Contemporary Climate Oscillations: ENSO and a case study of the Huanghe River
This is one component of the Source to Sink Mini Lesson Set
In this module, students will be provided with data of monthly mean sea level pressure (MSLP) from Tahiti and Darwin, Australia, from which they will calculate the Southern Oscillation Index (SOI) of ENSO from January 1933 to August 2013 and will compare their calculated SOI with a case study of the Huanghe river, China. Students will be provided with data of Huanghe River discharge and Huanghe basin-wide river discharge from 1950-2013. The anthropogenic effects and ENSO effects on the Huanghe will be examined in this exercise, with discussion of the impact on the river itself, and also the impact ENSO and humans are having on the delta and river mouth of the Huanghe.
The term El Niño-Southern Oscillation (ENSO) refers to a fluctuation as a result of changing sea surface pressures across the equatorial Pacific. ENSO and the quantitative SOI tell us when there is a shift in climate that affects weather phenomenon globally. The end members of ENSO are El Niño and La Niña events. The timing between these events is irregular, yet they typically recur every 3 to 7 years.
Context for Use
This module is appropriate for mid- and upper-level undergraduate courses in oceanography, environmental science, sedimentology and stratigraphy, and geography. Students should have a basic understanding of river hydrology and the role of river sediments in constructing the continental margin. The students will need computers connected to the internet, in order to access online databases and visualization freeware such as GeoMapApp , and Google Earth. The sub-modules are suitable for in-class, laboratory, or homework assignments. Combined the entire module is suitable for a multi-day activity.
Description and Teaching Materials
This module consists of:
Part 1: A lecture introducing ENSO and SOI. Brief discussion of the take-home assignment and groups are assembled.
Part 2: The take-home group assignment where the students will take sea surface pressure measurements and convert them into SOI values. They will then make the SOI plot.
Part 3: The Huanghe river is introduced in class. Students are sitting in the groups that worked on the SOI plot together. They can discuss answers to the in-class worksheet questions in this module.
ENSO and the Huanghe In-Class Group Assignment (Microsoft Word 644kB Dec1 14)
Part 4: Completion of module consists of a class discussion of their answers and any additional discussion of the Huanghe (other figures or conclusions from the Wang et al. (2006) study). doi:10.1016/j.gloplacha.2006.01.005
ENSO and the Huanghe PowerPoint Presentation (PowerPoint 6.9MB Dec1 14) (Portions of this PowerPoint presentation will be used for Part 1, 3 and 4 of this module. This presentation will have to be broken up into the ENSO/SOI introductory lecture for the beginning of the module, followed by the Huanghe introduction, and concluding the module with any slides that will aid with the final class discussion and/or additional information about the Huanghe).
Teaching Notes and Tips
Data Sources for ENSO Index/SOI: Bureau of Meteorology National Climate Centre, Australian Government
SOI Calculation/Plotting Guidelines:
Options for adding animations to PowerPoint presentation:
Click: Animation-> 3-D TAO Temp, Wind, Current, and 20°C->Animate!
Click: 60 months-> play!
Can see when there was El Niño and La Niña events since 2008!
Also: Section Plots->plot 1: Dynamic Height, plot 2: SST
Fill a large rectangular lunch container with water until approximately 1 inch from the top. Add numerous drops of blue food coloring. Mix. This is the deeper ocean of the equatorial Pacific. Slowly add oil (cooking oil is fine) on top of the water. This is the surface waters of the equatorial Pacific that get heated by the sun. Let the two layers become stratified. Label one side of the lunch container "South America" and the other side "Indonesia and Australia". The trade winds across the Pacific blow from South America to Indonesia. Use a hair dyer to illustrate the trade winds. Make sure the hairdryer does not get wet. Use the hairdryer to blow the trade winds across your model equatorial Pacific Ocean and show the students what happens during ENSO. During El Niño the trade winds are relaxed so more stratification across the Pacific occurs and there is less upwelling off the coast of South America. During La Niña the trade winds are stronger causing more upwelling offshore South America and the warmer surface waters are more concentrated towards Indonesia. Discuss the tie of this water movement due to the trade winds to changes in rain patterns during El Niño (more rain in the Pacific Ocean with drought conditions in Australia/Indonesia and eastern Asia gets less rain) and La Niña (overabundance of rain in Indonesia/Australia and dryer conditions in the central Pacific). This demonstration/discussion combined with the PowerPoint presentation should make it clear what happens during El Niño and La Niña.
References and Resources
- Australian Government Bureau of Meterology
- Wang, H., Z. Yang, Y. Saito, J.P. Liu, X. Sun, 2006, Interannual and seasonal variation of the Huanghe (Yellow River) water discharge over the past 50 years: Connections to impacts from ENSO events and dams, Global and Planetary Change, 50, 212-225.doi:10.1016/j.gloplacha.2006.01.005
- Wang, H., Z. Yang, Y. Saito, J.P. Liu, X. Sun, Y. Wang, 2007, Stepwise decreases of the Huanghe (Yellow River) sediment load (1950-2005): Impacts of climate change and human activities, Global and Planetary Change, 57, 331-354.doi:10.1016/j.gloplacha.2007.01.003
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