Kipp&Zonen UVS-E-T UV Radiometers - Manual (Page 13)

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The UVS Series is suitable for the measurement of UV
irradiance according to theoretically defined UV-A, B
and E spectra. In general all broad-band filter
instruments have limited performance due to the
intrinsic spectral mismatch of each sensor with respect
to the theoretical definitions of UV-A, B and E.
By knowing the spectral mismatch in detail, one can
compensate the instrument effects for different
measurement conditions. Kipp & Zonen has developed
a unique software program for post-processing and
analysis of UVS data. The UVIATOR program performs
automatically a number of UV measurement
corrections and thereby improves the measurement
quality significantly.
The spectral mismatch error correction is based on the
correction method described in the WMO Report No.
141 [Ref. 2]. Further explanations and discussions of
the spectral mismatch error are presented in a number
of publications listed at the end of this section.
4.1
UV RADIOMETER CALIBRATION AND
CORRECTION METHOD
To achieve the most accurate measurement result with
broad-band UV radiometers, the raw signals must be
transformed into UV irradiances using two “Calibration
Steps” (A and B), and an “Adjustment Step”.
Calibration Step A:
The raw signal of the instrument (in units of Volts) has
to be transformed into an irradiance (in units of W/m2).
To achieve this transformation a so-called “radiometric
calibration factor”, denoted as
ρ (in units of V/W/m2),
has to be determined.