New Radiation Data Quality (QCRAD) VAP Release Available for AWARE Field Campaign

Published: 23 September 2019
QCRAD value-added product for AWARE
The top plot shows best estimates of global shortwave (GSW) downwelling radiation at McMurdo Station, Antarctica, on January 1, 2016, during the AWARE field campaign. The bottom plot shows quality control (QC) flag values indicating the sources of the best estimates for GSW.

The Data Quality Assessment for ARM Radiation Data (QCRAD) value-added product (VAP) is now available for the ARM West Antarctic Radiation Experiment (AWARE) field campaign.

QCRAD has long been ARM’s recommended datastream for broadband surface irradiance measurements. The QCRAD methodology uses climatological analyses of the surface radiation measurements to define reasonable limits for testing the data for unusual values. QCRAD applies multiple data quality checks, corrects for errors due to infrared loss in shortwave (SW) radiometric measurements, and calculates a best-estimate total downwelling SW irradiance value.

Data are processed for the full length of the AWARE deployment at McMurdo Station (M1) and the supplemental site on the West Antarctic Ice Sheet (S1). Available QCRAD datastreams and date ranges for AWARE are:

  • c2—20151124.000000 to 20170102.000000
  • s2—20151124.000000 to 20170102.000000
  • c1—20151205.000000 to 20160119.000000
  • s1—20151205.000000 to 20160119.000000.

The QCRAD VAP produces two daily files containing 1-minute radiation measurement fields and their quality control (QC) values. The *.c1 file—the asterisk represents the datastream name—includes auxiliary information and detailed qc flags. The *.s1 summary file includes a simplified version of the qc flags and fewer auxiliary data values.

The .c1 data are created using a generic correction to the downwelling SW hemispheric flux to correct for infrared loss within the radiometer. The .c2 coefficients use infrared loss corrections derived for the specific instruments rather than the generic correction. This correction will affect the output of the downwelling SW values when the sum of the direct plus diffuse SW is not available as the best estimate for downwelling SW.

M1 datastreams for AWARE are available at the .c2/.s2 level. S1 data will only be available at the .c1/.s1 level because that portion of the deployment did not have any nighttime periods, so instrument-specific infrared loss correction coefficients cannot be generated (Dutton et al. 2001; Younkin and Long 2003).

Scientists can use the new QCRAD data now. To share your experience—such as how you use the data and how well it works for you—or to ask a question, contact Josh Howie.

More information on QCRAD is available on the VAP web page. To access these data, go to the ARM Data Center. (Go here to request an account.)

To cite the QCRAD data, please use doi:10.5439/1027372.

References: Dutton EG, JJ Michalsky, T Stoffel, BW Forgan, J Hickey, DW Nelson, TL Alberta, and I Reda. 2001. “Measurement of Broadband Diffuse Solar Irradiance Using Current Commercial Instrumentation with a Correction for Thermal Offset Errors.” Journal of Atmospheric and Oceanic Technology, 18(3), 10.1175/1520-0426(2001)018<0297:mobdsi>;2.

Younkin K and C Long. 2003. “Improved Correction of IR Loss in Diffuse Shortwave Measurements: An ARM Value-Added Product.” U.S. Department of Energy. ARM/TR-009.

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ARM is a DOE Office of Science user facility operated by nine DOE national laboratories.