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  • 1. Bais, A F
    et al.
    Gardiner, B G
    Slaper, H
    Blumthaler, M
    Bernhard, G
    McKenzie, R
    Webb, A R
    Seckmeyer, G
    Kjeldstad, B
    Koskela, T
    Kirsch, P J
    Grobner, J
    Kerr, J B
    Kazadzis, S
    Leszczynski, K
    Wardle, D
    Josefsson, Weine
    SMHI, Forskningsavdelningen, Atmosfärisk fjärranalys.
    Brogniez, C
    Gillotay, D
    Reinen, H
    Weihs, P
    Svenoe, T
    Eriksen, P
    Kuik, F
    Redondas, A
    SUSPEN intercomparison of ultraviolet spectroradiometers2001Inngår i: Journal of Geophysical Research, ISSN 0148-0227, E-ISSN 2156-2202, Vol. 106, nr D12, s. 12509-12525Artikkel i tidsskrift (Fagfellevurdert)
    Abstract [en]

    Results from an intercomparison campaign of ultraviolet spectroradiometers that was organized at Nea Michaniona, Greece July, 1-13 1997, are presented. Nineteen instrument systems from 15 different countries took part and provided spectra of global solar UV irradiance for two consecutive days from sunrise to sunset every half hour. No data exchange was allowed between participants in order to achieve absolutely independent results among the instruments. The data analysis procedure included the determination of wavelength shifts and the application of suitable corrections to the measured spectra, their standardization to common spectral resolution of 1 nm full width at half maximum and the application of cosine corrections. Reference spectra were calculated for each observational time, derived for a set of instruments which were objectively selected and used as comparison norms for the assessment of the relative agreement among the various instruments. With regard to the absolute irradiance measurements, the range of the deviations from the reference for all spectra was within +/- 20%. About half of the instruments agreed to within +/-5%, while only three fell outside the +/- 10% agreement limit. As for the accuracy of the wavelength registration of the recorded spectra, for most of the spectroradiometers (14) the calculated wavelength shifts were smaller than 0.2 nm. The overall outcome of the campaign was very encouraging, as it was proven that the agreement among the majority of the instruments was good and comparable to the commonly accepted uncertainties of spectral UV measurements. In addition, many of the instruments provided consistent results relative to at least the previous two intercomparison campaigns, held in 1995 in Ispra, Italy and in 1993 in Garmisch-Partenkirchen, Germany. As a result of this series of intercomparison campaigns, several of the currently operating spectroradiometers operating may be regarded as a core group Of instruments, which with the employment of proper operational procedures are capable of providing quality spectral solar UV measurements.

  • 2.
    Carlund, Thomas
    et al.
    SMHI, Samhälle och säkerhet.
    Landelius, Tomas
    SMHI, Forskningsavdelningen, Atmosfärisk fjärranalys.
    Josefsson, Weine
    SMHI, Forskningsavdelningen, Atmosfärisk fjärranalys.
    Comparison and uncertainty of aerosol optical depth estimates derived from spectral and broadband measurements2003Inngår i: Journal of applied meteorology (1988), ISSN 0894-8763, E-ISSN 1520-0450, Vol. 42, nr 11, s. 1598-1610Artikkel i tidsskrift (Fagfellevurdert)
    Abstract [en]

    An experimental comparison of spectral aerosol optical depth tau(a,lambda) derived from measurements by two spectral radiometers [a LI-COR, Inc., LI-1800 spectroradiometer and a Centre Suisse d'Electronique et de Microtechnique (CSEM) SPM2000 sun photometer] and a broadband field pyrheliometer has been made. The study was limited to three wavelengths ( 368, 500, and 778 nm), using operational calibration and optical depth calculation procedures. For measurements taken on 32 days spread over 1 yr, the rms difference in tau(a,lambda) derived from the two spectral radiometers was less than 0.01 at 500 and 778 nm. For wavelengths shorter than 500 nm and longer than 950 nm, the performance of the LI-1800 in its current configuration did not permit accurate determinations of tau(a,lambda). Estimates of spectral aerosol optical depth from broadband pyrheliometer measurements using two models of the Angstromngstrom turbidity coefficient were examined. For the broadband method that was closest to the sun photometer results, the mean (rms) differences in tau(a,lambda) were 0.014 (0.028), 0.014 (0.019), and 0.013 ( 0.014) at 368, 500, and 778 nm. The mean differences are just above the average uncertainties of the sun photometer tau(a,lambda) values (0.012, 0.011, and 0.011) for the same wavelengths, as determined through a detailed uncertainty analysis. The amount of atmospheric water vapor is a necessary input to the broadband methods. If upper-air sounding data are not available, water vapor from a meteorological forecast model yields significantly better turbidity results than does using estimates from surface measurements of air temperature and relative humidity.

  • 3. Cheymol, Anne
    et al.
    De Backer, Hugo
    Josefsson, Weine
    SMHI, Forskningsavdelningen, Atmosfärisk fjärranalys.
    Stuebi, Rene
    Comparison and validation of the aerosol optical depth obtained with the Langley plot method in the UV-B from Brewer Ozone Spectrophotometer measurements2006Inngår i: Journal of Geophysical Research - Atmospheres, ISSN 2169-897X, E-ISSN 2169-8996, Vol. 111, nr D16, artikkel-id D16202Artikkel i tidsskrift (Fagfellevurdert)
    Abstract [en]

    [ 1] The Aerosol Optical Depths (AODs) retrieved from Brewer Ozone Spectrophotometer measurements with a method previously developed (Cheymol and De Backer, 2003) are now validated by comparisons between AODs from six Brewer spectrophotometers and two CSEM SPM2000 sunphotometers: two Brewer spectrophotometers 016 and 178 at Uccle in Belgium; one Brewer spectrophotometer 128 and one sunphotometer CSEM SPM2000 at Norrkoping in Sweden; and three Brewer instruments 040, 072, 156 at Arosa and one CSEM SPM2000 sunphotometer at Davos in Switzerland. The comparison between AODs from Brewer spectrophotometer 128 at 320.1 nm and sunphotometer SPM2000 at 368 nm at Norrkoping shows that the AODs obtained from the Brewer measurements with the Langley Plot Method (LPM) are very accurate if the neutral density filter spectral transmittances are well known: with the measured values of these filters, the correlation coefficient, the slope, and the intercept of the regression line are 0.98, 0.85 +/- 0.004, and 0.02 +/- 0.0014, respectively. The bias observed is mainly owing to the wavelength difference between the two instruments. The comparison between AODs from different Brewer spectrophotometers confirm that AODs will be in very good agreement if they are measured with several Brewer instruments at the same place: At Uccle, the correlation coefficient, slope, and intercept of the regression line are 0.98, 1.02 +/- 0.003, and 0.06 +/- 0.001, respectively; at Arosa, the comparisons between the AODs from three Brewer spectrophotometers 040, 072, and 156 give a correlation coefficient, a slope, and an intercept of the regression line above 0.94, 0.98 and below 0.04, respectively.

  • 4. den Outer, P. N.
    et al.
    Slaper, H.
    Kaurola, J.
    Lindfors, A.
    Kazantzidis, A.
    Bais, A. F.
    Feister, U.
    Junk, J.
    Janouch, M.
    Josefsson, Weine
    SMHI, Samhälle och säkerhet.
    Reconstructing of erythemal ultraviolet radiation levels in Europe for the past 4 decades2010Inngår i: Journal of Geophysical Research - Atmospheres, ISSN 2169-897X, E-ISSN 2169-8996, Vol. 115, artikkel-id D10102Artikkel i tidsskrift (Fagfellevurdert)
    Abstract [en]

    This paper is based on a comparative study on ultraviolet radiation (UV) measurements and UV reconstruction models for eight sites in Europe. Reconstruction models include neural network techniques and radiative transfer modeling combined with empirical relationships. The models have been validated against quality-controlled ground-based measurements, 8 to 20 years, on time scales ranging from daily to yearly UV sums. The standard deviations in the ratios of modeled to measured daily sums vary between 10 and 15%. The yearly sums agree within a 5% range. Depending on the availability of ancillary measurements, reconstructions have been carried out to the early 1960s. A method has been set up to educe one best estimate of the historical UV levels that takes into account the long-term stability and underlying agreement of the models, and the agreement with actual UV measurements. Using this best estimate, the yearly sums of erythemally weighted UV irradiance showed a range of 300 kJ/m(2) at 67 degrees N to 750 kJ/m(2) at 40 degrees N. The year-to-year variability was lowest at 40 degrees N with a relative variation of 4.3%; for central and northern European latitudes this year-to-year variation was 5.2 to 6.5%. With regard to the period 1980 to 2006, first-order trend lines range from 0.3 +/- 0.1 to 0.6 +/- 0.2% per year, approximately two thirds of which can be attributed to the diminishing of cloudiness and one third to ozone decline.

  • 5. den Outer, P. N.
    et al.
    van Dijk, A.
    Slaper, H.
    Lindfors, A. V.
    De Backer, H.
    Bais, A. F.
    Feister, U.
    Koskela, T.
    Josefsson, Weine
    SMHI, Samhälle och säkerhet.
    Applying spaceborne reflectivity measurements for calculation of the solar ultraviolet radiation at ground level2012Inngår i: ATMOSPHERIC MEASUREMENT TECHNIQUES, ISSN 1867-1381, Vol. 5, nr 12, s. 3041-3054Artikkel i tidsskrift (Fagfellevurdert)
    Abstract [en]

    Long-term analysis of cloud effects on ultraviolet (UV) radiation on the ground using spaceborne observations requires the use of instruments that have operated consecutively. The longest data record can be built from the reflectivity measurements produced by the instruments Total Ozone Mapping Spectrometers (TOMS) flown on Nimbus 7 from 1979 to 1992, TOMS on Earth Probe from 1996 to 2005, and the Ozone Monitoring Instrument (OMI) flown on EOS Aura since 2004. The reflectivity data produced by TOMS on Earth Probe is only included until 2002. A comparison is made with cloud effects inferred from ground-based pyranometer measurements at over 83 World Radiation Data Centre stations. Modelled UV irradiances utilizing the standard reflectivity are compared with measurements of UV irradiances at eight European low-elevation stations. The reflectivity data of the two TOMS instruments shows a consistent agreement, and the required corrections are of low percentage, i.e. 2-3%. In contrast, the reflectivity product of OMI requires correction of 7-10%, and a solar angle dependency therein is more pronounced. These corrections were inferred from a comparison with pyranometer data, and tested using the UV measurements. The average reduction of UV radiation due to clouds for all sites together indicates a small trend: a diminishing cloudiness, in line with ground-based UV observations. Uncorrected implementation of the reflectivity data would have indicated the opposite. An optimal area was established for reflectivity data for the calculation of daily sums of UV radiation. It measures approximately 1.25 degrees in latitudinal direction for square-shaped areas overhead the ground-based UV stations. Such an area can be traversed within 5 to 7 h at the average wind speeds found for the West European continent.

  • 6. Feister, U.
    et al.
    Junk, J.
    Woldt, M.
    Bais, A.
    Helbig, A.
    Janouch, M.
    Josefsson, Weine
    SMHI, Samhälle och säkerhet.
    Kazantzidis, A.
    Lindfors, A.
    den Outer, P. N.
    Slaper, H.
    Long-term solar UV radiation reconstructed by ANN modelling with emphasis on spatial characteristics of input data2008Inngår i: Atmospheric Chemistry And Physics, ISSN 1680-7316, E-ISSN 1680-7324, Vol. 8, nr 12, s. 3107-3118Artikkel i tidsskrift (Fagfellevurdert)
    Abstract [en]

    Artificial Neural Networks (ANN) are efficient tools to derive solar UV radiation from measured meteorological parameters such as global radiation, aerosol optical depths and atmospheric column ozone. The ANN model has been tested with different combinations of data from the two sites Potsdam and Lindenberg, and used to reconstruct solar UV radiation at eight European sites by more than 100 years into the past. Special emphasis will be given to the discussion of small-scale characteristics of input data to the ANN model. Annual totals of UV radiation derived from reconstructed daily UV values reflect interannual variations and long-term patterns that are compatible with variabilities and changes of measured input data, in particular global dimming by about 1980/1990, subsequent global brightening, volcanic eruption effects such as that of Mt. Pinatubo, and the long-term ozone decline since the 1970s. Patterns of annual erythemal UV radiation are very similar at sites located at latitudes close to each other, but different patterns occur between UV radiation at sites in different latitude regions.

  • 7. Grobner, J
    et al.
    Rembges, D
    Bais, A F
    Blumthaler, M
    Cabot, T
    Josefsson, Weine
    SMHI, Forskningsavdelningen, Atmosfärisk fjärranalys.
    Koskela, T
    Thorseth, T M
    Webb, A R
    Wester, U
    Quality assurance of reference standards from nine European solar-ultraviolet monitoring laboratories2002Inngår i: Applied Optics, ISSN 1559-128X, E-ISSN 2155-3165, Vol. 41, nr 21, s. 4278-4282Artikkel i tidsskrift (Fagfellevurdert)
    Abstract [en]

    A program for quality assurance of reference standards has been initiated among nine solar-UV monitoring laboratories. By means of a traveling lamp package that comprises several 1000-W ANSI code DXW-type quartz-halogen lamps, a 0.1-Omega shunt, and a 6-1/2 digit voltmeter, the irradiance scales used by the nine laboratories were compared with one another; a relative uncertainty of 1.2% was found. The comparison of 15 reference standards yielded differences of as much as 9%; the average difference was less than 3%. (C) 2002 Optical Society of America.

  • 8.
    Jansson, Anna
    et al.
    SMHI, Samhälle och säkerhet.
    Josefsson, Weine
    SMHI, Samhälle och säkerhet.
    Modelling of surface global radiation and CIE-weighted UV-radiation for the period 1980-20002007Rapport (Annet vitenskapelig)
    Abstract [sv]

    saltning. Detta ökar dock vägslitaget och mängden vägdamm som ackumuleras i vägmiljön, som i sin tur

  • 9.
    Josefsson, Weine
    SMHI, Forskningsavdelningen, Atmosfärisk fjärranalys.
    Computed global radiation using interpolated, gridded cloudiness from the MESA-BETA analysis compared to measured global radiation1989Rapport (Annet vitenskapelig)
  • 10.
    Josefsson, Weine
    SMHI, Forskningsavdelningen, Atmosfärisk fjärranalys.
    Five years of solar UV-radiation monitoring in Sweden1996Rapport (Annet vitenskapelig)
  • 11.
    Josefsson, Weine
    SMHI, Forskningsavdelningen, Atmosfärisk fjärranalys.
    FOCUSED SUN OBSERVATIONS USING A BREWER OZONE SPECTROPHOTOMETER1992Inngår i: Journal of Geophysical Research, ISSN 0148-0227, E-ISSN 2156-2202, Vol. 97, nr D14, s. 15813-15817Artikkel i tidsskrift (Fagfellevurdert)
    Abstract [en]

    Accurate measurements of total ozone at high latitudes during winter have become increasingly important for studies of polar ozone depletion. The direct Sun measurements are the most direct and physically well defined type of measurement of total ozone with Dobson and Brewer spectrophotometers along with the focused Sun measurements. The direct Sun and focused Sun method are influenced by many sources of error at low solar elevations. A large error arises from the addition of radiation scattered from air along the path of the solar beam. A method to correct for this error using the Brewer instrument is described. The method gives reasonably accurate values down to solar elevations of 5-degrees compared to 10-degrees-20-degrees without corrections. This is especially important for high-latitude stations, where the low solar elevations are a limiting factor for accurate measurements of the total ozone particularly during the winter.

  • 12.
    Josefsson, Weine
    SMHI, Samhälle och säkerhet.
    Long-term global radiation in Stockholm, 1922-20182019Rapport (Annet vitenskapelig)
    Abstract [en]

    In 1922 monitoring of global irradiation started in Stockholm, Sweden. Over the years SMHI has been measuring this meteorological quantity with various instruments and at different sites within Stockholm. This type of changes of instruments and sites cause minor, but important systematic changes in the measured global irradiation. Therefore, it is not recommended to directly compare the results from different periods.The report presents methods how this can be done and there is a final data set with long-term global radiation data for Stockholm. Daily and monthly final data are presented on a web-page at www.smhi.seAs a bi-product the sunshine duration was also digitized, controlled and corrected. These data can be found in Appendix 3.

  • 13.
    Josefsson, Weine
    SMHI, Forskningsavdelningen, Atmosfärisk fjärranalys.
    Measurements of total ozone 1997 - 19992000Rapport (Annet vitenskapelig)
    Abstract [en]

    A summary of the quality control, quality assurance and measurements of total ozone at Norrköping and Vindeln during the period 1997-1999 is made. The Brewer #006 and Brewer #128 were compared to the travelling reference Brewer #017 at Vindeln in 1999. Major changes in the measurements and instruments are discussed. The reprocessing of all Brewer data since 1996 and the introduction of the new format recommended by WOUDC at the end of 1999 are documented.

    At the end of this three-year period the ozone layer has shown an increase after many years with several periods of considerable depletion. Therefore, the previous downward trend that was as large as -8% per decade has disappeared. The data set consists of 12 years of almost uninterrupted data at Norrköping. Most of the gaps have been possible to fill with satellite data to have monthly values based on a complete set of daily values. An intercomparison between ground based and TOMS Version 7 satellite based data shows an astonishing agreement in most cases.

    Data recorded at Abisko in 1926 and 1927 on the initiative of G.M.B. Dobson was found in the archive. They were recomputed to modem scales and the result shows that the thickness of the ozone layer at that time is similar to the present thickness. The long-term data sets now available from Vindeln and Norrköping give the opportunity to study the temporal and in some respect also the spatial characteristics of the total ozone. Both the spatial correlation and  he auto-correlation vary considerably over time.

    The Web-site for total ozone (under http://www.smhi.se) has made measurements available fora lot of people in almost real-time. Ozone data can be viewed as graphs or transferred by ftp. There are also some pages with general information as well as some links to related sites. In particular, this method for distribution of information has been found to be useful for the public, media and decision-makers.

  • 14.
    Josefsson, Weine
    SMHI, Forskningsavdelningen, Atmosfärisk fjärranalys.
    Normalvärden för perioden 1961-90 av globalstrålning och solskenstid i Sverige1993Rapport (Annet vitenskapelig)
  • 15.
    Josefsson, Weine
    SMHI, Forskningsavdelningen, Atmosfärisk fjärranalys.
    Quality of total ozone measured by the focused sun method using a Brewer spectrophotometer2003Inngår i: Journal of applied meteorology (1988), ISSN 0894-8763, E-ISSN 1520-0450, Vol. 42, nr 1, s. 74-82Artikkel i tidsskrift (Fagfellevurdert)
    Abstract [en]

    Strong ozone depletions and large natural variations in total ozone have been observed at high latitudes. Accurate measurements of total ozone are important so as not to misinterpret the involved processes and to track correctly the variations. The primary basis for ground-based monitoring of total ozone is the network of Dobson and Brewer ozone spectrophotometers. However, these instruments have limitations. At high latitudes, the fundamental direct sun observation used by these instruments is not possible during large parts of the year. In particular, the low sun and the resulting weak signals present a challenge. The focused sun observation method can extend the possible range of measurements using the Brewer instrument. Here, this method is discussed from the point of accuracy. Direct (synchronized) validation against the fundamental direct sun method is not possible with the current instrument configuration. Alternative methods to overcome the obstacle of nonsynchronous observations are applied. An estimate of the uncertainty of the validation is provided. The results show that the focused sun method gives data that are in line with the estimated uncertainty of the validation. No major additional uncertainty is needed to explain the observed scatter. The main conclusion is that the focused sun observation method can have an uncertainty close to the fundamental direct sun method and thus can be used to extend the possible range of observation for the Brewer ozone spectrophotometer.

  • 16.
    Josefsson, Weine
    SMHI, Forskningsavdelningen, Atmosfärisk fjärranalys.
    Solar ultraviolet radiation in Sweden1986Rapport (Annet vitenskapelig)
  • 17.
    Josefsson, Weine
    SMHI, Forskningsavdelningen, Atmosfärisk fjärranalys.
    Solar UV-radiation monitoring 19961996Rapport (Annet vitenskapelig)
  • 18.
    Josefsson, Weine
    SMHI, Forskningsavdelningen, Atmosfärisk fjärranalys.
    UV-radiation 1983-2003 measured at Norrkoping, Sweden2006Inngår i: Journal of Theoretical and Applied Climatology, ISSN 0177-798X, E-ISSN 1434-4483, Vol. 83, nr 1-4, s. 59-76Artikkel i tidsskrift (Fagfellevurdert)
    Abstract [en]

    Total ozone has been monitored with high accuracy at many sites for a relative long period of time. This is not the case for UV. The main reason is that UV is difficult to measure accurately. Extensive monitoring started first during the 1990s. However, there are some data series still in operation that were initiated at earlier dates. This paper will discuss one such series from Norrkoping, Sweden that began in March 1983. The instruments used to measure UV radiation have some characteristics producing an output signal that is not directly related to the UV. Here, these problems are discussed and corrections are applied. The goal is to produce a homogenous and an accurate set of UV data as is possible. An analysis of the various sources of uncertainty is done and summarised as total uncertainty. This was found to be about 6% for the yearly values of CIE weighted UV. However, the precision is much better at about 0.6%. Finally, some results are shown for yearly and seasonal UV. The trends for the full period 1983-2003 are tested for significance. The spring, summer, autumn and yearly data showed a significant increase in UV of respectively 0.8, 0.3, 0.8 and 0.5% per year. To get some indication of the cause of the variation of global radiation (indicator of cloudiness) and total ozone measured at the same site were also processed. A small, but insignificant, decrease of total ozone was found, whilst global radiation showed an increase. It seems that cloudiness is the major factor for the observed variation in UV for this period. The data are available on the internet.

  • 19.
    Josefsson, Weine
    SMHI, Forskningsavdelningen, Atmosfärisk fjärranalys.
    UV-radiation measured in Norrköping 1983-20032004Rapport (Annet vitenskapelig)
    Abstract [en]

    The purpose of this work is to homogenise a number of different data sets of daily values of UV-radiation to enable studies of the temporal variation of UV-radiation and atmospheric processes. Efforts are concentrated on the longest series measured using a Robertson-Berger and a Solar Light Model 501 radiometer. The lack of practical and reliable calibration standards have made measurements of UV uncertain. There are also several sources of uncertainty inherited in the designs of the instruments as well as uncertainties in the input data to the models used for corrections and for filling gaps of missing data.The primary goal is to achieve a homogenous data set. The second goal is to mimic a true CIE-weighted irradiation, McKinley and Diffey (1987). The third goal is to be as close as possible to an absolute irradiance scale.There are some factors that will prevent the achievement of these goals. These factors will introduce uncertainty in various fashions and affect the data differently. The applied corrections are assumed to remove systematic differences in a statistical sense. However, as will be discussed below, large differences may still remain in the hourly data.For those not familiar with measurements in the UV spectral range it may seem surprising that UV data recorded by different instruments differ so much. This is partly due to the very large change (several orders of magnitude) in the solar spectrum combined with small differences in the spectral responsivity of the instruments in this range. Apparently small differences in spectral responsivity will produce relatively large variable differences in the output only by changing the solar elevation during the day or during the year. The yearly effect will be seen in the results below.

  • 20.
    Josefsson, Weine
    et al.
    SMHI, Forskningsavdelningen, Atmosfärisk fjärranalys.
    Karlsson, Jan-Erik
    Measurements of total ozone 1994-19961997Rapport (Annet vitenskapelig)
  • 21.
    Josefsson, Weine
    et al.
    SMHI, Forskningsavdelningen, Atmosfärisk fjärranalys.
    Landelius, Tomas
    SMHI, Forskningsavdelningen, Atmosfärisk fjärranalys.
    Effect of clouds on UV irradiance: As estimated from cloud amount, cloud type, precipitation, global radiation and sunshine duration2000Inngår i: Journal of Geophysical Research - Atmospheres, ISSN 2169-897X, E-ISSN 2169-8996, Vol. 105, nr D4, s. 4927-4935Artikkel i tidsskrift (Fagfellevurdert)
    Abstract [en]

    Ten years of measurements of UV irradiance, monitored by the Robertson-Berger (RB) meter in Norrkoping, 58.58 degrees N, 16.15 degrees E, Sweden, have been combined with concurrent synoptic cloud observations, measurements of sunshine duration, and global radiation to establish the relative influence of clouds on UV irradiance. It is shown that the cloud effect for UV wavelengths is less than for the whole solar spectrum (global radiation). Relations retrieved for global radiation may be used by correcting for the differences. High-level clouds are more transparent than low- and medium-level clouds. As expected, it was found that precipitating clouds in general are more opaque than nonprecipitating clouds. If there is any solar elevation dependency in the effect of clouds, it is small. Using only total cloud amount as parameter to model, the cloud effect on UV irradiance will give a substantial uncertainty, which can be decreased considerably using cloud type and/or information on precipitation conditions. It has also been shown that sunshine duration can be used in a similar way as cloud covet.

  • 22.
    Josefsson, Weine
    et al.
    SMHI, Samhälle och säkerhet.
    Ottosson Löfvenius, Mikaell
    SMHI.
    Measurements of total ozone 2006-20082009Rapport (Annet vitenskapelig)
    Abstract [en]

    This report summarises the quality control, quality assurance and measurements of total ozone at Norrköping and Vindeln for the period 2006-2008. Significant incidents affecting the measurements are noted. Daily data are listed and plotted.

  • 23.
    Josefsson, Weine
    et al.
    SMHI, Samhälle och säkerhet.
    Ottosson Löfvenius, Mikaell
    SMHI.
    Total ozone from zenith radiance measurements: An empirical model approach2008Rapport (Annet vitenskapelig)
    Abstract [en]

    At Vindeln monitoring of the total ozone has been done using the Dobson spectrophotometer #30 since 1991. The fundamental observation is done by observing the direct solar radiance. However, when clouds cover the sun an observation of the zenith radiance is collected. This type of measurement is called a zenith observation and by using an empirical relation one can deduce the total ozone. Up to now an old empirical relation based on data from Boulder USA has been applied. In this report we present the development and testing of a site specific empirical relation.

  • 24.
    Josefsson, Weine
    et al.
    SMHI, Samhälle och säkerhet.
    Ottosson Löfvenius, Mikaell
    Perrnilla, Löfvenius
    Measurements of total ozone 2012-20152016Rapport (Annet vitenskapelig)
    Abstract [en]

    This report summarises the quality control, quality assurance and measurements of total

    ozone at Norrköping and Vindeln for the period 2012-2015. Significant incidents affecting the

    measurements are documented. Daily data are listed and plotted.

    This work was supported by the Swedish Environmental Protection Agency.

  • 25. Kaurola, J.
    et al.
    Lindfors, A.
    Lakkala, K.
    Hansen, G.
    Josefsson, Weine
    SMHI, Samhälle och säkerhet.
    Vuilleumier, L.
    Feister, U.
    Slaper, H.
    On the usability of the ERA-40 reanalysis in the estimation of past surface UV radiation over Europe2010Inngår i: Journal of Geophysical Research - Atmospheres, ISSN 2169-897X, E-ISSN 2169-8996, Vol. 115, artikkel-id D24107Artikkel i tidsskrift (Fagfellevurdert)
    Abstract [en]

    Erythemal daily UV doses have been calculated using input data from the ERA-40 reanalysis for years 1958-2002. The quality of input parameters for UV calculations has been validated with available ground based total ozone data and estimates of Cloud Modification Factor (CMF), and the results have been compared with existing UV data. Owing to limited availability of validation data especially during 1960s and 1970s the analysis focused on sites located in central and northern Europe. The current work is the first step in deriving reliable long-term UV time series from the ERA-40 reanalysis. Total ozone from the ERA-40 reanalysis is affected by significant biases, especially before satellite ozone measurements were available for assimilation. Estimations of the effect of clouds on surface UV were made using global radiation (300-3000 nm) budgets at the surface because available ERA-40 cloud data do not allow good estimates of surface daily UV doses. There are some problems with ERA-40 solar radiation budgets which cause systematic biases in calculated daily UV doses. Comparison of calculated daily erythemal UV doses against ground-based UV data indicate that ERA-40 UV doses are typically overestimated by 6-18% in central and northern Europe and underestimated by 9-17% at Davos, Switzerland. Root-mean-square errors of the calculated daily UV doses are usually in the range of 30-40%. Trends of UV doses were calculated for the concurrent period of the TOMS satellite UV data (1979-2002). The trends of zonally averaged ERA-40 and TOMS UV agree well and are mostly of the same sign and magnitude.

  • 26. Kaurola, J
    et al.
    Taalas, P
    Koskela, T
    Borkowski, J
    Josefsson, Weine
    SMHI, Forskningsavdelningen, Atmosfärisk fjärranalys.
    Long-term variations of UV-B doses at three stations in northern Europe2000Inngår i: Journal of Geophysical Research - Atmospheres, ISSN 2169-897X, E-ISSN 2169-8996, Vol. 105, nr D16, s. 20813-20820Artikkel i tidsskrift (Fagfellevurdert)
    Abstract [en]

    Recent analysis of the total ozone observations indicate a negative trend of about 4%/decade in the Northern Hemisphere midlatitudes during the last two decades [WMO, 1999]. The effect of this decline on surface UV levels is of interest to a variety of applications. In this work the long-term variation of UV radiation at three stations located in northern Europe (Belsk, Norrkoping, and Jokioinen) has been studied using data from (1) ground-based observations, (2) surface UV doses determined using TOMS satellite measurements, and (3) reconstructed UV doses using observations of global radiation, total ozone, and radiative transfer modeling. For each station the estimates of daily UV doses from various sources have been intercompared, and a trend analysis has been performed to reveal long-term changes in the UV radiation. Data sets, which start in the late 1970s or early 1980s, show a general positive trend in annual doses of UV radiation. Some of these upward trends are statistically significant. For Belsk the increases are in the range of 5-15% per decade during spring and summer. The largest increases, about 20%/decade, has been observed in Norrkoping during spring. At Jokioinen there has been a slight upward trend in UV throughout the year. The analysis of reconstructed Belsk data from 1966 onward shows that the positive trend since late 1970s was preceeded by a negative trend. The reason for such changes is probably not only related to the changes in the total ozone but also to changes in aerosol content and cloudiness. The agreement of the UV series based on different data sources is good. This was studied using a subset of data in which it was required that data from all possible sources were available. The different trend estimates were in very close agreement with each other. However, there were often differences in absolute values, which is probably related to problems in calibration and limitations of the models.

  • 27.
    Landelius, Tomas
    et al.
    SMHI, Forskningsavdelningen, Atmosfärisk fjärranalys.
    Andersson, Sandra
    SMHI, Samhälle och säkerhet.
    Carlund, Thomas
    SMHI, Samhälle och säkerhet.
    Josefsson, Weine
    SMHI, Samhälle och säkerhet. SMHI, Forskningsavdelningen, Atmosfärisk fjärranalys.
    Karteringen av solstrålningen i Sverige2018Inngår i: Polarfront, nr 168, s. 31-40Artikkel i tidsskrift (Annet vitenskapelig)
  • 28.
    Landelius, Tomas
    et al.
    SMHI, Forskningsavdelningen, Atmosfärisk fjärranalys.
    Josefsson, Weine
    SMHI, Forskningsavdelningen, Atmosfärisk fjärranalys.
    Methods for cosine correction of broadband UV data and their effect on the relation between UV irradiance and cloudiness2000Inngår i: Journal of Geophysical Research - Atmospheres, ISSN 2169-897X, E-ISSN 2169-8996, Vol. 105, nr D4, s. 4795-4802Artikkel i tidsskrift (Fagfellevurdert)
    Abstract [en]

    Irradiance measurements on a horizontal surface often deviate from theory where the irradiance is supposed to be proportional to the cosine of the angle of incidence. This discrepancy is known as the cosine error. In this paper, three different methods for cosine error correction are investigated. The simplest method is based on the assumption of an isotropic sky radiance distribution, regardless of sky conditions, and the irradiance is treated as a single component. In the second method the irradiance is divided into one direct solar and one diffuse sky component, where the latter is assumed to have an isotropic distribution. Finally, a third method also divides the irradiance into two components but under the assumption of an anisotropic sky radiance distribution. Irradiances under general sky conditions are found by interpolation between clear and overcast cases on the basis of sunshine duration or cloud cover. The three methods are applied to data from a Robertson-Berger sunburning meter located in Norrkoping, Sweden. Both methods, where the irradiance is divided into two components, produce acceptable and similar results, while the isotropic one-component method does not.

  • 29.
    Landelius, Tomas
    et al.
    SMHI, Forskningsavdelningen, Atmosfärisk fjärranalys.
    Josefsson, Weine
    SMHI, Forskningsavdelningen, Atmosfärisk fjärranalys.
    Persson, Thomas
    SMHI.
    A system for modelling solar radiation parameters with mesoscale spatial resolution2001Rapport (Annet vitenskapelig)
    Abstract [en]

    Today, modern analysis systems synthesise meteorological data from a number of sources, e.g.\ round based SYNOP, satellites, radar, etc., into field information which enable us to model radiation at the Earth’s surface on the mesoscale. At the Swedish Meteorological and Hydrological Institute (SMHI) we have set up a model system that produce hourly information in terms of field data with a resolution of about 22 ´ 22 km2 for a geographic area covering Scandinavia and the run off region of the Baltic sea.Presently, the model calculates fields of global-, photosynthetically active- (PAR), UV- and direct radiation based on output from a mesoscale analysis system, a high resolution limited area numerical weather prediction model (NWP), an ice model for the Baltic sea together with satellite measurements of total ozone. A spectral clear sky model lies at the heart of the model system. Its output is multiplied by a function which captures the influence of clouds and precipitation. Different cloud effect functions are applied to the different radiation components, with the exception of global- and PAR for which the same relation is assumed.Measurements from the radiation network of SMHI were used for estimation and validation purposes. A first evaluation of the model system suggests that the RMSE for hourly global radiation data is on the order of 28% and about 16% for daily values. These errors are comparable to those obtained for models purely based on synoptic observations (SYNOP) (29% and 13%) . For UV radiation the figures are similar but for the direct radiation component they are worse; 53% and 31% respectively compared to 25% and 15% for the SYNOP models. To some extent the larger errors for the direct component could be explained by its sensitivity to scale differences when model grid squares are validated against point measurements.

  • 30. Lindfors, Anders
    et al.
    Kaurola, Jussi
    Arola, Antti
    Koskela, Tapani
    Lakkala, Kaisa
    Josefsson, Weine
    SMHI, Forskningsavdelningen, Atmosfärisk fjärranalys.
    Olseth, Jan Asle
    Johnsen, Bjorn
    A method for reconstruction of past UV radiation based on radiative transfer modeling: Applied to four stations in northern Europe2007Inngår i: Journal of Geophysical Research - Atmospheres, ISSN 2169-897X, E-ISSN 2169-8996, Vol. 112, nr D23, artikkel-id D23201Artikkel i tidsskrift (Fagfellevurdert)
    Abstract [en]

    A method for reconstruction of past UV radiation has been developed. The idea of the method is to use measurements of global radiation (300 - 3000 nm) for determining the influence of clouds on UV radiation. In order to transfer the information contained in the global radiation data into a cloud effect in the UV range, a so-called cloud modification table was developed, which is based on physical relationships determined through radiative transfer calculations. The method was given as input the measured global radiation and total ozone column, the total water vapor column from the ERA-40 data set, the surface albedo as estimated from snow depth, and the altitude of the location. Using this method, erythemally weighted UV irradiances were reconstructed back to the early 1980s at four stations in northern Europe: Bergen in Norway, Norrkoping in Sweden, and Jokioinen and Sodankyla in Finland. The reconstructed daily UV doses are in good agreement with measurements. For the summer season, the systematic error was found to vary between 0% at Bergen and 4% at Jokioinen, and the correlation coefficient was 0.99 at all stations. The summer root-mean-square error was 5% at all stations except Jokioinen, where it was 9%. The method performs well also for spring and autumn, whereas for winter conditions of low Sun, a systematical underestimation was found. A large part of this underestimation was found to be due to the plane-parallel approximation used in the radiative transfer calculations. The time series of reconstructed UV exhibit a clear increase since the early 1980s at both Sodankyla " (4.1%/decade; statistically significant) and Norrkoping (3.3%/decade; not significant). At Jokioinen, a weak increase was found, while at Bergen there was no considerable overall change. At both Sodankyla and Norrkoping, the increase in the reconstructed UV radiation was primarily driven by an increase in the global radiation, that is, by decreased cloudiness. The method is general in the sense that it can be applied also to other stations.

  • 31. Lindfors, Anders
    et al.
    Tanskanen, Aapo
    Arola, Antti
    van der A, Ronald
    Bais, Alkiviadis
    Feister, Uwe
    Janouch, Michal
    Josefsson, Weine
    SMHI, Samhälle och säkerhet.
    Koskela, Tapani
    Lakkala, Kaisa
    den Outer, Peter N.
    Smedley, Andrew R. D.
    Slaper, Harry
    Webb, Ann R.
    The PROMOTE UV Record: Toward a Global Satellite-Based Climatology of Surface Ultraviolet Irradiance2009Inngår i: IEEE Journal of Selected Topics in Applied Earth Observations and Remote Sensing, ISSN 1939-1404, E-ISSN 2151-1535, Vol. 2, nr 3, s. 207-212Artikkel i tidsskrift (Fagfellevurdert)
    Abstract [en]

    This paper describes the PROMOTE UV Record, which aims to provide a global long-term record of the surface UV radiation. The algorithm developed takes as input cloud information from the International Satellite Cloud Climatology Project (ISCCP) and a recently developed multisensor assimilated record of the total ozone column. Aerosols and surface albedo are based on climatologies. Here, first validation results of the PROMOTE UV Record are presented through comparison against ground-based measurements of daily erythemal UV doses at eight European stations. The validation shows that the method is working reasonably, although there is a clear tendency toward overestimation. Typically, the median bias as compared to measurements is 3%-10% and 56%-68% of the daily doses are within +/- 20% from the ground-based reference. The prototype version of the PROMOTE UV Record included in this paper covers the period from July 2002 to June 2005. The time series will later be extended to start in 1983.

  • 32. Meinander, O.
    et al.
    Kazadzis, S.
    Blumthaler, M.
    Ylianttila, L.
    Johnsen, B.
    Lakkala, K.
    Koskela, T.
    Josefsson, Weine
    SMHI, Forskningsavdelningen, Atmosfärisk fjärranalys.
    Diurnal discrepancies in spectral solar UV radiation measurements2006Inngår i: Applied Optics, ISSN 1559-128X, E-ISSN 2155-3165, Vol. 45, nr 21, s. 5346-5357Artikkel i tidsskrift (Fagfellevurdert)
    Abstract [en]

    Unexpected diurnal discrepancies between high-quality spectroradiometers were observed during the 2000 Nordic Ozone Group Intercomparison campaign. The spectral ratios of the irradiances showed a diurnal variation of similar to 2-9%. This cannot be explained by the nonideal angular response of the instruments' input optics in one plane (cosine effect). Instead, by using a radiative transfer model, we show that differences in the angular response in four azimuth planes have the potential to bias the measured data by up to 4.4% (azimuth effect). Other relevant factors are also discussed and quantified and are shown to be significant when diurnal changes in radiation are explained by environmental factors, or when measured data are compared with model or satellite data. Again, intercomparison campaigns have the potential to reveal errors that would otherwise remain undetected. (c) 2006 Optical Society of America.

  • 33.
    Olsson, Jonas
    et al.
    SMHI, Forskningsavdelningen, Hydrologi.
    Josefsson, Weine
    SMHI, Samhälle och säkerhet.
    Skyfallsuppdraget ett regeringsuppdrag till SMHI2015Rapport (Annet vitenskapelig)
    Abstract [sv]

    Att uppskatta ett ”värsta möjliga skyfall” är av många olika skäl en synnerligen komplex uppgift. Dels finns ett begränsat historiskt dataunderlag, dels är de bakomliggande fysikaliska processerna inte fullständigt kända, dels förändras klimatet med osäker påverkan på extrema väderhändelser. En och samma extremt stora nederbördsmängd kan på olika platser eller vid olika tidpunkter få helt skilda effekter. För att kunna ge en uppskattning av värsta möjliga skyfall behöver vi precisera ett antal förutsättningar. Olika statistiskt eller fysikaliskt baserade metoder finns för att beskriva extrem korttidsnederbörd. I början av uppdraget identifierades sex huvudsakliga aspekter som måste beaktas om vi ska öka vår kapacitet att förstå och beskriva skyfall. Var och en av dessa aspekter har tillägnats ett kapitel i rapporten och i det följande ges en motivering till de aktiviteter som genomförts och redovisas i varje kapitel. Omvärlden (kapitel 3): Det finns både inom Sverige, bland våra grannländer och i den övriga världen mycket kunskap, erfarenheter och metodik rörande skyfall som vi försökt ta del av. Inom uppdraget genomfördes därför en litteraturstudie med målet att skapa en god och heltäckande översikt över det nuvarande kunskapsläget m.a.p. inträffade skyfall, analysmetodik och trender. Dessutom anordnades två workshops, en med syfte att utbyta erfarenheter och knyta kontakter med experter i våra grannländer och en med syfte att få respons på erhållna resultat från olika intressenter, exempelvis myndigheter och kommuner, inom Sverige. Båda dessa visade på behovet av och värdet av informationsutbyte, något som vi måste fortsätta med och att utveckla för att optimera samhällets förmåga att hantera effekterna av kraftiga skyfall. Observationer (kapitel 4): Observationer är vår huvudsakliga källa till kunskap om skyfall men de är kortvariga och lokala väderfenomen som är svåra att mäta. Mätningarna måste ske med ett mycket kort tidssteg, hög rumslig detaljeringsgrad och hög noggrannhet vad gäller regnmängd. Alla existerande instrument är begränsade i ett eller flera av dessa avseenden. Det finns behov av att regelbundet göra uppdaterade analyser av observationer från SMHIs nät av automatstationer. SMHI håller på att modernisera det svenska radarnätet och ska om några år uppgradera det nuvarande automatstationsnätet. Detta kommer att leda till förbättrad kvalité på radarprodukterna, vilket i sin tur direkt ger en högre kvalité på nederbördsanalyserna och nederbördsprognoserna och en tätare insamlingsfrekvens av nederbörd. För att hämta hem vinsterna med nya och bättre observationer bör vi utveckla vår metodik för att använda väderradar för skyfallsanalyser, och även börja utreda de möjligheter som ges med ny mätteknik via mobilmaster och satelliter. Analys (kapitel 5): Observationerna i sig innehåller den grundläggande informationen om skyfall men vanligtvis analyseras och beskrivs observationerna via statistiska funktioner för att jämna ut variationer och inte minst för att uppskatta storleken på ännu inte inträffade skyfall. Inom Sverige används ett par olika varianter. Vi måste göra en bredare översikt över de angrepp som finns och vilka som används i vår närhet och i liknande klimat. Vi bör så långt det går testa angrepp som hittills inte testats i Sverige samt försöka kvantifiera de osäkerheter som är förknippade med olika val av metodik. Prognoser (kapitel 6): Prognosmodellerna utvecklas fortlöpande och kommer allt närmre möjligheten att fysikaliskt beskriva enskilda moln (skyfall) på en övergripande nivå, men för att kunna beskriva hur enskilda moln utvecklas och rör sig ställs även krav på att det finns observationer som ligger mycket tätt i rummet och i tiden. Detta ligger dock en bit in i framtiden. När det gäller att göra skyfallsprognoser jobbar SMHI nu med ett system som kombinerar befintliga prognosmodeller med radarinformation. När radarekon (indikation på nederbörd) väl finns kan vi med hjälp av prognosmodellernas vindfält förflytta dessa. I dagsläget är alltså radar en nyckelkomponent men i framtiden kommer sannolikt även satellitobservationer att bidra till att förbättra prognoserna av skyfall. Vi måste analysera nuvarande prognossystem m.a.p. förmågan att beskriva lokal intensiv nederbörd. Klimatförändringen (kapitel 7): En viktig aspekt på intensiv korttidsnederbörd och skyfall är vilken effekt den globala uppvärmningen kommer att ha. Generellt bör skyfallen bli kraftigare eftersom en varmare atmosfär kan innehålla mer vattenånga och därmed skapar förutsättningar för högre nederbördsintensiteter. Å andra sidan kan det också leda till att nederbördstillfällena blir färre, och/eller att tidsavståndet mellan dem ökar. Inom uppdraget har vi sammanställt kunskapsläget både vad gäller observerade trender och beräknade framtida förändringar av extrem korttidsnederbörd, i Sverige och utomlands. Vi har också analyserat de högupplösta klimatprojektioner som nyligen blivit tillgängliga samt studerat effekten av analysmetodik på de beräknade förändringarna. Effekter (kapitel 8): Även om själva uppdraget handlar specifikt om korttidsnederbörd så är bakgrunden till uppdraget de negativa effekter på samhället som korttidsnederbörd och skyfall kan ha. En huvudsaklig konsekvens av skyfall är s.k. pluviala översvämningar. Dessa inträffar när nederbördsintensiteten överskrider markens förmåga till infiltration och avvattning vilket leder till att vatten ansamlas på markytan och översvämning sker. Översvämningen i Malmö augusti 2014 är det främsta exemplet under senare år, men åtskilliga andra händelser har rapporterats. Den ökade uppmärksamhet som skyfallsproblematiken fått under senare år har lett till att många städer och kommuner börjat analysera sin sårbarhet i detta avseende. Vi har försökt att ge en lägesbeskrivning av denna verksamhet. Vi har också börjat utreda hur den pågående utvecklingen av SMHIs system för flödesmodellering mot högre tidsupplösning kan användas för att beskriva skyfallseffekter. Vi avgränsade oss geografiskt till Sverige, men tog även en titt på våra grannländer och de erfarenheter som finns där. Vi har ju trots allt liknande klimat. Via en workshop den 22-23 oktober med speciellt inbjudna experter på skyfall från Sverige och övriga Norden försökte vi fånga in aktuell kunskap och idéer till uppdraget. Tyvärr blev den finske deltagaren sjuk vilket begränsade aktuell information från vårt östra grannland. Ett syfte med workshopen var att ta fram rekommendationer och förslag över vilka frågor kring skyfall som bör prioriteras. Via en litteraturstudie har vi försökt fånga upp hur motsvarande frågor har hanterats i Sverige och i övriga världen. Begränsningar infördes även i tiden så till vida att vi främst studerade kraftig nederbörd med varaktighet 24 timmar eller kortare (ner till 7,5 min). Vårt historiska material, d.v.s. observationer som finns i SMHIs databas, blev en given utgångspunkt. Bearbetning av befintliga observationer ger indikationer på hur vanliga skyfall har varit, deras geografiska fördelning och när de förekommer i tiden (under dygnet och när under året). Ett delprojekt var att försöka få till ett samarbete och utbyte med kommunernas nederbördsdata, vilket skulle bli ett bra komplement då dessa observationer ofta har en hög tidsupplösning och görs i tätorter där effekten av skyfall kan vara betydande. Vi hann knappt ta del av dessa data i år, men på sikt kan detta bli ett nationellt värdefullt data-set. Bearbetningen av nederbördsdata för att ta fram dimensionerande värden exempelvis så kallade 10-årsregn, 100-årsregn osv. bygger på olika statistiska metoder. Inom projektet testades olika metoder och en litteraturstudie gjordes för att sammanställa vad som gjorts tidigare i Sverige och i andra länder. Eftersom SMHIs nuvarande stationsnät (knappt 700 stationer varav flertalet endast ger dygnsnederbörd) är glest och att skyfallen har en liten geografisk utbredning hamnar många kraftiga skyfall vid sidan av mätstationerna. Inom projektet undersöktes hur väl det går att uppskatta nederbörden med hjälp av radar. Försök har gjorts tidigare men kvalitén har många gånger varit låg. En förbättring av metodiken kan ge bättre analyser men också möjligheter för korttidsprognoser av kraftig nederbörd. En mycket viktig fråga är ”Går det att göra användbara prognoser av kraftiga skyfall?”. Korttidsprognoser av nederbörd med hjälp av radarinformation i kombination med de vanliga prognosmodellerna kan vara en framkomlig väg. Dagens operationella prognosmodeller är för grova för att beskriva den konvektiva nederbörden som ger upphov till de kraftigaste skyfallen, men det finns modeller som kan testas i högre upplösning för att undersöka om detta är en framkomlig väg. Vi har kört en så kallad högupplöst modell på ett testfall för att se vilka framkomliga vägar som existerar. En begränsad teoretisk studie över prediktabiliteten gjordes för att bedöma vad som krävs för att våra modeller och av indata till dessa för att uppnå användbara skyfallsprognoser. Räcker det med att datorerna blir snabbare eller behöver också den fysikaliska beskrivningen i modellen ändras eller behöver vi ännu bättre observationer eller behöver alla delar förbättras för att prognoserna ska bli tillräckligt bra vad gäller skyfall för tex användbara varningar. Utöver radardata finns det potentiellt användbar information från alla mikrovågslänkar (mobilmaster) som redan finns i landet. En del av projektet har gjort en pilotstudie av användbarheten av dessa för att uppskatta nederbördsmängder. En annan del har bedömt vad som kan göras med befintliga och med kommande satellitdata. I och med den pågående klimatförändringen blir det också viktigt att ta den med i beräkningen. Vilka förändringar av skyfall kan förväntas? Fler eller färre skyfall, geografisk fördelning, ändras tiden på året, tiden på dygnet? Inom projektet har ingen sådan ny studie gjorts. När projektet började leverera resultat blev det viktigt att diskutera framtida projekt som kan medföra förbättringar i övervakning av skyfall, prognosering av skyfall och givetvis varningar och att förmedla detta till potentiella användare för att få en återkoppling huruvida resultaten och idéerna är användbara. Detta skedde i december vid en seminariedag, som planerades tillsammans med MSB, SGI och Karlstads universitet som riktade sig till kommuner, länsstyrelser och myndigheter (användare av skyfallsinformation). Läs mer om detta i avsnitt 3.3 samt bilaga III.SGI och Karlstads universitet som riktade sig till kommuner, länsstyrelser och myndigheter (användare av skyfallsinformation). Läs mer om detta i avsnitt 3.3 samt bilaga III.

  • 34. Petkov, Boyan H.
    et al.
    Vitale, Vito
    Tomasi, Claudio
    Siani, Anna Maria
    Seckmeyer, Gunther
    Webb, Ann R.
    Smedley, Andrew R. D.
    Casale, Giuseppe Rocco
    Werner, Rolf
    Lanconelli, Christian
    Mazzola, Mauro
    Lupi, Angelo
    Busetto, Maurizio
    Diemoz, Henri
    Goutail, Florence
    Koehler, Ulf
    Mendeva, Bogdana D.
    Josefsson, Weine
    SMHI, Samhälle och säkerhet.
    Moore, David
    Lopez Bartolome, Maria
    Moreta Gonzalez, Juan Ramon
    Misaga, Oliver
    Dahlback, Arne
    Toth, Zoltan
    Varghese, Saji
    De Backer, Hugo
    Stuebi, Rene
    Vanicek, Karel
    Response of the ozone column over Europe to the 2011 Arctic ozone depletion event according to ground-based observations and assessment of the consequent variations in surface UV irradiance2014Inngår i: Atmospheric Environment, ISSN 1352-2310, E-ISSN 1873-2844, Vol. 85, s. 169-178Artikkel i tidsskrift (Fagfellevurdert)
    Abstract [en]

    The strong ozone depletion event that occurred in Arctic during spring 2011 was found to cause appreciable reduction in the ozone column (OC) in Europe, even at lower latitudes. The features of this episode have been analysed using the data recorded at 34 ground-based stations located in the European area and compared with the similar events in 2000 and 2005. The results provided evidence that OC as far south as 40 degrees N latitude was considerably influenced by the Arctic ozone loss in spring 2011. The reduction of OC at the northernmost sites was about 40% with respect to the mean value calculated over the previous six-year period, while a similar decrease at the southern extreme ranged between 15 and 18%, and were delayed by nearly two weeks compared to the Arctic region. The ozone distributions reconstructed for the West Europe sector show that the decline of OC lasted from late March to late April 2011. The echo of the Arctic ozone depletion on mid-latitude UV irradiance has been analysed trough model computations that show an increase of the midday erythemal dose by 3-4 SED (1 SED = 100 J m(-2)) that was slightly higher than at polar regions. On the other hand it was assessed that the biosystems in the northernmost regions were a subject of about 4 times higher UV stress than those at mid-latitudes. Despite indications of an OC recovery, the event examined here shows that the issue of ozone depletion episodes cannot be belittled. (C) 2013 Elsevier Ltd. All rights reserved.

  • 35. Zerefos, Christos S.
    et al.
    Eleftheratos, Kostas
    Kapsomenakis, John
    Solomos, Stavros
    Inness, Antje
    Balis, Dimitris
    Redondas, Alberto
    Eskes, Henk
    Allaart, Marc
    Amiridis, Vassilis
    Dahlback, Arne
    De Bock, Veerle
    Diemoz, Henri
    Engelmann, Ronny
    Eriksen, Paul
    Fioletov, Vitali
    Grobner, Julian
    Heikkila, Anu
    Petropavlovskikh, Irina
    Jaroslawski, Janusz
    Josefsson, Weine
    SMHI, Samhälle och säkerhet.
    Karppinen, Tomi
    Koehler, Ulf
    Meleti, Charoula
    Repapis, Christos
    Rimmer, John
    Savinykh, Vladimir
    Shirotov, Vadim
    Siani, Anna Maria
    Smedley, Andrew R. D.
    Stanek, Martin
    Stubi, Rene
    Detecting volcanic sulfur dioxide plumes in the Northern Hemisphere using the Brewer spectrophotometers, other networks, and satellite observations2017Inngår i: Atmospheric Chemistry And Physics, ISSN 1680-7316, E-ISSN 1680-7324, Vol. 17, nr 1, s. 551-574Artikkel i tidsskrift (Fagfellevurdert)
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