The Atmospheric Radiation Measurement (ARM) user facility processes yearly data from the Data Quality Assessment for ARM Radiation Data (QCRAD) product—the recommended ARM datastream for broadband surface irradiance measurements—to produce level 2 (c2) files. These files undergo additional processing to improve the data.
New c2-level data are available for all three of ARM’s fixed-location atmospheric observatories, covering the following sites and date ranges:
- the Eastern North Atlantic observatory (Graciosa Island, Azores, Portugal) from October 29, 2022, to February 8, 2024
- the North Slope of Alaska observatory (Utqiaġvik, Alaska) from August 21, 2022, to August 19, 2023
- Southern Great Plains (SGP) extended facility E9 (Ashton, Kansas) from August 4, 2022, to September 29, 2023
- SGP E11 (Byron, Oklahoma) from August 5, 2022, to September 29, 2023
- SGP E12 (Pawhuska, Oklahoma) from August 3, 2022, to August 29, 2023
- SGP E13 (Lamont, Oklahoma) from August 10, 2022, to August 15, 2023
- SGP E15 (Ringwood, Oklahoma) from August 9, 2022, to September 29, 2023
- SGP E32 (Medford, Oklahoma) from August 5, 2022, to August 14, 2023
- SGP E33 (Newkirk, Oklahoma) from August 2, 2022, to August 14, 2023
- SGP E34 (Maple City, Kansas) from August 9, 2022, to September 29, 2023
- SGP E35 (Tryon, Oklahoma) from August 6, 2022, to September 29, 2023
- SGP E36 (Marshall, Oklahoma) from August 2, 2022, to September 29, 2023
- SGP E37 (Waukomis, Oklahoma) from August 3, 2022, to August 23, 2023
- SGP E39 (Morrison, Oklahoma) from August 6, 2022, to August 24, 2023
- SGP E40 (Pawnee, Oklahoma) from August 10, 2022, to September 29, 2023
- SGP E41 (Peckham, Oklahoma) from August 3, 2022, to August 2, 2023
- the broadband radiometer station at the SGP Central Facility (Lamont, Oklahoma) from August 10, 2022, to August 15, 2023.
QCRAD processing for fixed sites involves two steps: c1-level operational processing and the yearly c2-level processing.
During c1-level processing, QCRAD applies multiple data quality checks and calculates a best-estimate total downwelling shortwave irradiance value. Previously at the c1 level, QCRAD applied a generic correction for infrared loss within the unshaded pyranometer to correct the shortwave downwelling hemispheric flux. In 2022, it was found that the generic correction coefficients being used at the c1 level were overcorrecting the infrared loss. Because of this, starting in August 2022, these correction coefficients were set to zero for ARM’s three fixed observatories, eliminating corrections at the c1 level. However, note that full infrared loss corrections are still made at the c2 level.
The correction generated by the c2-level processing uses infrared loss corrections derived for the specific instruments. This correction will affect the output of the downwelling shortwave values when the sum of the direct plus diffuse shortwave is not available as the “best estimate” for downwelling shortwave. When c2 files are available, they should be used.
More information is available on the QCRAD web page. To share your experience using the data or to ask a question, contact ARM translator Damao Zhang.
Access the new QCRAD data in the ARM Data Center. (To download the data, first create an ARM account.)
To cite the QCRAD broadband radiometer station data (qcradbrs1long), please use doi:10.5439/1227217. For the other QCRAD data (qcrad1long), please use doi:10.5439/1227214.
# # #ARM is a DOE Office of Science user facility operated by nine DOE national laboratories.