Kipp&Zonen UVS-E-T UV Radiometers - Manual (Page 14)

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Calibration Step B:
The irradiances have to be corrected for the spectral
mismatch error with “conversion factors”, denoted as
γ
(no units).  These conversion factors are determined
using modelled UV irradiances as a function of various
total Ozone column densities and solar zenith angles.
Adjustment Step:
The corrected UV measurements are obtained by
multiplying the raw UV radiometer reading under
outdoor measurement conditions with an appropriate
“adjustment factor”,
χ, defined as 1/(ρ•γ). The
appropriate adjustment factor has to be chosen
according to the measurement conditions at the time of
the UV radiometer reading.
The Adjustment Step which provides the final,
corrected, UV irradiance (in units of W/m2) is carried
out by the UVIATOR program for each individual UVS
radiometer reading. Before the broad-band UVS
radiometer can be used in the field, it must be factory
calibrated according to Calibration Steps A and B,
which provide the calibration and correction factors for
a particular instrument.
The next two paragraphs describe Calibration Steps A
and B as they are performed at Kipp & Zonen. The final
paragraph of this chapter describes the Adjustment
Step as implemented in the UVIATOR program.
4.1.1 CALIBRATION STEP A:
DETERMINATION OF THE RADIOMETRIC
CALIBRATION FACTOR
The radiometric calibration of the broad-band UVS
radiometers is performed with a Xenon lamp, a
monochromator and a calibrated Silicon photo-diode
detector. The photo-diode and the test UVS radiometer
are mounted behind the exit slit of the monochromator.