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Polarization electric fields sustained by closed‐current dynamo structures in midlatitude sporadic E
Author(s) -
Cosgrove Russell B.,
Tsunoda Roland T.
Publication year - 2001
Publication title -
geophysical research letters
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 2.007
H-Index - 273
eISSN - 1944-8007
pISSN - 0094-8276
DOI - 10.1029/2000gl012178
Subject(s) - dynamo , middle latitudes , physics , electric field , polarization (electrochemistry) , dynamo theory , magnetic field , geophysics , ionosphere , electric current , computational physics , atmospheric sciences , quantum mechanics , chemistry
The existence of anomalously large midlatitude E region electric fields, occurring at night when sporadic‐ E ( E s ) is present, has now been verified experimentally. The only known source mechanism requires that the Hall current driven by the polarization electric field be sustained in some way. While current closure in the F layer is possible, we show that closure through nearby dynamo structures that involve E s patches may be more likely. To illustrate the concept, we have considered an analytically tractable problem in which two dynamo regions have formed, one above and one below an ion‐convergent wind‐shear node. We show that the polarization Hall current generated in each region can close through the other region via field‐aligned currents. With this kind of closure, we further show that the polarization electric field can approach the idealized Cowling‐conductivity‐enhanced field strength, which would be large enough to account for the observations that have been made by rocket and radar.