Super Site CNR4 Recalibration procedure

Pictures to take

• Instrument
• flipped
• sensor cables ends
• Also:
  • I photograph the old & new calibration stickers on the bottom of the CNR4s. If you do this with a bit of visible background (numbers need to be legible but the background can be blurry) it's clear which instrument is mounted on the tower vs the forest floor.

Tools

• Small channel lock pliers
• camera / cellphone camera
• optional: cloth or towel to catch small screws and to keep the glass protected
• bubble level
• 1/2" Nut Driver
• 1/2" box wrench
• 5/16" nut driver
• Campbell Scientific #2 phillips screwdriver
• Stubby #2 phillips screwdriver

Before the swap / at the shed

• Copy down the calibration coefficients from the new unit and modify the current program to reflect these values.
  • The coefficients are on a label stuck to the underside of the CNR4.
• The data logger these instruments are wired to is SS_Met
• Current program is ____
• I typically do a file -> save as and update the date in the file name each time I change coefficient values (or try to!)

Tower Instrument Process in field

• bring the tools to the top of the tower
• bring the replacement instrument to the top of the tower
• use the 1/2" box wrench & 1/2" nut driver to loosen the ubolts holding the cross arm in place.
• use the 5/16" nut driver to loose the hose clamp (loosen but do not remove)
• carefully wiggle / bump / shimmy the cross arm back to the platform.
• once the cabling is very close carefully unscrew the CNR4 from the slender cross arm.
• move the sensor to the tower platform
• use one of the phillips screwdrivers to remove the plastic radiation shield.
• use one of the phillips screwdrivers to remove the machine screws securing the CNR4 to the heater/fan part
• once the pieces are separated, use the small channel lock pliers to unscrew the sensor cables.
  • Note that there are three cables. The outside the case one is for the fan/heater. (four pins I believe)
  • The other two are for the net radiometer. I believe the one on the left is for the radiation and has eight pins. The one on the right has less pins and is used to measure the internal temperature of the radiometer.
• The old unit can be set aside and you can reverse these steps to deploy the freshly calibrated one (or at least the one which has not yet been placed in the field, it probably has been sitting on the shelf for a year or two after recalibration)

Forest Floor Instrument Process in field

• bring tools and set on ground.
• twist the sensor one-half turn so it is upside down. (counter clock-wise)
• use one of the phillips screwdrivers to remove the plastic radiation shield.
• use one of the phillips screwdrivers to remove the machine screws securing the CNR4 to the heater/fan part
• once the pieces are separated, use the small channel lock pliers to unscrew the sensor cables.
  • Note that there are three cables. The outside the case one is for the fan/heater. (four pins I believe)
  • The other two are for the net radiometer. I believe the one on the left is for the radiation and has eight pins. The one on the right has less pins and is used to measure the internal temperature of the radiometer.
• The old unit can be set aside and you can reverse these steps to deploy the freshly calibrated one (or at least the one which has not yet been placed in the field, it probably has been sitting on the shelf for a year or two after recalibration)

At the shed after the swap

• Connect to SS_Met data logger and send updated program.

Process out of field

• Submit PR to Ott-Hydromet and guess on shipping price
• Contact company for RMA number, fill out printable declarations and ship.
• Box up and send via UPS with RMA info on inside and outside of box.