Scintillation measurements of the 150 MHz NNSS beacon satellites at two midlatitude locations spaced approximately 400 km east-west revealed that as the east-west zenith angle increased the scintillation index decreased. The explanation of this observation is that the F region irregularities are in the form of (approximately) north-south magnetically field aligned sheets. The likely formation mechanism of the irregularities probably involves the Perkins instability. © 2005 Elsevier Ltd. All rights reserved.
MacDougall, J., & Eadie, D. C. (2005). The shape of midlatitude scintillation irregularities. Journal of Atmospheric and Solar-Terrestrial Physics, 67(10), 931–935. https://doi.org/10.1016/j.jastp.2005.02.007