Nonlinear Processes in Geophysics www.nonlin-processes-geophys.net 1023-5809 1607-7946 16 3 2009 10.5194/npg-16-443-2009 http://www.nonlin-processes-geophys.net/16/443/2009/ http://www.nonlin-processes-geophys.net/16/443/2009/npg-16-443-2009.html http://www.nonlin-processes-geophys.net/16/443/2009/npg-16-443-2009.pdf 443 452 2009-06-30 Joule heating and anomalous resistivity in the solar corona S. R. Spangler steven-spangler@uiowa.edu Department of Physics and Astronomy, University of Iowa, Iowa City, IA 52242, USA Recent radioastronomical observations of Faraday rotation in the solar corona can be interpreted as evidence for coronal currents, with values as large as 2.5×10⁹ Amperes (Spangler, 2007). These estimates of currents are used to develop a model for Joule heating in the corona. It is assumed that the currents are concentrated in thin current sheets, as suggested by theories of two dimensional magnetohydrodynamic turbulence. The Spitzer result for the resistivity is adopted as a lower limit to the true resistivity. The calculated volumetric heating rate is compared with an independent theoretical estimate by Cranmer et al. (2007). This latter estimate accounts for the dynamic and thermodynamic properties of the corona at a heliocentric distance of several solar radii. Our calculated Joule heating rate is less than the Cranmer et al estimate by at least a factor of 3×10⁵. The currents inferred from the observations of Spangler (2007) are not relevant to coronal heating unless the true resistivity is enormously increased relative to the Spitzer value. However, the same model for turbulent current sheets used to calculate the heating rate also gives an electron drift speed which can be comparable to the electron thermal speed, and larger than the ion acoustic speed. 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