More than one way. The linked graph cites the paper it was generated in which has all the details https://agupubs.onlinelibrary.wiley.com/doi/epdf/10.1029/1999G

More than one way. The linked graph cites the paper it was generated in which has all the details https://agupubs.onlinelibrary.wiley.com/doi/epdf/10.1029/1999GL900070 https://agupubs.onlinelibrary.wiley.com/doi/epdf/10.1029/199...