Contents

Title: West Pond - Radiometer Calibration 2021
Date:2021-06-22 - 2021-07-04
Data File: WP_calkit_20210720.csv
WP_calNDVI_20210720.csv
Refers to:WP,121038,060831,1049,1050,1457,110341,110336,1066703780,2046503378

From 2021-06-22 to 2021-07-21 we set up the radiometer calibration kit at West Pond. We set up all the calibration sensors on the radiometer boom. Unfortunately I didn't take any photos of the setup. The calibration sensors were a 4-way radiometer, a PAR sensor, and a pair of Apogee NDVI sensors. The PAR sensor was initially installed facing up to measure incoming light. Halfway through the calibration on 2021-07-06, we turned the PAR sensor so it faced downward and measured reflected radiation.

 

Reference Variable Reference Sensor Serial Number Factory coefficient
SWin Kipp & Zonen CNR4 sn 121038 14.56 uV/(W/m2)
SWout Kipp & Zonen CNR4 sn 121038 14.17 uV/(W/m2)
LWin Kipp & Zonen CNR4 sn 121038 6.83 uV/(W/m2)
LWout Kipp & Zonen CNR4 sn 121038 5.48 uV/(W/m2)
PAR Kipp & Zonen PQS 1 sn 060831 6.69?
NDVI Incoming Apogee S2-411 sn 1049 n/a
NDVI Outgoing Apogee S2-411 sn 1050 n/a

 

Tower Variable Tower Sensor Serial Number Factory coefficient New coefficient Summary
SWin Kipp & Zonen NR01 sn 1457 13.8

14.65 (+6%)

R2>99%

  
SWout Kipp & Zonen NR01 sn 1457 13.0

14.65 (+13%)

R2>99%

  
LWin Kipp & Zonen NR01 sn 1457 9.2

6.5 (-30%)

R2=91%

 Large jump in coefficient and relatively low R2. I would keep the factory coefficient for now.
LWout Kipp & Zonen NR01 sn 1457 9.8

11.0 (+12%)

R2=98%

  
PAR Incoming Kipp & Zonen PAR-LITE sn 110341 4.80

4.91 (+2%)

R2=99%

  
PAR Outgoing Kipp & Zonen PQS 1 sn 110336 4.70

4.29 (-9%)

R2=99%

  

 

Tower Variable Tower Sensor Serial Number Calibration Equation Summary
NDVI Incoming Decagon-METER SRS 1066703780    
NDVI Outgoing Decagon-METER SRS 2046503378    

 

Shortwave Incoming

Figure 1. Incoming shortwave radiation.

Regression Data

Residuals

Figure 2. Linear regression between tower and reference sensors.

 

Shortwave Outgoing

Figure 3. Outgoing shortwave radiation.

Regression Data

Residuals

Figure 4. Linear regression between tower and reference sensors.

 

Longwave Incoming

Figure 5. Incoming longwave radiation.

Regression Data

Residuals

Figure 6. Linear regression between tower and reference sensors.

 

Longwave Outgoing

Figure 7. Outgoing longwave radiation.

Regression Data

Residuals

Figure 8. Linear regression between tower and reference sensors.

 

Incoming PAR

Figure 9. Incoming PAR from the reference sensor and 2 tower sensors (PARin sensor and rotating shadowband (RSB) sensor used to measure diffuse PAR).

Regression Data

Residuals

Figure 10. Linear regression between tower and reference sensors. Measurements <1mV were discarded to avoid too much weight on nighttime values.

 

Outgoing PAR

Figure 11. Outgoing PAR.

Regression Data

Residuals

Figure 12. Linear regression between tower and reference sensors. Measurements <0.2mV were discarded to avoid too much weight on nighttime values.

 

NDVI

Figure 13. NDVI from tower and reference sensors.

Regression Data

Residuals

Figure 14. Linear regression between tower and reference sensors.

Figure 15. Red reflectance.

Figure 16. NIR reflectance.

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