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Journal of Geophysical Research: Space Physics

A model of Saturn's magnetic field based on all available data


  • Leverett Davis Jr.,

  • Edward J. Smith


The SPV (Saturn Pioneer Voyager) model of Saturn's magnetic field presented here uses the most accurate magnetometer data transmitted from Pioneer 11, Voyager 1, and Voyager 2 during their Saturn encounters. It fits the data observed between 1.3 and 8.0 Saturn radii from the planet's center with a 1.13% weighted root-mean-square average of the percent differences between the observed and modeled fields. The coefficients for the interior source terms for the SPV model are g10 = 21,160. nT, g20 = 1560. nT, and g30 = 2320. nT for a Saturn radius of 60,330 km. They are the same for all three encounters and should be valid for a decade and perhaps very much longer. The distance unit (the radius of Saturn) affects the values of the Gaussian coefficients. We have adjusted the coefficients of all the models to correspond to 60,330 km so that they can be compared. On the basis of our weights and the use of percent residuals, rather than absolute residuals, the SPV model fits the observed fields better than does the previously published P1184 model or the Z3 model. The part of the field due to currents in the outer regions is not axisymmetric and varies by approximately 5 nT from one encounter to another and from the inbound to outbound legs. The best available, but crude, models for the part of the field due to these external sources are six uniform fields, two for each encounter.

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