UVA Biometer (broadband)
UVA Biometer (broadband)

The UV-Biometer Model 501A (UVA), manufactured by Solar Light Company, measures global irradiance in the UV spectral range of 320-400 nm. The measurement technique employs a combination of colored glass optical filters to block the Sun's visible spectra and a UV sensitive fluorescent phosphor to convert the UV light to green light which is then measured with a solid-state GaAsP photodiode. The UVA is environmentally sealed and thermally stabilized at ~25C.

This measurement is not converted into any units; the raw millivolts are used for display on the UVMRP website.

These instruments have not been calibrated since their initial factory calibrations, the dates of which vary, and can be found under the instrument history section on the individual site page.

The UVA instrument is connected to the UV-MFRSR datalogger, so its output is measured every 20 seconds and integrated into 3-minute averages, and its data is retrieved nightly in conjunction with the polling of the UV-MFRSR datalogger.

Only some sites have this UVA instrument, which came to the UVMRP from NASA\Goddard. They specified the locations (Alaska, Davis California, Pawnee Grasslands Colorado, Florida, Beltsville Maryland, Saskatchewan(closed 2012) and Big Bend Texas(closed 2012)) for these units along a latitude line, a longitude line, and at two extremes, as they were using them to ground-truth their satellite data. NASA's need for them ended in mid-2004, and they were transferred to UVMRP, so they remain a part of the network. The Big Bend Texas instruments(barometer and UVA) were moved to Baton Rouge, Louisiana at the beginning of 2013.