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1.
Such high-resolution indirect data on solar activity as the 14C and 10Be cosmogenic isotopes have been considered. The long-term solar activity cyclicity during the last millennium with periods
of approximately 90 and 210 years, which can be related to substantial climatic warming and cooling events in this millennium,
has been established based on an analysis of these data. It has been indicated that long-term recent climate warming can result
from the effect of the ∼90- and ∼210-year solar cycles on the climatic system, which is characterized by the nonlinear dynamics. 相似文献
2.
A. A. Gusev 《Geomagnetism and Aeronomy》2011,51(1):131-138
Many climatic parameters (ground and ocean surface temperatures, pressure, atmospheric precipitation, etc.) have temporal
variations with characteristic periods from several to several tens of years or more. The unknown cause of these oscillations,
together with the similarity of some of them to known solar cycles, has stimulated attempts to relate these two phenomena.
The basic arguments against the existence of such a relationship are that variations in climatic parameters do not always
occur synchronously with the corresponding 11- and 22-year solar cycles: the phase shift between climatic and solar variations
is inconstant and changes with time from 0° to 180°. In addition, the energy of terrestrial manifestations of solar activity
seems insufficient to stimulate the considered weather-climatic processes, at least within the limits of the linear approach.
In the present work, it is shown that in some cases, these contradictions can be removed for variations with a period more
than 11 years under the assumption that climatic variations are forced oscillations driven by an external force (for example,
a force related to solar activity), that implies the existence of intrinsic (natural) climatic oscillations. The result serves
as an additional argument in favor of the reality of a sun-climate connection and probably points to its probable nonlinear
mechanism. 相似文献
3.
The response of the thermobaric characteristics of the high-latitude troposphere to short-term events attributed to solar
activity (solar cosmic rays and geomagnetic storms) has been investigated. The spatial manifestation of these disturbances
in the troposphere is shown to be of a “focal” character. It is found that the manifestation is most evident in the cold period
and depends on the properties of the underlying surface (land, ocean). The properties of the variations of the troposphere
air temperature in the manifestation “foci” on the standard isobaric surfaces, as well as the variations of the altitude profile
of temperature and the long-wave radiation flux at the upper boundary of the atmosphere, have been considered. The variations
of the heat content of the high-latitude troposphere after solar flares have been analyzed. The variation of the thermobaric
field is shown to be accompanied by the rearrangement of circulation forms in moderate and polar latitudes. The revealed properties
are completely explained within the mechanism proposed here for the solar activity effect on the climatic characteristics
of the troposphere. 相似文献
4.
The possible contribution of solar and geomagnetic activity to changes in the characteristics of the main components of the climatic system—the ocean and the atmosphere—is considered and discussed. The mechanisms and models of the solar activity impact on thermobaric and climatic characteristics of the troposphere are presented. Based on a complex analysis of hydrometeorological data, it has been shown that changes in the temperature of the troposphere and the World Ocean reflect a response both to individual helio-geophysical perturbations and to long-term changes (1854–2015) of solar and geomagnetic activity. It is established that the climatic response to the influence of solar and geomagnetic activity is characterized by considerable spatio-temporal heterogeneity, is of a regional nature, and depends on the general circulation of the atmosphere. The largest contribution of solar activity to the global climate changes was observed in the period 1910–1943. 相似文献
5.
D. M. Volobuev 《Geomagnetism and Aeronomy》2013,53(7):887-890
It is known that the solar component is difficult to find in a climatic signal due to its small size and significant internal random disturbances of the climatic system, such as variations in cloudiness, precipitation, winds, and oceanic currents. In the center of the polar cap, these disturbances are as minimal as possible; therefore, solving the inverse heat conduction problem, we can calculate the informative heat flux through the ice cover based on temperature data. Variations in the heat flux are quite significant in amplitude (0.2–0.3 W/m2) and coincide with the 11-year solar cycle in phase. Application of this approach to the indices of the global and sea surface temperatures cannot yield a solar signal, yet it can be traced for solar cycles with big amplitude (cycles 19 and 21). Thus, the found variation in the heat flux is most probably caused by a change in the solar constant (TSI); however, other mechanisms are also possible. 相似文献
6.
Evaluation of FEMA-440 for including soil-structure interaction 总被引：1，自引：1，他引：0
Replacing the entire soil-structure system with a fixed base oscillator to consider the effect of soil-structure interaction
(SSI) is a common analysis method in seismic design. This technique has been included in design procedures such as NEHRP,
ASCE, etc. by defining an equivalent fundamental period and damping ratio that can modify the response of the structure. However,
recent studies indicate that the effects of SSI should be reconsidered when a structure undergoes a nonlinear displacement
demand. In recent documents on Nonlinear Static Procedures (NSPs), FEMA-440 (2005), a modified damping ratio of the replacement
oscillator was proposed by introducing the ductility of the soil-structure system obtained from pushover analysis. In this
paper, the damping defined in FEMA-440 to include the soil-structure interaction effect is evaluated, and the accuracy of
the Coefficient Method given in FEMA-440 and the Equivalent Linearization Method is studied. Although the improvements for
Nonlinear Static Procedures (NSPs) in FEMA-440 are achieved for a fixed base SDOF structure, the soil effects are not perfectly
obtained. Furthermore, the damping definition of a soil-structure system is extended to structures to consider bilinear behavior. 相似文献
7.
地磁活动是太阳爆发现象引起地球近地空间磁场扰动的重要空间天气过程之一.地球磁场的变化具有多种时间尺度,其中从数十年到数世纪的长时间地磁场变化主要是由地核磁场引起的,而从数秒到数年的短时间地磁变化与太阳活动有关.近年来,越来越多的统计研究表明,地磁活动与太阳活动和地球气候变化之间存在着显著的相关性.地球磁场和地球大气系统的耦合现象驱动着人们探索地磁活动对地球天气和气候系统影响的研究.本文的目的就是综述国内外地磁变化对气候影响的研究进展,介绍我们最新的研究成果,探索地磁活动对气候要素的影响特征和可能机理过程,为深入研究地磁活动对地球天气和气候的影响提供基础和依据,以期对地磁活动和气候要素关系有进一步的认识. 相似文献
8.
A spherical approximation makes the basis for a majority of formulas in physical geodesy. However, the present-day accuracy
in determining the disturbing potential requires an ellipsoidal approximation. The paper deals with constructing Green’s function
for an ellipsoidal Earth by an ellipsoidal harmonic expansion and using it for determining the disturbing potential. From
the result obtained the part that corresponds to the spherical approximation has been extracted. Green’s function is known
to depend just on the geometry of the surface where boundary values are given. Thus, it can be calculated irrespective of
the gravity data completeness. No changes of gravity data have an effect on Green’s function and they can be easily taken
into account if the function has already been constructed. Such a method, therefore, can be useful in determining the disturbing
potential of an ellipsoidal Earth. 相似文献
9.
Abstract We study the nonlinear stability of MHD waves propagating in a two-dimensional, compressible, highly magnetized, viscous plasma. These waves are driven by a weak, shear body force which could be imposed by large scale internal fluctuations present in the solar atmosphere. The effects of anisotropic viscosity (leading to a cubic damping) and of the nonlinear coupling of the Alfven and the magnetoacoustic waves are analysed using Galerkin and multiple-scale analysis: the MHD equations are reduced to a set of nonlinear ordinary differential equations which is then suitably truncated to give a model dynamical system, representing the interaction of two complex Galerkin modes. For propagation oblique to the background magnetic field, analytical integration shows that the low-wavenumber mode is physically unstable. For propagation parallel to the background magnetic field the high-wavenumber wave can undergo saddlenode bifurcations, in way that is similar to the van der Pol oscillator; these bifurcations lead to the appearance of a hysteresis cycle. A numerical integration of the dynamical system shows that a sequence of Hopf bifurcations takes place as the Reynolds number is increased, up to the onset of nonperiodic behaviour. It also shows that energy can be transferred from the low- wavenumber to the high-wavenumber mode. 相似文献
10.
I. N. Myagkova M. I. Panasyuk Yu. I. Denisov V. V. Kalegayev A. V. Bogomolov V. O. Barinova D. A. Parunakyan L. I. Starostin 《Geomagnetism and Aeronomy》2011,51(7):897-901
The study of variations in the electron flux in the outer Earth radiation belt (ERB) and their correlations with solar processes
is one of the important problems in the experiment with the Electron-M-Peska instrument onboard the CORONAS-Photon solar observatory.
Data on relativistic and subrelativistic electron fluxes obtained by the Electron-M-Peska in 2009 have been used to study
the outer ERB dynamics at the solar minimum. Increases in outer ERB relativistic electron fluxes, observed at an height of
550 km after weak magnetic disturbances induced by high-velocity solar wind arriving to the Earth, have been analyzed. The
geomagnetic disturbances induced by the high-velocity solar wind and that resulted in electron flux variations were insignificant:
there were no considerable storms and substorms during that period; however, several polar ground-based stations observed
an increase in wave activity. An assumption has been made that the wave activity caused the variations in relativistic electron
fluxes. 相似文献
11.
The climatic variability in the past on the time scales from several tens to several hundreds of million years has been analyzed
based on the paleoclimatic data with a time resolution of several years (the variations in the fossil tree ring widths, varve).
The revealed periodicity in the climatic parameters correlates with the observed solar activity cyclicity, which indicates
that this periodicity effectively influences climate changes independently of differences in the climatic conditions in the
considered interval. 相似文献
12.
《Journal of Atmospheric and Solar》2000,62(5):335-346
The effect of the 11-year solar cycle on the response of the stratospheric geopotential height and temperature fields at 10 and 30 hPa in winter to solar activity oscillations with periods related to the period of the Sun’s rotation (27.2 days) is discussed, applying methods of statistical spectral analysis to daily data for the period from 1965 to 1996. Atmospheric responses for three periodicities — 27.2 days (period of the Sun’s rotation), 25.3 days (periodicity caused by the modulation of the 27.2 days oscillation by annual atmospheric variation), and 54.4 days (doubled period of the solar rotation) — are studied. A significant effect of the 11-year solar cycle on the atmospheric response to the 27.2 days solar periodicity has not been found. We explain it by a frequency shift of the response from the 27.2 days to the 25.3 days periodicity via amplitude modulation. For the 25.3 days oscillation, prominent differences between the maximum and minimum of the 11-year solar cycle have been found in the coherence between the 10.7 cm solar radio flux and the height/temperature fields: the relationships are stronger at solar maximum than at the minimum of the 11-year cycle. The same differences, but to a greater extent, are revealed for the oscillation with a period of 54.4 days. Coherence and amplitude estimates for this doubled solar rotation periodicity exhibit strong differences between extrema of the 11-year solar cycle. Phase estimates also demonstrate a clear difference between high and low solar activity: on the average, the delay of the atmospheric response after the solar signal is smaller at solar maximum than at solar minimum. Thus, we conclude that the mechanism of the influence of the 11-year solar cycle on the winter middle stratosphere can include both a direct effect of the frequency corresponding to the doubled solar rotation periodicity and an indirect effect of modulation of the intensity of the interaction between the solar 27.2 days oscillation and seasonal atmospheric variations. 相似文献
13.
The response of the magnetopause surface to time-varying solar wind dynamic pressure is examined. We argue that to a first approximation the magnetopause surface may be considered as analogous to an elastic membrane. Upon displacement from equilibrium resulting from a change in applied external pressure, it moves to a new equilibrium under the equation of motion of a forced, damped, simple harmonic oscillator. We derive this equation of motion by linearising for small perturbations the momentum equation for flow past a nonrigid ellipsoidal body in the Newton-Busemann limit. Though our approach is only an approximation to the real dynamics of the magnetopause boundary, it serves to demonstrate the importance of inertia in the system response. It allows us to estimate the natural eigenperiod of magnetopause oscillation as typically around 7 min, the precise value depending on solar wind conditions. However, the magnetopause eigenoscillation is furthermore found to be strongly damped, regardless of solar wind conditions. One consequence of these properties is that short-period fluctuations in the solar wind dynamic pressure elicit a suppressed magnetospheric response. We outline other theoretical expectations by which our model may be tested against observation, and discuss the implications of our findings for current interpretations of spacecraft observations made in the dynamic magnetopause environment. 相似文献
14.
Yu. Ya. Ruzhin V. E. Chertoprud G. S. Ivanov-Kholodnyi 《Geomagnetism and Aeronomy》2016,56(5):585-591
The influence of the earthquake probability diurnal variation on specific features in the weekend effect in global seismic activity is revealed. The dependence of the global earthquake number on the local time and its possible relation to a quiet solar diurnal variation (Sq) in the geomagnetic field have been considered in detail. It has been indicated that a stable diurnal effect, which has a maximum near midnight and a minimum near local noon, exists in the global seismicity of the Earth. The diurnal variation amplitude changes insignificantly during days of week and substantially decreases (by a factor of almost 3) on Saturday and Sunday. The weekend effect is not revealed during “local nights.” Since the daily effect of a quiet solar diurnal variation (Sq) should not depend on days of week, we arrive at the conclusion that the diurnal variation in global seismicity evidently contains the anthropogenic activity product. The Sunday effect in the earthquake number decreases over the course of time and is most probably real but weak and not stationary since weekly variations occur against a background (or under the action) of stronger variations, i.e., an increase in the earthquake number and diurnal variations. 相似文献
15.
Time variations in strong and weak photospheric magnetic fields have been considered based on synoptic maps from the Kitt Peak observatory for 1976?C2003. The magnetic fields of positive and negative polarities of the Northern and Southern hemispheres of the Sun and their imbalance were studied. It has been indicated that different groups of magnetic fields vary with 11-or 22-year periods depending on their values. The difference between positive and negative fluxes for each hemisphere always varies with a 22-year period. For weak fields, the 22-year cycle is related to the manifestation of the global solar magnetic field. For strong fields, the imbalance between positive and negative fluxes reflects the predominant role of leading sunspots in a given solar hemisphere. It has been detected that the total magnetic flux over the entire solar disk varies with an 11-year period in antiphase with the solar activity cycle for the weakest magnetic fields (0?C5 G). 相似文献
16.
S. A. Grib 《Geomagnetism and Aeronomy》2013,53(4):424-429
The motion of the MHD nonlinear shock in the Earth’s magnetosphere is considered in the scope of magnetic hydrodynamics. This wave comes from the solar wind and is refracted into the magnetosphere, generating a fast return rarefaction wave. It has been indicated that a wave refracted into the magnetosphere is a weak fast dissipative shock, propagating in magnetospheric plasma at a velocity higher than its propagation velocity in a solar wind stream. The wave motion near the Earth-Sun line with regard to the effect of the geomagnetic field transverse component is described. In this case, shock damping follows the generalized Crussard-Landau law and a wave retains its shock character up to the plasmapause, interacting with this region when an arbitrary MHD discontinuity is disintegrated. It is stated that an MHD shock loses its shock character when moving in a strongly inhomogeneous plasma within the plasmasphere and a weak shock reflected from the plasmapause can combine with a return secondary shock in the magnetosheath, promoting the experimentally observed backward motion of the bow shock front. 相似文献
17.
G. A. Zherebtsov V. A. Kovalenko S. I. Molodykh O. A. Rubtsova 《Geomagnetism and Aeronomy》2009,49(8):1264-1270
The scenario of climatic changes in the 20th century has been presented in the scope of the developed model concerning the
effect of solar activity on the parameters of the climatic system governing the energy flux, outgoing from the Earth into
space in the high-latitude regions. The regularities of changes in the circulation in the atmosphere and ocean are discussed.
Specific attention is paid to the causes of a “cold snap” in 1940–1976 in the Northern Hemisphere and the nature of an anomalous
increase in the heat content in the Earth climatic system (ocean) in 1969–1980. It has been indicated that these phenomena
result from changes in the circulation in the atmosphere and ocean (specifically, a change in the thermohaline circulation
in the Northern Atlantic), heat exchange between the ocean and the atmosphere and cryosphere. 相似文献
18.
《Journal of Atmospheric and Solar》2003,65(4):469-482
Solar radiation (both total and in various wavelengths) varies at different time scales—from seconds to decades or centuries—as a consequence of solar activity. The energy received from the Sun is one of the natural driving forces of the Earth's atmosphere and since this energy is not constant, it has been argued that there must be some non-zero climate response to it. This response must be fully specified in order to improve our understanding of the climate system and the impact of anthropogenic activities on it. However, despite all the efforts, if and how subtle variations of solar radiation affect climate and weather still remains an unsolved puzzle. One key element that is very often taken as evidence of a response, is the similarity of periodicities between several solar activity indices and different meteorological parameters. The literature contains a long history of positive or negative correlations between weather and climate parameters like temperature, rainfall, droughts, etc. and solar activity cycles like the 27-day cycle, the prominent 11-year sunspot cycle, the 22-year Hale cycle and the Gleissberg cycle of 80–90 years. A review of these different cycles is provided as well as some of the correlative analyses between them and several stratospheric parameters (like stratospheric geopotential heights, temperature and ozone concentration) and tropospheric parameters (like temperature, rainfall, water level in lakes and river flooding, clouds) that point to a relationship of some kind. However, the suspicion on these relationships will remain as long as an indisputable physical mechanism, which might act to produce these correlations, is not available. 相似文献
19.
Displacement reduction effect and simplified evaluation method for SDOF systems using a clutching inerter damper 
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下载免费PDF全文 This study evaluates the response reduction effect of linear single degree of freedom systems with a clutching inerter damper (CID) via parametric analysis under harmonic excitations and real earthquake records. The cause of the displacement reduction effect of a CID is inherited from the inertial mass damper (IMD)—reducing the nominal load intensity by increasing the mass by inertance. Additionally, the displacement reduction effect is further enhanced by the clutching effect, which speeds up the decreasing of the velocity response from an instantaneous extremum to 0. Thus, the CID is more effective than the IMD at reducing displacement responses. For example, the displacement response for a long‐period structure with a CID can be reduced by approximately 53%, while for an IMD, it can only be reduced by approximately 24%. Additionally, the linear single degree of freedom system with a CID is a weak nonlinear system reserving homogeneity, indicating that the response reduction factor will provide enough information to reveal the seismic reduction effect of the CID and that there is no need to consider the amplitude of the input excitations. To simplify the analysis of such nonlinear systems, an equivalent linearization method and a simplified formula of displacement reduction factors for code‐based designs are proposed and validated by another independent set of records from the European Strong‐motion Database. 相似文献
20.
Tree ring studies are usually used to determine or verify climatic factors prevailing at a given place or region that may cause tree-ring width variations. Few studies are dedicated to the solar phenomena which may underlie these tree-ring width variations. Furthermore, it is known that some terrestrial phenomena are influenced by short- and long-time scale solar variability. An optical and computational method was set up and applied to tree samples (Araucaria angustifolia from Santa Catarina State in Southern Brazil) in order to obtain a growth ring width mean chronology. Spectral analysis is used for the search of periodicities, by maximum entropy and iterative regression methods. The results evidenced several embedded signals at periods which may be related to solar activity variations. Cross-correlation analysis between sunspot number and tree-ring data was performed and a lag of zero year was obtained. From our work, it seems that the tropical conifer species Araucaria angustifolia may be a good choice for studies on Sun-Earth relationships and their regional effects. 相似文献