1. Scripps Institution of Oceanography, University of California, San Diego, La Jolla, CA 92093–0244, USA.
2. Institut de Physique du Globe de Paris, Université Paris Diderot, Sorbonne Paris Cité, 1 rue Jussieu, 75005 Paris, France.
3. McDonnell Center for the Space Sciences, Washington University in Saint Louis, Saint Louis, MO 63130, USA.
4. Lyndon B. Johnson Space Center, Houston, TX 77058, USA.