Structure and Evolution of the Transition Region Network Observed in he ii λ304

Abstract

The length scale and life time of the transition region network cells were studied using He ii λ304 filtergrams. The temporal structure function was calculated from spatially aligned He ii λ304 images. The estimated life time of the network cell was about 27 hr. We compared this life time with the life time of photospheric magnetic network and of the extrapolated magnetic network. The spatial structure function was calculated from the He ii λ304 filtergrams. The calculated spatial structure function saturates at ∼ 25 000 km. The transition region network elements are bigger in size than the photospheric magnetic network element. The magnetic network element equals the size of the He ii λ304 network element when the photospheric magnetic field is extrapolated to a height of 3000 km above the photosphere where the magnetic fluxes are deployed. The derived value of the diffusion speed of the network elements was 0.098 km s−1.