Abstract

Abstract. A ground-based ultraviolet (GUV) multi-filter radiometer was set up at Marambio, 64∘ S, 56∘ W, Antarctica, in 2017. The instrument continuously measures ultraviolet (UV) radiation, visible (VIS) radiation and photosynthetically active radiation (PAR). The measurements are designed for providing high-quality long-term time series that can be used to assess the impact of global climate change in the Antarctic region. The quality assurance includes regular absolute calibrations and solar comparisons performed at Marambio and at Sodankylä, Finland. The measurements continue observations at Marambio that were performed with (Norwegian Institute for Air Re-search UV Radiometer (NILU-UV) radiometers between 2000 and 2010 as part of the Antarctic NILU-UV network. These measurements are ideally suited for assessing the effects of the ongoing stratospheric ozone recovery on the ecosystem, as the data products include information on radiation at various wavelengths ranging from UV to VIS so that changes on biologically effective radiation due to ozone can be separated from those due to other factors. Data products include total ozone, photosynthetically active radiation (PAR), visible (VIS) radiation at 555 nm, UV index, UV irradiance at 5 channels, UVB and UVA dose rate and daily dose, and biologically weighted UV dose rate and daily dose, calculated with 10 different action spectra. The data from the last 5 d and the daily maximum UV index time series are plotted and updated daily on the following web page: http://fmiarc.fmi.fi/sub_sites/GUVant/ (last access: 17 April 2020). The first 2 years of UV measurements were very different in terms of the results: for October, November and December the monthly average of daily maximum UVB dose rates were clearly higher in 2018 than in 2017. The largest difference was observed in October, when the average of daily maximum UVB dose rates was 76 and 102 µW cm−2 in 2017 and 2018, respectively. Monthly averages of the 3 months were similar in 2018, while in 2017 the monthly average of October was lower than those of November and December. The VIS and PAR time series show that daily maxima in 2018–2019 exceed those in 2017–2018 during late spring and summer (mid-November–January). The studied dataset, including daily maximum irradiances at five UV channels and one VIS channel; daily maximum UVB, UVA, and PAR dose rates; noon UVB, UVA, and PAR dose rates; noon total column ozone; and UVB and UVA daily doses, is freely accessible at https://doi.org/10.5281/zenodo.3688700 (Lakkala et al., 2019).

Highlights

  • The Antarctic area has suffered from the well-known springtime ozone hole since the late 1970s (e.g. Farman et al, 1985; World Meteorological Organization (WMO), 1990)

  • Bernhard et al (2005) compared measurements of UVB irradiance, UVA irradiance, UV index, and DNA-damaging irradiance performed at the South Pole with a solar UV (SUV)-100 and a ground-based ultraviolet (GUV) radiometer, which were calibrated with the method described in this paper

  • The results show that the GUV radiometer UV indices were within ±5 % from the QASUME UV indices for solar zenith angles (SZAs) smaller than 60◦

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Summary

Introduction

The Antarctic area has suffered from the well-known springtime ozone hole since the late 1970s (e.g. Farman et al, 1985; WMO, 1990). To detect the recovery and its effects on UV radiation and the ecosystem, the Finnish Meteorological Institute (FMI) and the Servicio Meteorológico Nacional Argentina (SMN) started UV and total ozone measurements with multifilter ground-based ultraviolet (GUV) radiometers at Marambio in 2017. The total ozone, UV radiation, visible (VIS) radiation and PAR measurements of the GUV multi-filter radiometer can be used in research assessing the effects of the ongoing climate change. PAR measurements are directly applicable in studies of the effects of climate change on the photosynthesis of plants, algae and bacteria Both UV and PAR affect micro-organisms living in Antarctic ice and the Southern Ocean (Deppeler and Davidson, 2017; Häder et al, 2014). Time series of the first 2 years of measurements are shown

GUV multi-filter radiometer measurements at Marambio
Marambio station
GUV radiometer
Data retrieval and products
Quality assurance of the measurements
Absolute calibration
Comparisons against spectroradiometers at Sodankylä
Total ozone column
Solar comparison at Marambio
First 2 years of measurements
Findings
Discussion and conclusions
Full Text
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