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Mountain pastures dominated by the pasture grass Setaria sphacelata in the Andes of southern Ecuador are heavily infested by southern bracken (Pteridium arachnoideum), a major problem for pasture management. Field observations suggest that bracken might outcompete the grass due to its competitive strength with regard to the absorption of photosynthetically active radiation (PAR). To understand the PAR absorption potential of both species, the aims of the current paper are to (1) parameterize a radiation scheme of a two-big-leaf model by deriving structural (LAI, leaf angle parameter) and optical (leaf albedo, transmittance) plant traits for average individuals from field surveys, (2) to initialize the properly parameterized radiation scheme with realistic global irradiation conditions of the Rio San Francisco Valley in the Andes of southern Ecuador, and (3) to compare the PAR absorption capabilities of both species under typical local weather conditions. Field data show that bracken reveals a slightly higher average leaf area index (LAI) and more horizontally oriented leaves in comparison to Setaria. Spectrometer measurements reveal that bracken and Setaria are characterized by a similar average leaf absorptance. Simulations with the average diurnal course of incoming solar radiation (1998-2005) and the mean leaf-sun geometry reveal that PAR absorption is fairly equal for both species. However, the comparison of typical clear and overcast days show that two parameters, (1) the relation of incoming diffuse and direct irradiance, and (2) the leaf-sun geometry play a major role for PAR absorption in the two-big-leaf approach: Under cloudy sky conditions (mainly diffuse irradiance), PAR absorption is slightly higher for Setaria while under clear sky conditions (mainly direct irradiance), the average bracken individual is characterized by a higher PAR absorption potential. (approximately 74 MJ m(-2) year(-1)). The latter situation which occurs if the maximum daily irradiance exceeds 615 W m(-2) is mainly due to the nearly orthogonal incidence of the direct solar beam onto the horizontally oriented frond area which implies a high amount of direct PAR absorption during the noon maximum of direct irradiance. Such situations of solar irradiance favoring a higher PAR absorptance of bracken occur in approximately 36% of the observation period (1998-2005). By considering the annual course of PAR irradiance in the San Francisco Valley, the clear advantage of bracken on clear days (36% of all days) is completely compensated by the slight but more frequent advantage of Setaria under overcast conditions (64% of all days). This means that neither bracken nor Setaria show a distinct advantage in PAR absorption capability under the current climatic conditions of the study area.

This paper discusses human thermoregulation and how this relates to health problems during exposure to climatic stress. The heat exchange of the body with the environment is described in terms of the heat balance equation which determines whether the body heats up, remains at stable temperature, or cools. Inside the body the thermoregulatory control aims at creating the right conditions of heat loss to keep the body temperature stable. In the heat the main effector mechanism for this is sweating. The heat balance is affected by air temperature, radiant temperature, humidity and wind speed as climatic parameters and by activity rate, clothing insulation, and sweat capacity as personal parameters. Heat tolerance is discussed in the light of personal characteristics (age, gender, fitness, acclimatisation, morphology and fat) indicating age and fitness as most important predictors. Heat related mortality and morbidity are strongly linked to age.

The comprehensive data from Orsted and CHAMP adding to the data base from the earlier Magsat magnetometry mission have made it possible to develop sophisticated models for the high-latitude field-aligned currents (FAC) relating to solar wind and magnetospheric parameters. However, there are still large uncertainties involved in using the new models primarily due to the lack of precise knowledge of the temporal and spatial development of the currents in relation to the highly variable solar wind parameters and the still unpredictable effects of magnetospheric substorms. A further problem is the lack of proper account of fine-structure currents in the statistical models. By considering separately the upward and downward FAC intensities the paper presents some first attempts to examine the possible diminishing effects on modelled FAC magnitudes from averaging oppositely directed currents.

Recently Olsen & Kuvshinov (2003) presented an approach for modelling the ocean effect of geomagnetic storms by solving the induction equation given the conductivity distribution of the Earth's interior and the time-space structure of the storm. The results for several major storms show much better agreement between the observed and the simulated magnetic vertical component at coastal sites if the oceans are considered and contributions from spherical harmonics other than P{sk1/0} are included. In that paper we report on the results for selected ground observatories. Here we investigate the time-space distribution of the anomalous induction (ocean) effect of geomagnetic storms at ground as well as at satellite altitudes in order to answer the following question: Where and during which phase of the storm can we expect to observe the ocean effect from ground and from satellite altitudes, and what is the expected amplitude? Our simulations show that during the main phase of major geomagnetic storms the ocean effect in the radial component, B r , and in the scalar field, dF, should be clearly visible at CHAMP and Orsted altitudes and might reach magnitudes of tens of nT. The effect is especially prominent near the Pacific coast of North America, and near the southern edges of Africa, Australia and South America.

Model estimations are presented on the annual average atmospheric concentrations and depositions of sulfur and nitrogen species, as well as on toxic elements in Hungary and its surrounding regions. Spatial and temporal variations of the distributions are discussed in the paper. The temporal variation of atmospheric sulfur budget was calculated based on a simple box model. In the case of Pb, the cumulative atmospheric depositions were also estimated for the period of 1955–2015. It was found that Hungary belongs to the moderately polluted regions in Europe. It is also demonstrated that significant part of tropospheric ozone and its precursors are imported to Hungary through longrange atmospheric transport processes.

This paper analyses climate variability in a numerical simulation of the impact of a doubling of atmospheric carbon dioxide concentrations. The sea surface temperatures (SST) come from a 240-year simulation with the Hadley Centre coupled model. Two 10-year time slices are simulated with a variable resolution version of the ARPEGE-IFS atmosphere general circulation model (AGCM). This model has a maximum horizontal resolution over Europe (60 to 100 km mesh size). The impact over Europe is analysed through the daily minimum and maximum temperature, and precipitation. Minimum and maximum temperatures increase whatever the season. Precipitation increases during the colder half of the year. The impact on temporal variability is analysed separately for three parts of the spectrum. Seasonal variability increases for the three variables. The intraseasonal variability of temperature decreases, whereas the intraseasonal variability of precipitation increases in winter, with more heavy rainy days and less dry days. The impact on the interannual variability is not significant. The extreme temperatures are warmer, but no significant impact is found on extreme precipitation.