Improved Broadband Irradiance Data Released for EPCAPE Campaign

Published: 26 February 2025

Radiometers and other ARM instruments and containers are situated on a pier surrounded by the Pacific Ocean. A wall of gray clouds is visible along the horizon. A white cloud streaks above the water. — ARM radiometers are visible on the roof of an ARM Mobile Facility instrument container on the Ellen Browning Scripps Memorial Pier in La Jolla, California. The pier hosted ARM instruments as part of the 2023–2024 EPCAPE campaign. Photo is by John Bilberry, Los Alamos National Laboratory.

The Atmospheric Radiation Measurement (ARM) User Facility’s longtime recommended datastream for broadband surface irradiance measurements is Data Quality Assessment for ARM Radiation Data (QCRAD). The QCRAD value-added product (VAP) is now available for the Eastern Pacific Cloud Aerosol Precipitation Experiment (EPCAPE), which ran from February 15, 2023, to February 14, 2024, in La Jolla, California.

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 radiometric measurements, and calculates a best-estimate total downwelling shortwave irradiance value.

The QCRAD VAP produces daily files containing 1-minute radiation measurement fields and their quality control values. The EPCAPE QCRAD files have been processed to the final c2 level, which includes the full infrared loss corrections.

Please note that ocean conditions affected upwelling shortwave data collected during the EPCAPE ARM Mobile Facility deployment on the Ellen Browning Scripps Memorial Pier. Details on how the data are flagged for these conditions are covered in Data Quality Report D240528.4.

Scientists can use the EPCAPE QCRAD data now. Access the data in the ARM Data Center. (To download the data, first create an ARM account.)

More information on QCRAD is available on the VAP web page. To share your experience—such as how you use the data and how well they work for you—or to ask a question, contact ARM translator Damao Zhang.

To cite the QCRAD data, please use doi:10.5439/1227214.

# # #

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