The method of active day fraction (ADF) was proposed recently to calibrate different solar observers to the standard observational conditions. The result of the calibration may depend on the overall ...level of solar activity during the observational period. This dependency is studied quantitatively using data of the Royal Greenwich Observatory, by formally calibrating synthetic pseudo-observers to the full reference dataset. It is shown that the sunspot group number is precisely estimated by the ADF method for periods of moderate activity, may be slightly underestimated by 0.5\,--\,1.5 groups (\(\leq\)10\,\%) for strong and very strong activity, and is strongly overestimated by up to 2.5 groups (\(\leq\)30\,\%) for weak--moderate activity. The ADF method becomes unapplicable for the periods of grand minima of activity. In general, the ADF method tends to overestimate the overall level of activity and to reduce the long-term trends.
As a contribution to the definition of environmental science, this article describes an interdisciplinary, problem-oriented approach for studying environmental problems. It can be used both in ...research and in education. Problem orientation can be expressed in three questions: a) Why are there environmental problems? b) What are their characteristics? and c) In which ways can they be mitigated? The fundamental part of the approach is the systematic study of each environmental question. In order to frame the study, a conceptual framework - the Environmental Protection Process framework (EPP), which describes the process of environmental protection from the creation of environmental problems to their possible solutions - is presented and illustrated through examples of transport and climate change issues.Original Abstract: En tant que contribution a la definition des sciences de l'environnement, cet article decrit une approche interdisciplinaire centree sur les problemes, specialement developpee pour l'etude des problemes environnementaux et qui peut etre employee tant en recherche qu'en enseignement. L'approche centree sur les problemes peut se resumer a l'aide de trois questions: a) pourquoi y a-t-il des problemes environnementaux? b) quelles en sont les caracteristiques? et c) comment peuvent-ils etre attenues? L'objectif principal de cette approche est l'etude systematique de chaque question environnementale.
Context. Studying the spots of late-type stars is crucial for distinguishing between the various proposed dynamo mechanisms believed to be the main cause of starspot activity. For this research it is ...important to collect observation time series that are long enough to unravel both long- and short-term spot evolution. Doppler imaging is a very efficient method for studying spots of stars that cannot be angularly resolved. Aims. High-resolution spectral observations during 1994-2017 are analysed in order to reveal long- and short-term changes in the spot activity of the FK Comae-type subgiant HD 199178. Methods. Most of the observations were collected with the Nordic Optical Telescope. The Doppler imaging temperature maps were calculated using an inversion technique based on Tikhonov regularisation and utilising multiple spectral lines. Results. We present a unique series of 41 temperature maps spanning more than 23 years. All reliable images show a large cool spot region centred near the visible rotation pole. Some lower latitude cool features are also recovered, although the reliability of these is questionable. There is an expected anti-correlation between the mean surface temperature and the spot coverage. Using the Doppler images, we construct the equivalent of a solar butterfly diagram for HD 199178. Conclusions. HD 199178 clearly has a long-term large and cool spot structure at the rotational pole. This spot structure dominated the spot activity during the years 1994-2017. The size and position of the structure has evolved with time, with a gradual increase during the last years. The lack of lower latitude features prevents the determination of a possible differential rotation.
Sunspot number series are composed from observations of hundreds of different observers that requires careful normalization of the observers to the standard conditions. Here we present a new ...normalized series of the number of sunspot groups for the period 1749-1996. The reconstruction is based on the active day fraction (ADF) method, which is slightly updated with respect to the previous works, and a revised database of sunspot group observations. Stability of some key solar observers has been evaluated against the composite series. The Royal Greenwich Observatory dataset appears fairly stable since the 1890s but is about 10% too low before that. A declining trend of 10-15% in the quality of Wolfer's observation is found between the 1880s and 1920s, suggesting that using him as the reference observer may lead to additional uncertainties. Wolf (small telescope) appears fairly stable between the 1860s and 1890s, without any obvious trend. The new reconstruction reflects the centennial variability of solar activity as evaluated using the singular spectrum analysis method. It depicts a highly significant feature of the Modern grand maximum of solar activity in the second half of the 20th century, being a factor 1.33-1.77 higher than during the 18-19th centuries. The new series of the sunspot group numbers with monthly and annual resolution, available also in the electronic format, is provided forming a basis for new studies of the solar variability and solar dynamo for the last 250 years.
Atomic absorption analyses were performed on plants growing in the catchment areas of an acidified lake (Hauklampi) and a non-acidified lake (Kurkijärvi) lying near each other in an uncultivated, ...uninhabited area in Espoo, S Finland. The material comprised 14 species of the Fungi, 7 Lichenes, 11 Musci, 5 Pteridophyta, 2 Gymnospermae and 25 Angiospermae. In spruce and pine, the contents of metals other than zinc were 2—3 times as high as the roughly natural levels measured in Lapland. The contents of mercury in the plants did not differ between the two study areas, but aluminium, zinc and cadmium clearly tended to have higher contents in the more acidic surroundings of Lake Hauklampi and iron in the surroundings of the nonacidified Lake Kurkijärvi. Many Rosaceae showed higher cadmium contents in the more alkaline catchment area of Kurkijärvi. Plants that appeared to be specially sensitive indicators were the rock moss Ceratodon purpureus for iron, the fungus Rozites caperata for cadmium and possibly Anemone nemorosa for the springtime movements of aluminium.
