We present scaling laws for advection , radiation , magnetic drag and ohmic dissipation in the atmospheres of hot giant exoplanets .
In the limit of weak thermal ionization , ohmic dissipation increases with the planetary equilibrium temperature ( T _ { eq } \mathrel { \hbox to 0.0 pt { \lower 4.0 pt \hbox { $ \sim$ } } \raise 1.0 pt \hbox { % $ > $ } } 1000 K ) faster than the insolation power does , eventually reaching values \mathrel { \hbox to 0.0 pt { \lower 4.0 pt \hbox { $ \sim$ } } \raise 1.0 pt \hbox { $ > $ } } 1 \% of the insolation power , which may be sufficient to inflate the radii of hot Jupiters .
At higher T _ { eq } values still , magnetic drag rapidly brakes the atmospheric winds , which reduces the associated ohmic dissipation power .
For example , for a planetary field strength B = 10 G , the fiducial scaling laws indicate that ohmic dissipation exceeds 1 \% of the insolation power over the equilibrium temperature range T _ { eq } \sim 1300 – 2000 K , with a peak contribution at T _ { eq } \sim 1600 K. Evidence for magnetically dragged winds at the planetary thermal photosphere could emerge in the form of reduced longitudinal offsets for the dayside infrared hotspot .
This suggests the possibility of an anticorrelation between the amount of hotspot offset and the degree of radius inflation , linking the atmospheric and interior properties of hot giant exoplanets in an observationally testable way .
While providing a useful framework to explore the magnetic scenario , the scaling laws also reveal strong parameter dependencies , in particular with respect to the unknown planetary magnetic field strength .