排序方式： 共有23条查询结果，搜索用时 15 毫秒
1.
Hgne Jungner 《Quaternary Science Reviews》1988,7(3-4)
The influence of artificial UV light and sunlight on natural glow curves were compared for K-feldspar and quartz from a fluvial and an aeolian deposit. The results for feldspar grains show that the use of a UV lamp for bleaching instead of sunlight does not influence the accumulated dose plateau. Results on the quartz sample on the other hand show clear differences. This fact makes dating using quartz grains more complicated. The problem of finding the correct residual reached at sedimentation by using the regenaration technique starting from different artificial residuals is also discussed. 相似文献
2.
V. A. Dergachev P. B. Dmitriev O. M. Raspopov H. Jungner 《Geomagnetism and Aeronomy》2006,46(1):118-128
Direct and indirect data on variations in cosmic rays, solar activity, geomagnetic dipole moment, and climate from the present to 10–12ka ago (the Holocene Epoch), registered in different natural archives (tree rings, ice layers, etc.), have been analyzed. The concentration of cosmogenic isotopes, generated in the Earth’s atmosphere under the action of cosmic ray fluxes and coming into the Earth archives, makes it possible to obtain valuable information about variations in a number of natural processes. The cosmogenic isotopes 14C in tree rings and 10Be in ice layers, as well as cosmic rays, are modulated by solar activity and geomagnetic field variations, and time variations in these concentrations gives information about past solar and geomagnetic activities. Since the characteristics of natural reservoirs with cosmogenic 14C and 10Be vary with climate changes, the concentrations of these isotopes also inform about climate changes in the past. A performed analysis indicates that cosmic ray flux variations are apparently the most effective natural factor of climate changes on a large time scale. 相似文献
3.
Ogurtsov M.G. Jungner H. Kocharov G.E. Lindholm M. Eronen M. Nagovitsyn Yu.A. 《Solar physics》2003,218(1-2):345-357
Bidecadal fluctuations in terrestrial climate were analyzed. It was shown that this variability might arise if Earth's climate reacts to galactic cosmic-ray intensity, integrated over its full quasi-11-year cycle. It was further shown that this integral effect should also lead to an effective link between climate and the duration of the quasi-11-year cycle in cosmic ray flux. That, in turn, must result in appearance of some connection between climate and the length of the solar cycle, which is currently a topic of active debate. Analyses of temperature proxies, obtained for northern Fennoscandia, confirmed the connection of the climate in this region and the length of the cycle in galactic cosmic-ray intensity. Decadal and bidecadal variability of integrated cosmic-ray flux was quantitatively estimated. 相似文献
4.
New radiocarbon dates from Finnish subfossil mammoth material (Mammuthus sp.), transported by glacial ice, range in age from ca. 32000 to ca. 22500 yr BP. These results suggest that there was a larger ice-free area in Fennoscandia during the Middle Weichselian than previously assumed. In addition, two dates are also presented for bones found in clay with a different transport history. Copyright © 1999 John Wiley & Sons, Ltd. 相似文献
5.
G. E. Kocharov I. V. Kudryavtsev M. G. Ogurtsov E. Sonninen H. Jungner 《Astronomy Reports》2000,44(12):825-829
Past solar activity is studied based on analysis of data on the nitrate content of Greenland ice in the period from 1576–1991. Hundred-year (over the entire period) and quasi-five-year (in the middle of the 18th century) variations in the nitrate content are detected. These reflect the secular solar-activity cycle and cyclicity in the flare activity of the Sun. 相似文献
6.
V. A. Dergachev P. B. Dmitriev O. M. Raspopov H. Jungner 《Geomagnetism and Aeronomy》2007,47(1):109-117
A joint analysis of paleodata on variations in cosmic ray fluxes, solar activity, geomagnetic field, and climate during the period from ～10000 to ～100000 years ago has been performed. Data on the time variations in the concentration of 14C and 10Be cosmogenic isotopes, which are generated in the Earth’s atmosphere under the action of cosmic ray fluxes modulated by solar activity and geomagnetic field variations, were used to detect variations in solar activity and the geomagnetic dipole. Information about climate changes has been obtained mainly from variations in the concentration of stable isotopes in the natural archives. A performed analysis indicates that the variations in cosmic ray fluxes under the action of variations in the geomagnetic field and solar activity are apparently one of the most effective natural factors of long-term climate changeability on a large time scale. 相似文献
7.
V. A. Dergachev S. S. Vasiliev O. M. Raspopov H. Jungner 《Geomagnetism and Aeronomy》2012,52(8):959-976
Recent studies have shown that, in addition to the role of solar variability, past climate changes may have been connected with variations in the Earth??s magnetic field elements at various timescales. An analysis of variations in geomagnetic field elements, such as field intensity, reversals, and excursions, allowed us to establish a link between climate changes at various timescales over the last millennia. Of particular interest are sharp changes in the geomagnetic field intensity and short reversals of the magnetic poles (excursions). The beginning and termination of the examined geomagnetic excursions can be attributed to periods of climate change. In this study, we analyzed the possible link between short-term geomagnetic variability (jerks) and climate change, as well as the accelerated drift of the north magnetic pole and surface temperature variations. The results do not rule out the possibility that geomagnetic field variations which modulate the cosmic ray flux could have played a major role in climate change in addition to previously induced by solar radiation. 相似文献
8.
Maxim Ogurtsov Eloni Sonninen Emmi Hilasvuori Igor Koudriavtsev Valentin Dergachev Högne Jungner 《Journal of Atmospheric and Solar》2011,73(2-3):383-387
Within a project on climate in Europe during the past few hundred years we have collected a record on stable isotope ratios 13C/12C and 18O/16O in tree ring cellulose from pine trees in northern Finland. The records cover the time interval 1600–2002 AD and have an annual time resolution. The carbon stable isotope record from northernmost Finland correlates quite strongly with local growth period temperature. Statistical analysis of the carbon and oxygen stable isotope records reveals variations in the periods around 100, 11 and 3 years. A century scale connection between the 13C/12C record and solar activity is most evident. These results based on stable isotope records support previous evidences of a centennial solar-climatic link obtained for northern Finland using tree ring data. 相似文献
9.
M. G. Ogurtsov O. M. Raspopov M. Oinonen H. Jungner M. Lindholm 《Geomagnetism and Aeronomy》2010,50(1):15-20
The response of the nonlinear oscillatory system to an insignificant external disturbance has been considered as applied to the effect of solar activity on climatic processes. Based on a simplified model, it has been indicated that the response of a nonlinear oscillator to a weak disturbing impact can be substantial. The oscillator fluctuation spectrum can decrease under the action of a disturbing factor. This means that the effect of an even weak solar or cosmophysical signal to the Earth’s climatic system can lead to significant climate variations if this system is nonlinear. However, it will be rather difficult to identify the solar—climatic nature of these variations because a linear relation between the cause and response is absent. 相似文献
10.
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