Research

Schematic diagram of MJO wind and SLP effects. Madden and Julian (1972)

The Madden-Julian Osciallation is the primary source of intraseasonal variability affecting the Pacific Ocean. It consists of an envelope of convective activity that originates in the Indian Ocean, crosses the Maritime Continent, and continues to propagate eastward over the Pacific Ocean. The fingerprint of MJO is mostly seen in the 800mb and 200mb winds, as well as the convective signature left in the OLR field.

Naturally, bouts of convective activity affect the radiative balance at the ocean surface, and wind variability produces effects on the thermocline through affecting turbulent mixing. Indeed, MJO has been shown to affect the Pacific Ocean primarily due to the excitation of Kelvin waves, which extend the oceanic influence of MJO beyond local effects. ENSO events have also been shown to be affected by Kelvin wave activity, particularly the 1997/98 event.

However, MJO activity is neither necessary nor sufficient for El Niño to occur, so how can we quantify the influence of MJO on the evolution of ENSO? This question is the topic of my first paper, the appropriately named "The Effect of the MJO on the Energetics of El Niño" (Lybarger and Stan, 2017). There, the ocean energetics framework established by Goddard and Philander (2000) was used to derive an index involving the wind stress anomaly associated with MJO and the ocean current anomaly associated with Kelvin wave activity which was found to be related to El Niño strength.

My research since then has focused on modeling studies, where a simple model of the Pacific Ocean was forced with MJO wind stress to quantify the effects of that forcing on El Niño development. The results are currently undergoing peer review. The last section of my thesis work will use this information in a forecasting context with the hope of showing a relationship between MJO effects and the resulting forecasted El Niño event.

Goddard, L., and S. G. Philander, 2000: The energetics of El Nino and La Nina. J. Clim., 13, 1496–1516, doi:10.1175/1520-0442(2000)013<1496:TEOENO>2.0.CO;2.
Lybarger, N. D., and C. Stan, 2017: The effect of the MJO on the energetics of El Niño. Climate Dynamics, doi:10.1007/s00382-017-4047-5. https://www.readcube.com/articles/10.1007/s00382-017-4047-5 (Accessed December 22, 2017).
Madden, R., and P. Julian, 1972: Description of Global-Scale Circulation Cells in Tropics with a 40-50 Day Period. J. Atmos. Sci., 29, 1109–+, doi:10.1175/1520-0469(1972)029<1109:DOGSCC>2.0.CO;2.