Latitudinal Enhancements of 630 nm Midnight Brightness Using FORMOSAT-2/ISUAL
P K Rajesh1, C. H. Chen2, Charles Lin3, Jann-Yenq G Liu4, J. D. Huba5, Alfred Bing-Chih Chen6, Rue-Ron Hsu7 and Yu-Tsung Chen7, (1)NCKU National Cheng Kung University, Department of Earth Sciences, Tainan, Taiwan, (2)Department of Earth Sciences, National Cheng Kung University, Tainan, Taiwan, (3)NCKU National Cheng Kung University, Earth Sciences, Tainan, Taiwan, (4)NCU National Central University of Taiwan, Department of Space Science and Engineering, Taoyuan, Taiwan, (5)US Naval Research Laboratory, Plasma Physics Division, Monterey, CA, United States, (6)NCKU National Cheng Kung University, Department of Physics, Tainan, Taiwan, (7)NCKU National Cheng Kung University, Tainan, Taiwan
Abstract:
In this study, intense airglow brightness that appear in the latitude scans of 630.0 nm limb images, taken at local midnight period, using Imager of Sprites and Upper Atmospheric Lightnings (ISUAL), onboard FORMOSAT-2 satellite, are investigated. The enhancements appear as single or multiple peaks and in some cases as bright and dark bands of airglow intensity modulation. Though the peaks mostly appear near the equatorial region, in some cases they are seen at mid-latitudes as well. Detailed simulations are carried out using SAMI2 (SAMI2 is Another Model of the Ionosphere) model parameters to understand such intense emission in the near midnight period. The simulations reproduced the measured airglow intensity pattern quite remarkably and suggest that plasma density distribution by meridional neutral wind could play a major role in producing the brightness, while the intensity bands could be caused by Medium Scale Traveling Ionospheric Disturbances.
