A Cellular Automata Model of Perturbed Magnetosphere to Study Geomagnetic Disturbances

Abstract

Geomagnetic storms and substorms are complex phenomena. The newlinecomposite and intricate internal structure of magnetospheric activity newlinepresent difficulties both in its analysis and prediction. It eventually newlinebecame an important field of study in Physics in the last decades as an newlineintense geomagnetic event can trigger severe adverse effects on modern newlinehuman society, both in terms of money and hazards in everyday life. In the newlinecurrent thesis, a two-dimensional cellular automata model of Earth s newlinemagnetosphere has been presented to study the characteristic complexity newlineof geomagnetic fluctuations. The model is based on the concept of selforganized newlinecriticality and many-body interactive system and accepts newlinenatural solar wind ion density, flow speed, and IMF BZ as the inputs. To newlinedevelop a proper running model of geomagnetic activities, the algorithm newlineis refined gradually through detailed analysis and investigations. newlineIn the first step, a simple two-dimensional running model has been newlineestablished based on the theory of self-organized criticality in a newlinedissipative, dynamic system. The model generates an output that shows newlinestatistical similarity to the natural Dst index. The role of the systemiv newlinecontrolling parameters in determining the amount of energy injection is newlineinvestigated in detail. newlineNext, the internal magnetospheric dynamical nature, as well as the newlinespatially localized instabilities of the magnetotail plasma sheet, are newlineinspected in terms of the self-organized critical behavior of the system. newlineThe model dynamics follow a 1/fand#947; newlinepower spectrum, a distinguishing newlinecharacteristic of geomagnetic activity. newlineThen, the focus of the study becomes magnetosphere-ionosphere energy newlinetransfer and the formation of electrojet currents. A new system controlling newlineparameter is introduced in the model to estimate the fraction of the newlinetransmitted energy present in the ionosphere. The model generates a newlinesecond output that shows statistical similarity to the natural AE index. newlineThe influence of IMF BZ on the solar wind-magnetosphere energy transfer newlineprocess drives the