Portable Irradiance Calibration System

The energy from the sun is the overall engine that drives our climate. Widespread concern over thedepletion of the stratospheric ozone layer, and the effect that this may have on UV-B irradiance levelsat the surface of the Earth, has highlighted the need for improved technology for precisely measuringsolar ultraviolet radiation. Instruments deployed in the field require frequent calibration to ensureaccurate and reliable measurements. However, many instruments are operating without reference-grade calibrations due to the cost and downtime associated with laboratory recalibrations. Thisproposal describes a novel portable irradiance calibration system that permits absolute calibrations inthe field, thereby eliminating the process delays associated with traditional laboratory calibrations.The atmospheric sciences, photobiology, and agricultural communities are faced with the difficult taskof assessing and analyzing long-term changes in atmospheric ozone and the resulting changes inultraviolet light levels. An understanding of long-term changes in the biosphere is critical tocircumventing potentially devastating changes in the world's food production due to global warmingand other factors. The USDA is the lead Federal agency in this area and is in the process of deployingthe UV-B Trends and Status Network, which will greatly benefit from the proposed technology.