Highly structured tropical airglow and TEC signatures during strong geomagnetic activity

A remarkable set of all-sky images using the 630 nm airglow emission has be en taken over the Arecibo Observatory:in Puerto Rico. Wave-like structures at a height of about 250 km are commonly found to travel in the southwest d irection at speeds ranging from 20-120 m/s. Most surprising is that; geomag netic activity seems to greatly amplify them, forming very intricate patter ns of light and dark. Simultaneous observations using GPS satellite transmi ssions on one night reveal that dark regions are severely plasma depleted w hile bright regions have nighttime content as large as the full noontime io nosphere. This unexpected geomagnetic effect at mid-latitudes has implicati ons for trans-ionospheric radiowave propagation and Space Weather.