Af. Bais et al., SOLAR UVB MEASUREMENTS WITH THE DOUBLE-MONOCHROMATOR AND SINGLE-MONOCHROMATOR BREWER OZONE SPECTROPHOTOMETERS, Geophysical research letters, 23(8), 1996, pp. 833-836
In this work, the new double-monochromator version of the Brewer Ozone
Spectrophotometer, especially designed for spectral UV measurements,
is briefly described and its measurements are compared with those obta
ined by a conventional, single-monochromator Brewer instrument. The co
mparison shows that the performance of the new instrument is much supe
rior in the low UVB wavelengths (lambda<305 nm), because of the much h
igher stray-light rejection capability of the instrument. The conventi
onal Brewer spectrophotometer is capable of recording accurately solar
UVB spectra at wavelengths greater than about 300 nm. The error in UV
B dose calculations made using data from the conventional Brewer is es
timated to be of the order of +1%, while the absolute irradiances at w
avelengths below 300 nm may be overestimated by more than 10%, dependi
ng on the measured wavelength and the solar zenith angle.