8
Cosine Response
Mean cosine response of twenty-three SQ
series quantum sensors (
error bars
represent two standard deviations above
and below mean
). Cosine response
measurements were made by direct side-
by-side comparison to the mean of four
reference thermopile pyranometers, with
solar zenith angle-dependent factors
applied to convert total shortwave
radiation to PPFD. Blue points represent
the AM response and red points represent
the PM response.
Directional, or cosine, response is defined as the measurement
error at a specific angle of radiation incidence. Error for Apogee
SQ series quantum sensors is approximately ± 2 % and ± 5 % at
solar zenith angles of 45° and 75°, respectively.