Homogenization of the Belsk UV‐B series (1976–1997) and trend analysis

Borkowski, J.

doi:10.1029/1999jd900500

Cited by 26 publications

(22 citation statements)

References 10 publications

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“…Time series of surface UV-B irradiance are rather short, usually not longer than 1 decade. As far as it is known to the authors, one of the longer time series, which underwent a quality control procedure, comes from Belsk (Borkowski, 2000). Thus, comparison of the Belsk's time series and the reconstructed series by various models may provide a kind of validation of the models.…”

Section: The Data Usedmentioning

confidence: 99%

“…the erythemal action spectrum). Calibration of the Belsk RB instrument and a homogenization of the Belsk UV-B time series were discussed by Krzyścin (1996) and Borkowski (2000). The analyzed daily UV time series comprises the homogenized RB time series for the period 1976-1992, and daily doses from 5-min scans by Solar Light UV biometer (model 501a) since January 1993.…”

Section: The Data Usedmentioning

confidence: 99%

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Long-term variations of the UV-B radiation over Central Europe as derived from the reconstructed UV time series

2004

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Abstract. The daily doses of the erythemally weighted UV radiation are reconstructed for three sites in Central Europe: Belsk-Poland (1966-2001, Hradec Kralove-Czech Republic (1964-2001, and Tõravere-Estonia (1967-2001 to discuss the UV climatology and the long-term changes of the UV-B radiation since the mid 1960s. Various reconstruction models are examined: a purely statistical model based on the Multivariate Adaptive Regression Splines (MARS) methodology, and a hybrid model combining radiative transfer model calculations with empirical estimates of the cloud effects on the UV radiation. Modeled long-term variations of the surface UV doses appear to be in a reasonable agreement with the observed ones. A simple quality control procedure is proposed to check the homogeneity of the biometer and pyranometer data. The models are verified using the results of UV observations carried out at Belsk since 1976. MARS provides the best estimates of the UV doses, giving a mean difference between the modeled and observed monthly means equal to 0.6±2.5%. The basic findings are: similar climatological forcing by clouds for all considered stations (∼30% reduction in the surface UV), long-term variations in UV monthly doses having the same temporal pattern for all stations with extreme low monthly values (∼5% below overall mean level) at the end of the 1970s and extreme high monthly values (∼5% above overall mean level) in the mid 1990s, regional peculiarities in the cloud long-term forcing sometimes leading to extended periods with elevated UV doses, recent stabilization of the ozone induced UV long-term changes being a response to a trendless tendency of total ozone since the mid 1990s. In the case of the slowdown of the total ozone trend over Northern Hemisphere mid-latitudes it seems that clouds will appear as the most important modulator of the UV radiation both in long-and short-time scales over next decades.

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Section: The Data Usedmentioning

confidence: 99%

Section: The Data Usedmentioning

confidence: 99%

Long-term variations of the UV-B radiation over Central Europe as derived from the reconstructed UV time series

2004

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“…The Brewer instrument is regularly calibrated against Brewer#17, maintained by the International Ozone Services. The Belsk UV-B data have been temperature corrected and homogenized (Borkowski, 2000) and were submitted to the European UV database. Measurements of the solar global radiation have been carried out by means of a Kipp&Zonen CM11 pyranometer.…”

Section: Datamentioning

confidence: 99%

Modelling of UV radiation variations at different time scales

Borkowski

2008

Ann. Geophys.

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Abstract. Solar UV radiation variability in the period 1976-2006 is discussed with respect to the relative changes in the solar global radiation, ozone content, and cloudiness. All the variables were decomposed into separate components, representing variations of different time scales, using wavelet multi-resolution decomposition. The response of the UV radiation to the changes in the solar global radiation, ozone content, and cloudiness depends on the time scale, therefore, it seems reasonable to model separately the relation between UV and explanatory variables at different time scales. The wavelet components of the UV series are modelled and summed to obtain the fit of observed series. The results show that the coarser time scale components can be modelled with greater accuracy than fine scale components and the fitted values calculated by this method are in better agreement with observed values than values calculated by the regression method, in which variables were not decomposed. The residual standard error in the case of modelling with the use of wavelets is reduced by 14% in comparison to the regression method without decomposition.

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“…14 sites in the United States were analyzed by Weatherhead et al (1997) and only one site, Belsk, in Europe by Borkowski (2000). Length of reliable data records is up to 10-15 year for the most European UV observing stations.…”

Section: Introductionmentioning

confidence: 99%

Variability of the total ozone trend over Europe for the period 1950–2004 derived from reconstructed data

Krzyścin

Borkowski

2008

Atmos. Chem. Phys.

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Abstract. The total ozone data over Europe are available for only few ground-based stations in the pre-satellite era disallowing examination of the spatial trend variability over the whole continent. A need of having gridded ozone data for a trend analysis and input to radiative transfer models stimulated a reconstruction of the daily ozone values since January 1950. Description of the reconstruction model and its validation were a subject of our previous paper. The data base used was built within the objectives of the COST action 726 "Long-term changes and climatology of UV radiation over Europe". Here we focus on trend analyses. The long-term variability of total ozone is discussed using results of a flexible trend model applied to the reconstructed total ozone data for the period 1950-2004. The trend pattern, which comprises both anthropogenic and "natural" component, is not a priori assumed but it comes from a smooth curve fit to the zonal monthly means and monthly grid values. The ozone long-term changes are calculated separately for cold (October-next year April) and warm (May-September) seasons. The confidence intervals for the estimated ozone changes are derived by the block bootstrapping. The statistically significant negative trends are found almost over the whole Europe only in the period 1985-1994. Negative trends up to −3% per decade appeared over small areas in earlier periods when the anthropogenic forcing on the ozone layer was weak . The statistically positive trends are found only during warm seasons 1995-2004 over Svalbard archipelago. The reduction of ozone level in 2004 relative to that before the satellite era is not dramatic, i.e., up to ∼−5% and ∼−3.5% in the cold and warm subperiod, respectively. Present ozone level is still depleted over many popular resorts in southern Europe and northern Africa. For high latitude regions the trend overturning could be inferred in last decade

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Homogenization of the Belsk UV‐B series (1976–1997) and trend analysis

Cited by 26 publications

References 10 publications

Long-term variations of the UV-B radiation over Central Europe as derived from the reconstructed UV time series

Long-term variations of the UV-B radiation over Central Europe as derived from the reconstructed UV time series

Modelling of UV radiation variations at different time scales

Variability of the total ozone trend over Europe for the period 1950–2004 derived from reconstructed data

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