NSF UV Monitoring Network

NSF Polar Programs UV Monitoring Network

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Network Data and Reports

Solar UV irradiance data from the NSF UV Monitoring Network is available at no cost to qualified researchers. Data is distributed on CD-ROM(s) or can be downloaded from our ftp site. All data is complemented by comprehensive Operations Reports, which are available in hard copy or online via this web site.

To access network data and reports, you may:

Order data on CD-ROM and hard copies of Network Operations Reports (1992-1999)

Download individual data files from our ftp site (1997-2000)

Download Network Operations Reports as a series of pdf files (1997-2000)

View graphs of UV irradiance levels at all sites (updated weekly)

Download preliminary data from austral and boreal sites. These data cover most recent measurements and are not yet available on CD-ROM or our ftp site.

Data Overview and Quality Control

The data is based on measurements of global (sun+sky) spectral irradiance conducted with Biospherical Instrument's high-resolution SUV-100 spectroradiometers. Data are sampled on a quarter-hourly basis (half-hourly before 1997) for solar zenith angles smaller than 93°. The published datasets include:

Solar spectra in full spectral resolution between 280 and 605 nm (sampling is performed in 0.2 nm steps below 345 nm). Each spectrum is stored in a separate file in ASCII format.
Databases in ASCII format with measurements at specific wavelengths, which were extracted from the full-resolution irradiance spectra. These databases provide an easy way to analyze time series over extended time periods.
Databases with spectral integrals (e.g., UV-B and UV-A) and weighted spectral irradiances ("dose rates"). A total of six biological action spectra have been implemented, including the CIE action spectrum for erythema and Setlow's action spectrum for DNA damage.
Databases with daily doses that were calculated by integrating spectral integrals and dose rates over time.
Ancillary measurements with pyranometers (Eppley PSP) and broadband UV-A sensors (Total Scene Irradiance sensors from Biospherical Instruments and TUVR sensors from Eppley). These measurements are part of the databases.
Databases with system parameters, which are helpful for quality control.
NASA TOMS Earth Probe ozone data for spectroradiometer sites.
Weather data for the spectroradiometer sites for the periods of interest (purchased from the National Climatic Data Center).

To assure high quality of the published datasets (i.e., Level 3 data), a rigorous quality control protocol has been implemented. This includes well-defined operational procedures at each site and various quality checks during data analysis. The instruments are checked daily by site operators who also clean the collectors. The instruments are calibrated bi-weekly with standards of spectral irradiance that are traceable to NIST. Further, daily automated scans with irradiance and wavelength standards, which are internal to the instrument, allow the detection and correction of drifts. All instruments are visited annually by personnel from Biospherical Instruments. During these site visits the on-site irradiance standards are validated and the spectroradiometers are serviced, cleaned, upgraded, and repaired if needed.

The conversion from raw data to the published data includes a careful review of the calibration chain and corrections for fluctuations in the instrument's wavelength registration. The data are further screened for outliers or other events that might compromise data accuracy. Measurements with reduced quality are either excluded from the published data set or mentioned in the Operations Reports.

More details on the quality control protocol and data format can be found in the Operations Reports that complement each volume of data.