UV-mittaukset napa-alueilla : tieteellinen analyysi ja irradianssiskaalan siirto

The Earth's ecosystems are protected from the dangerous part of the solar ultraviolet (UV) radiation by stratospheric ozone, which absorbs most of the harmful UV wavelengths. Severe depletion of stratospheric ozone has been observed in the Antarctic region, and to a lesser extent in the Arctic and midlatitudes. Concern about the effects of increasing UV radiation on human beings and the natural environment has led to ground based monitoring of UV radiation. In order to achieve high-quality UV time series for scientific analyses, proper quality control (QC) and quality assurance (QA) procedures have to be followed. In this work, practices of QC and QA are developed for Brewer spectroradiometers and NILU-UV multifilter radiometers, which measure in the Arctic and Antarctic regions, respectively. These practices are applicable to other UV instruments as well. The spectral features and the effect of different factors affecting UV radiation were studied for the spectral UV time series at Sodankylä. The QA of the Finnish Meteorological Institute's (FMI) two Brewer spectroradiometers included daily maintenance, laboratory characterizations, the calculation of long-term spectral responsivity, data processing and quality assessment. New methods for the cosine correction, the temperature correction and the calculation of long-term changes of spectral responsivity were developed. Reconstructed UV irradiances were used as a QA tool for spectroradiometer data. The actual cosine correction factor was found to vary between 1.08-1.12 and 1.08-1.13. The temperature characterization showed a linear temperature dependence between the instrument's internal temperature and the photon counts per cycle. Both Brewers have participated in international spectroradiometer comparisons and have shown good stability. The differences between the Brewers and the portable reference spectroradiometer QASUME have been within 5% during 2002-2010. The features of the spectral UV radiation time series at Sodankylä were analysed for the time period 1990-2001. No statistically significant long-term changes in UV irradiances were found, and the results were strongly dependent on the time period studied. Ozone was the dominant factor affecting UV radiation during the springtime, whereas clouds played a more important role during the summertime. During this work, the Antarctic NILU-UV multifilter radiometer network was established by the Instituto Nacional de Meteorogía (INM) as a joint Spanish-Argentinian-Finnish cooperation project. As part of this work, the QC/QA practices of the network were developed. They included training of the operators, daily maintenance, regular lamp tests and solar comparisons with the travelling reference instrument. Drifts of up to 35% in the sensitivity of the channels of the NILU-UV multifilter radiometers were found during the first four years of operation. This work emphasized the importance of proper QC/QA, including regular lamp tests, for the multifilter radiometers also. The effect of the drifts were corrected by a method scaling the site NILU-UV channels to those of the travelling reference NILU-UV. After correction, the mean ratios of erythemally-weighted UV dose rates measured during solar comparisons between the reference NILU-UV and the site NILU-UVs were 1.007±0.011 and 1.012±0.012 for Ushuaia and Marambio, respectively, when the solar zenith angle varied up to 80°. Solar comparisons between the NILU-UVs and spectroradiometers showed a ±5% difference near local noon time, which can be seen as proof of successful QC/QA procedures and transfer of irradiance scales. This work also showed that UV measurements made in the Arctic and Antarctic can be comparable with each other.Auringon säteilystä noin 8 % on ultraviolettisäteilyä (UV-säteily), jonka lyhyet aallonpituudet ovat haitallisia maapallon ekosysteemeille. Ilmakehän yläkerroksissa sijaitsevat otsonimolekyylit suojaavat kuitenkin maapalloa UV-säteilyn haitallisimmilta aallonpituuksilta. Ilmakehässä noin 15-30 km:n korkeudella sijaitsevassa stratosfäärin otsonikerroksessa on havaittu 1980-luvulta lähtien otsonin kausittaista vähenemistä erityisesti napa-alueiden läheisyydessä. Voimakkainta otsonin väheneminen on ollut etelänavan ympäristössä eteläisen pallonpuoliskon kevätaikaan. Suojaavan otsonikerroksen oheneminen herätti huolen maapallon pinnalle saapuvan UV-säteilyn mahdollisesta lisääntymisestä, ja järjestelmällinen UV-säteilyn mittaus aloitettiin monin paikoin 1980-luvun loppupuolella. Suomessa Ilmatieteen laitos aloitti spektrisen UV-säteilyn mittaukset Sodankylän mittausasemalla vuonna 1990. Mittausaikasarja on yksi Euroopan pisimmistä ja edustaa arktisen otsonikadon alueella tehtyjä UV-mittauksia. Korkeilla leveysasteilla tehtävät UV-mittaukset ovat haastavia runsaan ja vaihtelevan pilvisyyden, matalien auringon korkeuskulmien, kylmien lämpötilojen ja talvisten jäätämis- ja lumiolosuhteiden vuoksi. Korkealaatuiset tieteelliseen käyttöön soveltuvat UV-mittaukset vaativat järjestelmällisiä laadunvalvonta- ja laadunvarmistusmenetelmiä. Tässä työssä on kehitetty Ilmatieteen laitoksen Brewer-spektroradiometreillä mitatuille UV-mittauksille prosessointiketju, jossa tuotetaan tieteelliseen tutkimuskäyttöön soveltuvaa UV-mittausaineistoa. Ketju sisältää laadunvalvonta- ja laadunvarmistusmenetelmiä, jotka perustuvat laboratoriokarakterisointien mittaustulosten ja teoreettisten sovellutusten yhdistämiseen. Menetelmät ovat sovellettavissa muillekin UV-säteilyä mittaaville radiometreille. Uutta on mm. pilvisyyden vaihtelut huomioiva kosinikorjausmenetelmä, jolla on korjattu matalista auringon korkeuskulmista aiheutuva virhe mittaustuloksissa. Uusia menetelmiä on myös kehitetty lämpötilariippuvuudesta ja mittauskyvyn muutoksista aiheutuvien virheiden korjaamiseen pitkistä aikasarjoista. Mittausten laatua on arvioitu osallistumalla säännöllisesti kansainvälisiin vertailukampanjoihin. Ilmatieteen laitoksen spektroradiometrien ja Euroopan kiertävän QASUME-vertailuspektroradiometrin mittaustulosten erot ovat olleet noin 5 % tai vähemmän vuosina 2002-2010. Työssä analysoitiin Sodankylän spektrisen UV-säteilyn aikasarjassa esiintyviä lyhyt- ja pitkäaikaisia vaihteluja vuosina 1990-2001. Aikasarjaa kuvasti kuukausikeskiarvojen suuri vuosittainen vaihtelu, minkä seurauksena havaitut muutokset riippuivat valituista ajanjaksoista eivätkä olleet tilastollisesti merkittäviä. Kokonaisotsonin vaikutus UV-säteilyn vaihteluissa oli suurin keväisin, kun taas pilvisyyden vaikutus korostui kesällä. Tämän työn yhtenä osana on ollut osallistuminen Etelämantereen alueella sijaitsevan UV-säteilyä mittaavan mittausverkoston suunnitteluun ja toteuttamiseen. Mittausverkoston on perustanut espanjalainen Instituto Nacional de Meteorogía (INM) espanjalais-argentiinalais-suomalaisena yhteistyönä vuosina 1999-2000. Käytettävät mittalaitteet ovat NILU-UV-monikaistaradiometrejä. Tässä työssä on kehitetty mittausverkostolle soveltuvat laadunvalvonta- ja laadunvarmistusmenetelmät, jotka voidaan ottaa käyttöön muissakin vastaavissa mittausverkostoissa. Menetelmät perustuvat kaksi kertaa kuukaudessa tehtäviin lamppumittauksiin ja kiertävällä vertailumittarilla tehtäviin auringon UV-säteilyn mittauksiin. Kehitettyjen menetelmien avulla voidaan korjata laitteiden mittauskyvyn muutoksista aiheutuvat virheet, sekä saattaa verkoston eri mittausasemien mittaustulokset vertailukelpoisiksi keskenään. Tämä työ osoitti, että kiertävää NILU-UV-vertailumittalaitetta voidaan käyttää irradianssiskaalan siirtämiseen pohjoisen ja eteläisen pallonpuoliskon korkeiden leveysasteiden välillä. Lisäksi kiertävän NILU-UV-mittalaitteen vertailumittaukset spektroradiometrien kanssa osoittivat, että Euroopan arktisten alueiden ja Etelämantereen alueen UV-mittauksia on mahdollista vertailla keskenään

Quality assurance of a solar UV network in the Antarctic

Póster elaborado para la 27th General Assembly of the European Geophysical Society celebrada en Niza los días 21-26 de abril de 200

Correcting Stray Light in Single-monochromator Brewer Spectrophotometers

Póster presentado en: Quadrennial Ozone Symposium 2012 (QOS 2012), celebrado del 27 al 31 de agosto de 2012 en Toronto, Canada

Correction and validation of total ozone data series from an antarctic multichannel filter radiometer solar UV network

Póster elaborado para la 27th General Assembly of the European Geophysical Society celebrada en Niza los días 21-26 de abril de 2002The MAR Project is financed by the National R+D Plan of the Ministry of Science and Technology (National Research Program at the Antarctica) under contract REN2000-0245-C02-2

Traveling reference NILU-UV at the Antarctic region: solar UV comparisons at Ushuaia and Marambio in 2002

Póster elaborado para la EGS - AGU - EUG Joint Assembly celebrada en Niza, los días 6-11 de abril de 2003The MAR Project is financed by the National R+D Plan of the Ministry of Science and Technology (National Research Program at the Antarctica) under contract REN2000-0245-C02-02

The NILU-UV6 multichannel moderate bandwidth filter radiometer in the MAR project’s Antarctic network

Ponencia presentada en: 3ª Asamblea Hispano Portuguesa de Geodesia y Geofisica, celebrada en Valencia en 2002During the last years multichannel moderate bandwidth filter instruments have been used for UV radiation measurement and the reconstruction of the solar spectra. These instruments are now part of several UV and ozone monitoring networks, due to its easy management, low maintenance, robustness and high efficiency. In this work the characteristics, the algorithms for different products calculation, and the quality control and quality assurance system of the multichannel filter radiometer NILU-UV6 are presented. This instrument measures at five UV channels (305, 312, 320, 340 and 380 nm) and PAR (400-700 nm) channel. A radiative transfer model is used to calculate the total ozone content, clouds transmitance and the biologically effective UV doses. The preliminary results obtained by the NILU-UV6 instruments of the MAR project (Measurement of Antarctic radiance for monitoring the ozone layer) Antarctic network, managed by the Instituto Nacional de Meteorología (INM) and the Instituto Nacional de Técnica Aeroespacial (INTA), are also shown and discussed

Impact of Selected Meteorological Factors on COVID-19 Incidence in Southern Finland during 2020-2021

We modelled the impact of selected meteorological factors on the daily number of new cases of the coronavirus disease 2019 (COVID-19) at the Hospital District of Helsinki and Uusimaa in southern Finland from August 2020 until May 2021. We applied a DLNM (distributed lag non-linear model) with and without various environmental and non-environmental confounding factors. The relationship between the daily mean temperature or absolute humidity and COVID-19 morbidity shows a non-linear dependency, with increased incidence of COVID-19 at low temperatures between 0 to -10 degrees C or at low absolute humidity (AH) values below 6 g/m3. However, the outcomes need to be interpreted with caution, because the associations found may be valid only for the study period in 2020-2021. Longer study periods are needed to investigate whether severe acute respiratory syndrome coronavirus 2 (SARS-CoV-2) has a seasonal pattern similar such as influenza and other viral respiratory infections. The influence of other non-environmental factors such as various mitigation measures are important to consider in future studies. Knowledge about associations between meteorological factors and COVID-19 can be useful information for policy makers and the education and health sector to predict and prepare for epidemic waves in the coming winters.</p

Observations from the NILU-UV Antarctic network since 2000

Póster elaborado para la SCAR Open Science Conference celebrada en Auckland, Nueva Zelanda los días 25-28 de agosto de 2014Total ozone and UV measurements have been performed with the NILU-UV radiometer at the station of Ushuaia (54◦S), Marambio (64◦S) and Belgrano II (77◦S) since 2000. The network was established in 1999/2000 by the Spanish Agencia Estatal de Meteorología (AEMET) in collaboration with the innishMeteorological Institute (FMI), the Argentinian Dirección Nacional del Antártico-Instituto Antártico (DNA-IAA) and Centro Austral de Investigaciones Cientificas (CADIC). The location of the network was chosen in order to monitor total ozone and UV radiation at different sides of the polar vortex: Belgrano II is mostly located inside the vortex, Marambio at various times inside, on the edge of, or outside the vortex, while Ushuaia is mostly outside the vortex.The MAR Project was financed by the National R+D Plan of the Spanish Ministry of Science and Technology (National Research Program in the Antarctic) under contract REN2000-0245-C02-01

The effect of vernal solar UV radiation on serum 25-hydroxyvitamin D concentration depends on the baseline level : observations from a high latitude in Finland

Humans obtain vitamin D from conversion of 7-dehydrocholesterol in the skin by ultraviolet B (UVB) radiation or from dietary sources. As the radiation level is insufficient in winter, vitamin D deficiency is common at higher latitudes. We assessed whether vernal solar UVB radiation at latitudes 61 degrees N and 67 degrees N in Finland has an impact on serum 25-hydroxyvitamin D [S-25(OH) D] concentrations. Twenty-seven healthy volunteers participated in outdoor activities in snow-covered terrain for 4-10 days in March or April, with their face and hands sun-exposed. The personal UVB doses and S-25(OH) D levels were monitored. A mean UVB dose of 11.8 standard erythema doses (SED) was received during an average of 12.3 outdoor hours. The mean S-25(OH) D concentration in subjects with a baseline concentration below 90.0 nmol/L (n=13) increased significantly, by 6.0 nmol/L from an initial mean of 62.4 nmol/L (pPeer reviewe