Mesospheric wave signatures and equatorial plasma bubbles: A case study

Simultaneous monitoring of mesospheric and thermospheric airglow emissions over low latitudes in the Pacific sector is utilized to study the signatures of mesospheric waves during equatorial spread F events as characterized by their optical signature in the thermospheric airglow layer, equatorial plasma bubbles (EPBs). Two case studies are presented, each consisting of two consecutive nights, one on which EPBs were observed and the other without EPBs. Significant differences are observed in mesospheric wave growth during EPB nights compared to the nights when no EPBs were observed. It is also found that short-period gravity waves with periods less than 3 h exhibited larger wave growth between the OH and O-2 emission altitudes during the nights when EPBs were observed. The observed mesospheric wave signatures are discussed in connection with the causative mechanisms for EPBs.