Atmosphere Models of Coronal Hole Network

Energy balance models of the chromosphere-corona transition region are computed for a segment of coronal hole assuming a nonradial magnetic field geometry.The energy fluxes considered include radiation,conduction,convection and mechanical wave (e.g.Alfven waves) heating.The calculated results show that the temperature T is about 60% lower,the electron density N is twice smaller and the thickness of the transition region is four times larger in the coronal hole network than in those the quiet region.This atmosphere model can satisfactorily explain the emission measure distribution obtained from the EUV observations for T>10⁵K.In addition it is also found that the Alfven wave heating at the base of the transition region of coronal hole may exceed the heat conduction.The convection energy losses could be important in coronal hole atmosphere due to the wave momentum deposition.In the transition region at the heights greater than 650 km above the base of the transition region the convection energy losses may gradually exceed the radiation energy losses.