Group seminar on 14. December, 16:00 CET
Discovery of the MJO: a Story of the Power of Spectrum Analysis
Roland Madden
Paul Julian and I stumbled on what we called the “40-50 Day Oscillation” while looking for variations in recently discovered equatorial waves whose time scales were 5- to 15- days (mixed Rossby gravity and Kelvin waves respectively). Following the lead of other researchers, we used spectrum analysis to diagnose our data. It allowed us to arrive at a comprehensive description of what is often now called the MJO with limited data.
In this talk I will spend a few minutes describing spectrum analysis. Next, I’ll describe the exciting discoveries in equatorial meteorology in the 1960’s, which were the background for our work. These discoveries kindled our interest, and because we were at the National Center for Atmospheric Research we were in a unique position to study data from the Tropics. I will outline the sorts of results that led us to our description of the MJO. Finally, if there is time, I will relate a feature of the MJO oscillation that we completely missed because of the effects of seasonal variations on the spectral results.