This project has the goal of improving understanding of the basic dynamical processes that drive tropical/extratropical interaction on the intraseasonal time by performing both idealized numerical model experiments and diagnostic analyses. Enhanced understanding of tropical/extratropical interaction is crucial for improving medium range (1-4 week) weather forecasts.
Recent studies have shown that different phases of an active tropical Madden-Julian Oscillation (MJO) are followed 1-4 weeks later by the excitation of the dominant Northern Hemisphere teleconnection patterns (both the North Atlantic Oscillation and the Pacific/North American patterns), and coincide with large changes in the frequency of occurrence of these teleconnection patterns. It has been found that probabilistic weather forecasts based on both MJO and El-Nino-Southern-Oscillation phases outperform state-of-the-art numerical weather prediction models for North America with lead times of 2 to 4 weeks. Changes to Arctic surface air temperature have even been observed following an active MJO.
