Multi-scale variability patterns in NCEP/NCAR reanalysis sea-level pressure
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Atmospheric pressure varies within a wide range of scales and thus a multi-scale description of its variability is particularly appealing. In this study, a scale-by-scale analysis of the global sea-level pressure field is carried out from reanalysis data. Wavelet-based analysis of variance is applied in order to describe the variability of the pressure field in terms of patterns representing the contribution of each scale to the overall variance. Signals at the seasonal scales account for the largest fraction of sea-level pressure variance (typically more than 60%) except in the Southern Ocean, in the Equatorial Pacific and in the North Atlantic. In the Southern Ocean and over the North Atlantic, high-frequency signals contribute to a considerable fraction (30–50%) of the overall variance in sea-level pressure. In the Equatorial Pacific, large-scale variability, associated with ENSO, contributes up to 40% of the total variance.
KeywordsSouthern Ocean Variability Pattern Annual Signal Wavelet Variance Pressure Time Series
This work has been supported by FCT (Fundação para a Ciência e Tecnologia, grant SFRH/BPD/23992/2005) and by program POCTI through the Centro de Investigação em Ciências Geo-espaciais (CICGE). NCEP Reanalysis data provided by the NOAA/OAR/ESRL PSD, Boulder, Colorado, USA, from their Web site at http://www.cdc.noaa.gov/. Data analysis was performed with R software (http://R-project.org) and with R-package waveslim from B. Whitcher.
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