Biological and Environmental Research - Earth and Environmental System Sciences
Earth and Environmental System Modeling

Evaluation of the Energy Distribution Across Time Scale in the Power Spectra of Extratropical Modes of Variability

Monday, December 9, 2019 - 13:40
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In this study, we will discuss the analysis of power spectra as part of a space-time diagnosis of modes of extratropical variability (Northern Annular Mode-NAM, the North Atlantic Oscillation-NAO, the Pacific North America pattern-PNA, the Southern Annular Mode-SAM, and the Pacific Decadal Oscillation-PDO). In addition to assessing the overall shape of the power spectra, we consider the skill in representing variability in four separate time bins: interdecadal (over 10 year), interannual (2 to 10 year), quasi-annual (10 month to 2 year), and sub-annual (2 to 10 month).The metrics are applied to all available Historical simulations from CMIP5 and CMIP6. For each model, we average data across initial condition realizations and/or the time bins to reduce sampling uncertainty and improve the signal-to-noise ratio to assess if statistically significant periodicities exist in the data. Where possible, the metrics and significance are assessed relative to a variety of statistical models of the noise.


Acknowledgement: This work was supported by the Office of Science (BER), U.S. Department of Energy through Lawrence Livermore National Laboratory contract DE-AC52-07NA27344.

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