In 1990, the USDA became concerned about the decreasing stratospheric ozone over North America, and the potential for increases of crop- and biosphere-damaging levels of ultraviolet radiation. In January 1991 and March 1992 they sponsored two workshops to develop their concept of a national UV monitoring network. Later in 1992, the USDA, under their Cooperative State Research, Education and Extension Service (CSREES) initiated and funded the UV-B Monitoring and Research Program (UVMRP), headquartered at Colorado State University (CSU) in Fort Collins, Colorado. The UVMRP was tasked to provide information on the geographical distribution and temporal trends of UV-B (ultraviolet -B) radiation in the United States, as this information is critical to the assessment of the potential impacts of increasing ultraviolet radiation levels on agricultural crops and forests. Specifically the monitoring program:

• Provides information to the agricultural community and others about the climatological and geographical distribution of UV-B irradiance;
• Furnishes the basic information necessary to support evaluations of the potential damaging effects of UV-B to agricultural crops and forests;
• Supplies ground truth for satellite measurements of UV-B, and basic information for radiation transfer model calculations;
• Establishes long-term records of UV-B irradiance necessary to assess trends.

The program consists of both a research component and a climatologic network.

The climatologic network is designed to provide an adequate density of measurement sites to establish the spatial and temporal characteristics of UV-B irradiance. The network follows a grid-based design which divides the country into 26 regions of approximately equal-area. Sites are located primarily in rural areas, with particular consideration given to agricultural and forest regions. As of year-end 2008, a total of 36 sites have been established in 27 states and in two other countries, Canada and New Zealand, for coordination with their respective monitoring networks.

Research activities are focused towards challenging our current understanding of factors which control UV irradiance and towards improving the quality of UV monitoring instrumentation and data. Within the UVMRP, this research is coordinated by the Center of Remote Sensing and Modeling for Agricultural Sustainability (CRSMAS). This component of the UVMRP program works with agricultural and forest researchers to evaluate both the isolated effects of elevated UV-B on agricultural crops, livestock, forests, and range resources, and the combined effects of UV-B radiation and other climate stress factors [such as moisture (drought), temperature, ozone, soil nutrients and carbon dioxide]. By understanding both compounding and antagonistic effects of multiple stress factors, this research will help develop solutions that allow producers to cope with these detrimental effects and ensure future agriculture and livestock quality and productivity. Specifically, the research component:

• Evaluates the response of plants, forests, ecosystems, and animals to UV-B and other climate stress factors in collaboration with researchers at other universities;
• Is developing a climate-crop model, known as the Integrated Agricultural Impact Assessment System, to aid agricultural producers and decision-makers who are responsible for developing plans to cope with the on-going changes in our climate. Such a system will be sufficiently comprehensive to include crop growth models, ultraviolet-visible solar radiation, Earth’s climate, air and water quality models, plus satellite and in-situ observations.

In a broader sense, the USDA UV-B Monitoring and Research Program supports research that increases our understanding of the factors controlling surface UV-B irradiance and provides the data necessary for assessing the impact of UV-B radiation on ecosystems, human health, materials and agricultural commodities.