8
Cosine Response
Directional, or cosine, response is defined as the measurement
error at a specific angle of radiation incidence. Error for Apogee
SQ-500 series quantum sensors is approximately ± 2 % and ± 5 %
at solar zenith angles of 45° and 75°, respectively.
Mean cosine response of seven apogee
SQ-500 quantum sensors. Cosine response
measurements were made on the rooftop
of the Apogee building in Logan, UT.
Cosine response was calculated as the
relative difference of SQ-500 quantum
sensors from the mean of replicate
reference quantum sensors (LI-COR
models LI-190 and LI-190R, Kipp & Zonen
model PQS 1).