On a Correlation between the Ionospheric Electric Field and the Time Derivative of the Magnetic Field

Figure 1

From top to bottom: The AU, AL indices; five superposed midlatitude magnetograms (Kakioka, Tashkent, Tangerang, San Juan, Honolulu) with the arrow pointing to the San Juan magnetogram; the zonal electric field at the equator (Jicamarca, Peru); the auroral zonal electric field at College, Alaska; the time derivative of the horizontal component of the magnetic field at San Juan, Puerto Rico. In the last three panels, the dots indicate local magnetic midnight. (After [5]. Reproduced with permission of the American Geophysical Union).