Ultraviolet Multifilter Rotating Shadowband Radiometer
Ultraviolet Multifilter Rotating Shadowband Radiometer

UV-MFRSR interior The Ultraviolet Multifilter Rotating Shadowband Radiometer (UV-MFRSR) measures solar irradiance at seven narrowband wavelengths (nominal 300, 305, 311, 317, 325, 332, and 368 nm; each 2 nm FWHM) in the UV-B and UV-A regions. These wavelengths were selected to permit a Langley analysis (Slusser, et al., 2000) for the direct determination of optical depth. The 332 nm wavelength serves as a reference to Dobson instruments and the 311 is designed to be a reference point to a relatively unstructured (flat) portion of the UV spectra. The shadowband enables the instrument to measure the three components of solar irradiance, total horizontal, diffuse, and direct normal simultaneously across all seven channels through a single Lambertian diffuser made of Teflon®. The UV-MFRSR is environmentally sealed and thermally stabilized at ~42°C, and uses state-of-the-art interference filter photodiode detectors. The 300 and 305 channels use silicon-carbide (SiC) photodiodes, and the 311 through 368 channels use silicon (Ai) or gallium phosphate (GaP) photodiodes.


Measurements are made every 20 seconds and integrated into 3-minute averages and stored by an on-board computer, which is part of the datalogger for the UV-MFRSR.


Originally these instruments were lamp calibrated at the CUCF facility in Boulder, Colorado. Now the calibration of this instrument is done by cycling the instruments through NOAA’s calibration facility at Mauna Loa obtaining an MLO calibration factor, although several are still sent each year to CUCF to receive full calibration. We also use the data at the deployment site to provide an In-Situ Langley calibration factor as well. The calibration information for this instrument can be found under the Location Information, Deployment History. Detailed information about our Langley Analysis can be found under our Data Processing Procedures.


The first Ultraviolet Multifilter Rotating Shadowband Radiometers (UV-MFRSR), units 231 and 232, were developed in the early 1990's by scientists from the Atmospheric Sciences Research Center (ASRC) at the State University of New York at Albany (SUNY-Albany) in conjunction with the licensed manufacturer, Yankee Environmental Systems (YES) of Turners Falls, MA. These prototype instruments were deployed in 1995 at Colorado State University's (CSU) research facility at the Central Plains Experimental Range (CPER) [known as Pawnee site by UVMRP] in the Pawnee National Grassland (PNG) of northeast Colorado. Based on the results from these two units, two additional prototype instruments, units 270 and 271, were built by YES with refinements to the optical and electronic components. Unit 270 was deployed to the Pawnee site and unit 271 was used to start up a new climatological monitoring site at the University of California at Davis Climate Station. Throughout late 1996 into early 1997, the bulk of the UV-MFRSR instruments were delivered by YES to UVMRP, and were subsequently deployed to existing and new climatological sites, such that by the end of 1997 there were 22 climatological sites in operation.