Solar Influences on the Return Direction of High-Frequency Radar Backscatter

A. G. Burrell, S. E. Milan, and T. K. Yeoman were supported by NERC grant NE/K011766/1. The research at the University of Calgary was supported by the Natural Sciences and Engineering Research Council of Canada (NSERC) Discovery Grant Program and Discovery Accelerator Supplement Program. The development and operations of the CASSIOPE/e-POP mission were supported by the Industrial Technologies Office (ITO), Canadian Space Agency (CSA), and MacDonald, Dettwiler and Associates (MDA), respectively. R. Stoneback was supported by NSF grant 1259508. e-POP RRI data can be accessed at http://epop-data.phys.ucalgary.ca. The authors acknowledge the use of IDL GEOPACK DLM in the production of the RRI data products used in this work. The authors acknowledge the use of SuperDARN data. SuperDARN is a collection of radars funded by the national scientific funding agencies of Australia, Canada, China, France, Italy, Japan, Norway, South Africa, the United Kingdom, and the United States. The Virginia Tech SuperDARN database (described at http://vt.superdarn.org/) provides up-to-date public access to the Hankasalmi observations, which were analyzed with the aid of DaViTpy. We acknowledge use of NASA/GSFC’s Space Physics Data Facility’s OMNIWeb service and OMNI data. Galactic Cosmic Ray data were obtained from the Sodankyla Geophysical Observatory at http://cosmicrays.oulu.fi. GPS TEC data products and access through the Madrigal distributed data system are provided to the community by the Massachusetts Institute of Technology under support from U.S. National Science Foundation grant AGS-1242204. Data for the TEC processing is provided by the following organizations: UNAVCO, Scripps Orbit and Permanent Array Center, Institut Geographique National, France, International GNSS Service, The Crustal Dynamics Data Information System (CDDIS), National Geodetic Survey, Instituto Brasileiro de Geografia e Estatística, RAMSAC CORS of Instit