Apogee Silicon-cell Pyranometers

Measuring short-wave radiation, the Apogee Pyranometer is a Class C (ISO 9060:2018) rated pyranometer. Available in handheld (with either an integral or separate meter) or packages, as well as sensors with a range of outputs, the Apogee pyranometer is an ideal solution for agricultural, ecological, and hydrological weather networks. They can also be used for the measurement of global solar radiation, and optimisation of photovoltaic systems. When used in a agricultural network, the Pyranometer is used in the calculation of evapotransipration rates.

About the sensor

The silicon-cell pyranometer provides a faster response, at a lower cost, than the thermopile pyranometer. Designed to maintain accurate and stable measurements, the silicon-cell pyranometer is designed for low maintenance once installed. The domed body reduces the build-up of moisture, whilst a heated version is available for to minimise errors from dew, frost, rain, or snow.

Why use a pyranometer in canopy measurements

Plant light interception efficiency is a key determinant of carbon uptake by plants; plant productivity over seasonal time-scales is approximately proportional to intercepted light. Canopy architecture, leaf area, leaf angle distribution, and leaf dispersion are determinants in the light distribution and interception within the canopy. In horticultural crops pruning strategies can optimise tree structure and drive higher productivity and increase plant health and longevity. The measurement of fraction of intercepted PAR (f) is an indicator of a plant’s light use efficiency or its ability to convert sunlight into biomass. The simple method requires at least one PAR sensor above the canopy to measure direct beam and one or more PAR arrays beneath the canopy. A PAR array is necessary beneath or within a canopy because it samples a larger area and considers sunlight variability caused by the canopy. Plotting f over a growing season against some measure of yield or biomass indicates the light use efficiency of crops.