Discrete wavelet analysis of the influence of the North Atlantic Oscillation on Baltic Sea level

• Published in: Tellus A: Dynamic Meteorology and Oceanography
• Main Authors: A. Bastos, R. M. Trigo, S. M. Barbosa
• Format: Article in Journal/Newspaper
• Language: English
• Published: Stockholm University Press 2013
• Subjects: Baltic Sea; NAO; Discrete wavelet analysis; MSL; Wavelet correlation; Oceanography; GC1-1581; Meteorology. Climatology; QC851-999; North Atlantic; North Atlantic oscillation
• Online Access: https://doi.org/10.3402/tellusa.v65i0.20077; https://doaj.org/article/c1ade082173340bb88ab96114fa70bf6

Mean sea level (MSL) in the Baltic Sea is influenced by several factors and therefore presents a complex behaviour over a wide range of time-scales. This work performs a multi-scale analysis of MSL variability in the Baltic Sea using discrete wavelet analysis. The North Atlantic Oscillation (NAO) is well known for having a strong influence in MSL variability over the Baltic; however, the relationship between MSL and NAO at different time-scales is still little understood. In this work a comparison of MSL and NAO variability is performed for a wide range of temporal scales, uncovering distinct relationships in high-frequency and long-term temporal variability. The annual and sub-annual scales are found to account for more than 50% of the total MSL variability. The MSL annual cycle is analysed and a shift from low to high amplitude values is identified in the 1970s for most stations. MSL is found to be anti-correlated to NAO at short time-scales while on the long-term NAO and MSL appear to be positively correlated for most stations. The physical mechanisms behind these distinct relationships deserve deeper study.