Session F: ACRs and GCRs

Discussion in this breakout session will focus on the observations and interpretations of the ACR and GCR intensities during the present unusually long, deep solar minimum. In particular, in 2009 GCR intensities at 1 AU reached higher levels than had ever been previously directly measured during the Space Age, while ACR intensities at 1 AU were quite "typical", very similar to those observed 2 solar minima ago (during the last A<0 minimum) and well below those seen during the previous (A>0) solar minimum in 1996-97. How do these observations confirm or challenge our ideas of energetic particle propagation and modulation in the heliosphere? What constraints do they place on the origin of anomalous cosmic rays? What can we learn by monitoring the rapid decline in ACR and GCR intensities that began this year now that solar minimum modulation conditions have finally passed? How can multi-spacecraft measurements at 1 AU (from, e.g., ACE, Wind, SoHO, STEREO) together with observations out of the ecliptic from Ulysses and in the outer heliosphere from Voyager contribute to addressing these questions?

Invited speakers and attendees who have expressed an interest in making a presentation (or have been encouraged to do so) are listed below. We have a total of 3 hours in this session, so there is plenty of time for discussion and additional presentations. If you would like to make a presentation, please contact the session organizers by email or at the workshop.

Confirmed speakers:

  • Frank McDonald: Voyager observations of anomalous and galactic cosmic rays in the outer heliosphere (invited)
  • Nathan Schwadron: GCRs and ACRs in the present solar minimum compared with previous ones (invited)
  • Bruce McKibben: Ulysses observations of ACRs and GCRs
  • Dick Mewaldt: Record GCR intensities
  • Alan Cummings: Review of the tilt model and inner heliospheric ACR gradients