Future Considerations

The USDA UVMRP is constantly reviewing its research goals and evaluating the needs expressed by the stakeholders in USDA research. Although fiscal years 2007, 2008 and 2009 saw budget reductions, the activities at UVMRP are ongoing in a manner as to consistently respond to the needs of the agricultural research community in the best possible manner.

With an eye toward the future, UVMRP also collaborates with developers of UV products from satellite observations. While satellite platforms have a more restrictive temporal sampling program, they offer superior geographic coverage. One challenge to the satellite community is that retrieval of surface UV irradiance requires correction for presence of clouds and aerosols. As an example of how well satellite data can be used at a particular site, data from NASA's CERES SYNI (Clouds and the earth's Radiant Energy System, SYNoptic Interpolated) program is shown in Fig. 8.12. The retrieved UV-A irradiances compare with UV-A irradiance derived from the UVMRP synthetic spectrum to within 0.6 watts/m in the mean

with an RMS difference of 5.6 watts/m for this particular case. 234

Figure 8.12 Satellite retrieved values of unweighted UV-A total horizontal irradiance compared to the same quantities deduced from a synthetic spectrum fit to UV-MFRSR data measured at the DOE Atmospheric Radiation Monitoring Program's Southern Great Plains site near Ponca City, OK during July 2002 (satellite retrieved data provided by NASA CERES SYNI effort)

70 rI I I I I I I E I I I I I I I I L I I I I I I I I L I I I [

Sample: 3652 : Mean SYNI: 24,3

Figure 8.12 Satellite retrieved values of unweighted UV-A total horizontal irradiance compared to the same quantities deduced from a synthetic spectrum fit to UV-MFRSR data measured at the DOE Atmospheric Radiation Monitoring Program's Southern Great Plains site near Ponca City, OK during July 2002 (satellite retrieved data provided by NASA CERES SYNI effort)

Conversely, as an example of the spatial coverage provided by the USDA UVMRP network, the UV Index from the Total Ozone Mapping Spectrometer (TOMS) is compared to gridded values from the UVMRP values (Gao et al., 2009) averaged over the summers from 2000 through 2004. Figure 8.13 shows two examples that demonstrate the level of agreement between the surface and satellite monitoring communities, and lends hope that resources may be focused between the two efforts in obtaining higher quality products useful to agricultural, medical, industrial and meteorological researchers.

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