Relating the Interplanetary Electric Fields (IEFs) With the Low Latitude Electric Fields (LLEFs) Under Both Geomagnetically Quiet and Disturbed Conditions

We present first results that illustrate how dependent the ionospheric, daytime low latitude electric field (LLEF) is on the Interplanetary Electric Field (IEFy) under both geomagnetically quiet and disturbed conditions. The IEFy values are calculated from the ACE L1 satellite observations of the Bz and Vx components in the GSM coordinate system (IEFy = -Vx x Bz) and time shifted to the magnetopause position using the solar wind speed, Vx. Daytime, eastward ionospheric F region electric fields are inferred from ground-based magnetometer observations using a recently-developed neural network algorithm that realistically calculates daytime, vertical ExB drift velocities at the magnetic equator incorporating the difference in the horizontal (H) components between a magnetometer on the magnetic equator and one located 6 to 9 degrees away in dip latitude. Magnetometer observations on and off the magnetic equator for all of the days in 2001 have been obtained for the Peruvian, Philippine and Indian longitude sectors. We analyze the IEFy observations as a function of Universal Time (UT) for each of the days chosen using 1.) Fourier transform, 2.) Lomb-Scargle transform and 3.) Morlet wavelet transform to obtain the dominant periods between 10 minutes and 6 hours. We compare these periodicities with the periodicities obtained for the LLEF observations using the same techniques at each of the 3 longitude sectors as a function of UT for each of the days chosen. We present these comparisons and illustrate how, for quiet days and portions of the UT day that are quiet, the IEFy periodicities match the LLEF periodicities (long periods) while for the disturbed part of the UT day, the short periodicities in IEFy match the LLEF periodicities in the appropriate longitude sectors. The implications of these findings are discussed with respect to prompt penetration and overshielding electric fields and how the evolution of quiet-to-disturbed LLEF signatures can be related to IEFy conditions as they evolve from low frequency fluctuations to higher and higher frequency fluctuations.