Premium
The Role of the Main Geomagnetic Field in Locating Conjugate Points
Author(s) -
Cain Joseph C.
Publication year - 1968
Publication title -
radio science
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 0.371
H-Index - 84
eISSN - 1944-799X
pISSN - 0048-6604
DOI - 10.1002/rds196837766
Subject(s) - conjugate points , earth's magnetic field , equator , geodesy , field (mathematics) , latitude , geology , conjugate , physics , magnetic field , geophysics , geometry , mathematics , mathematical analysis , quantum mechanics , pure mathematics
A sample distribution of conjugate points is calculated from various models of the main geomagnetic field, evaluated at different epochs. A summary of the conclusions is: (1) For L < 4 the errors are of the order of a few tens of kilometers; (2) older models of the field such as the Finch‐Leaton give results within a few degrees of the latest more accurate models; (3) use of the eccentric dipole approximation gives errors that range from a few tens of kilometers at high latitude to several hundred kilometers near the equator; and (4) the secular change of conjugate‐point locations is very small, averaging 1 to 10 km/yr. Inclusion of Mead's boundary field for a trace from Macquarie Island to Alaska ( L = S) shifts the conjugate only about 100 km. It is concluded that for L ⩾ 5 the field line passes through regions where the field intensity is weak enough to require that realistic estimates of the distortions due to plasma interactions be included in conjugate‐point determinations. (These estimates are not now available.)