Seasonal dependence of MSTIDs obtained from 630.0 nm airglow imaging at Arecibo

All‐sky imaging data of 630.0 nm airglow emissions are used to study the seasonal and solar activity dependence of medium‐scale traveling ionospheric disturbances (MSTIDs) over Arecibo, Puerto Rico (18.3° N, 66.7° W, 28° N mag lat). MSTIDs are typical F‐region signatures at midlatitudes, yet limited statistical results in the American sector hindered the progress in our understanding of these dynamical structures. This study compiles data from 2002 to 2007 and shows for the first time that optically‐determined MSTIDs at Arecibo present a semiannual pattern with peak occurrence at both solstices. In the Japanese longitude sector, a similar pattern has been found, but one with a main peak during local summer. This paper explains the high occurrence rate during local winter at Arecibo via E‐layer/F‐layer coupling and inter‐hemispheric coupling, thus accounting for a consistent morphology between the two longitude sectors.