CNR2 Net Radiometer Revision: 5/10 C o p y r i g h t © 2 0 0 0 - 2 0 1 0 C a m p b e l l S c i e n t i f i c , I n c .
Warranty and Assistance The CNR2 NET RADIOMETER is warranted by CAMPBELL SCIENTIFIC, INC. to be free from defects in materials and workmanship under normal use and service for twelve (12) months from date of shipment unless specified otherwise. Batteries have no warranty. CAMPBELL SCIENTIFIC, INC.'s obligation under this warranty is limited to repairing or replacing (at CAMPBELL SCIENTIFIC, INC.'s option) defective products.
CNR2 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 CNR2 Specifications ................................................................................1 2.2 Pyranometer Specifications .............................................
CNR2 Table of Contents 8-1. Dirt, Rain, or Snow on CNR2 Sensor will Reduce the Readings ......... 12 8-2. CNR2 Net Radiometer Bubble-Level................................................... 13 8-3. Replacing Drying Cartridge.................................................................. 13 Tables 5-1. 5-2. 5-3. 9-1. CRBasic Datalogger Connections for Differential Measurement........... 6 Edlog Datalogger Connections for Differential Measurement ............... 7 Campbell Scientific Cable vs.
CNR2 Net Radiometer 1. General Description The CNR2 Net Radiometer is intended for the analysis of the radiation balance of short-wave and long-wave infrared radiation. The most common application is the measurement of total net radiation at the earth's surface. The CNR2 design is such that both the upward facing and the downwardfacing instruments measure the energy that is received from the hemisphere.
CNR2 Net Radiometer FIGURE 2-1. The Dimensions of the CNR2 2.2 Pyranometer Specifications 310 to 2800 nm Spectral range: Zero offset: Type A; 200 W/m FIR <15 W/m2 Field of view for upper detector: 180° Field of view for lower detector: 150° Directional error: <20 W m-2 Non-linearity (0-1000 W m-2) net irradiance: <2.0% 2 2.3 Pyrgeometer Specifications Spectral range: 4.
CNR2 Net Radiometer FIGURE 3-1. Mounting According to Hemisphere Mount the CNR2 at a height of at least 1.5 meters above the surface to avoid the 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%.
CNR2 Net Radiometer FIGURE 3-2. The CNR2 mounted to a pole (top) and crossarm (bottom) via the 26120 Mounting Bracket Kit. For installation in buildings or in solar energy applications, users will often have to mount the CNR2 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.
CNR2 Net Radiometer 4. Using the CNR2 in the Two Separate Components Mode (2SCM) The two pyranometers will measure the short-wave radiation (incoming from the sky and reflected from the soil surface); the two pyrgeometers will measure the long-wave radiation (incoming from the sky and reflected from the soil surface). However, only one output for short-wave radiation (net short-wave) and one output for long-wave radiation (net long-wave) will be given as a result of the CNR2 measurements. 4.
CNR2 Net Radiometer 4.3 Calculation of the Net Solar Radiation The net radiation, ENET, is calculated using the sensor measurement results for net short-wave radiation and net long-wave radiation. The net radiation is the difference between the net short-wave and net long-wave radiation. ENET = ENETSW + ENETLW 5. Wiring The two radiation outputs from CNR2 Net Radiometer can be measured using differential or single-ended inputs on the datalogger.
CNR2 Net Radiometer TABLE 5-2.
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.
CNR2 Net Radiometer Minimum(1,Net_Longwave, IEEE4,False,True) Maximum(1,Net_Longwave, IEEE4,False,True) Average(1,Net_Longwave, IEEE4,False) Average(1,Net_Rad, IEEE4,False) EndTable 'Main Program BeginProg Scan(1,Sec,1,0) 'CNR2 Net Radiation Measurements VoltDiff(Net_Shortwave,1,mV25,1,True,200,250, CNR2_SW_CAL,0.0) VoltDiff(Net_Longwave,1,mV25,2,True,0,250, CNR2_LW_CAL,0.0) Net_Rad = Net_Shortwave+Net_Longwave 'Call Data Tables and Store Data CallTable(Table1) NextScan EndProg 6.2.
CNR2 Net Radiometer ; Measure Net Longwave Radiation 2: Volt (Diff) (P2) 1: 1 Reps 2: 22 7.5 mV 60 Hz Rejection Range 3: 2 DIFF Channel 4: 2 Loc [ Net_LW ] 5: 86.21 Multiplier 6: 0.
CNR2 Net Radiometer 12: Average (P71)^29073 1: 1 Reps 2: 2 Loc [ Net_LW ] 13: Average (P71)^15174 1: 1 Reps 2: 3 Loc [ Net_Rad ] *Table 2 Program 01: 10.0000 Execution Interval (seconds) 1: Serial Out (P96) 1: 71 Storage Module *Table 3 Subroutines End Program 7. Calibration Recalibrate the CNR2 every two years, or as an alternative, by running a higher standard next to it. Compare the pyranometers over a two-day period when the days are clear. Compare the pyrgeometers during the night.
CNR2 Net Radiometer 8. Maintenance Clean domes and windows with distilled water or alcohol. Readings are reduced if domes and/or windows are not clean. FIGURE 8-1.
CNR2 Net Radiometer Keep instrument leveled at all times during the measurements. FIGURE 8-2. CNR2 Net Radiometer Bubble-Level Replace drying cartridge every 6 months. FIGURE 8-3. Replacing Drying Cartridge (first replacement cartridge comes with the CNR2) 9. Typical Values TABLE 9-1.
CNR2 Net Radiometer 14
Campbell Scientific Companies Campbell Scientific, Inc. (CSI) 815 West 1800 North Logan, Utah 84321 UNITED STATES www.campbellsci.com • info@campbellsci.com Campbell Scientific Africa Pty. Ltd. (CSAf) PO Box 2450 Somerset West 7129 SOUTH AFRICA www.csafrica.co.za • cleroux@csafrica.co.za Campbell Scientific Australia Pty. Ltd. (CSA) PO Box 444 Thuringowa Central QLD 4812 AUSTRALIA www.campbellsci.com.au • info@campbellsci.com.au Campbell Scientific do Brazil Ltda.
