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Quantitative analysis of the relationship between polar ionospheric currents and auroral electrojet indices

Science China Earth Sciences 2005年第3期48卷 376-383页

作者： XU Wenyao CHEN Gengxiong Institute of Geology and Geophysics Chinese Academy of Sciences Beijing 100029 China Institute of Geology and Geophysics Chinese Academy of Sciences Beijing 100029 China

The ionospheric currents in the polar region are caused mainly by field-aligned currents. The quiet polar current system consists of a pair of current vertices at dawn and dusk. When substorm occurs, however, intense magnetic disturbances are generated by enhanced polar currents, especially the westward electrojet of a millions Amperes in the auroral oval. The intensity of the auroral electrojet is commonly described by the auroral electrojet indices AL, AU, AE and AO. In this paper the relationship between the polar current system and the auroral electrojet indices is quantitatively studied by means of polar current functions obtained from the data recorded at 71 magnetic stations in the northern polar region during the International Mag- netospheric Study (IMS). Fairly well linear correlation of AL (or AU) with AE index has been found, indicating that AE index multiplied by a proper factor can approximately substitute AL and AU indices. The total polar current, JT, and the strengths of the dawn and dusk current vortices, JT 1 and JT , can be characterized by AE index, an increment of 1nT in AE index corresponding to 2 1000A in JT. A fairly well direct proportion is found between AE and the maximal westward current density, an increment of 1 nT in AE corresponding to 1 A/km of the maximal westward current density at magnetic midnight. The latitudinal profiles of the current density are similar for different local time in night sector. The maximal density of the westward electrojet usually occurs at geo- magnetic latitude 65°—70°around midnight, as for the eastward electrojet, it is around 80°. The analysis shows that for 5-mimute mean values, the saturation values of AE and AL are 700 nT and –500 nT, respectively. Accordingly, a caution should be taken when the indices greater than the saturation values would be used for studying magnetospheric or ionospheric processes.

关键词： polar current system, auroral electrojet, auroral electrojet indices, magnetic disturbance.

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Exact Solution in the New Inflation Scenario with Induced Gravity

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Communications in Theoretical Physics 2001年第10期36卷 509-512页

作者： WANG Wen-Fu Department of Industrial Automation Southwest Petroleum Institute Nanchong 637001 Sichuan Province China

Taking the Hubble parameter directly as a function of the scalar field instead of as a function of time,H = H( ), we present a new exact solution in the new inflation model with induced gravity. This includes solution which is inflation for > end, and develops smoothly towards radiation-like evolution for ≥ end. The inflation is driven by the evolution of the field with inflation potential, V( ) = λ 2 v2)***, ns, is computed and ns lies well inside the limits set by the cosmic background explorer (COBE) *** dex of the scalar effective cosmological constant Aeff tends to zero when inflation ends.

关键词： induced gravity, new inflation, exact solution, spectral indices, effective cosmological constant

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