September 21, 2018, 1:00 pm - 2:00 pm

September 21, 2018, 1:00 pm - 2:00 pm, SED Director's Seminar, Hosted by the Heliophysics Science Division (670)

Energetic Particles in the Heliosphere and Magnetosphere

Georgia De Nolfo (672)

The heliosphere is bathed in energetic particles that span energies from keVs in the solar wind to GeVs in Galactic cosmic rays. The processes that energize and transport these particles throughout the heliosphere are not completely understood however. These processes occur across a variety of spatial and temporal domains as well as across different boundaries (e.g., solar wind/magnetosphere) and are a critical part of heliospheric particle dynamics. The recently awarded ISFM Work Package entitled ?Energetic Particles in the Heliosphere and Magnetosphere? seeks to advance our understanding of particle energization and transport by a multi-pronged approach combining expertise in data analysis, modeling, and theory to study solar energetic particle dynamics within the inner heliosphere and magnetosphere. Specifically, we address the following questions: 1) Does diffusive shock acceleration account for the recently discovered, ubiquitous spectral roll overs at high-energies in SEP events, and if so, what is then the cause of the well-established low-energy spectral breaks? 2) How are high-energy SEPs transported through the heliosphere and magnetosphere? 3) Do the particles accelerated by CME-driven shocks in gradual SEP events also account for the Long-Duration Gamma-ray Flares that accompany some of these events? and 4) What role does the suprathermal particle population play in particle acceleration? .

Shear-driven ionospheric instabilities and equatorial electrojet currents discovered by Goddard?s electric field and magnetic field instruments on C/NOFS

Robert Pfaff (675)

The earth?s low latitude ionosphere contains a number of unique physical processes which represent important natural phenomena within Geospace and which also contribute to numerous space weather applications. Goddard?s Vector Electric Field Investigation (VEFI) includes a number of key instruments on the Air Force C/NOFS satellite that gathered 7.5 years of data in this region. Among the many phenomena that VEFI data address, shear-driven instabilities in the low latitude ionosphere and equatorial electrojet currents are among the areas where important new discoveries have been revealed by this comprehensive data set. This work package includes both high level processing and archiving of these data as well as important scientific analysis of new phenomena revealed by the measurements. We present an overview of the objectives and methodologies of our work package including a summary of the main achievements of the first year.

Using global transport of metals in the MLT to diagnose neutral circulation

Diego Janches (675)

All regions of the Earth?s atmosphere are coupled via radiative, dynamical, and chemical processes, and the Mesosphere/Lower Thermosphere (MLT) serves as the critical boundary between the terrestrial atmosphere and space. Originating from ablated meteoroids, meteoric metal layers are directly affected by, and act as diagnostics of, MLT chemical and dynamical processes, thus providing a unique tool to improve our understanding of this complex region. This portion of the work package focuses on understanding the drivers of neutral circulation, dynamics, and chemistry in the mesosphere and lower thermosphere (MLT) using the Na layers as a tracer of these processes. In this talk we present a summary of the progress performed during the first year.