EnsoFbSshSst

SSH-SST_feedback: coupling between SSH anomalies and SST anomalies in the eastern equatorial Pacific

Description:

Computes sea surface height anomalies (SSHA; used as a proxy for subsurface temperature) regressed onto sea surface temperature anomalies (SSTA) both in the eastern equatorial Pacific (horizontal Niño3 average).

Reference observations:

TropFlux and AVISO 1993-2018 (main)

SSH: JPL-MEASURES 1993-2021, CSIRO-SSH 1993-2019, GODAS 1980-2023, ORAS5 1958-2022, SODA3.4.2 1979-2018
SST: ERSSTv5 1854-2023, HadISST 1870-2023, COBE2 1850-2023, ERA5 1940-2022, 20CRv3 1836-2015, NCEP2 1979-2023

Region:

Niño3

Regridding:

None

Steps (computation):

Niño3 SSHA

seasonal cycle removed
detrending (if applicable)
spatial average

Niño3 SSTA

seasonal cycle removed
detrending (if applicable)
spatial average

Feedback

SSTA regressed onto SSHA (slope)
abs((model-ref)/ref)*100

Time frequency:

monthly

Units:

% of error

Variable names:

sea surface height (SSH)
sea surface temperature (SST)

Dive down Level 1:

The first level shows the diagnostic used to compute the metric and highlight the difference between the model and the reference. Figure 1: scatterplot of sea surface height anomalies (SSHA) and sea surface temperature anomalies (SSTA) in the eastern equatorial Pacific (Niño3 averaged), showing the strength of the SSH-to-SST coupling (usually too strong). The black and blue markers show respectively the reference and the model. The metric is based on the slope of the regression and is the absolute value of the relative difference: abs((model-ref)/ref)*100.

Dive down Level 2:

The second level tests the hypothesis of a nonlinear relationship between SSHA<0 and SSHA>0. Figure 2: scatterplot of sea surface height anomalies (SSHA) and sea surface temperature anomalies (SSTA) in the eastern equatorial Pacific (Niño3 averaged), showing the possible nonlinearity in the strength of the SSH-to-SST coupling (usually shows no nonlinearity in both reference and model). The black, red and blue lines and numbers show respectively linear regression computed for all SSHA, SSHA>0 and SSHA<0, the left and right scatterplots show respectively the reference and the model.

Dive down Level 3:

The third level shows the local coupling in the equatorial Pacific. Figure 3: spatial structure of sea surface temperature anomalies (SSTA) regressed onto sea surface height anomalies (SSHA) both in the equatorial Pacific (meridional 5°S-5°N average; zonal 30° running average), showing the possible nonlinearity in the strength of the SSH-to-SST coupling (usually shows too strong coupling in the central and eastern equatorial Pacific, no nonlinearity in both reference and model; here the model shows a nonlinearity in the far eastern equatorial Pacific). The black, red and blue lines and numbers show respectively linear regression computed for all SSHA, SSHA>0 and SSHA<0, the dashed and solid curves show respectively the reference and the model.

Dive down Level 4:

The fourth level shows the spatio-mean annual structure of the coupling. Figure 4: spatio-mean annual structure of sea surface temperature anomalies (SSTA) regressed onto sea surface height anomalies (SSHA) both in the equatorial Pacific (meridional 5°S-5°N average; zonal 30° running average), showing the possible nonlinearity in the strength of the SSH-to-SST coupling (usually shows too strong coupling in the central and eastern equatorial Pacific, no nonlinearity in both reference and model, too strong seasonality; here the model shows a nonlinearity in the far eastern equatorial Pacific). The first, second and third rows show respectively linear regression computed for all SSHA, SSHA>0 and SSHA<0, the left and right Hovmöllers show respectively the reference and the model.