Reconstruction and analysis of erythemal UV radiation time series from Hradec Králové (Czech Republic) over the past 50 years
This paper evaluates the variability of erythemal ultraviolet (EUV) radiation from Hradec Králové (Czech Republic) in the period 1964–2013. The EUV radiation time series was reconstructed using a radiative transfer model and additional empirical relationships, with the final root mean square erro...
| Main Authors: | , , , |
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| Format: | Article |
| Language: | English |
| Published: |
Copernicus Publications
2018-02-01
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| Series: | Atmospheric Chemistry and Physics |
| Online Access: | https://www.atmos-chem-phys.net/18/1805/2018/acp-18-1805-2018.pdf |
| Summary: | This paper evaluates the variability of erythemal ultraviolet (EUV) radiation
from Hradec Králové (Czech Republic) in the period 1964–2013. The
EUV radiation time series was reconstructed using a radiative transfer model
and additional empirical relationships, with the final root mean square error
of 9.9 %. The reconstructed time series documented the increase in EUV
radiation doses in the 1980s and the 1990s (up to 15 % per decade), which
was linked to the steep decline in total ozone (10 % per decade). The
changes in cloud cover were the major factor affecting the EUV radiation
doses especially in the 1960s, 1970s, and at the beginning of the new
millennium. The mean annual EUV radiation doses in the decade 2004–2013
declined by 5 %. The factors affecting the EUV radiation doses differed
also according to the chosen integration period (daily, monthly, and
annually): solar zenith angle was the most important for daily doses, cloud
cover, and surface UV albedo for their monthly means, and the annual means of
EUV radiation doses were most influenced by total ozone column. The number of
days with very high EUV radiation doses increased by 22 % per decade, the
increase was statistically significant in all seasons except autumn. The
occurrence of the days with very high EUV doses was influenced mostly by low
total ozone column (82 % of days), clear-sky or partly cloudy conditions
(74 % of days) and by increased surface albedo (19 % of days). The
principal component analysis documented that the occurrence of days with very
high EUV radiation doses was much affected by the positive phase of North
Atlantic Oscillation with an Azores High promontory reaching over central
Europe. In the stratosphere, a strong Arctic circumpolar vortex and the
meridional inflow of ozone-poor air from the southwest were favorable for
the occurrence of days with very high EUV radiation doses. This is the first
analysis of the relationship between the high EUV radiation doses and
macroscale circulation patterns, and therefore more attention should be
given also to other dynamical variables that may affect the solar UV
radiation on the Earth surface. |
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| ISSN: | 1680-7316 1680-7324 |