Untangling El Niño-Southern Oscillation precursors
Dr. Kathleen Pegion
University of Colorado/CIRES and NOAA/ESRL/PSD, Boulder, Colorado
Cookies / Coffee / Punch @ 3:30 PM
10 March 2014, 4:00 PM
National Weather Center, Room 1350
120 David L. Boren Blvd.
University of Oklahoma
There are several proposed precursors to the El Niño-Southern Oscillation (ENSO) that may provide the ability to predict ENSO as much as one year in advance. Some of these precursors are associated with stochastic forcing from extratropical atmospheric variability. Two examples are the seasonal footprinting mechanism (SFM) and the Pacific meridional mode (PMM). Both of these ENSO precursors are thought to be forced by the North Pacific Oscillation (NPO), a north-south sea level pressure dipole in the north Pacific. Additionally, both the PMM and SFM are thought to impact the tropics through sea-surface temperature feedbacks and have a correlation with ENSO up to one year in advance. Various indices used to define these two precursors are discussed interchangeably throughout the literature. Whether they are independent of each other or are part of the same process has not been investigated. The research presented in this talk is focused on untangling the relationships between the PMM, SFM, NPO, and ENSO using observational datasets and model simulations. Results demonstrate that the two considered are different, are forced by different atmospheric circulations, and result in different manifestations of ENSO.