INSTRUCTION MANUAL CNR4 Net Radiometer Revision: 2/15 C o p y r i g h t © 2 0 0 0 - 2 0 1 5 C a m p b e l l S c i e n t i f i c , I n c .
Limited Warranty “Products manufactured by CSI are warranted by CSI to be free from defects in materials and workmanship under normal use and service for twelve months from the date of shipment unless otherwise specified in the corresponding product manual. (Product manuals are available for review online at www.campbellsci.com.) Products not manufactured by CSI, but that are resold by CSI, are warranted only to the limits extended by the original manufacturer.
Assistance Products may not be returned without prior authorization. The following contact information is for US and international customers residing in countries served by Campbell Scientific, Inc. directly. Affiliate companies handle repairs for customers within their territories. Please visit www.campbellsci.com to determine which Campbell Scientific company serves your country. To obtain a Returned Materials Authorization (RMA), contact CAMPBELL SCIENTIFIC, INC., phone (435) 227-9000.
Precautions DANGER — MANY HAZARDS ARE ASSOCIATED WITH INSTALLING, USING, MAINTAINING, AND WORKING ON OR AROUND TRIPODS, TOWERS, AND ANY ATTACHMENTS TO TRIPODS AND TOWERS SUCH AS SENSORS, CROSSARMS, ENCLOSURES, ANTENNAS, ETC. FAILURE TO PROPERLY AND COMPLETELY ASSEMBLE, INSTALL, OPERATE, USE, AND MAINTAIN TRIPODS, TOWERS, AND ATTACHMENTS, AND FAILURE TO HEED WARNINGS, INCREASES THE RISK OF DEATH, ACCIDENT, SERIOUS INJURY, PROPERTY DAMAGE, AND PRODUCT FAILURE.
Table of Contents PDF viewers: These page numbers refer to the printed version of this document. Use the PDF reader bookmarks tab for links to specific sections. 1. Introduction ................................................................. 1 2. Cautionary Statements ............................................... 1 3. Initial Inspection ......................................................... 1 3.1 Ships With............................................................................................
Table of Contents 9. Maintenance and Recalibration ...............................24 9.1 9.2 9.3 9.4 Cleaning Windows and Domes ......................................................... 24 Recalibration ..................................................................................... 24 Replacing the Drying Cartridge......................................................... 24 Replacement Parts ............................................................................. 25 Appendices A.
Table of Contents D-4. D-5. D-6. D-7. CNF4 solar shield and four flat-head screws .................................. D-5 Attaching the solar shield to CNF4 using four flat-head screws ..... D-6 Affixing the sensor label to CNF4 .................................................. D-6 Connecting the CNF4 power control cable and the mounting rod .. D-6 7-1. 7–2. 7-3. 7-4. B-1. Resistance values versus CNR4’s thermistor temperature in °C........ 14 Resistance values versus CNR4’s Pt–100 temperature in °C ....
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CNR4 Net Radiometer 1. Introduction The CNR4 is a research-grade net radiometer that measures the energy balance between incoming and outgoing radiation. Our dataloggers measure the CNR4’s output. This net radiometer offers a professional solution for scientific-grade energy balance studies. Before using the CNR4, please study: • • • 2. 3.
CNR4 Net Radiometer 4. Quickstart Please review Section 7, Operation, for wiring and CRBasic programming. Appendix D, CNF4 Heater/Ventilator, provides information about using the CNF4 heater/ventilator. 4.1 4.2 Siting Considerations 1. Mount the sensor so no shadows or reflections will be cast on it at any time of day from obstructions such as trees, buildings, or the mast or structure on which it is mounted.
CNR4 Net Radiometer 2. Attach the 26120 mounting bracket to the vertical mounting pipe, or CM200-series crossarm using the provided U-bolt (see FIGURE 4-2). If mounted to a vertical pipe, ensure that the pipe does not cast a reflection on the sensor. This includes both the incoming and outgoing sections of the sensor. FIGURE 4-2. Attaching the CNR4 onto the mounting rod (pn 26120) using vertical pole or horizontal crossarm 3.
CNR4 Net Radiometer 4.3 5. Tighten the four screws on top of the mounting bracket to properly secure the support arm so that it does not rotate (see FIGURE 4-2). 6. Perform the fine leveling using the two spring-loaded leveling screws— one on the front and the other on the back of the bracket. 7. Route the sensor cable to the instrument enclosure. 8. Use the UV-resistant cable ties included with the tripod or tower to secure the cable to the vertical pipe or crossarm and tripod/tower.
CNR4 Net Radiometer 3. When Short Cut opens, select New Program. 4. Select Datalogger Model and Scan Interval (default of 5 seconds is OK for most applications). Click Next.
CNR4 Net Radiometer 5. Under the Available Sensors and Devices list, select Sensors | Meteorological | Solar Radiation folder. Select CNR4 Net Radiation. Click to move the selection to the Selected device window. 6. Enter the sensitivity values supplied on the manufacturer’s certificate of calibration; these sensitivity values are unique to each sensor. The public variables defaults can typically be used. After entering the information, click on OK, and then select Next.
CNR4 Net Radiometer 7. After selecting the sensitivity values, click at the left of the screen on Wiring Diagram to see how the sensor is to be wired to the datalogger. The wiring diagram can be printed out now or after more sensors are added. 8. Select any other sensors you have, then finish the remaining Short Cut steps to complete the program. The remaining steps are outlined in Short Cut Help, which is accessed by clicking on Help | Contents | Programming Steps. 9.
CNR4 Net Radiometer Two temperature sensors, a thermistor and a Pt-100, are integrated with the CNR4 body. The temperature sensor is used to provide information to correct the infrared readings for the temperature of the instrument housing. Care has been taken to place the long-wave sensors close to each other and close to the temperature sensors. This ensures that the temperatures of the measurement surfaces are the same and accurately known, improving the quality of the longwave measurements.
CNR4 Net Radiometer • Separate outputs of short-wave and long-wave infrared radiation for better accuracy and more thorough quality assurance • Solar shield reduces thermal effects on the sensors Compatible Dataloggers: CR6 CR1000 CR3000 CR5000 The properties of the CNR4 are mainly determined by the properties of the individual probes.
CNR4 Net Radiometer 6.1 CNR4 Specifications Sensor sensitivities: Four probes with unique sensitivity values. Please refer to the calibration sheets or label on the bottom of the sensor for the sensitivity values. Operating temperature: –40 to 80 °C (–40 to 176 °F) Operating humidity: 0 to 100% RH Bubble level sensitivity: < 0.
CNR4 Net Radiometer Directional error*: Zero offset due to 0 to -200 W/m2 IR net irradiance*: Zero offset due to temperature change*: Operating temperature: Field of view Upper detector: Lower detector: 6.
CNR4 Net Radiometer Field of view Upper: Lower: 180 degrees 150 degrees Net-irradiance: –250 to +250 W/m2 Non-stability: < 1% (sensitivity change per year) Window heating offset: < 6 W/m2 (1000 W/m2 solar irradiance) Uncertainty in daily total: < 10% (95% confidence level) indoor calibration Typical signal output for atmospheric application: ±5 mV Temperature sensors Thermistor: 10k Ω Pt-100: DIN class A Instrument calibration: 6.
CNR4 Net Radiometer 7.1 Using the CNR4 in the Four Separate Components Mode In the four separate components mode configuration (measuring two shortwave radiation signals and two long-wave signals), all signals are measured separately. Calculation of net-radiation and albedo can be done online by the datalogger, or offline by the user during post-processing, using the stored raw data. The two pyranometers will measure the short-wave radiation, both incoming and reflected.
CNR4 Net Radiometer In this equation, C is the sensitivity of the sensor. NOTE T is in Kelvin, and not in Celsius or Fahrenheit. The downward-facing pyrgeometer measures the far infrared radiation that is emitted by the ground. The upward-facing pyrgeometer 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 pyrgeometer.
CNR4 Net Radiometer TABLE 7-1. Resistance values versus CNR4’s thermistor temperature in °C Temperature [°C] –7 –6 –5 –4 –3 –2 –1 Resistance [Ω] 41070 39140 37310 35570 33930 32370 30890 Temperature [°C] 23 24 25 26 27 28 29 Resistance [Ω] 10840 10410 10000 9605 9227 8867 8523 Temperature [°C] 53 54 55 56 57 58 59 Resistance [Ω] 3504 3385 3270 3160 3054 2952 2854 Relatively small errors occur when the CNR4 is not in thermal equilibrium.
CNR4 Net Radiometer TABLE 7–2. Resistance values versus CNR4’s Pt–100 temperature in °C Temperature [°C] –30 –29 –28 –27 –26 –25 –24 –23 –22 –21 –20 –19 –18 –17 –16 –15 –14 –13 –12 –11 –10 –9 –8 –7 –6 –5 –4 –3 –2 –1 Resistance [Ω] 88.22 88.62 89.01 89.40 89.80 90.19 90.59 90.98 91.37 91.77 92.16 92.55 92.95 93.34 93.73 94.12 94.52 94.91 95.30 95.69 96.09 96.48 96.87 97.26 97.65 98.04 98.44 98.83 99.22 99.
CNR4 Net Radiometer site, the calculation of albedo can also serve as a tool for quality control of your measured data at a specific site. 7.1.5 Calculation of Net Short-wave Radiation The net short-wave solar radiation is equal to the incoming (downwelling) short-wave radiation minus the reflected (upwelling) short-wave radiation. Net Short-wave Radiation = (E upper Pyranometer) – (E lower Pyranometer) (7-4) In the equation above, E is calculated according to Equation 7-1.
CNR4 Net Radiometer 7.1.7 Calculation of Net (Total) Radiation In the four separate components mode, net radiation, Rn, can be calculated using the individual sensor measurement results: Rn = {(E upper Pyranometer) - (E lower Pyranometer)} + {(E upper Pyrgeometer) - (E lower Pyrgeometer)} (7-8) Where E upper/lower pyranometers are calculated according to Equation 7-1, and E upper/lower pyrgeometers are calculated according to Equation 7-2. The terms with T cancel each other out. 7.
CNR4 Net Radiometer FIGURE 7-2. The marks on the end of the CNR4: S for SOLAR cable, and T for TEMP cable The measurement details for Pt-100 sensor, including the wiring diagram and sample program, are explained in Appendix B.4, CR3000 Program for Measuring Pt-100 Temperature Sensor. The four radiation outputs can be measured using differential or single-ended inputs on the datalogger. A differential voltage measurement is recommended because it has better noise rejection than a single-ended measurement.
CNR4 Net Radiometer FIGURE 7-4. Labels on the pigtail end of the TEMP cable. TABLE 7-3.
CNR4 Net Radiometer TABLE 7-4.
CNR4 Net Radiometer The CNR4 outputs four voltages that typically range from 0 to 15 mV for the pyranometers, and ± 5 mV for the pyrgeometers. A differential voltage measurement is recommended because it has better noise rejection than a single-ended measurement. If differential channels are not available, singleended measurements can be used.
CNR4 Net Radiometer 8.1 Testing the Pyranometer As a first test, check the sensor impedance. It should have a nominal value as indicated in the specifications. Zero, or infinite resistance, indicates a failure in hardware connection. Before starting the second test measurement, let the pyranometer rest for at least five minutes to let it regain its thermal equilibrium. For testing, set a voltmeter to its most sensitive range setting. Darken the sensor.
CNR4 Net Radiometer 8.4 Testing the Pt-100 Using a multimeter, measure the resistance between the two opposite wires of the Pt-100 (gray-yellow, gray-brown, green-yellow, green-brown), and compare the measured value with the resistance values listed in TABLE 7–2. The resistance should be above 100 Ω at 0 °C, and the cable resistance should add about 0.026 Ω per each foot of cable. When in doubt, the thermistor resistance (temperature) can be checked as well for reference. 9.
CNR4 Net Radiometer Drying Cartridge Rubber Gasket FIGURE 9-1. Replacing the drying cartridge 9.4 Replacement Parts The following is the list of replacement parts for the CNR4 and CNF4 (heater/ventilator) available from Campbell Scientific. CSI Part Number Description CNR4CBL1-L Replacement CNR4 Solar Cable CNR4CBL2-L Replacement CNR4 Temperature Cable CNF4CBL-L Replacement CNF4 Cable 26006 Replacement Drying Cartridges 26010 Replacement Fan Filter (Set of 5).
CNR4 Net Radiometer 26
Appendix A. Importing Short Cut Code Into CRBasic Editor This tutorial shows: • • How to import a Short Cut program into a program editor for additional refinement How to import a wiring diagram from Short Cut into the comments of a custom program A.1 Importing Short Cut Code into a Program Editor Short Cut creates files that can be imported into either CRBasic Editor or Edlog program editor. These files normally reside in the C:\campbellsci\SCWin folder and have the following extensions: • • • • • .
Appendix A. Importing Short Cut Code Into CRBasic Editor mark) begins each line. This character instructs the datalogger compiler to ignore the line when compiling the datalogger code.
Appendix B. Example Programs B.1 CR1000 Program Using Differential Measurements This example requires four differential channels to measure the four radiation outputs, one excitation channel, and one single-ended channel to measure the thermistor. The program measures the sensors every 1 second, performs the online processing of the data, and stores the following processed data to a data table called cnr4_data once every 60 minutes.
Appendix B.
Appendix B.
Appendix B. Example Programs B.2 CR3000 Program Using Differential Measurements This example requires four differential channels to measure the four radiation outputs and one excitation channel and one single-ended channel to measure the thermistor. The program measures the sensors every 1 second, performs the online processing of the data and stores the following processed data to a data table called cnr4_data once every 60 minutes.
Appendix B.
Appendix B.
Appendix B. Example Programs B.3 CR5000 Program Using Differential Measurements This example requires four differential channels to measure the four radiation outputs, one excitation channel, and one single-ended channel to measure the thermistor. The program measures the sensors every 1 second, performs the online processing of the data, and stores the following processed data to a data table called cnr4_data once every 60 minutes.
Appendix B.
Appendix B.
Appendix B. Example Programs B.4 CR3000 Program for Measuring Pt-100 Temperature Sensor This example measures the Pt-100 sensor for the body temperature of the CNR4. This program requires four differential channels to measure the four radiation outputs, one current excitation channel, and one differential channel for Pt-100 measurement.
Appendix B. Example Programs 'CR3000 Series Datalogger ' 'CNR4 program 'This program measures CNR4 four-component net radiometer 'This program also measures the Pt-100 sensor inside the CNR4 ' 'User must enter the sensitivity values for all four probes in the program and save/compile 'prior to downloading it to the datalogger. 'Search for the text string "unique" to find places to enter the sensitivity values.
Appendix B. Example Programs Units Units Units Units Units Units Units cnr4_T_K = K long_up_corr = W/m^2 long_dn_corr = W/m^2 Rs_net = W/m^2 Rl_net = W/m^2 albedo = W/m^2 Rn = W/m^2 Dim cnr4_prt_R, Rs_R0 'CNR4 sensitivities: refer to the Certificate of Calibration from Kipp & Zonen 'for each probes, and enter them below. Const pyranometer_up_sensitivity = 15.35 'unique sensitivity '(microV/W/m^2) Const pyranometer_dn_sensitivity = 15.
Appendix B. Example Programs PRT (cnr4_T_C,1,Rs_R0,1,0) 'Convert CNR4 temperature to Kelvin cnr4_T_K = cnr4_T_C+273.15 'Correct the long-wave radiation values from pyrgeometers long_up_corr = long_up+5.67e-8*cnr4_T_K^4 long_dn_corr = long_dn+5.
Appendix B.
Appendix C. CNR4 Performance and Measurements under Different Conditions TABLE C-1 shows what one might typically expect to measure under different meteorological conditions. The first parameter is day and night. At night, the solar radiation is zero. The second column shows if it is cloudy or clear. A cloud acts like a blanket, absorbing part of the solar radiation, and keeping net far infrared radiation close to zero.
Appendix C. CNR4 Performance and Measurements under Different Conditions FIGURE C-1.
Appendix C. CNR4 Performance and Measurements under Different Conditions Upwelling signal Signal(downward (Downwardfacing) Facing) Pyrgeometer upwelling pyrgeometer 30 Pyrgeometer: U-emf / sensitivity [W/m²] Temp of instrument [°C] 20 10 0 -10 -20 -30 0:00:00 23:00:00 22:00:00 21:00:00 20:00:00 19:00:00 18:00:00 17:00:00 16:00:00 15:00:00 14:00:00 13:00:00 12:00:00 11:00:00 10:00:00 9:00:00 8:00:00 7:00:00 6:00:00 5:00:00 4:00:00 3:00:00 2:00:00 1:00:00 0:00:00 FIGURE C-3.
Appendix C. CNR4 Performance and Measurements under Different Conditions E upper CG3 Sky Temperature = 5.67 ⋅10 −8 1/ 4 E lower CG3 Ground Temperature = 5.
Appendix D. CNF4 Heater/Ventilator NOTE Whenever the heater is used, the heating may cause errors in the measurement of the sensor temperature. Under most conditions, the accuracy gained by heating will be larger than the errors introduced by heating. In both the pyranometer and the pyrgeometer, thermal sensors are used, and these sensors, in principle, measure a heat flow. For optimal performance, these sensors should be at thermal equilibrium with the ambient air.
Appendix D. CNF4 Heater/Ventilator 10 watt power available? Not available DO NOT HEAT Consider options below Available Clock and relay available? Not Available DO NOT HEAT (recommendation) Available Heat from 1 hour before sunset until 1 hour after sunrise. The heater power can be controlled using one of the SW12V channels of the Campbell Scientific dataloggers. The heater’s current drain is approximately 850 mA at 12 Vdc (10 W). The ventilator draws additional 5 W of power at 12 Vdc.
Appendix D. CNF4 Heater/Ventilator D.2 Attaching the Optional CNF4 Heater/Ventilator Unit to CNR4 1. The CNF4 heater/ventilator unit comes with the following: the heater/ventilator, the white solar shield, three pan-head screws with washers, and four flat-head screws as shown in FIGURE D-1. FIGURE D-1.
Appendix D. CNF4 Heater/Ventilator 2. Attach the heater/ventilator unit unto the bottom of the CNR4 sensor, using the three pan-head screws and washers, as shown in FIGURE D-2. Make sure that the pyranometer and the pyrgeometer windows are not scratched during the installation. FIGURE D-2.
Appendix D. CNF4 Heater/Ventilator 3. Make sure the cables are cleared from the edges of the CNF4, as shown in FIGURE D-3, and place the white solar shield over it. Use the four flathead screws provided to complete the solar shield installation to the CNF4, as shown in FIGURE D-4 and FIGURE D-5. FIGURE D-3. Making sure the cables are clear from the edges FIGURE D-4.
Appendix D. CNF4 Heater/Ventilator FIGURE D-5. Attaching the solar shield to CNF4 using four flat-head screws 4. Once the CNF4 heater/ventilator unit is attached to the bottom side of the CNR4, the CNF4 will cover the label that contains the serial number and the sensitivity values for the four sensors. Affix the extra label that came with the sensor to the bottom side of the CNF4’s anodized aluminium base so that the label is in a visible location. See FIGURE D-6 below. FIGURE D-6.
Appendix D. CNF4 Heater/Ventilator D.3 Wiring The following table shows the recommended datalogger wiring for using the CNR4 sensor with the CNF4 heater/ventilator while making the differential measurement. TABLE D-1.
Appendix D. CNF4 Heater/Ventilator D.4 CR3000 Datalogger Program with Heater/Ventilator Control This example measures the four radiation outputs, thermistor temperature, and controls the ventilator and heater using SW12V-1 and SW12V-2 channels on the CR3000, respectively. In this example program, the ventilator and heater can be turned on or off by manually setting the flag(1) and flag(2) high or low, respectively.
Appendix D.
Appendix D.
Appendix D. CNF4 Heater/Ventilator D.5 CNF4 Heater/Ventilator Maintenance D.5.1 Testing the Heater The optional CNF4 consists of a heater and a ventilator. To check the heater unit, measure the resistance between the two heater wires (green and yellow). The resistance value of the heating resistor inside should be around 15 Ω (cable resistance should add about 0.026 Ω per each foot of cable). An infinite resistance reading indicates the likelihood of a broken wire, or cable. D.5.
Appendix D.
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