Open AccessDaytime vertical E × B drift velocities inferred from ground‐based magnetometer observations at low latitudes
Author(s) -
Anderson David,
Anghel Adela,
Chau Jorge,
Veliz Oscar
Publication year - 2004
Publication title -
space weather
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 1.254
H-Index - 56
ISSN - 1542-7390
DOI - 10.1029/2004sw000095
Subject(s) - daytime , electrojet , equatorial electrojet , ionosphere , longitude , latitude , geodesy , equator , magnetic dip , magnetometer , incoherent scatter , geology , altitude (triangle) , geophysics , meteorology , atmospheric sciences , physics , geometry , earth's magnetic field , magnetic field , mathematics , quantum mechanics
The daytime equatorial electrojet is a narrow band of enhanced eastward current flowing in the 100–120 km altitude region within ±2° latitude of the dip equator. A unique way of determining the daytime strength of the electrojet is to observe the difference in the magnitudes of the horizontal ( H ) component between a magnetometer placed directly on the magnetic equator and one displaced 6°–9° away. The difference between these measured H values provides a direct measure of the daytime electrojet current and, in turn, the magnitude of the vertical E × B drift velocity in the F region ionosphere. This paper discusses a recent study where 27 months of magnetometer H component observations and daytime, vertical E × B drift velocities were obtained in the Peruvian longitude sector between August 2001 and December 2003. In order to establish the relationships between Δ H and E × B drift velocities for the 270 days of observations, three approaches were chosen: (1) a linear regression analysis, (2) a multiple regression approach, and (3) a neural network approach. The neural network method gives slightly lower RMS error values compared with the other two methods. The relationships for all three techniques are validated using an independent set of E × B drift observations from the Jicamarca incoherent scatter radar (ISR) located at Jicamarca, Peru. The techniques presented here will be incorporated into a recently developed, real‐time Global Assimilation of Ionospheric Measurements (GAIM) model.