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Measures and consequences of high solar activityкнига
- Автор: Yakovchouk O.S.
- Год издания: 2012
- Место издания: Uniprint Oulu, Finland
- Объём: 122 страниц
- ISBN: 978-951-42-9977-3
- Аннотация: This thesis deals with different forms of high or even extreme solar activity and their consequences in the heliosphere, the space dominated by the Sun, and in the near-Earth space. Main emphasis is given to the question of how solar activity and the effects caused by the Sun have changed in time during the last 150 years. While the basic concepts of solar-terrestrial physics are by now well established, many questions on solar activity, especially on its extreme forms still remain open and unsubstantiated both at short time scales (space weather) and at long time scales (space climate). The Sun affects the Earth not only by electromagnetic fields but also by particles. Solar wind and solar cosmic ray particles were discovered only during the last century, much later than electromagnetic radiation. Their properties are related to different forms of solar activity. In events of extreme solar activity solar-related particles can cause large-scale disturbances in the heliosphere and in the near-Earth space, the magnetosphere, the ionosphere and the upper atmosphere. In recent years, intense studies using versatile ground-based and satellite measurements complemented by theoretical and numerical modeling have been made in order to better understand these events, their relation to the Sun, and their consequences on the Earth. The most dramatic disturbances in the near-Earth space are geomagnetic storms, one of the strongest of which, the Carrington storm in 1859, can be regarded as the start of modern solar-terrestrial physics. Long data sets have been collected with considerable effort from rather inhomogeneous and fragmentary observations of solar activity and its terrestrial effects. One of the main aims of this work is to enlarge and investigate the empirical data base of the most powerful solar, heliospheric and magnetospheric disturbances in order to find their statistical properties and relations. Historical and modern cases of extreme solar disturbances have been studied to have a better perspective for the occurrence and other properties of such events. When using old, fragmentary observations it is important to evaluate the quality of the available data before attempting to draw conclusions, e.g., on early solar activity. We have critically analyzed one such case, the recent reconstruction of the sunspot number series using the daily range of geomagnetic declination as a proxy. We noted on serious problems and inconsistencies when using such a proxy to recalibrate the early sunspot number series. We have also provided the first statistical analysis of a significant number of extreme solar and heliospheric perturbations. We find that the lists of events selected according to one single parameter like the power of the X-ray flare, the intensity of solar proton flux or the strength of the following geomagnetic storm, were typically distinct. However, the October 2003 event was among the most powerful events in all parameters, making it unique within the last 40 years. Using newly recovered archival data of observations by a Russian magnetic network, we were able to study the Carrington storm, which is still among the strongest events of all times. We argue that this event was not sporadic but the first and strongest member of a series of recurrent perturbations. We also discuss the average properties of geomagnetic storms over the last 80 years. A unique data base of local storm indices was used for this purpose. The results show several features of geomagnetic storms not known before and not accessible by global storm indices. Overall this thesis presents results leading to a more quantitative estimate and a better understanding of the various forms of extreme solar activity and their consequences in the near-Earth space.
- Добавил в систему: Яковчук Олеся Станиславовна