VAP : Data Quality Assessment for ARM Radiation Data (QCRAD)

Instrument Categories
Radiometric

Data plot of upwelling LW testing versus air temperature. Green and red represent the 1st and 2nd level maximum, while light and dark blue represent the 1st and 2nd level minimum limits.

The QCRAD VAP has been developed to assess the data quality, and to enhance data continuity, for the ARM radiation data collected at all ARM Central and Extended facilities. The QCRAD methodology uses climatological analyses of the surface radiation measurements to define reasonable limits for testing the data for unusual data values. The main assumption is that the majority of the measurements are "good" data, which for field sites operated with care such as those of the Atmospheric Radiation Measurement (ARM) Program is a reasonable assumption. Data that fall outside the normal range of occurrences are labeled either "indeterminate" or "bad", depending on how far outside the normal range the particular datum reside. The methodology not only sets fairly standard maximum and minimum value limits, but includes many cross-comparisons based on what we have learned about how these instruments behave in the field in developing other VAPs such as the Diffuse IR Loss Correction VAP (Younkin and Long, 2004) and the Best Estimate Flux VAP (Shi and Long, 2002).

The QCRAD VAP produces two daily files containing 1-minute radiation measurement fields and their QC values. The *.c1 level file includes auxiliary information and detailed aqc and bit-packed 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 fits derived for the specific instruments (rather than the generic correction) is applied. This correction will affect the output of the downwelling SW values for those occasions where the sum of the direct plus diffuse SW is not available as the "best estimate" for downwelling SW. So that the user may easily tell whether this full correction has been applied, files which have had the full correction implemented are labeled as *.c2 and *.s2. Once the *.c2 and *.s2 files are available, they will replace the *.c1 and *.s1 files in the archive.

In September 2011, an end-to-end reprocessing of the QCRad datastreams was undertaken to:

Include the newest data from a previous end-to-end reprocessing of the MFRSR datastreams
Remove a qc test on the longwave upwelling and downwelling fluxes that was found to be too restrictive and was throwing out good data
Correct inconsistencies between the original ‘aqc’ flags and the ARM-standard ‘qc’ flags
Correct the coding of the logic for calculating the BestEstimate_down_short_hemisp; this correction only affects some cases where the BestEstimate was calculated from morning or afternoon fit.

The new version of the code has been released and is now being run in operational processing. All of the historical QCRad data at all sites/facilities is being reprocessed, reviewed, and sent to the archive. The status of the reprocessing effort is available here.

Additional Information on the QCRAD VAP

Output Products

qcrad1long : Surface Radiation Measurement Quality Control testing, including climatologically configurable limits
qcradbeflux1long : Surface Radiation Measurement (BEFLUX input) QC testing, incl. climatologically configurable limits
qcradbrs1long : Surface Radiation Measurement (BRS input) QC testing, incl. climatologically configurable limits

Primary Measurements

The following measurements are those considered scientifically relevant.

Locations

North Slope Alaska (NSA)
- Central Facility, Atqasuk AK (C2)
- Central Facility, Barrow AK (C1)
Southern Great Plains (SGP)
- Anthony, KS (E31)
- Ashton, KS (E9)
- Byron, OK (E11)
- Central Facility, Lamont, OK (C1)
- Coldwater, KS (E8)
- Cordell, OK (E22)
- Cyril, OK (E24)
- Earlsboro, OK (E27)
- El Reno, OK (E19)
- Elk Falls, KS (E7)
- Halstead, KS (E5)
- Hillsboro, KS (Extended) (E2)
- Lamont, OK (Extended) (E13)
- Larned, KS (E1)
- LeRoy, KS (E3)
- Maple City, KS (E34)
- Marshall, OK (E36)
- Medford, OK (E32)
- Meeker, OK (Extended) (E20)
- Morris, OK (Extended) (E18)
- Newkirk, OK (E33)
- Okmulgee, OK (E21)
- Omega, OK (E38)
- Pawhuska, OK (E12)
- Plevna, KS (E4)
- Ringwood, OK (E15)
- Seminole, OK (E25)
- Towanda, KS (E6)
- Tryon, OK (E35)
- Tyro, KS (E10)
- Vici, OK (Extended) (E16)
- Waukomis, OK (E37)
Tropical Western Pacific (TWP)
- Central Facility, Darwin, Australia (C3)
- Central Facility, Manus I., PNG (C1)
- Central Facility, Nauru Island (C2)
ARM Mobile Facility (FKB)
- Black Forest, Germany (M1)
ARM Mobile Facility (GAN)
- Gan Airport, Gan Island, Maldives (M1)
ARM Mobile Facility (HFE)
- Shouxian, Anhui, China (M1)
ARM Mobile Facility (NIM)
- Niamey, Niger (M1)
ARM Mobile Facility (PGH)
- ARIES Observatory, Nainital, Uttarkhand, India (M1)
ARM Mobile Facility (PYE)
- Point Reyes, CA (M1)