The Impact of Tropical/Extratropical Interaction on Atmospheric Teleconnections

该项目的目标是通过执行理想化的数值模式实验和诊断分析，提高对驱动热带/温带相互作用的季节内基本动力过程的理解。加强对热带/温带相互作用的了解对于改进中期(1-4周)天气预报至关重要。最近的研究表明，热带马登-朱利安涛动(MJO)活动的不同阶段在1-4周后伴随着北半球主要遥相关型(北大西洋涛动和太平洋/北美型)的激发，并与这些遥相关型出现频率的较大变化相吻合。研究发现，基于MJO和厄尔尼诺-南方涛动两个阶段的概率天气预报优于北美最先进的数值天气预报模式，提前时间为2-4周。甚至在活跃的MJO之后，还观察到了北极表面气温的变化。

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.