U.S. Integrated Surface Irradiance Study (ISIS) Level 1 - Hourly Values is digital data set DSI-9871, archived at the National Climatic Data Center (NCDC).ISIS is a continuation of earlier National Oceanic and Atmospheric Administration (NOAA) surface-based solar monitoring programs. ISIS provides basic surface radiation data with repeatability, consistency, and accuracy based on reference ... standards maintained at levels better than 1%. ISIS addresses questions of spatial distributions and time trends at sites selected to be regionally representative and long-term continuous records of observations. The Air Resources Laboratory (ARL) operates the NOAA national broadband solar radiation network, which collects data in both the visible and ultraviolet (UV-B) wavebands. ISIS operates at two levels: Level 1 stations are basic, monitoring incoming radiation only; and Level 2 stations are more fully instrumented, focusing on surface radiation balance (SURFRAD). ISIS Level 1 stations operate in the United States of America. Currently NCDC has in archive data from ten stations located in Albuquerque, New Mexico; Bismarck, North Dakota; Desert Rock, Nevada; Hanford, California; Madison, Wisconsin; Oak Ridge, Tennessee; Seattle, Washington; Salt Lake City, Utah; Sterling, Virginia; and Tallahassee, Florida; from 1995 onward. Major parameters in Level 1 Hourly data are: global and direct beam irradiance, diffuse irradiance, and UV-B global irradiance.