Level 2 (c2/s2) data for the Data Quality Assessment for ARM Radiation Data (QCRAD) value-added product (VAP) have now been processed at all Atmospheric Radiation Measurement (ARM) user facility fixed sites through summer 2017. These sites include the Southern Great Plains central and extended facilities, Barrow (known officially as Utqiaġvik) and Oliktok Point, Alaska, and Graciosa Island in the Azores.
QCRAD has long been the recommended ARM datastream for broadband surface irradiance measurements. QCRAD applies multiple data quality checks, corrects for errors due to infrared loss in shortwave radiometric measurements, and calculates a best-estimate total downwelling shortwave irradiance value.
The QCRAD VAP routinely produces two daily files containing 1-minute radiation measurement fields and their QC values. The *.c1 level file—* represents the datastream name—includes auxiliary information and detailed QC flags. The *.s1 level summary file includes a simplified version of the QC flags and fewer auxiliary data values.
During operational processing, the QCRAD VAP applies a generic correction to the shortwave (SW) downwelling hemispheric flux to correct for infrared loss within the radiometer. On a yearly basis, a more detailed correction that uses infrared loss corrections derived for the specific instruments—rather than the generic correction—is applied. This correction will affect the output of the SW downwelling values for those occasions when the sum of the direct plus diffuse SW is not available as the “best estimate” for SW downwelling data.
When c2/s2 files are available, they should be used. The c2/s2 files have additional processing to improve the data.
To share your experience—such as how you use the data and how well it works for you—or to ask a question, contact Laura Riihimaki, the translator for this VAP.
The ARM Climate Research Facility is a DOE Office of Science user facility. The ARM Facility is operated by nine DOE national laboratories.