Predictability of the North Atlantic Oscillation on Intraseasonal Time Scales.

摘要

Recent evidence suggests more clearly that the intra-seasonal variability of the atmospheric circulation in the North Atlantic, and in particular the North Atlantic Oscillation (NAO), is impacted by tropical convection related to the phase of the Madden-Julian Oscillation (Cassou 2008; Lin et al. 2009). The long-term goals of this project include: (1) Understanding more clearly the mechanisms that mediate the tropical-NAO connection in nature. (2) Assessing the prospects for utilizing this source of tropical predictability to improve dynamical forecasts of the North Atlantic intra-seasonal variations within a seamless prediction system. (1) Assess the perfect model (idealized) predictability of the NAO at forecast ranges from 1- 45 days in the Community Earth System Model (CESM) of NCAR and possibly the Coupled Forecast System Model (CFSv2) of NOAA. (2) To make predictions of observed NAO events at ranges of 1-45 days using CESM and CFSv2. (3) To assess the changes in the predictability and prediction skill when realistic MJO- related tropical diabatic heating is added to the models. (4) To diagnose the dynamical mechanisms by which the tropical heating variations affect the North Atlantic.