Earth Science · Ocean · Climate · Water Cycle / Principles and Exploration
Trade winds and El Niño — principles and investigation
Trade winds in the equatorial Pacific influence the movement of warm surface water and upwelling of the eastern ocean. Change the wind to weak or strong and compare the status of normal, El Niño, and La Niña concepts. This is an activity to connect and read the east-west water temperature difference, thermocline slope, and precipitation zone.
How does it work?
In weak trade winds, the east warms and the precipitation zone moves east. The opposite is true in strong trade winds.
Trade winds ↑ → western warm water accumulation ↑ · eastern upwelling ↑
Try this investigation
- Slowly transitions from steady state to selected wind conditions. Connect the thermocline slope, eastern upwelling, warm water, and the location of clouds.
- Run normal and weak trade winds respectively and record the east-west surface water temperature and thermocline depth.
- Just increase the wind to 1.8. Compare the eastern water temperature and upwelling and the difference in thermocline depth at the two ends with the previous record.
Interpreting your results
What combination appears in La Niña's strong trade winds?
When east to west winds are strong, more warm water accumulates in the west and the thermocline in the east becomes shallower. As the upwelling becomes stronger, the eastern surface becomes colder.
Assumptions and limitations
It is a conceptual state model that interpolates normal, El Niño, and La Niña with continuous trade wind values. The temperature and thermocline depth are virtual values, and the change time is model s. It does not include atmospheric/oceanic feedbacks or actual ENSO standards/cycles/forecasts.