Comparisons of USDA UV shadow-band irradiance measurements with TOMS satellite and DISORT model retrievals under all sky conditions

Comparisons of UV irradiances measured by the USDA UVB Monitoring and Research Network at 305- and 368-nm with retrievals from the NASA TOMS and a multiple scattering radiative transfer code were made for an 18-month period from January 1, 2000 through May 31, 2001 for Las Cruces, New Mexico, USA (32.6°N, 106.7°W, 1317 m elevation) and Billings, Oklahoma, USA (36.6°, 97.5°W, 317 m elevation). Agreement is generally within ±12% for all sky conditions and 8% for clear skies. The effects of aerosols is mostly <5%, consistent with the measured aerosol optical depths at 368 nm within the range of 0.05 and 0.25.