TY - JOUR
T1 - Uncertainty analysis of total ozone derived from direct solar irradiance spectra in the presence of unknown spectral deviations
AU - Vaskuri, Anna
AU - Kärhä, Petri
AU - Egli, Luca
AU - Gröbner, Julian
AU - Ikonen, Erkki
N1 - Funding Information:
Atmospheric ozone has been defined as an essential climate variable in the global climate observing system (GCOS-200, 2016) of the World Meteorological Organization (WMO). Its long-term monitoring is necessary to document the expected recovery of the ozone layer due to the implementation of the Montreal Protocol (UNTC, 1987) and its amendments on the protection of the ozone layer. Atmospheric ozone, first discovered by Fabry and Buisson (1913), protects humans, the biosphere, and infrastructure from adverse effects of ultraviolet (UV) radiation by shielding the Earth’s surface from excessive radiation levels (McElroy and Fogal, 2008). Since the 1970s, it is known that human-produced chlorofluorocarbons (CFCs) destroy atmospheric ozone (Molina and Rowland, 1974) and lead to recurring massive losses of total ozone in the Antarctic in the form of the ozone hole (Farman et al., 1985; Solomon et al., 1986). Unprecedented ozone depletion has also been recently observed in the Arctic (Man-ney et al., 2011), while in the midlatitudes, moderate ozone depletion has been observed (Solomon, 1999). The Montreal Protocol and its amendments have been successful in reducing the emission of ozone-depleting substances (Velders et al., 2007). Nevertheless, recent studies give conflicting results with respect to the observation of the recovery of the ozone layer, and model projections have shown the recovery to not occur before the middle of the 21st century (Ball et al., 2018; Weber et al., 2018). Therefore, careful monitoring of the thickness of the ozone layer with uncertainties of 1 % or less is crucial for verifying the successful implementation of the Montreal Protocol and the eventual recovery of the ozone layer to pre-1970s levels. “Traceability for atmospheric total column ozone” (AT-MOZ) was a 3-year project funded partly by the European Metrology Research Programme (EMRP) and the European Union (ATMOZ project, 2014–2017). The goal of this project was to produce traceable measurements of total ozone column (TOC) with uncertainties down to 1 % through a systematic investigation of the radiometric and spectroscopic aspects of the methodologies used in retrieval. Another objective of the project was to provide a comprehensive treatment of uncertainties in all parameters affecting the TOC retrievals using spectrophotometers. This paper presents an outcome of the work on studying the uncertainty in TOC obtained from spectral direct solar irradiance measurements, taking unknown spectral errors explicitly into account.
Funding Information:
Acknowledgements. Peter Sperfeld from PTB is acknowledged for measuring and providing the BTS data set. Alberto Redondas and all personnel from Izaña Atmospheric Research Center, AEMET, Tenerife, Canary Islands, Spain, are acknowledged for measuring and providing the Brewer #183 data set and the environmental parameters such as the sonde data. Anna Vaskuri is grateful for the grant by the Emil Aaltonen Foundation, Finland. This work has been supported by the European Metrology Research Programme (EMRP) within the joint research project ENV59 “Traceability for atmospheric total column ozone” (ATMOZ). The EMRP is jointly funded by the EMRP participating countries within EURAMET and the European Union.
Publisher Copyright:
© Author(s) 2018.
Copyright:
Copyright 2018 Elsevier B.V., All rights reserved.
PY - 2018/6/20
Y1 - 2018/6/20
N2 - We demonstrate the use of a Monte Carlo model to estimate the uncertainties in total ozone column (TOC) derived from ground-based direct solar spectral irradiance measurements. The model estimates the effects of possible systematic spectral deviations in the solar irradiance spectra on the uncertainties in retrieved TOC. The model is tested with spectral data measured with three different spectroradiometers at an intercomparison campaign of the research project "Traceability for atmospheric total column ozone" at Izaña, Tenerife on 17 September 2016. The TOC values derived at local noon have expanded uncertainties of 1.3% (3.6 DU) for a high-end scanning spectroradiometer, 1.5% (4.4 DU) for a high-end array spectroradiometer, and 4.7% (13.3 DU) for a roughly adopted instrument based on commercially available components and an array spectroradiometer when correlations are taken into account. When neglecting the effects of systematic spectral deviations, the uncertainties reduce by a factor of 3. The TOC results of all devices have good agreement with each other, within the uncertainties, and with the reference values of the order of 282DU during the analysed day, measured with Brewer spectrophotometer #183.
AB - We demonstrate the use of a Monte Carlo model to estimate the uncertainties in total ozone column (TOC) derived from ground-based direct solar spectral irradiance measurements. The model estimates the effects of possible systematic spectral deviations in the solar irradiance spectra on the uncertainties in retrieved TOC. The model is tested with spectral data measured with three different spectroradiometers at an intercomparison campaign of the research project "Traceability for atmospheric total column ozone" at Izaña, Tenerife on 17 September 2016. The TOC values derived at local noon have expanded uncertainties of 1.3% (3.6 DU) for a high-end scanning spectroradiometer, 1.5% (4.4 DU) for a high-end array spectroradiometer, and 4.7% (13.3 DU) for a roughly adopted instrument based on commercially available components and an array spectroradiometer when correlations are taken into account. When neglecting the effects of systematic spectral deviations, the uncertainties reduce by a factor of 3. The TOC results of all devices have good agreement with each other, within the uncertainties, and with the reference values of the order of 282DU during the analysed day, measured with Brewer spectrophotometer #183.
UR - https://www.scopus.com/pages/publications/85048900611
U2 - 10.5194/amt-11-3595-2018
DO - 10.5194/amt-11-3595-2018
M3 - Article
AN - SCOPUS:85048900611
SN - 1867-1381
VL - 11
SP - 3595
EP - 3610
JO - Atmospheric Measurement Techniques
JF - Atmospheric Measurement Techniques
IS - 6
ER -