avg temperature corrected CG3 Up
Avg temperature corrected CG3 Down
14

CNR1 Net Radiometer
'CR5000 Series Datalogger
'ANALOG INPUT
'1H CM3 UP - downwelling shortwave radiation signal (red)
'1L CM3 UP - downwelling shortwave radiation signal reference (blue)
'gnd CNR1 shield (clear)
'2H CM3 DOWN - upwelling shortwave radiation signal (white)
'2L CM3 DOWN - upwelling shortwave radiation signal reference (black)
'3H CG3 UP - downwelling longwave radiation signal (gray)
'3L CG3 UP - downwelling longwave radiation signal reference (yellow)
'4H CG3 DOWN - upwelling longwave radiation signal (brown)
'4L CG3 DOWN - upwelling longwave radiation signal reference (green)
'6H CNR1 Pt100 (yellow)
'6L CNR1 Pt100 (green)
'Current Excitation
'IX1 CNR1 Pt100 (red)
'IXR CNR1 Pt100 (blue)
'Declare Variables and Units
Public Batt_Volt
Public CM3Up
Public CM3Dn
Public CG3Up
Public CG3Dn
Public CNR1TC
Public CNR1TK
Public NetRs
Public NetRl
Public Albedo
Public UpTot
Public DnTot
Public NetTot
Public CG3UpCo
Public CG3DnCo
Units Batt_Volt=Volts
Units CM3Up=W/meter²
Units CM3Dn=W/meter²
Units CG3Up=W/meter²
Units CG3Dn=W/meter²
Units CNR1TC=Deg C
Units CNR1TK=K
Units NetRs=W/meter²
Units NetRl=W/meter²
Units Albedo=W/meter²
Units UpTot=W/meter²
Units DnTot=W/meter²
Units NetTot=W/meter²
Units CG3UpCo=W/meter²
Units CG3DnCo=W/meter²
15

CNR1 Net Radiometer
'Define Data Tables
DataTable(Table1,True,-1)
DataInterval(0,60,Min,10)
Average(1,CM3Up,FP2,False)
Average(1,CM3Dn,FP2,False)
Average(1,CG3Up,FP2,False)
Average(1,CG3Dn,FP2,False)
Average(1,CNR1TC,FP2,False)
Average(1,CNR1TK,FP2,False)
Average(1,NetRs,FP2,False)
Average(1,NetRl,FP2,False)
Average(1,Albedo,FP2,False)
Average(1,UpTot,FP2,False)
Average(1,DnTot,FP2,False)
Average(1,NetTot,FP2,False)
Average(1,CG3UpCo,FP2,False)
Average(1,CG3DnCo,FP2,False)
EndTable
'Main Program
BeginProg
Scan(1,Sec,1,0)
'Default Datalogger Battery Voltage measurement Batt_Volt:
Battery(Batt_Volt)
'CNR1 Net Radiometer measurements CM3Up, CM3Dn, CG3Up, CG3Dn, CNR1TC, CNR1TK,
'NetRs, NetRl, Albedo, UpTot, DnTot, NetTot, CG3UpCo, and CG3DnCo:
'CNR1 Sensitivity 7.30 uV/m^2
VoltDiff(CM3Up,1,mV20C,1,True,200,250,136.99,0)
VoltDiff(CM3Dn,1,mV20C,2,True,200,250,136.9,0)
VoltDiff(CG3Up,1,mV20C,3,True,200,250,136.9,0)
VoltDiff(CG3Dn,1,mV20,4,True,200,250,136.9,0)
Resistance (CNR1TC,1,mV200,6,Ix1,1,1675,True ,True,200,250,1.0,0)
'Formulate the ratio Rs/R0
CNR1TC=CNR1TC/100
PRT(CNR1TC,1,CNR1TC,1,0)
'Compute Net short-wave radiation, Net long-wave radiation, Albedo and Net Radiation
CNR1TK=CNR1TC+273.15
NetRs=CM3Up-CM3Dn
NetRl=CG3Up-CG3Dn
Albedo=CM3Dn/CM3Up
UpTot=CM3Up+CG3Up
DnTot=CM3Dn+CG3Dn
NetTot=UpTot-DnTot
CG3UpCo=CG3Up+5.67*10^-8*CNR1TK^4
CG3DnCo=CG3Dn+5.67*10^-8*CNR1TK^4
'Call Data Tables and Store Data
CallTable(Table1)
NextScan
EndProg
16