Data Processing Procedures

In order to convert the output voltage of the various sensors to physically meaningful quantities various data processing procedures must be employed. These range from the application of a responsivity based on various calibration methods to methods that involve cloud filtering and regression analysis. USDA UVMRP constantly examines the data processing procedures with the goals of improved accuracy and relevance to the user community in mind. Please look at the methods provided in the menu at the top.

A critical issue for continued operation of the monitoring program is the accurate and frequent characterization of the radiometric, spectral, and angular responses of the instruments in a manner that is traceable to the National Institute of Standards and Technology (NIST). The Central UV Calibration Facility (CUCF), established in 1994 at the NOAA Earth System Research Laboratory in Boulder, CO, is recognized as the premier UV calibration lab by the World Meteorological Organization. However, with the declining funding for this project, we are unable to maintain the level of calibration services formerly provided by the CUCF and/or the manufacturer, Yankee Environmental Services (YES).

graph of number of increased days

Lastly UVMRP augments our langley calibration by cycling the instruments through an observation platform at NOAA's Mauna Loa Observatory (MLO), which is used by several other atmospheric monitoring organizations for similar calibration purposes. Our original project instrumentation was deployed at MLO in November 1997 as part of the climatological network, and these have now become part of our suite of reference instruments. In December 2009, additional mounting pads and associated data loggers were installed to increase the number of reference instruments and provide space for field instruments that are cycling through for calibration. Since we began these in-situ Langley-based solar calibrations at MLO in mid-December 2009, we have cycled 94% of the UV-MFRSR, 87% of the UVB-1 and 13% of the VIS-MFRSR instruments through MLO, many now with repeat placements. We anticipate cycling up to 30 instruments per year through MLO. MLO facility instruments

In addition, to promote scientific collaborations, UVMRP plans to use data from instrumentation placed at MLO by other entities (e.g. NOAA, NASA, NIWA) as an additional check of the accuracy of our calibration procedures. Furthermore, satellite and ground-based measurements from collocated stations of these same entities are planned to be incorporated into radiative transfer routines used by UVMRP to provide corroboration to ensure the UVMRP data quality.