The existence of anomalously large midlatitude E region electric fields, occurring at night when sporadic-E (Es) 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 Es 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. ¿ 2001 American Geophysical Union |