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External verification based on ground-based data is commonly used to assess the accuracy of satellite products for total ozone. However, the spatial representativeness of ground-based observations at the pixel scale and the effects of the spatial mismatch between ground observations and satellite pixels are often overlooked. Therefore, this study focused on an Ozone Monitoring Instrument (OMI) and proposed a novel method to evaluate spatial representativeness using the total ozone product itself without relying on higher spatial resolution imagery from other sensors. A Pixel-level Spatial Mismatch Index (PSMI) was developed to quantify the peaks and stable intervals of the spatial response to the relative deviation of total ozone observations. The analysis revealed that increased uncertainty at the pixel edges can cause significant relative deviation, with the peak deviation occurring within a range of 4–7 km near the pixel boundary. The position of the high precision interval in PSMI was found to be <–22.38 km or >10 km, with mean values of 3.70 % and standard deviations of 3.45 % for the relative deviation. This interval is spatially distance-independent and can be observed on both sides of the pixel boundary. These findings highlight the importance of considering spatial patterns between satellite pixels and ground stations for external validation. Furthermore, avoiding a spatial response peak of the relative deviation at the pixel edge is crucial. Overall, this research provides new perspectives and insights for the verification of total ozone products. By considering these factors mentioned above, future verification of total ozone products can be improved, leading to enhanced their evaluation systems., External verification based on ground-based data is commonly used to assess the accuracy of satellite products for total ozone. However, the spatial representativeness of ground-based observations at the pixel scale and the effects of the spatial mismatch between ground observations and satellite pixels are often overlooked. Therefore, this study focused on an Ozone Monitoring Instrument (OMI) and proposed a novel method to evaluate spatial representativeness using the total ozone product itself without relying on higher spatial resolution imagery from other sensors. A Pixel-level Spatial Mismatch Index (PSMI) was developed to quantify the peaks and stable intervals of the spatial response to the relative deviation of total ozone observations. The analysis revealed that increased uncertainty at the pixel edges can cause significant relative deviation, with the peak deviation occurring within a range of 4–7 km near the pixel boundary. The position of the high precision interval in PSMI was found to be <–22.38 km or >10 km, with mean values of 3.70 % and standard deviations of 3.45 % for the relative deviation. This interval is spatially distance-independent and can be observed on both sides of the pixel boundary. These findings highlight the importance of considering spatial patterns between satellite pixels and ground stations for external validation. Furthermore, avoiding a spatial response peak of the relative deviation at the pixel edge is crucial. Overall, this research provides new perspectives and insights for the verification of total ozone products. By considering these factors mentioned above, future verification of total ozone products can be improved, leading to enhanced their evaluation systems.

External verification based on ground-based data is commonly used to assess the accuracy of satellite products for total ozone. However, the spatial representativeness of ground-based observations at the pixel scale and the effects of the spatial mismatch between ground observations and satellite pixels are often overlooked. Therefore, this study focused on an Ozone Monitoring Instrument (OMI) and proposed a novel method to evaluate spatial representativeness using the total ozone product itself without relying on higher spatial resolution imagery from other sensors. A Pixel-level Spatial Mismatch Index (PSMI) was developed to quantify the peaks and stable intervals of the spatial response to the relative deviation of total ozone observations. The analysis revealed that increased uncertainty at the pixel edges can cause significant relative deviation, with the peak deviation occurring within a range of 4–7 km near the pixel boundary. The position of the high precision interval in PSMI was found to be <–22.38 km or >10 km, with mean values of 3.70 % and standard deviations of 3.45 % for the relative deviation. This interval is spatially distance-independent and can be observed on both sides of the pixel boundary. These findings highlight the importance of considering spatial patterns between satellite pixels and ground stations for external validation. Furthermore, avoiding a spatial response peak of the relative deviation at the pixel edge is crucial. Overall, this research provides new perspectives and insights for the verification of total ozone products. By considering these factors mentioned above, future verification of total ozone products can be improved, leading to enhanced their evaluation systems., External verification based on ground-based data is commonly used to assess the accuracy of satellite products for total ozone. However, the spatial representativeness of ground-based observations at the pixel scale and the effects of the spatial mismatch between ground observations and satellite pixels are often overlooked. Therefore, this study focused on an Ozone Monitoring Instrument (OMI) and proposed a novel method to evaluate spatial representativeness using the total ozone product itself without relying on higher spatial resolution imagery from other sensors. A Pixel-level Spatial Mismatch Index (PSMI) was developed to quantify the peaks and stable intervals of the spatial response to the relative deviation of total ozone observations. The analysis revealed that increased uncertainty at the pixel edges can cause significant relative deviation, with the peak deviation occurring within a range of 4–7 km near the pixel boundary. The position of the high precision interval in PSMI was found to be <–22.38 km or >10 km, with mean values of 3.70 % and standard deviations of 3.45 % for the relative deviation. This interval is spatially distance-independent and can be observed on both sides of the pixel boundary. These findings highlight the importance of considering spatial patterns between satellite pixels and ground stations for external validation. Furthermore, avoiding a spatial response peak of the relative deviation at the pixel edge is crucial. Overall, this research provides new perspectives and insights for the verification of total ozone products. By considering these factors mentioned above, future verification of total ozone products can be improved, leading to enhanced their evaluation systems.

In this paper, a method previously developed for reconstructing daily erythemal ultraviolet (UVery) doses in Novi Sad (Serbia) was improved and used for estimating daily UVery over the period 1971–2018. The proposed new method uses reanalysed total ozone column (TOC) data and snow cover as an input and is based on the empirical relationship between relative sunshine duration and relative UVery doses. Introducing reanalysed TOC data and snow cover data significantly improved the quality and accuracy of the reconstructed UVery time series, particularly in the winter season. The reconstructed time series revealed the statistically significant increase in summer and winter UVery in the 1980s and the first half of the 1990s (+8.78% and + 13.14% per decade, respectively), which was linked to the statistically significant decline in TOC (−4.13 and −7.36% per decade, respectively). The study focuses on days with high erythemal UV dose (highUVery), which is defined based on the 90th percentile of the daily UVery for each month. Moreover, the influence of low TOC, low cloud cover conditions, and high surface albedo on highUVery was analysed on a seasonal basis. The results of this study show that highUVery days increased from the 1980s, particularly strongly in the period of TOC depletion. A fraction of highUVery days in the last two decades was large (12.29%), which is higher than in the previous periods (6.97 and 8.68% in the period before and during TOC depletion, respectively). The occurrence of highUVery days was influenced mostly by low cloud cover (89.71% of days), and low TOC (82.23% of days). In the winter season, high surface albedo influenced the appearance of 19.18% of highUVery days. However, overall the interaction of low cloud cover and low TOC in all seasons most often led to the appearance of highUVery days.

A compact array spectroradiometer that enables precise and robust measurements of solar UV spectral direct irradiance is presented. We show that this instrument can retrieve total ozone column (TOC) accurately. The internal stray light, which is often the limiting factor for measurements in the UV spectral range and increases the uncertainty for TOC analysis, is physically reduced so that no other stray-light reduction methods, such as mathematical corrections, are necessary. The instrument has been extensively characterised at the Physikalisch-Technische Bundesanstalt (PTB) in Germany. During an international total ozone measurement intercomparison at the Izaña Atmospheric Observatory in Tenerife, the high-quality applicability of the instrument was verified with measurements of the direct solar irradiance and subsequent TOC evaluations based on the spectral data measured between 12 and 30 September 2016. The results showed deviations of the TOC of less than 1.5% from most other instruments in most situations and not exceeding 3% from established TOC measurement systems such as Dobson or Brewer. © 2018 Author(s).

The two Brewer spectrophotometers of the Finnish Meteorological Institute at Jokioinen and Sodankyla have been operated according to the highest levels of the WMO/GAW (World Meteorological Organization/Global Atmosphere Watch) recommendations with rigorous quality control and quality assurance. The calibration of the instruments is based on annual recalibrations of primary standard lamps in the VTT MIKES Metrology National Standards Laboratory in Finland and an exhaustive measurement program with measurements of standard and working lamps in the on-site optical laboratories. Over the years, the maintenance of the calibration has produced data sets of approximately 2000 lamp scans for both instruments. An extensive re-examination of the lamp measurements and the response of the spectrophotometers was carried out. The primary standard lamps were found to age on an average rate of 0.3% per burn. The responsivity at wavelength 311 nm was found to exhibit both long-term and short-term changes. The overall long-term change was declining. In addition, abrupt changes of as large as 25% were detected. The short-term changes were found to fluctuate on time frames shorter than the interval between the measurements of the primary standard lamps. This underlines the importance of the use of more frequently measured working standard lamps.

Polysulphone (PS) dosimetry has been a widely used technique for more than 30 years to quantify the erythemally effective UV dose received by anatomic sites (personal exposure). The calibration of PS dosimeters is an important issue as their spectral response is different from the erythemal action spectrum. It is performed exposing a set of PS dosimeters on a horizontal plane and measuring the UV doses received by dosimeters using calibrated spectroradiometers or radiometers. In this study, data collected during PS field campaigns (from 2004 to 2006), using horizontal and differently inclined dosimeters, were analyzed to provide some considerations on the transfer of the horizontal calibration to differently inclined dosimeters, as anatomic sites usually are. The role of sky conditions, of the angle of incidence between the sun and the normal to the slope, and of the type of surrounding surface on the calibration were investigated. It was concluded that PS horizontal calibrations apply to differently inclined dosimeters for incidence angles up to approximately 70 degrees and for surfaces excluding ones with high albedo. Caution should be used in the application of horizontal calibrations for cases of high-incidence angle and/or high albedo surfaces.

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.

A human being is often influenced both by natural and artificial UV radiation, that is why it is relevant to select adequate methodology and evaluate levels of UV radiation as well as determine the tendencies of their change. The aim is to investigate the changes of UV radiation and to assess the relationship between physical and chemical parameters of the environment. Tasks of the work is to perfect the methodology of registration of UV radiation parameters, to adjust the available survey meters for UV radiation registration; to determine and make assessments determining the relationship of UV radiation, total amount of ozone and the ground level ozone concentration; to assess the changes of natural and artificial UV radiation intensity is a vital task as well; to study the influence of albedo of UV radiation of various natural and artificial surfaces on the total UV radiation intensity; to implement the forecasted model on UV radiation intensity within the environment of values is important., Disertacijoje nagrinėjami gamtinės ir dirbtinių šaltinių skleidžiamos UV spinduliuotės intensyvumo pokyčiai bei juos sąlygojantys aplinkos parametrai. Analizuojami gamtiniai, dirbtinių šaltinių, nuo įvairių paviršių atsispindėjusios UV spinduliuotės pokyčiai. Šių pokyčių tyrimų rezultatai, įvertinantys gamtinę, dirbtinių šaltinių skleidžiamą bei įvairių paviršių atspindėtą UV spinduliuotę, yra svarbūs vertinant UV spinduliuotės intensyvumą konkrečiomis sąlygomis. Pagrindinis disertacijos tikslas yra ištirti UV spinduliuotės pokyčius aplinkoje ir įvertinti jų priklausomybę nuo fizinių ir cheminių aplinkos parametrų. Remiantis darbo rezultatais galima įvertinti veiksnius, lemiančius UV spinduliuotės intensyvumo pokyčius prie Žemės paviršiaus. Pagal aprašytas metodikas galima įvertinti dirbtinės UV spinduliuotės intensyvumo variacijas uždarose patalpose.

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.

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.

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.

This visualization shows the total ozone concentrations for the Earth from January 1, 2000 through December 31, 2003. Low ozone (less than 200 Dobson units) is depicted as regions of dark blue, with high ozone (greater that 330 Dobson units) depicted as yellow and red. The most visible and dynamic feature of the ozone distribution is the ozone hole that forms over Antarctica during September of each year. The amount of ozone in the stratosphere over Antarctica is reduced during this period due to unique atmospheric conditions which chemically reduce the amount of ozone in the region and prevent that ozone from mixing with the higher ozone concentrations just outside the hole. Ozone blocks harmful ultraviolet B rays, and loss of statospheric ozone has been linked to skin cancer in humans and other adverse biological effects in plants and animals. The 2000 Antarctic ozone hole reached 11.5 million square miles on September 10, 2000, the largest hole ever recorded, slightly larger than the North American continent. The 2002 ozone hole was much smaller than normal, dividing into two parts on September 24 before dissipating completely, while the 2003 hole was the second largest observed, reaching 10.9 million square miles on September 11. This data was measured by the TOMS instrument on the Earth Probe satellite. TOMS experienced some days during this period for which data was not measured due to instrument problems. Educational levels: Undergraduate lower division, Undergraduate upper division, Graduate or professional

This visualization shows the total ozone concentrations for the Earth from January 1, 2000 through December 31, 2003, as measured by theTOMS instrument on the Earth Probe satellite. Low ozone (less than 200 Dobson units) is depicted as regions of dark blue, with high ozone (greater that 330 Dobson units) depicted as yellow and red. The most visible and dynamic feature of the ozone distribution is the ozone hole that forms over Antarctica during September of each year. The amount of ozone in the stratosphere over Antarctica is reduced during this period due to unique atmospheric conditions which chemically reduce the amount of ozone in the region and prevent that ozone from mixing with the higher ozone concentrations just outside the hole. Ozone blocks harmful ultraviolet B rays, and loss of statospheric ozone has been linked to skin cancer in humans and other adverse biological effects in plants and animals. This visualization explicitly shows the TOM ozone data coverage and does not interpolate data into regions of the Earth that the instrument did not observe. Since TOMS measures ozone by observing the characteristics of sunlight reflected from the Earths surface, no measurements are available for the poles during the polar winter, i.e., around January for the North Pole and July for the South Pole. Also, there is an unobserved region between successive satellite orbits around the equator. Finally, the instrument has periods where technical issues make measurement impossible for a matter of hours or days. This visualization shows that the dynamics of the ozone layer remain visible despite these measurement issues. Educational levels: Undergraduate lower division, Undergraduate upper division, Graduate or professional

Measurements of solar UV-racliation in a small Sweclish network are presented for 1996. this report can be regarded as a supplement to a previous report, Josefsson (l996) where the results of the previous five years were reported, and where details not presented in this small repor! can be found. The quantity ancl unit of the UV-radiation in this presentation is CIE-weighted irradiance expressed as MED (minimum erythemal dose), where one MED equals 210 Jm-2. The values have been recomputed to refer to the international intercomparison of broad-band meters at Helsinki in 1995. In the following referred to as the WMO-STUK 1995 scale.Although, the stratospheric ozone was severely depleted during the early parts of 1996, the yearly UV radiation recorded was slightly less than in previous years. This was mainly due to the very cloudy months of May, June and July. By combining the UV-record with concurrent records of the total ozone a small study of the anticorrelation of these two atmospheric parameters is illustrated. There are many sources of error and detailed studies are prevented by the !arge uncertainty connected with these data of UV-irradiance. Due to the short period of the record and the low accuracy no attempt to study trends is done.

Measurements of solar UV-racliation in a small Sweclish network are presented for 1996. this report can be regarded as a supplement to a previous report, Josefsson (l996) where the results of the previous five years were reported, and where details not presented in this small repor! can be found. The quantity ancl unit of the UV-radiation in this presentation is CIE-weighted irradiance expressed as MED (minimum erythemal dose), where one MED equals 210 Jm-2. The values have been recomputed to refer to the international intercomparison of broad-band meters at Helsinki in 1995. In the following referred to as the WMO-STUK 1995 scale.Although, the stratospheric ozone was severely depleted during the early parts of 1996, the yearly UV radiation recorded was slightly less than in previous years. This was mainly due to the very cloudy months of May, June and July. By combining the UV-record with concurrent records of the total ozone a small study of the anticorrelation of these two atmospheric parameters is illustrated. There are many sources of error and detailed studies are prevented by the !arge uncertainty connected with these data of UV-irradiance. Due to the short period of the record and the low accuracy no attempt to study trends is done.

A study of the Antarctic ozone hole has been made with a three-dimensional chemical transport model (CTM) using a linearized photochemistry for ozone. The tracer model uses the winds and convection from the Goddard Institute for Space Studies general circulation model (8° × 10° × 23 layers). The general circulation model (GCM) develops an Antarctic circumpolar vortex in early winter with strong westerlies that reverse in austral spring; the circulation compares favorably with the observed climatologies. A 4-year control run of the CTM with annually repeating winds produces ozone distributions that compare reasonably with the observed climatology. We examine different linearizations of the ozone chemistry and show that the calculated column ozone is sensitive to the chemical time constants in the lower stratosphere. In separate numerical experiments a hypothetical Antarctic ozone “hole” is induced on September 1 and on October 1; the CTM is integrated for 1 year with a linearized model that assumes standard photochemistry, not including the heterogeneous reactions and unusual chemistry associated with formation of the ozone hole. The initial depletion, assumed to be 90% of the O3poleward of 70°S between 22 and 200 mbar, amounts to about 5% of the total O3 in the southern hemisphere. As the vortex breaks down and the ozone hole is dispersed, significant depletions to column ozone, of order 10 Dobson units (3%) occur as far north as 40°S during austral summer. One year later, only 30% of the original depletion remains, mostly below 100 mbar and poleward of 30°S. The October 1 initialization is continued for a second year, the ozone hole being reinduced 1 year later with the same parameterization. The cumulative effects from the year before are noticeable but add only 20% to the depletion. A budget analysis for the southern high-latitude stratosphere (10–350 mbar × 31°–90°S) indicates the ozone hole is replenished equally by photochemical regeneration and by reduced tra

A study of the Antarctic ozone hole has been made with a three-dimensional chemical transport model (CTM) using a linearized photochemistry for ozone. The tracer model uses the winds and convection from the Goddard Institute for Space Studies general circulation model (8° × 10° × 23 layers). The general circulation model (GCM) develops an Antarctic circumpolar vortex in early winter with strong westerlies that reverse in austral spring; the circulation compares favorably with the observed climatologies. A 4-year control run of the CTM with annually repeating winds produces ozone distributions that compare reasonably with the observed climatology. We examine different linearizations of the ozone chemistry and show that the calculated column ozone is sensitive to the chemical time constants in the lower stratosphere. In separate numerical experiments a hypothetical Antarctic ozone “hole” is induced on September 1 and on October 1; the CTM is integrated for 1 year with a linearized model that assumes standard photochemistry, not including the heterogeneous reactions and unusual chemistry associated with formation of the ozone hole. The initial depletion, assumed to be 90% of the O3poleward of 70°S between 22 and 200 mbar, amounts to about 5% of the total O3 in the southern hemisphere. As the vortex breaks down and the ozone hole is dispersed, significant depletions to column ozone, of order 10 Dobson units (3%) occur as far north as 40°S during austral summer. One year later, only 30% of the original depletion remains, mostly below 100 mbar and poleward of 30°S. The October 1 initialization is continued for a second year, the ozone hole being reinduced 1 year later with the same parameterization. The cumulative effects from the year before are noticeable but add only 20% to the depletion. A budget analysis for the southern high-latitude stratosphere (10–350 mbar × 31°–90°S) indicates the ozone hole is replenished equally by photochemical regeneration and by reduced tra