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Arrival of low-rigidity solar cosmic rays into the geomagnetic field in terms of ring current effects and limitation of the radial extent of the magnetosphere
Unstable growth rate of unducted whistler waves propagating at angle to geomagnetic field
Algorithms used in geomagnetic main-field modelling have for the most part treated the noise in the field measurements as if it were white. A major component of the noise consists of the field due to magnetization in the crust and it has been realized for some time that such signals are highly correlated at satellite altitude. Hence approximation by white noise, while of undoubted utility, is of unknown validity. In this paper we study two plausible statistical models for the crustal magnetization, in which the magnetization is a realization of a stationary, isotropic, random process. At a typical satellite altitude the associated fields exhibit significant correlation over ranges as great as 15 deg. or more, which introduces off-diagonal elements into the covariance matrix, elements that have usually been neglected in modelling procedures. Dealing with a full covariance matrix for a large data set would present a formidable computational challenge, but fortunately most of the entries in the covariance matrix are so small that they can be replaced by zeros. The resultant matrix comprises only about 3 per cent non-zero entries and thus we can take advantage of efficient sparse matrix techniques to solve the numerical system. We construct several main-field models based on vertical-component data from a selected 5 deg. by 5 deg. data set derived from the Magsat mission. Models with and without off-diagonal terms are compared.
Calculation by moment technique of perturbation of geomagnetic field by solar wind
Growth rate along whistler path for waves propagating at angle to geomagnetic field
Ring current effect on boundary of geomagnetic field in solar wind
Cosmic ray neutron monitors in geomagnetic field distorted by solar wind
Sample distribution of conjugate points calculated using various models of main geomagnetic field
Dayside distortion of geomagnetic field by solar wind beyond 3.5 earth radii measured and compared with three magnetosphere models
Geomagnetic field and secular perturbation
On the choice of condition to apply at the boundary of the geomagnetic field in the steady state chapman-ferraro problem
Comparison between diurnal geomagnetic field and cosmic ray intensity variations
Drift of noninteracting charged particles in simple geomagnetic field
Some features of the secular variation of the geomagnetic field are examined. Contours encircling constant magnetic flux (third adiabatic invariant), corresponding to a shell of field lines in secular motion, reveal a general westward drift that is longitude and latitude dependent (with minima in the north Pacific and south Atlantic areas). Some invariant relationships appear among the field coefficients in the tilted, centered dipole (geomagnetic) coordinate system.
Orbital noise of Earth's obliquity can provide an insight into the core of the Earth that causes intensity fluctuations in the geomagnetic field. Here we show that noise spectrum of the obliquity frequency have revealed a series of frequency periods centered at 250-, 1OO-, 50-, 41-, 30-, and 26-kyr which are almost identical with the observed spectral peaks from the composite curve of 33 records of relative paleointensity spanning the past 800 kyr (Sint-800 data). A continuous record for the past two million years also reveals the presence of the major 100 kyr periodicity in obliquity noise and geomagnetic intensity fluctuations. These results of correlation suggest that obliquity noise may power the dynamo, located in the liquid outer core of the Earth, which generates the geomagnetic field.
Theoretical determination of the boundary of the geomagnetic field in a steady solar wind
Tables of geomagnetic field line data for solar eclipse of November 12, 1966
Explorer VI satellite observations of low frequency hydromagnetic wave fluctuations in distant geomagnetic field