MFRSR
The MFRSR takes spectral measurements of direct normal, diffuse horizontal, and total horizontal solar irradiances. These measurements are at nominal wavelengths of 415, 500, 615, 673, 870, and 940 nm. The measurements are made at a user specified time interval; typically this interval is about one minute or less, at the SGP site, the sampling interval is 20 seconds. From such measurements, one may infer the atmosphere's optical depth at the wavelengths mentioned above. In turn, these optical depths may be used to derive information about the column abundances of ozone and water vapor (Michalsky et al. 1995), as well as aerosol (Michalsky et al. 1994) and other atmospheric constituents. A silicon detector is also part of the MFRSR. This broadband detector provides a measure of the broadband direct normal, diffuse horizontal, and total horizontal solar irradiances. These quantities are uncalibrated and reported in units of "counts." An MFRSR head that is mounted to look vertically downward can measure upwelling spectral irradiances (obviously at the same wavelengths as the MFRSR!). In the ARM system, this instrument is called an "MFR". At the SGP there are two MFRs; one mounted at the 10 m height and the other at 25 m. At the NSA sites, the MFRs are mounted at 10 m. Additional information available at "http://www.arm.gov/docs/instruments.html" [Summary provided by ARM]
Radiometers