Variations of Earth's radiation belt intensities on time scales of days throughout the 11-year solar cycle

The Earth's radiation belts show pronounced differences in their characteristics as the Sun's magnetic and solar wind properties change over the approximately 11-year solar cycle. Solar coronal holes can produce regular, recurrent solar wind stream interactions in geospace, often enhancing highly relativistic electrons and causing recurrent magnetic storms. These phenomena are characteristic of the approach to solar minimum. This contrasts with major geomagnetic disturbances associated with aperiodic coronal mass ejections that occur most frequently around sunspot maximum. We present observational results and power spectral estimates, via Welch, Lomb, or maximum entropy periodograms, to demonstrate the electron acceleration and loss effects throughout the inner part of geospace during various parts of the solar cycle. We place particular emphasis on long-term, electron flux measurements from the SAMPEX mission where we currently are studying enhancements across the entire outer radiation zone. We discuss how this work can contribute to improved understanding of electron acceleration, loss, and transport.