A model-based examination of multivariate physical modes in the Gulf of Alaska. (October 2016)

• Record Type: Journal Article
• Authors: Hermann, A.J.; Ladd, C.; Cheng, W.; Curchitser, E.N.; Hedstrom, K.
• Is Part Of: Deep sea research. Volume 132(2016)
• Page Start: 68
• Page End: 89
• Publication Date: 2016-10
• Subjects: USA -- Alaska -- Gulf of Alaska -- Modeling; Oceanography -- Periodicals; Ocean bottom -- Periodicals; Marine biology -- Periodicals; 551.46
• DOI: 10.1016/j.dsr2.2016.04.005
• Languages: English
• ISSNs: 0967-0645

Abstract

Abstract: We use multivariate output from a hydrodynamic model of the Gulf of Alaska (GOA) to explore the covariance among its physical state and air/sea fluxes. We attempt to summarize this coupled variability using a limited set of patterns, and examine their correlation to three large-scale climate indices relevant to the Northeast Pacific. This analysis is focused on perturbations from monthly climatology of the following attributes of the GOA: sea surface temperature, sea surface height, mixed layer depth, sea surface salinity, latent heat flux, sensible heat flux, shortwave irradiance, net long wave irradiance, currents at 40 m depth, and wind stress. We identified two multivariate modes, both substantially correlated with the Pacific Decadal Oscillation (PDO) and Multivariate El Nino (MEI) indices on interannual timescales, which together account for ~30% of the total normalized variance of the perturbation time series. These two modes indicate the following covarying events during periods of positive PDO/MEI: (1) anomalously warm, wet and windy conditions (typically in winter), with elevated coastal SSH, followed 2–5 months later by (2) reduced cloud cover, with emerging shelf-break eddies. Similar modes are found when the analysis is performed separately on the eastern and western GOA; in general, modal amplitudes appear stronger in the western GOA.