Weather Regime Transitions and the Interannual Variability of the North Atlantic Oscillation. Part II: Dynamical Processes

• Main Authors: Dehai Luo, Jing Cha, Steven B Feldstein
• Other Authors: The Pennsylvania State University CiteSeerX Archives
• Format: Text
• Language: English
• Subjects: North Atlantic; North Atlantic oscillation
• Online Access: http://citeseerx.ist.psu.edu/viewdoc/summary?doi=10.1.1.1055.6546; http://www.meteo.psu.edu/%7Esbf1/papers/Luo_Cha_Feldstein.part2.pdf

ABSTRACT In this study, attention is focused on identifying the dynamical processes that contribute to the negative North Atlantic Oscillation (NAO) 2 to positive NAO (NAO This finding cannot be detected for NAO events without transition. Moreover, it is found that the amplification of retrograding wavenumber 1 is more important for the NAO 2 to NAO 1 transition during P1, but the marked reintensification and retrograde movement of both wavenumbers 1 and 2 after the NAO 1 event decays is crucial for the NAO 1 to NAO 2 transition during P2. It is further shown that destructive (constructive) interference between wavenumbers 1 and 2 over the North Atlantic during P1 (P2) is responsible for the subsequent weak NAO 1 (strong NAO 2 ) anomaly associated with the NAO 2 to NAO 1 (NAO 1 to NAO 2 ) transition. Also, the weakening (strengthening) of the vertically integrated zonal wind (upstream Atlantic storm track) is found to play an important role in the NAO regime transition.