SGP/CO2FLX/C1 - Reprocessed: User Notes

Replacement of LI-200 sensor (total downwelling shortwave radiation, variable r_tot) by a 
new LI-190 sensor (upwelling photosynthetic photon flux density, variable ppfd_up).

The new LI-190 sensor was:
- installed on December 9, 2004. 
- being tested from December 9, 2004 to December 22, 2004.
- operational after December 22, 2004.

Consequently:
1. variable "r_tot" is filled with missing values (qc_r_tot = 1) after December 9, 2004,
2. variable "ppfd_up" is filled with missing values (qc_ppfd_up = 1) prior December 22, 
2004.

• ppfd_up
• Total downwelling shortwave radiation (LI-200 sensor)(r_tot)

SGP/CO2FLX/C1 - downwelling longwave hemispheric irradiance incorrect

A problem was identified with the downwelling longwave hemispheric irradiance (variable 
"r_down_long_hemisp") calibration of our Kipp & Zonen CNR1 radiometer. The offset of the 
instrument is believed to be incorrect over the specified time frame, and a correction of 
the problem is underway.

• Downwelling longwave hemispheric irradiance; t_rad corrected(r_down_long_hemisp)

SGP/CO2FLX/C1 - Soil Temperature measurements

Current data quality check (qc) procedure does not catch spikes in soil temperature 
measurements. A new qc procedure is being tested and will improve the current procedure.

• Average of two upper soil temperature sensors(mean_t_soil_upper)
• Average of two middle soil temperature sensors(mean_t_soil_middle)
• Average of two lower soil temperature sensors(mean_t_soil_lower)

SGP/CO2FLX/C1 - Reprocess: calibration error

A problem was identified with the calibration of the instrument performed on May 27, 2005. 
A study to correct this bad calibration is underway.

• Mean H2O density(mean_q)
• WPL corrected CO2 flux(fc_corr)
• WPL corrected latent heat flux(le)

SGP/CO2FLX/C1 - Met stand was moved

Ameriflux program (Hank Loescher from Oregon state university) visits the site to 
intercompare his instruments with our 4m flux system.
The met stand was moved by 30 feet and consequently:
1. Soil moisture sensors were disconnected,
2. Soil temperature sensors were disconnected,
3. Soil heat plates were disconnected,
4. The true direction of the anemometer boom was 230 degrees instead of the regular 270 
degrees.

• Average of four upper soil moisture sensors(mean_m_soil_upper)
• Average of four lower soil moisture sensors(mean_m_soil_lower)
• Average of two upper soil temperature sensors(mean_t_soil_upper)
• Unit Vector Wind Direction(wdir)
• Average of two middle soil temperature sensors(mean_t_soil_middle)
• Average of two lower soil temperature sensors(mean_t_soil_lower)
• Average of four soil heat flux probes(mean_g_soil)

SGP/CO2FLX/C1 - downwelling longwave hemispheric irradiance incorrect

Downwelling longwave radiation measurements (variable "r_down_long_hemisp") are bad due to 
a wiring issue. Users should not use the downwelling longwave hemispheric irradiance 
during this period. The downwelling shortwave and longwave radiation at CF is also available 
from the Broadband Radiometer Station (BRS).

• Downwelling longwave hemispheric irradiance; t_rad corrected(r_down_long_hemisp)

SGP/CO2FLX/C1 - Disturbance around site

A bulldozer used to excavate the SGP Tower anchors was right around (within 10 feet) our 
systems.

• WPL corrected CO2 flux(fc_corr)
• Mean CO2 density(mean_c)

• WPL corrected CO2 flux(fc_corr)
• Mean CO2 density(mean_c)

• Mean CO2 density(mean_c)
• WPL corrected CO2 flux(fc_corr)

• WPL corrected CO2 flux(fc_corr)
• Mean CO2 density(mean_c)

SGP/CO2FLX/C1 - Farm operation

Soil temperature, soil moisture, soil heat flux and upwelling surface radiation (long, 
short, and PAR) measurements were not valid from 20070822 to 20070907 due to farm operations.

• stderr_mean_t_soil_lower
• Average of four upper soil moisture sensors(mean_m_soil_upper)
• stderr_mean_m_soil_lower
• Upwelling shortwave hemispheric irradiance; t_rad corrected(r_up_short_hemisp)
• stderr_mean_m_soil_upper
• stderr_mean_t_soil_middle
• Average of two lower soil temperature sensors(mean_t_soil_lower)
• Average of four soil heat flux probes(mean_g_soil)
• stderr_mean_t_soil_upper
• ppfd_up
• Average of four lower soil moisture sensors(mean_m_soil_lower)
• Upwelling longwave hemispheric irradiance; t_rad corrected(r_up_long_hemisp)
• Average of two upper soil temperature sensors(mean_t_soil_upper)
• stderr_mean_g_soil
• Average of two middle soil temperature sensors(mean_t_soil_middle)

SGP/CO2FLX/C1 - Reprocess: 4m instruments height

The height of the 4m instruments is 4.8 m and not 4.65 m as shown in b1 datastream

• zm

SGP/CO2FLX/C1 - Reprocessed: Recalibration

The 4m CO2 flux system was calibrated on May 25, 2005. After the calibration was 
performed, calibration coefficients used to measure CO2 density were not updated. This added an 
OFFSET to the CO2 density measurements.

The data have been reprocessed to address the offset.  The reprocessed data were archived 
in December 2008. Please retrieve the updated files for use in your analysis.

• Mean CO2 density(mean_c)