Instrument : Multifilter Rotating Shadowband Radiometer (MFRSR)
The visible Multifilter Rotating Shadowband Radiometer (MFRSR) is a passive instrument that measures global and diffuse components of solar irradiance at six narrowband channels and one open, or broadband, channel. Direct irradiance is not a primary measurement, but is calculated using diffuse and global measurements. To collect one data record, the MFRSR takes measurements at four different shadowband positions. The first measurement is taken with the shadowband in the nadir (home) position. The next three measurements are, in order, the first side-band, sun-blocked, and second side-band. The side-band measurements are used to correct for the portion of the sky obscured by the shadowband. The nominal wavelengths of the narrowband channels are 415, 500, 615, 673, 870, and 940 nm. From such measurements, one may infer the atmosphere’s aerosol optical depth at each wavelength. In turn, these optical depths may be used to derive information about the column abundances of ozone and water vapor, as well as aerosol and other atmospheric constituents.
The MFRSR was among the original instruments deployed at the first U.S. Department of Energy Atmospheric Radiation Measurement (ARM) Climate Research Facility sites. Over time, the MFRSR network degraded to the point at which a significant number of stations that were intended to have an instrument did not. Lack of spare instruments and replacement parts were the primary reasons for the slow degradation. Around 2005, it was decided to bring the network back to full capacity. After much consideration, it was decided the best way to accomplish this was to refurbish all the heads in-house and to transition to a different data-logging system. By early 2007, the first refurbished units were deployed, and by the end of 2008, every Southern Great Plains (SGP) site that was intended to have an MFRSR had a functioning unit. The new loggers provided expanded measurement capabilities over the previously used loggers. They provide researchers with the ability to tailor instrument operation for specific measurement needs. The hardware updates and changes necessitated significant changes to the data collection and ingest software. The data files available include a host of information. MFRSR Value-Added Products have been updated. For example, ARM is now producing a high-quality, Langley-calibrated data product.
Output Value-Added Products
This instrument is an input to the following value-added products, which provide improved measurements or derived quantities.
- mfrsraod1mich : MFRSR: derived total & aerosol optical depth from 1st Michalsky algorithm
- mfrsrcldod1min : Derived: Cloud Optical Properties from MFRSR, MWR, Langley Analysis
- nimfraod1mich : NIMFR: derived total & aerosol optical depth from 1st Michalsky algorithm
- qcrad1long : Surface Radiation Measurement Quality Control testing, including climatologically configurable limits
- qcradbeflux1long : Surface Radiation Measurement (BEFLUX input) QC testing, incl. climatologically configurable limits
- qcradbrs1long : Surface Radiation Measurement (BRS input) QC testing, incl. climatologically configurable limits
- sasheniraod : Shortwave Array Spectroradiometer-Hemispheric, NIR Aerosol Optical Depths
- sashevisaod : Shortwave Array Spectroradiometer-Hemispheric, VIS Aerosol Optical Depths
- mfrsr : Multi-Filter Rotating Shadowband Radiometer (MFRSR): irradiances
The following measurements are those considered scientifically relevant.
- Shortwave narrowband diffuse downwelling irradiance
- Shortwave narrowband direct normal irradiance
- Shortwave narrowband total downwelling irradiance