Quality assurance of measured surface UV spectra at the European UV database
Quality indicators are provided for all measured UV spectra
submitted to the European UV database. They include wavelength scale
errors, spectral shape errors and irradiance scale errors.
The quality indicators are compared with a set of quality
criteria and referred to as quality flags. In general GREEN
flags meet the highest quality criteria, YELLOW flags do not
fully meet the highest criteria, but do meet the secondary
criteria, RED flags identify spectra with a doubtful
quality, not meeting the secondary criteria, but not
exceeding the lowest/rejection criteria. BLACK flags
indicate spectra that do not meet the lowest criteria and
therefore normally are not retrieved from the database,
unless specifically requested by the user. In addition a
GREY flag is used if the spectra are doubtful but the
algorithm is not allowing a final conclusion.
A master flag is also provided which indicates the overall
quality of the UV spectrum. The master flag reflects the
worst flag for any of the quality indicators, in the order
from worst to best: BLACK, GREY, RED, YELLOW, and
GREEN. Thus, the master flag is GREEN only if all flagged
indicators are GREEN, and is BLACK if one of the flags is
BLACK.
The quality criteria used to determine the GREEN flags are,
where possible in line with the recommended specifications
provided for type S-1 spectral instruments in the WMO TD no
1066 (Seckmeyer et al GAW-WMO report 125).
In addition to the quality flags, indicative diagnostic
information is provided on the atmospheric conditions and
variability of conditions during a scan.
The analysis is based on the integration of two
complementary QA/QC tools which were developed in the
EDUCE-project: SHICrivm (www.rivm.nl/shic) and
AtmosphericSignature. More information on the flags and
quality criteria used are given in the document:
NPI-RIVM-QA-flagging_long.htm.
The CheckUVSpec QA program and more documentation is
available at
http://zardoz.nilu.no/~olaeng/CheckUVSpec/CheckUVSpec.html.
A windows-version of the SHICrivm package and further
documentation is available from http://www.rivm.nl/shic.
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