16-day free-traveling Rossby waves and their association with Northern Hemisphere blocking

• Main Author: Findlay, Ernesto W
• Format: Text
• Language: English
• Published: Scholars Archive 2019
• Subjects: 16-day Wave; Blocking; Rossby-Haurwitz; Rossby waves; North Atlantic oscillation; Blocking (Meteorology); Atmospheric Sciences; North Atlantic
• Online Access: https://scholarsarchive.library.albany.edu/legacy-etd/2279; https://scholarsarchive.library.albany.edu/context/legacy-etd/article/3278/viewcontent/Findlay_4uU7yCkMBEF3hw3daBZHfm.pdf

An analysis of the 16-day free Rossby wave is performed. The behavior of this wave includes a barotropic vertical structure that is independent of local forcing. An Empirical Orthogonal Function (EOF) analysis was performed on 15–30-day filtered geopotential height anomalies to extract the spatial patterns of the wave. Results show that the first two EOFs are in quadrature with each other, representing a westward moving signal with an average period of around 23 days and a phase velocity of. The Principal Components (PCs) from these EOFs were used to construct a 16-day wave index, which was employed as a tool to monitor and track the 16-day wave across eight phases. A composite analysis of each phase was performed to analyze the spatial structures of the wave, which is represented by a wavenumber-one pattern in the geopotential height anomaly field. The signal has the same sign in the Southern Hemisphere, but with amplitude smaller than that in the Northern Hemisphere. Meridional temperature transport plays a role in the westward movement of the geopotential height anomalies. A vertical composite of the wave was also performed for each of the phases of the index. Results show that the vertical structure is consistent with that theorized and with the previously observed vertical structure of the wave.