Journal of Earth Science & Climatic Change
Open Access

Magnetosphere; Ionosphere; Polar Cusp; Solar wind interaction; Geomagnetic storms

Introduction

Polar Cap and Auroral Zone Geomagnetic Indices. The polar Cap index is characterstics of the Polar Cap magnetic activity generated by geoeffective Solar Wind acting on the Magnetosphere. The index is derived by magnetic data of only two stations Thule and Vostak located in northern (PCN) and Southern (PCS). Near –Pole regions, in 2013 the international of Geomagnetisim and aeronomy (IAGA) recommended to international scientific community to use PC Index as a proxy for energy that eneter that into magnetosphere during Solar Wind Magnetosphere-ionosphere Coupling. The Procedure adopt in AARI and DTU. Provideon line calculation of the PCS and PCN indices corresponding to geo effective interplanetary electric Field Ekl value irrespective of time, season and Solar Cycle (Figure 1a).

Figure 1(a): Shows Ionospheric Convection pattern derived by AMIE procedure for the Summer and Winter Polar regions.

The polar cap (PC) index is measure of the high-latitude geomagnetic disturbances due to Hall Effect field-aligned currents. The index is well correlated with the auroral electrojet AL and AU indices (correlation with the PC index is 76% and 60% resp.). Several type databases relate to the PC to the AL and AU indices in the winter time, when the ionospheric conductivity is mostly due to precipitating particles of the field- aligned currents.

The Polar Cap (PC) index measure geomagnetic disturbances at the polar cap which are due to ionospheric and Field-aligned Currents [1, 2].The Former ones are hall Currents induced by the field time convection and form a part of DP2 current system. The relative importance of each current type depends on the ionospheric conductivity which is modulated on the dayside by the seasonally and daily varying solar illumination and on the night side by particle precipation. The index is derived from Horizontal geomagnetic disturbances HDP2 at a standard high-latitude station which for the Northern polar cap is THULE at 83.3˚N (a separate index is calculated for Southern cap.). The PC index was designed to measure the part of HDP2 disturbances due to magnetosphere field aligned convection. Convection is assumed to be linearly correlated with Solar wind input and hence PC index is the part of HDP2 disturbances correlated with solar wind input and normalized to its unit (mV/m). The relation between the PC index and solar wind input varies as a function of season and UT [1, 2]. The second source for Polar cap geomagnetic disturbances is field aligned currents which become dominant in the winter and summer time, when the polar cap is dark and convection-induced currents wane significantly. At the time the PC index becomes well-correlated with the AU and AL indices. The indices measure the geomagnetic effects of the auroral electro jets, which connect the foot point of field aligned currents in the ionosphere [3, 4, 5, 6, 7]. In winter (November-February) the correlation with AL varry with UT in The range 85-90% and AU 60-85% [1, 2]. Intermediate correlation occurs during the enquinax periods.Geomagnetic disturbances due to other current types, for example the DPY current, Have a negligible correlation with the PC index [2]. The database of PC_Thule is from November 1, 1978 to February 28,1979.The 1-minAL/ AU indices Compete,the 15- min PC index,and the 5-min ISEE-3- Measured solar wind input, are linearly interpolated to time resolution of 2.5 min (Figure 1b).

Figure 1(b): Shows North-South Solar Polar Field (Micro tesla).

The correlation is maximum(77%) when PC is shifted in time to precede AL by 7.5 min. but individual events each index may precede the other by more than 10 minutes. the PC-AU correlation is 66% for individual UT(Vennerstroem et al.,1991). And the correlation is maximum AL-AU correlation occurs when AL leads by 10 min.) Thus typical disturbances begin at polar latitudes on the night side and then spread equatorward reaching the auroral zone stations in several minutes [8]. Even when AU starts increasing before PC, the PC index reaches its maximum level faster. Which might shows a relation between rate of polar cap expansion and driven and loadingunloading effects, but we did not find systematic dependences. The high correlation between geomagnetic activity from the polar cap and auroral zone shows that the two regions are strongly coupled. The electromagnetic coupling allows the two magnetospheric regions to produce Coordinated, organized activity [9, 10].

The PC index is expected to rapidly become important for specification of the magnetospheric state, and useful in scientific and Space Weather applications.

Conclusion

Solar wind-magnetosphere-ionosphere coupling are dominated with solar wind Plasma mediated by magnetic reconnection at magnetopause interface. As consequences earth’s magnetosphere dynamics depends primarily on concurrent orientation of the interplanetary magnetic field. The polar Cusp is region in which the magneto sheath plasma has direct access to the Ionosphere. It is exisiting weather the interplanetary magnetic field is northward or southward. In no-reconnecting magnetosphere the location of the cusp depend on the shape of magnetosphere but when the magnetosphere reconnection with either southward or north ward Interplanetary magnetic field the location of the polar cusp altered polarity.

Solar wind-magnetosphere-ionosphere coupling has major relevance as the plasma medium in which space craft must designed to operate in space. Using e.g. for communication, Navigation, meterology and defence.

Key point of conclusion of research paper.

Demonstration of close relationship between Solar wind-parameter, Polar Cap (PC) indices and Major magnetospheric current system.

Specification of relation between polar cusp (PC) auroral Al, Au and SML and ring current Dst, SYm-H, Asy-H indices.

Acknowledgement

I hereby acknowledge and support of all academic and Nonacademic staff of department of Physics in APS Univ .Rewa (MP), India for success of research study.

The authours would like to acknowledge the encouragement and motivation of Dr. Peter Carter work as climate agency institute, and Dr. Anil Bhradwaj sir, director Physical research laboratory Ahemedabad, India

Competing Interest and Disclousure of conflict interest

The author declear that they have no competing interest Athour discloused that there is no conflict interest in carrying out this research study.

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