Dataset: EUC intensification analyses

Name: Investigation of EUC strengthening via analysis of SODA 2.2.6 and the TAO array (Thermal Thresholds and Projections project, ROGER project)
Published: 2015-06-26
Keywords: oceans

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Cite This Dataset

Project:

Constraining Thermal Thresholds and Projections of Temperature Stress on Pacific Coral Reefs Over the 21st Century: Method Refinement and Application (Thermal Thresholds and Projections)

Repeat Observations by Gliders in the Equatorial Region (ROGER)

Principal Investigator:

Elizabeth Drenkard (Rutgers University)

Co-Principal Investigator:

Kristopher Karnauskas (Woods Hole Oceanographic Institution, WHOI)

Contact:

Elizabeth Drenkard (Rutgers University)

BCO-DMO Data Manager:

Shannon Rauch (Woods Hole Oceanographic Institution, WHOI BCO-DMO)

Version:

26 June 2015

Version Date:

2015-06-26

Validated:

Current State:

Preliminary and in progress

Investigation of EUC strengthening via analysis of SODA 2.2.6 and the TAO array (Thermal Thresholds and Projections project, ROGER project)

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Description

Investigation of EUC strengthening via analysis of SODA 2.2.6 and the TAO array. Figures published in:
Drenkard, E.J., and Karnauskas, K.B. 2014. Strengthening of the Pacific Equatorial Undercurrent in the SODA
Reanalysis: Mechanisms, Ocean Dynamics, and Implications. J. Climate, 27, 2405–2416. doi:10.1175/JCLI-D-13-00359.1

Methods & Sampling

The investigators:

calculated the linear trends in zonal velocity, and the significance of these trends, in the short, coinciding SODA and TAO time series (Figure 1; results and locations are reported in Table 1). Analysis performed on monthly and normalized time series;
calculated the linear trends in maximum zonal velocity (SODA) and their significance over the whole equatorial Pacific domain and at a single location (See Figure 2);
calculated the linear trends in zonal velocity and vertical density gradient at each SODA grid location in a depth-longitude transect along the equator;
calculated the long-term, linear trends, by longitude for the windstress, surface zonal velocity and the maximum zonal velocity (over depth range 10-300m);
calculated the climatological values, climatological linear trends and trend significance for windstress, surface zonal velocity, sea surface hight, zonal transport, and maximum EUC core velocity;
calculated zonal momentum budget terms for the mean state of the equatorial Pacific and the decadal seasonal difference among these terms (Figures 6 & 7).

Data Processing Description

Both monthly means and normalized, filtered (13-month running mean) time series for TAO and SODA were used for comparing concurrent records.
Maximum zonal velocity is calculated as the maximum east west velocity occurring within the EUC core domain (2 degrees N – 2 degrees S, 150 degrees – 90 degrees W and 10 – 300m).
Monthly means were used to calculate trends in SODA zonal velocity; a 7-yr filtering of this time series of is also shown in Figure 2.
All longitudinal cross sections are meridionally averaged SODA data from 2 degrees N - 2 degrees S.
The investigators calculated the zonal momentum budget terms using the equations outlined in the paper and use SODA values for temperature, salinity, sea surface height, velocity (zonal, meridional, and vertical). Values for the vertical and horizontal coefficients of eddy viscosity are approximated from literature estimates as these values were not saved during runs of the SODA reanalysis.
Momentum budget terms were conducted along isopycnals, which were determined by density binning.

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Funding Sources