Visible Multifilter Rotating Shadowband Radiometer
The Visible Multifilter Rotating Shadowband Radiometer (vis-MFRSR) measures solar irradiance at six narrowband wavelengths (nominal 415, 500, 615, 673, 870, and 940 nm; each 10 nm FWHM) plus one unfiltered (open) silicon photodiode of 300-1040 nm. These wavelengths (except the 940 nm water-vapor band) were selected to permit a Langley analysis (Slusser, et al., 2000) for the direct determination of optical depth. 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 Spectralon®. The vis-MFRSR is environmentally sealed and thermally stabilized at ~40°C, and uses state-of-the-art interference filter photodiode detectors. All channels use silicon (Si) photodiodes, which for the six discrete wavelengths are each hermetically encapsulated with the appropriate filter. Measurements are made every 15 seconds and integrated into 3-minute averages and stored by an on-board computer, which is part of the datalogger for the vis-MFRSR. Each vis-MFRSR is polled nightly via a dedicated telephone line or Internet connection.
The Multifilter Rotating Shadowband Radiometer (MFRSR) was initially developed in the late 1980’s by scientists at Battelle Laboratories in Richland, WA for the direct determination of optical depth properties of the atmosphere. All six discrete wavelengths are sensitive, in varying degree, to both aerosol scattering and Rayleigh scattering. In addition, the 500, 615 and 673 wavelengths are sensitive to ozone absorption, and the 940 is sensitive to water vapor absorption. By the early 1990’s demand for these radiometers increased to the level where Battelle Labs licensed out the manufacturing technology to the private sector, in this case to Yankee Environmental Systems (YES) of Turners Falls, MA. YES made several changes to facilitate mass production of these instruments, though the optical and electronic components and assemblies remained the same as originally developed at Battelle. Throughout 1995 into early 1997, the bulk of the vis-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. As of year end 2008, there are 36 climatological sites in operation.
The Multifilter Rotating Shadowband Radiometer (MFRSR) was initially developed in the late 1980’s by scientists at Battelle Laboratories in Richland, WA for the direct determination of optical depth properties of the atmosphere. All six discrete wavelengths are sensitive, in varying degree, to both aerosol scattering and Rayleigh scattering. In addition, the 500, 615 and 673 wavelengths are sensitive to ozone absorption, and the 940 is sensitive to water vapor absorption. By the early 1990’s demand for these radiometers increased to the level where Battelle Labs licensed out the manufacturing technology to the private sector, in this case to Yankee Environmental Systems (YES) of Turners Falls, MA. YES made several changes to facilitate mass production of these instruments, though the optical and electronic components and assemblies remained the same as originally developed at Battelle. Throughout 1995 into early 1997, the bulk of the vis-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. As of year end 2008, there are 36 climatological sites in operation.