Apogee S2-122 Посібник користувача - Сторінка 4

Переглянути онлайн або завантажити pdf Посібник користувача для Аксесуари Apogee S2-122. Apogee S2-122 16 сторінок. Pri sensors

INTRODUCTION

Radiation reflected from surfaces (e.g., plant canopies, soil) provides information about the state of the surface.

Reflectance is the ratio of radiation reflected by the surface to radiation incident on the surface.

A common index calculated from reflectance measurements is photochemical reflectance index (PRI). PRI is

calculated from reflectance at 531 nm (green) and 570 nm (yellow) and provides an indication of canopy

photosynthetic activity.

The typical application of PRI sensors is monitoring plant canopies. PRI is related to plant canopy light use

efficiency and is often used in studies of canopy photosynthesis and response to stress.

Apogee Instruments S2 series two-band sensors consist of a cast acrylic diffuser (upward-looking sensor) or acrylic

window (downward-looking sensor), pair of photodiodes that measure specific wavelength ranges, and signal

processing circuitry mounted in an anodized aluminum housing. A cable to connect the sensor to a measurement

device is also included. S2 series sensors are designed for continuous irradiance (upward-looking sensor) or

radiance (downward-looking sensor) measurements in indoor and outdoor environments. Reflectance derived

from paired upward-looking and downward-looking sensors can be used to calculate PRI. Apogee PRI sensors are

offered with digital SDI-12 output or with analog voltage output.