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It is suggested that recurrent and nonrecurrent geomagnetic disturbances which are related to the release of solar magnetic energy in the form of unipolar and bipolar magnetic regions respectively, are connected with the variations in the solar energy source. The true beginning of the solar cycle takes place when unipolar magnetic regions start to develop, i.e, when nuclear energy generation becomes dominant over the neutrino energy loss according to the photon-neutrino coupling theory. 相似文献
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F. Z. Feygin N. G. Kleimenova O. A. Pokhotelov M. Parrot K. Prikner K. Mursula J. Kangas T. Pikkarainen 《Annales Geophysicae》2000,18(5):517-522
We analyse long-lasting (several hours) Pc1 pearl pulsations with decreasing, increasing or constant central frequencies. We show that nonstationary pearl events (those with either decreasing or increasing central frequency) are observed simultaneously with increasing auroral magnetic activity at the nightside magnetosphere while the stationary events (constant central frequency) correspond to quiet magnetic conditions. Events with decreasing central frequency are observed mostly in the late morning and daytime whereas events with increasing central frequency appear either early in the morning or in the afternoon. We explain the diurnal distribution of the nonstationary pearl pulsations in terms of proton drifts depending on magnetic activity, and evaluate the magnetospheric electric field based on the variation of the central frequency of pearl pulsations. 相似文献
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Hilkka Pellikka Jenni Rauhala Kimmo K. Kahma Tapani Stipa Hanna Boman Antti Kangas 《Natural Hazards》2014,74(1):197-215
We present four case studies of exceptional wave events of meteorological origin, observed on the Finnish coast in the summers of 2010 and 2011. Eyewitnesses report unusually rapid and strong sea-level variations (up to 1 m in 5–15 min) and strong oscillating currents during these events. High-resolution sea-level measurements confirm the eyewitness observations, but the oscillations recorded by tide gauges mostly have a considerably smaller amplitude. The oscillations coincide with sudden jumps in surface air pressure at coastal observation stations, related to the passage of squall lines or gust fronts. These fronts propagate above the sea at a resonant speed, allowing efficient energy transfer between the atmospheric disturbance and the sea wave that it generates. Thus, we interpret the observed sea-level oscillations as small meteotsunamis, long tsunami-like waves generated by meteorological processes and resonance effects. 相似文献
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Prikner K. Mursula K. Kangas J. Feygin F. Z. Kerttula R. 《Studia Geophysica et Geodaetica》2002,46(3):507-526
The ionospheric Alfvén resonator (IAR) was numerically simulated under non-stationary ionospheric and magnetospheric conditions of the IPDP event of December 4, 1986. The full numerical wave method was applied using height profiles of the ionospheric plasma parameters obtained from the Scandinavian EISCAT radar measurements close to the Ivalo latitude. An attempt to model the inverse problem of numerical simulation—prolongation of the electron density profiles at altitudes above the ionospheric F layer—was made on the basis of the IAR simulation in correlation with the IPDP frequency increase. The change of the IAR wave characteristics during the substorm was illustrated by height profiles of the total wave amplitude and various polarization characteristics, taking into consideration the ordinary L-mode and the extraordinary R-mode waves for parallel and non-parallel incidence with respect to the magnetic field line. 相似文献
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Variability Of The Stable And Unstable Atmospheric Boundary-Layer Height And Its Scales Over A Boreal Forest 总被引：3，自引：2，他引：1
S. M. Joffre M. Kangas M. Heikinheimo S. A. Kitaigorodskii 《Boundary-Layer Meteorology》2001,99(3):429-450
Radiosondes releases during the NOPEX-WINTEX experiment carried out in late winter in Northern Finland were analysed for the determination of the height h of the atmospheric boundary layer. We investigate various possible scaling approaches, based on length scales using micrometeorological turbulence surface measurements and the background atmospheric stratification above h. Under stable conditions, the three previously observed turbulence regimes delineated by values of z/L (L is the Obukhov length) appears as a blueprint for understanding the departures found for the suitability of the Ekman scaling based on LE = u/f (u is the friction velocity and f the Coriolis parameter). The length scale LN = u/N (where N is the Brunt–Väisälä frequency) appears to be a useful scale under most stable conditions, especially in association with L. Under unstable conditions, shear production of turbulence is still significant, so that the three scales L, LN and LE are again relevant and the dimensionless ratios N = LN/L and LN/LE = N/f describe well the WINTEX data. Furthermore, in the classical scaling framework, the unstable domain may also be divided into three regimes as reflected by the dependence ofu/f on instability (z/L). 相似文献
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It is suggested that the observed differences in the periods of variation of some solar phenomena (solar brightness, appearance of sunspot maximum and interplanetary sector structure) occurring close to 27 days are due to differences in the rotation periods of the solar regions in which these phenomena are originated. Changes in periods during the solar cycle can be attributed to changes in the solar energy generation. On the basis of these considerations changes in the sign of the gradient of the Sun's angular velocity can be expected. 相似文献
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Identifying Environmental and Natural Resource Management Conflict Potential Using Participatory Mapping 总被引：1，自引：0，他引：1
Methods have been proposed for identifying land use conflict potential using participatory mapping data and models. In a case study from Finland, we extend conflict mapping research by evaluating the capacity for participatory mapping to identify conflict for land uses that include mining, tourism development, commercial forestry, recreation, and nature protection. We evaluated two conflict models using reference sites where conflict was expected and assessed whether conflict potential was influenced by participant social group (resident, visitor, holiday home owner). The conflict models correctly identified the locations of current and proposed mining projects and major tourism locations (ski areas) in the region, while conflict for commercial forestry and reindeer herding was spatially distributed. Preferences for land use by social group were more similar than different across the study region. Identification of conflict potential using participatory mapping can provide a useful planning diagnostic but would benefit from additional research for validation. 相似文献
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F. Z. Feygin A. K. Nekrasov K. Mursula J. Kangas T. Pikkarainen 《Annales Geophysicae》1994,12(2-3):147-151
A fair fraction of Pc1 pulsation events observed on the ground includes more than one simultaneous pulsation band. In most such multiband events the bands display different characteristics and, therefore, come from different source regions via horizontal ducting in the ionosphere. However, in this report we identify a new “coherent” subclass of multiband Pc1 events where the pearls of the simultaneous bands have the same group velocities (repetition rates) as well as dispersion and other properties, thus implying that the bands are produced by the same source. Studying one example of such a coherent multiband event in more detail, we argue that these events defy an explanation in terms of band splitting by magnetospheric heavy ions because the observed frequency gap between the bands is smaller than would result in such a case. We interpret these events to be due to the frequency dependence of the ionospheric reflection coefficient of Alfvén waves. An oscillatory frequency dependence of the coefficient is a natural consequence of the idea that the ionosphere acts as a resonator for Alfvén waves. We also discuss other predictions of this interpretation. 相似文献
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Geomagnetic pulsations in the frequency range of Pc1 pearl waves with the dynamic spectra having a very narrow spectrum width
at the beginning of the event and a very broad spectrum width (Δf/f0 ∼ 1) in the later part of the event are analyzed. One of the observed events shown by the dynamic spectrum resembles a goose
with the beak at the beginning of the event and with the wing in the later part of the event. Various interpretations of these
geomagnetic pulsations are presented taking into account nonlinear effects, quasilinear interaction of electromagnetic ion-cyclotron
waves with energetic, anisotropic protons and modulation of plasma parameters in the magnetosphere by Pc3–5 hydromagnetic
waves. The ionospheric effect in the signal formation is determined by the ionospheric Alfvén resonator. It can control the
frequency range of the dynamic spectra, but not the internal structure of the signal. 相似文献