The African Easterly Jet: Double Core Structure and Effect on Easterly Wave Development

• Other Authors: Hosten, Amana (author)
• Format: Others
• Language: English; English
• Published: Florida State University
• Subjects: Meteorology
• Online Access: http://purl.flvc.org/fsu/fd/2018_Su_Hosten_fsu_0071N_14570

The African Easterly Jet (AEJ) is one of the phenomena driving regional as well as global atmospheric circulation. Specifically, within the Sahel region, the AEJ and African Eastern Waves (AEWs) are main features that are linked and associated with the West African Monsoon. Both features determine rainfall and tropical cyclone development in this region. For certain years, the AEJ has a double core structure during the month of August when the jet is the strongest. The goal of this study is to identify distinct cases of the AEJ structure and determine the possible effect on AEW development. For this study, zonal and meridional wind data at 600 hPa was obtained from NCEP reanalysis during the month of August from 1948 to 2016. Maps of zonal wind were made to show the structure of the AEJ. Hovmöller diagrams of the 2.5 to 6-day meridional wind and maps of meridional wind variance were made to show the strength and track of AEWs. Results identified distinct cases where the structure of the AEJ deviated from its long-term mean, including the western (eastern) core being located north relative to the eastern (western) core. The double core cases with the southward eastern core has significantly stronger AEW activity with longer average tracks. However, on inter-annual scales, there is not a strong link between the AEW activity and east Atlantic tropical cyclone activity. The difference between the cases provide valuable insight about the relationship between the AEJ, easterly waves and tropical cyclone formation at the West African coast. === A Thesis submitted to the Department of Earth, Ocean and Atmospheric Science in partial fulfillment of the requirements for the degree of Master of Science. === Spring Semester 2018. === April 5, 2018. === Includes bibliographical references. === Sharon E. Nicholson, Professor Directing Thesis; Jeffrey Chagnon, Committee Member; Robert Hart, Committee Member.