Campbell CNR4 Instruction Manual
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Campbell CNR4 Instruction Manual

Net radiometer
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CNR4 Net Radiometer
Revision: 2/17
C o p y r i g h t
©
2 0 0 0 - 2 0 1 7
C a m p b e l l
S c i e n t i f i c ,
I n c .

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Summary of Contents for Campbell CNR4

  • Page 1 CNR4 Net Radiometer Revision: 2/17 C o p y r i g h t © 2 0 0 0 - 2 0 1 7 C a m p b e l l S c i e n t i f i c ,...
  • Page 3 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.
  • Page 4 (435) 227-9106. Campbell Scientific is unable to process any returns until we receive this form. If the form is not received within three days of product receipt or is incomplete, the product will be returned to the customer at the customer’s expense.
  • Page 5 Periodically (at least yearly) check electrical ground connections. • WHILE EVERY ATTEMPT IS MADE TO EMBODY THE HIGHEST DEGREE OF SAFETY IN ALL CAMPBELL SCIENTIFIC PRODUCTS, THE CUSTOMER ASSUMES ALL RISK FROM ANY INJURY RESULTING FROM IMPROPER INSTALLATION, USE, OR MAINTENANCE OF TRIPODS, TOWERS, OR ATTACHMENTS TO TRIPODS AND TOWERS SUCH AS SENSORS, CROSSARMS, ENCLOSURES, ANTENNAS, ETC.

  • Page 7: Table Of Contents

    8. Operation ..............17 Measuring Short-wave Solar Radiation with Pyranometer ....17 Measuring Long-wave Far Infrared Radiation with Pyrgeometer..18 Measuring CNR4 Temperature with Thermistor ....... 18 Calculation of Albedo ................ 20 Calculation of Net Short-wave Radiation .......... 21 Calculation of Net Long-wave Radiation ........... 21 Calculation of Net (Total) Radiation ..........
  • Page 8 7-3. The CNR4 sensor with SOLAR and TEMP cables ......13 7-4. The marks on the end of the CNR4: S for SOLAR cable, and T for TEMP cable ................14 7-5. Labels on the pigtail end of the SOLAR cable ........14 7-6.
  • Page 9 7-2. TEMP Cable (Wire Color, Function, and Datalogger Connection) ..................15 8-1. Resistance values versus CNR4’s thermistor temperature in °C ..19 8–2. Resistance values versus CNR4’s Pt–100 temperature in °C ..... 20 B-1. Datalogger Connections for Differential Measurement with Pt-100 ..................
  • Page 10 Table of Contents...

  • Page 11: Introduction

    CNR4 Net Radiometer 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.

  • Page 12: Quickstart

    CNR4 Net Radiometer QuickStart The SCWin example provided here uses the thermistor to provide NOTE the temperature correction. Short Cut is an easy way to program your datalogger to measure the pyranometer and assign datalogger wiring terminals. Short Cut is available as a download on www.campbellsci.com...
  • Page 13 Select Datalogger Model and Scan Interval (default of 5 seconds is OK for most applications). Click Next. 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.
  • Page 14 CNR4 Net Radiometer 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.

  • Page 15: Overview

    The pyranometer pair measures short-wave solar radiation, and the pyrgeometer pair measures long-wave far infrared radiation. The upper long- wave detector of CNR4 has a meniscus dome to ensure that water droplets roll off easily while improving the field of view to nearly 180°, compared with a 150°...

  • Page 16: Specifications

    CNR4 Net Radiometer The CNR4 is manufactured by Kipp & Zonen, but cabled for use with Campbell Scientific dataloggers. Its cables can terminate in: • Pigtails that connect directly to a Campbell Scientific datalogger (cable termination option –PT). Connector that attaches to a prewired enclosure (cable termination •...

  • Page 17: Cnr4 Specifications

    CNR4 Net Radiometer FIGURE 6-1. The CNR4 net radiometer with cables and mounting rod, top view FIGURE 6-2. The CNR4 net radiometer with CNF 4 heater/ventilator unit, top view CNR4 Specifications Four probes with unique sensitivity Sensor sensitivities: values. Please refer to the calibration sheets or label on the bottom of the sensor for the sensitivity values.

  • Page 18: Pyranometer Specifications

    CNR4 Net Radiometer Cable length: User defined Weight Sensor: 0.85 kg (1.89 lb) without cables Heater/ventilator, CNF4 (optional): 0.50 kg (1.11 lb) without cables Mounting rod: 34.7 cm (13.67 in) length 1.6 cm (0.63 in) diameter Pyranometer Specifications Spectral range:...

  • Page 19: Pyrgeometer Specifications

    CNR4 Net Radiometer Uncertainty in daily total: < 5% (95% confidence level) Instrument calibration: Indoors. Side by side against reference CMP3 pyranometer according to ISO 9847:1992 annex A.3.1 Indicates ISO specifications. Pyrgeometer Specifications Spectral range: 4.5 to 42 μm (50% points) 5 to 15 μV/W/m...

  • Page 20: Cnf4 Specifications

    For example, in the Northern Hemisphere, point the cable toward the North Pole. Mounting A mounting bracket kit, pn 26120, is used to mount the CNR4 directly to a vertical pipe, or to a CM202, CM203, CM204, or CM206 crossarm. Mount the sensor as follows:...

  • Page 21: Attaching The Mounting Rod To The Cnr4 Body

    CNR4 Net Radiometer FIGURE 7-1. Attaching the mounting rod to the CNR4 body Attach the 26120 mounting bracket to the vertical mounting pipe, or CM200-series crossarm using the provided U-bolt (see FIGURE 7-2). If mounted to a vertical pipe, ensure that the pipe does not cast a reflection on the sensor.

  • Page 22: Attaching The Cnr4 Onto The Mounting Rod (Pn 26120) Using Vertical Pole Or Horizontal Crossarm

    SENSOR on top of the bracket (see FIGURE 7-2). NOTE If the CNR4 is being used at a location where snow and ice accumulate, or high winds are expected, then the mounting rod should not be fully extended.

  • Page 23: Wiring

    CNR4. The wiring diagrams for the thermistor in this manual is applicable only if the CNR4 and the cables were purchased from Campbell Scientific, Inc.

  • Page 24: The Marks On The End Of The Cnr4: S For Solar Cable, And T For Temp Cable

    CNR4 Net Radiometer FIGURE 7-4. 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 (p.

  • Page 25: Solar Cable (Wire Color, Function, And Datalogger Connection)

    CNR4 Net Radiometer TABLE 7-1. SOLAR Cable (Wire Color, Function, and Datalogger Connection) Wire Differential Datalogger Connection Single-Ended Datalogger Color Wire Function Terminal Connection Terminal U configured for differential input U configured for single-ended analog Pyranometer Top DIFF H (differential high, analog-...

  • Page 26: Datalogger Programming

    Appendix B, Example Programs (p. B-1) 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.

  • Page 27: Sensor Sensitivity

    CNF4 in a visible location. The extra label containing the serial number and sensitivity values is supplied with the purchase of the CNR4. Please refer to Appendix D, CNF4 , for more details.

  • Page 28: Measuring Long-Wave Far Infrared Radiation With Pyrgeometer

    T, into account. This is why the temperature sensors are incorporated in the CNR4’s body near the pyrgeometer sensing element, and has, therefore, the same temperature as the pyrgeometer sensor surface. The calculation of the long-wave far infrared irradiance, E, is done according to Equation 8-2.

  • Page 29: Resistance Values Versus Cnr4'S Thermistor Temperature In °C

    8523 2854 Relatively small errors occur when the CNR4 is not in thermal equilibrium. This happens for example when the heater is on, or when the sun is shining. When the heater and ventilator are on, the largest expected deviation between the real sensor temperature and the thermistor reading is 1 degree.

  • Page 30: Calculation Of Albedo

    Pt-100 resistance values as a function of temperature. Please refer to Appendix B.4, CR3000 Program for Measuring Pt-100 Temperature Sensor , for a sample program to measure Pt-100. (p. B-10) TABLE 8–2. Resistance values versus CNR4’s Pt–100 temperature in °C Temperature Resistance Temperature Resistance...

  • Page 31: Calculation Of Net Short-Wave Radiation

    Equation 8-5, the terms that contain the sensor body temperature, T, cancel each other. Therefore, if only interested in the net long-wave radiation, instead of separate upper and lower components of the long-wave radiation, the CNR4 temperature measurement is not required.

  • Page 32: Calculation Of Net (Total) Radiation

    CNR4 Net Radiometer lower Pyrgeomete   (8-7) Ground Temperatur   − ⋅   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...

  • Page 33: Testing The Pyrgeometer

    (see second test in Section 9.1.1, Testing the Pyranometer (p. 22) The CNR4 body and the ambient air should be at the same temperature. Let the pyrgeometer rest for at least five minutes to regain its thermal equilibrium. Set the voltmeter to its most sensitive range. To test if the pyrgeometer is working properly, put your hand in front of the pyrgeometer.

  • Page 34: Maintenance

    9.2.2 Replacing the Drying Cartridge The CNR4 has a drying cartridge inside the sensor to help keep the electronics dry. The manufacturer recommends replacing the drying cartridge every 6 to 12 months.

  • Page 35: Recalibration

    Recalibration For quality assurance of the measured data, the manufacturer recommends the CNR4 be recalibrated on a regular schedule by an authorized Kipp & Zonen calibration facility. The CNR4 should be recalibrated every two years. Alternatively, one can check the sensor calibration by letting a higher standard run parallel to it over a two-day period and, then, comparing the results.
  • Page 36 CNR4 Net Radiometer...

  • Page 37: Importing Short Cut Code Into Crbasic Editor

    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 Short Cut creates files, which can be imported into CRBasic Editor.

  • Page 39: Example Programs

    'CNR4 program 'This program measures CNR4 four-component net radiometer 'This program also measures the thermistor 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.
  • Page 40 = W/m^2 Units Rn = W/m^2 Rs, Vs_Vx 'CNR4 sensitivities: refer to the Certificate of Calibration from Kipp & Zonen for sensitivity values 'for each probes, and enter them below. Const pyranometer_up_sensitivity = 15.35 'unique sensitivity for upper pyranometer...
  • Page 41 DataTable (cnr4_ts,True,-1) DataInterval (0,1,Sec,10) CardOut (1,-1) Sample (4,cnr4(1),IEEE4) Sample (1,cnr4_T_K,IEEE4) EndTable BeginProg 'Load the multiplier values for the CNR4 cnr4_mult(1) = pyranometer_up_mult cnr4_mult(2) = pyranometer_dn_mult cnr4_mult(3) = pyrgeometer_up_mult cnr4_mult(4) = pyrgeometer_dn_mult Scan (1,Sec,3,0) PanelTemp (logger_temp,250) Battery (batt_volt) 'CNR4 radiation measurements...

  • Page 42: Cr3000 Program Using Differential Measurements

    'CNR4 program 'This program measures CNR4 four-component net radiometer 'This program also measures the thermistor 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.
  • Page 43 = W/m^2 Units Rn = W/m^2 Rs, Vs_Vx 'CNR4 sensitivities: refer to the Certificate of Calibration from Kipp & Zonen for sensitivity values 'for each probes, and enter them below. Const pyranometer_up_sensitivity = 15.35 'unique sensitivity for upper pyranometer...
  • Page 44 DataTable (cnr4_ts,True,-1) DataInterval (0,1,Sec,10) CardOut (1,-1) Sample (4,cnr4(1),IEEE4) Sample (1,cnr4_T_K,IEEE4) EndTable BeginProg 'Load the multiplier values for the CNR4 cnr4_mult(1) = pyranometer_up_mult cnr4_mult(2) = pyranometer_dn_mult cnr4_mult(3) = pyrgeometer_up_mult cnr4_mult(4) = pyrgeometer_dn_mult Scan (1,Sec,3,0) PanelTemp (logger_temp,250) Battery (batt_volt) 'CNR4 radiation measurements...

  • Page 45: Cr5000 Program Using Differential Measurements

    'CNR4 program 'This program measures CNR4 four-component net radiometer 'This program also measures the thermistor 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.
  • Page 46 = W/m^2 Units Rn = W/m^2 Rs, Vs_Vx 'CNR4 sensitivities: refer to the Certificate of Calibration from Kipp & Zonen for sensitivity values 'for each probes, and enter them below. Const pyra_up_sensitiv = 15.35 'unique sensitivity for upper pyranometer (microV/W/m^2) Const pyra_dn_sensitiv = 15.41...
  • Page 47 DataTable (cnr4_ts,True,-1) DataInterval (0,1,Sec,10) CardOut (1,-1) Sample (4,cnr4(1),IEEE4) Sample (1,cnr4_T_K,IEEE4) EndTable BeginProg 'Load the multiplier values for the CNR4 cnr4_mult(1) = pyra_up_mult cnr4_mult(2) = pyra_dn_mult cnr4_mult(3) = pyrg_up_mult cnr4_mult(4) = pyrg_dn_mult Scan (1,Sec,3,0) PanelTemp (logger_temp,250) Battery (batt_volt) 'CNR4 radiation measurements...
  • Page 48 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. 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.

  • Page 49: Cr3000 Program For Measuring Pt-100 Temperature Sensor

    '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.
  • Page 50 = W/m^2 Units Rn = W/m^2 cnr4_prt_R, Rs_R0 'CNR4 sensitivities: refer to the Certificate of Calibration from Kipp & Zonen for sensitivity values 'for each probes, and enter them below. Const pyranometer_up_sensitivity = 15.35 'unique sensitivity for upper pyranometer '(microV/W/m^2) Const pyranometer_dn_sensitivity = 15.41...
  • Page 51 Appendix B. Example Programs Rs_R0 = cnr4_prt_R/100 (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 LWTopC = LWTop+5.67e-8*cnr4_T_K^4 LWBottomC = LWBottom+5.67e-8*cnr4_T_K^4 'Compute short-wave net radiation Rs_net = SWTop - SWBottom 'Compute long-wave net radiation...
  • Page 52 Appendix B. Example Programs B-14...

  • Page 53: Cnr4 Performance And Measurements Under Different Conditions

    This can roughly be attributed to the water vapor in the air, which is a major contributor to the far infrared radiation. TABLE C-1. Typical output signals of CNR4 under different meteorological conditions. Explanation can be found in the text.
  • Page 54 Appendix C. CNR4 Performance and Measurements under Different Conditions FIGURE C-1. Different measurement conditions and signals Upper pyrgeometer Day with alternating cloud fields Upper Pyrgeometer Day with Alternating Cloud Fields pyrgeometer: U_emf / Sensitivity [W/m²] Temp YSI 44031 [°C] -100...
  • Page 55 Appendix C. CNR4 Performance and Measurements under Different Conditions Upwelling Signal (Downward Facing) Pyrgeometer upwelling signal (downward facing) pyrgeometer Pyrgeometer: U-emf / sensitivity [W/m²] Temp of instrument [°C] FIGURE C-3. Clear day for the downward facing pyrgeometer It is assumed that when ambient temperature varies, the net far infrared radiation remains roughly the same, independent of ambient temperature.
  • Page 56 Appendix C. CNR4 Performance and Measurements under Different Conditions upper   Temperatur   (C-1) − ⋅   lower   Ground Temperatur   − ⋅   (C-2)

  • Page 57: Cnf4 Heater/Ventilator

    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.
  • Page 58 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.

  • Page 59: Attaching The Optional Cnf4 Heater/Ventilator Unit To Cnr4

    Appendix D. CNF4 Heater/Ventilator D.2 Attaching the Optional CNF4 Heater/Ventilator Unit to CNR4 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.

  • Page 60: Attaching The Cnf4 To Cnr4 Using Pan-Head Screws And Washers

    Appendix D. CNF4 Heater/Ventilator 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.
  • Page 61 Appendix D. CNF4 Heater/Ventilator 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 flat- head screws provided to complete the solar shield installation to the CNF4, as shown in FIGURE and FIGURE D-5.

  • Page 62: Connecting The Cnf4 Power Control Cable And The Mounting Rod

    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...

  • Page 63: Wiring

    Depending on the datalogger that is used with the CNR4-L and the older, four-wire version of the CNF4-L, the tachometer output may not work for 25-m (82-ft) or 50-m (164-ft) cables.

  • Page 64: Cr3000 Datalogger Program With Heater/Ventilator Control

    'CR3000 Series Datalogger 'CNR4 program 'This program measures CNR4 four-component net radiometer 'This program also measures the thermistor inside the CNR4 'In addition this program controls heater and ventilator 'using separate SW12V-1 and SW12V-2 channels 'The heater and ventilator are turned on/off by setting flag(1), and flag(2) high and low, respectively.
  • Page 65 = W/m^2 Units Rn = W/m^2 Rs, Vs_Vx 'CNR4 sensitivities: refer to the Certificate of Calibration from Kipp & Zonen for sensitivity values 'for each probes, and enter them below. Const pyranometer_up_sensitivity = 15.35 'unique sensitivity for upper pyranometer...
  • Page 66 DataTable (cnr4_ts,True,-1) DataInterval (0,1,Sec,10) CardOut (1,-1) Sample (4,cnr4(1),IEEE4) Sample (1,cnr4_T_K,IEEE4) EndTable BeginProg 'Load the multiplier values for the CNR4 cnr4_mult(1) = pyranometer_up_mult cnr4_mult(2) = pyranometer_dn_mult cnr4_mult(3) = pyrgeometer_up_mult cnr4_mult(4) = pyrgeometer_dn_mult Scan (1,Sec,3,0) PanelTemp (logger_temp,250) Battery (batt_volt) 'CNR4 radiation measurements...

  • Page 67: Cnf4 Heater/Ventilator Maintenance

    Inspect the filter for dust and particles that might impede the air flow into the ventilator. The filter can be cleaned with warm clean water, or can be replaced with the new one. You can purchase the replacement filters, pn 26010, from Campbell Scientific. D-11...
  • Page 68 Appendix D. CNF4 Heater/Ventilator D-12...
  • Page 70 Santo Domingo, Heredia 40305 SOUTH AFRICA COSTA RICA • cleroux@csafrica.co.za • info@campbellsci.cc www.campbellsci.co.za www.campbellsci.cc Campbell Scientific Southeast Asia Co., Ltd. Campbell Scientific Ltd. 877/22 Nirvana@Work, Rama 9 Road Campbell Park Suan Luang Subdistrict, Suan Luang District 80 Hathern Road Bangkok 10250...

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