3 Months | 1 Year | Events (3 Mon) | Events (1 Yr)

Equatorial Pacific Zonal Wind Stress Anomaly

Zonal wind stress anomalies over the equatorial Pacific ocean provide a dominant driver of the upper ocean circulation changes and equatorial Pacific sea surface temperaure anomaly development associated with El Niño and La Niñ events. During El Niño events, positive equatorial zonal wind stress anomalies over the western and central part of the basin drive and maintian anomalous warming of sea surface temperatures to the east of the wind anomalies. During La Niña events, negative wind stress anomalies develop over the equatorial Pacific and drive anomalous surface cooling of central and eastern equatorial Pacific sea surface temperature. The time-longitude plot above shows 5S-to-5N averaged zonal wind stress anomaly.

Daily averages are shown in both the '3 Months' and '1 Year' figures. The 'Events' figures are based on the same zonal stress information shown in the 3 Months and 1 Year figures, except masked using the sub-seasonal wind event detection algorithm developed by Chiodi and Harrison (2015).

Data source

The zonal stress anomaly is calculated using moored buoy winds made available by the Global Tropical Moored Buoy Array (GTMBA) office at NOAA's Pacific Marine Environmental Laboratory and satellite-based scatterometer wind measurements, when the moored-buoy winds are unavailable. The scatterometer data is made available by Remote Sensing Systems based on the QuikSCAT instrument during 2000-2009 and the ASCAT-A instrument thereafter.

Calculation

The anomaly is calculated relative to a monthly climatological seasonal cycle based on the period 1 Jan 1992-present for the moored-buoy winds, and 2000-present for the scatterometer winds. In the mooring case, daily averaged winds are used to estimate wind stress. In the scatterometer case, 3-day averages are used. The monthly climatologies are linearly interpolated to determine daily anomalies.

References

Chiodi, A.M., and D.E. Harrison (2015): Equatorial Pacific easterly wind surges and the onset of La Niña events. J. Climate, 28(2), 776.792, doi: 10.1175/JCLI-D-14-00227.1.

Chiodi, A.M. (2019): Diagnosing and predicting ENSO SSTA development with TAO/TRITON and scatterometer winds. J. Climate, doi: 10.1175/JCLI-D-19-0183.1.

External Links

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Daily averaged winds from the tropical Pacific moored buoy array are available at the GTMBA site

Daily averaged winds are available from Remote Sensing Systems based surface roughness measurments from the QuikSCAT and ASCAT-A scatterometers.