Solar and Infrared Radiation Measurements

7 Rotating Shadowband Radiometers

The total assembly is called the “dial” radiometer both because the rotating shade resembles the face of a dial with a revolving arm and because the device is used to measure “D-and-I-AL” quantities (Diffuse, Incident direct-beam, and globAL irradiance).

Marvin L. Wesely

(1944–2003)

7.1 Introduction

A simple rotating shadowband radiometer was introduced by Wesely (1982), as discussed in Chapter 3; it used a LI-COR LI-200 photodiode pyranometer because a rapid response time (10 μsec for the LI-200) was needed as the shading band passed over the detector to block direct sunlight. The band rotated at constant speed and completely shaded the diffuser every 4 or 5 minutes depending on the motor selected. The output ...