Variations of erythemal ultraviolet irradiance and dose at Tartu/Tõravere, Estonia

Eerme, K.; Veismann, U.; Koppel, R.

doi:10.3354/cr022245

Cited by 15 publications

(15 citation statements)

References 20 publications

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“…3. Similar result was found by [8] which states that the variation of solar UV Index in Estonia for March 29 (2000), September 13 (1998) and September 8 (1999) are 2.51, 3.60 and 3.58 respectively. Data analysis showed that, clouds sometimes enhanced the solar UV radiation while in other cases it reduced the solar UV radiation reaching the earth's surface.…”

Section: Resultssupporting

confidence: 84%

Variability of Solar UV Index in Nepal

Sharma

2017

J. Inst. Engineering

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N 87.27 0 E) are located at an elevation of 1350m, 800m and 72m respectively from the sea level. The NILU-UV irradiance meter of serial number (135, 137 and 133) was used to record UV radiation on these stations. From the measurement and data analysis it was found that there were distinct diurnal, hourly mean and spring variations in the UV index. The UV index is primarily controlled by solar zenith angle for both the diurnal and seasonal variations. The highest values of hourly mean UV index was found at noon time in all seasons. Atmospheric parameters such as Solar Zenith angle (SZA), Cloud cover, aerosols and Ozone contribute to the daily fluctuations in the UV Index.

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Section: Resultssupporting

confidence: 84%

Variability of Solar UV Index in Nepal

Sharma

2017

J. Inst. Engineering

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“…However, in some recent studies the groundbased/satellite measurements and model simulations have been used to identify changes in the surface UV and processes responsible for the UV radiation changes (e.g. McElroy, 1993, Borderwijk et al, 1995;Zerefos et al, 1995;Krzyścin, 1996;Weatherhead et al, 1997;Udelhofen et al, 1999;den Outer et al, 2000;Kaurola et al, 2000;Matthijsen et al, 2000;Eerme et al, 2002). These studies confirm that the UV changes are driven by various factors: ozone, cloudiness, aerosols, and surface albedo.…”

Section: Introductionmentioning

confidence: 84%

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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“…In our previous reconstructions only the period from the vernal equinox to the autumnal equinox was treated (Eerme et al, 2002b(Eerme et al, , 2003 and also a smaller data set of measured erythemal doses was used for deriving the statistical relationships between the daily erythemal dose and its proxies.…”

Section: Methodsmentioning

confidence: 99%

“…The reconstructions of erythemal doses based on proxy data and radiative transfer calculations have recently been made by several authors (Kaurola et al, 2000;Ziemke et al, 2000;Fioletov et al, 2001;Eerme et al, 2002b;Lindfors et al, 2003;Fioletov et al, 2004;Kryścin et al, 2004;Lindfors and Vuilleumier, 2005;den Outer et al, 2005).…”

Section: Introductionmentioning

confidence: 99%

Proxy-based reconstruction of erythemal UV doses over Estonia for 1955–2004

2006

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Abstract.A proxy-based reconstruction of the erythemallyweighted UV doses for has been performed for the 26 • 28 E, 70 m a.s.l.) site. The pyrheliometer-measured daily sum of direct irradiance on partly cloudy and clear days, and the pyranometer-measured daily sum of global irradiance on overcast days were used as the cloudiness influence related proxies. The TOMS ozone data have been used for detecting the daily deviations from the climatic value (averaged annual cycle). In 1998-2004, the biases between the measured and reconstructed daily doses in 55.5% of the cases were within ±10% and in 83.5% of the cases within ±20%, on average. In the summer half-year these amounts were 62% and 88%, respectively. In most years the results for longer intervals did not differ significantly, if no correction was made for the daily deviations of total ozone from its climatic value. The annual and summer half-yearly erythemal doses (contributing, on average, 89% of the annual value) agreed within ±2%, except for the years after major volcanic eruptions and one extremely fine weather year (2002). Using the daily relative sunshine duration as a proxy without detailed correction for atmospheric turbidity results in biases of 2-4% in the summer half-yearly dose in the years after major volcanic eruptions and a few other years of high atmospheric turbidity. The year-to-year variations of the summer half-yearly erythemal dose in 1955-2004 were found to be within 92-111% relative to their average value. Exclusion of eight extreme years reduces this range for the remaining to 95-105.5%. Due to the quasi-periodic alternation of wet and dry periods, the interval of cloudy summers 1976-1993 regularly manifests summer half-yearly erythemal dose values lower than the 1955-2004 average. Since 1996/1997 midwinters have been darker than on average.

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Variations of erythemal ultraviolet irradiance and dose at Tartu/Tõravere, Estonia

Cited by 15 publications

References 20 publications

Variability of Solar UV Index in Nepal

Variability of Solar UV Index in Nepal

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

Proxy-based reconstruction of erythemal UV doses over Estonia for 1955–2004

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