ENSO Jigsaw[Key Science Knowledge Module]Use contents of this packet as you feel appropriate. You are free to copy and use any of the material in this lesson plan.

Packet Contents

ENSO Jigsaw Components

The four Becoming on Expert on ___ readings and questions

Trade winds / Southern Oscillation / Walker Circulation El Niño – Warm PhaseLa Niña – Cold PhaseImpact of ENSO on Climate Variability

Three sections of ENSO Jigsaw Worksheet

ENSO Jigsaw – Pacific Ocean AspectsENSO Jigsaw – U.S. Climate Variability AspectsENSO Jigsaw – Worldwide Climate Variability Aspects

ENSO Crossword Puzzle

Other Effects of ENSO

3Student Packet

Becoming an Expert on Trade Winds,Southern Oscillation, and the Walker Circulation

To become an expert on trade winds, the Southern Oscillation, and the Walker Circulation, read the following information and complete the questions. Your teacher may require you to read other sources of information.

Trade Winds

The ocean and atmosphere are related or interact. This relationship is called coupled by scientists. Trade winds and the Walker Circulation in the tropical Pacific Ocean play important roles in understanding ENSO.

Differences in sea surface temperatures between the east and west equatorial Pacific Ocean cause the trade winds. The sun heats the sea surface to a higher temperature near the equator than the rest of the world. Heating the sea surface temperature causes the air to rise from the surface. The rising air is replaced by air inflows from the cooler subtropics. This is seen in the following trade wind patterns for the winds at the equator.

As shown in the figure, the northern and southern trade winds turn in different directions. By turning in different directions, the trade-wind belts are made. The trade winds blow towards the equator

and westward in the tropical Pacific Ocean. The trade winds are part of the coupled ocean-atmosphere interaction in the tropical Pacific. The trade winds determine the water temperature at the same time the water temperature determines the trade winds. This is the coupling of the ocean and atmosphere. They are linked to the point that they cannot be separated. The trade winds are so named as early sailing ships used the winds to sail from South America westward. The strength of the winds is such that the Pacific Ocean level is approximately half a meter higher in the western Pacific (Indonesian) than it is in the eastern Pacific (Peru, South America).

Southern Oscillation

Coupled with the sea surface temperature is air pressure. The Southern Oscillation is a seesaw of air pressure near the equator between the eastern and western Pacific Ocean. This oscillation is measured as changes in the differences in air pressure between Tahiti, French Polynesia and Darwin, Australia. In general, lower air pressure is found where the air is rising and higher pressure where the air is sinking. The Southern Oscillation is a measure of the strength of the trade winds, which flow from regions of high to low pressure.

Walker Circulation

The Walker Circulation associated with the trade winds is the vertical and horizontal circulation of air associated with the trade winds. The following figure (http://www.pmel.noaa.gov/tao/elnino/nino-home.html#) shows the coupling of sea surface temperatures and the Walker circulation.

Equator

Under normal conditions, the winds blowing westward cause a large pool of warm water in the western Pacific Ocean. Air rises over this warm pool. Rising air leaves the lower atmosphere and airflows in to fill the gap. The air filling the gap causes the winds to blow towards the warm water. The winds blowing in to fill the gap are the trade winds.

The warm pool of water releases large amounts of heat and moisture into the atmosphere. Sea surface temperatures in the warm pool are up to 6 degrees Celsius warmer than in the cooler pools. This warm pool is an important force in determining world climate by altering the jet streams (storm tracks) that control weather in the temperate-zones. Changes in the position of the warm pool in the Pacific Ocean can affect much of the world's weather.

One other important aspect shown in the figure is the position of the thermocline. The thermocline is the boundary between the colder deep water and warmer upper water layer. By blowing westward, the trade winds force the thermocline to be deep in the western Pacific Ocean and shallow in the eastern Pacific Ocean. In the west, the thermocline is up to 150 meters deep. In the east, the thermocline is around 30 meters deep. This difference in thermocline location has an affect on the biological make up of the Pacific Ocean. Colder deep water is usually richer in life-supporting nutrients than the warmer surface water. These nutrients support high primary production

by phytoplankton, which support high fish production. With a shallower thermocline, nutrients necessary for life in the ocean are closer to the surface making for more abundant plant and animal life. Having the thermocline moving close to the surface is called upwelling. Wherever upwelling occurs there is more abundant life than other areas of the ocean where upwelling does not occur.

These normal conditions provide the starting point to understand La Niña and El Niño events.

Western Pacific Eastern Pacific

Questions Concerning Trade Winds/Southern Oscillation/Walker Circulation

1. The ocean and atmosphere are related. Scientist call this relationship

2. Where are the sea surface temperatures the greatest?

3. What happens to the air when the sea surface temperature heats up?

4. What causes the trade winds?

5. How do the northern and southern trade winds different?

6. How are the trade winds and the ocean coupled?

7. What is the southern oscillation?

8. What is air normally doing where the air pressure is low?

9. What is air normally doing where the air pressure is high?

10. What is the Southern Oscillation a measure of?

11. What is the Walker Circulation?

12. Why is the warm pool so important?

13. How does the thermocline affect the biological make up of the Pacific Ocean?

14. What is upwelling?

15. Understand the figure in the readings concerning the Pacific Ocean during normal ENSO conditions.

After completing the questions above you are now an expert on trade winds, Southern Oscillation, and Walker Circulation. Your job is to share your knowledge with new partners tomorrow. You should study your information and answers for homework and be ready to explain these processes to your classmates. Be sure you explain the key terms.

Becoming an Expert on El Niño – Warm Phase

To become an expert on El Niño read the following information and complete the questions. Your teacher may require you to read other sources of information.

Recall from Learning Module 2, the three most common phases associated with ENSO are El Niño, La Niña, and neutral. El Niño is also referred to as the warm phase and La Niña the cold phase. The popular story of how El Niño got its name is as follows. El Niño originally referred to the warming of the Pacific Ocean off the coast of the South American country of Peru that appears around Christmas time. In Spanish, El Niño means small boy or child. If the word is capitalized, El Niño refers to Jesus as an infant. So, the anticipation of the celebration of the birth of Christ and the warming of the Pacific Ocean became known as El Niño. Exact origin and date of the use of the word El Niño is not known. Be prepared to give the story of the naming of El Niño in the jigsaw groups.

Referring to El Niño as the warm phase is simply in reference to the warming of the Pacific off the South American coast.

Scientists do not know what causes El Niño phases to develop. They do know, however, the affects of the phase. The following are changes from normal conditions. The trade wind experts will provide you with information on normal conditions. During El Niño phases, the trade winds weaken. The warm pool of water in the equatorial Pacific moves eastward. El Niño is defined by sea surface temperatures that are warmer than or equal to 0.5 degrees Celsius higher than normal

when averaged over three consecutive months in the Niño 3.4 region. El Niño is sometimes referred to as the warm phase because of the warmer sea surface temperatures in the eastern Pacific. The eastward movement of the warm pool causes the thermocline to move down in the eastern Pacific Ocean and to become shallower in the western Pacific. The thermocline is the boundary between the colder deep water and warmer upper water layer.

Opposite air pressure conditions than those that occur in an El Niño event are generally associated with La Niña events. Lower than normal air pressure in the eastern Pacific and higher air than normal air pressure in the western Pacific are associated with El Niño. Smaller pressure difference in the Southern Oscillation is associated with weaker than normal trade winds during an El Niño. These changes are shown in the figure (http://www.pmel.noaa.gov/tao/elnino/nino-home.html#).

Western Pacific Eastern Pacific

These changes in the coupled ocean-atmosphere system can lead to changes in climate variability around the world. These changes in climate conditions are associated with the changes in location of the warm pool. The warm pool is a major source of heat and moisture to the atmosphere. Changes in the thermocline cause changes in upwelling in the Pacific Ocean. Biological aspects of the ocean change with the changes in upwelling. With the change in upwelling, there is less biological life near the ocean surface in the eastern Pacific Ocean than under neutral conditions.

The following figure shows some the global affect of El Niño’s on climate

variability. El Niño’s affect is stronger during the northern hemisphere winter season, December – February than during the summer season. This does not mean for the gulf region of the U.S. all El Niño years will have higher precipitation levels during the winter season, but there is an increased probability of higher precipitation. During an El Niño, the western Pacific tends to experience warmer and dryer climate conditions. The southern U.S. tends to experience wetter and cooler climate conditions. Western Canada and Northwestern U.S. experience warmer than normal temperatures. Other worldwide affects of El Niño are shown in the figure.

Questions on El Niño – Warm Phase

1. El Niño phase is also referred to as the __________________ phase.

2. Do scientists know what causes El Niño to develop? Yes No

3. What happens to the trade winds during an El Niño phase?

4. What happens to the southern oscillation pressure difference during an El Niño phase?

5. What happens to the pool of warm water winds during an El Niño phase?

6. What is the definition of an El Niño phase?

7. What happens to the thermocline during an El Niño phase?

8. What happens to the air pressure during an El Niño phase?

9. Analyze the maps of the global effects of El Niño. How could this possibly affect Joe Soccer’s decision? Remember Joe Soccer lives in the Southern U.S.

10. Are the effects of El Niño on precipitation the same worldwide? Yes No

11. Are the effects of El Niño on temperature the same worldwide? Yes No

12. Provide one example where the effects differ or are the same.

13. Understand the figure in the readings concerning the Pacific Ocean during El Niño conditions.

After completing the questions above you are an expert on El Niño. Your job is to explain this event to your new partners tomorrow. You should study your information and answers for homework and be ready to explain this process to your classmates tomorrow.

Becoming an Expert on La Niña – Cold Phase

To become an expert on La Niña read the following information and complete the questions. Your teacher may require you to read other sources of information.

Recall from Learning Module 2, the three most common phases associated with ENSO are El Niño, La Niña, and neutral. El Niño is also referred to as the warm phase and La Niña the cold phase. In Spanish, La Niña refers to the girl child. Once you come together in the jigsaw groups, ask your El Niño expert how El Niño got its name.

Scientists do not know what causes La Niña phases to develop. They do know, however, the affects of the phase. The following are changes from normal conditions. The trade wind experts will provide you with information on normal conditions. During La Niña phases, the trade winds strengthen. The warm pool of water in the equatorial Pacific moves farther west. La Niña is sometimes referred to as the cold phase because of the cooler sea surface temperatures in the eastern Pacific. La Niña is defined by sea surface temperatures in the Niño 3.4 region that are 0.5 degrees Celsius or cooler than normal temperatures when averaged over three consecutive months. The westward movement of the warm pool causes the thermocline to become shallower in the eastern Pacific Ocean and deeper in the western Pacific Ocean. The thermocline is the boundary between the colder deep water and warmer upper water layer.

Opposite air pressure conditions than

those that occur in an El Niño event are

generally associated with La Niña events. Air pressure is higher than normal in the eastern Pacific and lower than normal in the western Pacific. This large pressure difference in the Southern Oscillation is associated with stronger than normal trade

winds during a La Niña phase. These changes are shown in the figure (http://www.pmel.noaa.gov/tao/elnino/nino-home.html#).

These changes in the coupled ocean-atmosphere system can lead to changes in climate variability globally. The warm pool is a major source of heat and moisture to the atmosphere. Changes in the thermocline cause changes in upwelling in the Pacific Ocean. Biological aspects of the ocean change with the changes in upwelling. With additional upwelling, there is more biological life near the ocean surface in the eastern Pacific Ocean than under neutral conditions.

General changes in climate variability associated with La Niña are shown in the figure below. La Niña’s affect is stronger

Western Pacific Eastern Pacific

during the northern hemisphere winter season, December – February than during the summer season. This does not mean for the gulf region of the U.S. all La Niña years will have lower than normal precipitation levels during the winter season, but there is an increased probability of less rain. During a La Niña phase, the western Pacific tends to

experience cooler and wetter climate conditions. The southern U.S. tends to experience dryer and warmer climate conditions. Western Canada and Northwestern U.S. experience cooler than normal temperatures. Other worldwide affects of La Niña are shown in the figure.

Questions on La Niña – Cold Phase

1. La Niña phase is also referred to as the __________ ________ phase.

2. Do scientists know what causes El Niño to develop? Yes No

3. What happens to the trade winds during a La Niña event?

4. What happens to the southern oscillation pressure difference during a La Niña event?

5. What happens to the warm pool of water during a La Niña phase?

6. What is the definition of a La Niña phase?

7. What happens to the thermocline during a La Niña phase?

8. What happens to the air pressure during a La Niña phase?

9. Analyze the maps of the global effects of La Niña. How could this possibly affect Joe Soccer’s decision? Remember Joe Soccer lives in the Southern U.S.

10. Are the effects of La Niña on precipitation the same worldwide? Yes No

11. Are the effects of La Niña on temperature the same worldwide? Yes No

12. Provide one example where the effects differ or are the same.

13. Understand the figure in the readings concerning the Pacific Ocean during La Niña conditions.

After completing the questions above you are an expert on La Niña. Your job is to explain this event to your new partners tomorrow. You should study your information and answers for homework and be ready to explain this process to your classmates tomorrow.

Becoming an Expert on Impact of ENSO on Climate Variability

To become an expert on climate variability related to ENSO read the following information and complete the questions. Your teacher may require you to read other sources of information.

The coupling of the ocean and atmosphere laid the foundation for explaining teleconnections between ENSO and climate variability in regions outside the Pacific Ocean. A teleconnection is a linkage between a physical process in one region and climate anomalies in other regions. Teleconnections between ENSO and climate conditions have been made for parts of Australia, North and South America, southern Africa, India, northern Africa, and, Southeast Asia. The strength of the teleconnection depends on the strength of the ENSO event. The affect of ENSO on climate variability also depends on the time of the season. The strongest ENSO impacts are found close to the equator.

Two important points associated with ENSO’s affect on climate variability must be explained. First, the affect of ENSO on climate variability is a change in the probability of increase or decrease in precipitation amounts and temperatures. Second, no one storm can be attributed to an ENSO. Often in the popular media, nonscientific writers attribute a single storm to the ENSO event. For example, a snowstorm is attributed to a La Niña phase during the winter. This is incorrect. Snowstorms occur every year. Rather, the ENSO event is associated with an increase in the probability of higher or lower precipitation amounts or temperatures.

Pacific / North American Jet stream Changes

Scientists do not know what causes ENSO phases to develop. They do know, however, the affects of the different phases. Teleconnections partially depend on the Walker circulation. Shifts in the Walker Circulation change airflows east and west over the tropical Pacific. These shifts affect the jet stream that, in turn, modifies storm patterns. Jet streams are a relatively narrow band of strong winds in the upper levels of the atmosphere. Jet streams are usually found approximately 6-9 miles above the earth's surface. Changes in the jet stream causes changes in the storm patterns for North America are illustrated in the following figure. During an El Niño event, cooler, wetter weather occurs in the southern U.S. because the Pacific jet stream tends to stay on a southern track. This jet stream pattern brings in storms from the Pacific Ocean to the southern U.S. The Polar jet stream is pushed to the east, which is associated with warmer weather in Northern U.S. and parts of Canada.

La Niña conditions tend to push the Pacific jet stream northward. This is associated with fewer storms in the southern U.S. The northern track of the Pacific jet stream is associated with wetter weather in northwest U.S. The polar jet stream tends to be pushed westerly. The western position of the polar jet stream is associated with cooler temperatures in the northern U.S. and parts of Canada.

Questions on ENSO’s Impact on Climate Variability

1. What is a teleconnection?

2. What parts of the world have teleconnections been made between ENSO and climate conditions?

3. Where are the strongest ENSO impacts found?

4. Two important points are discussed in the information regarding ENSO’s affect on climate variability. Explain those two points in your own words.

5. Why is a change in the jet stream important in determining climate variability for the U.S.?

6. What happens to the Pacific jet stream during an El Niño phase during January to March?

7. What general affect does the change of the jet stream during an El Niño phase have on climate conditions in the southern U.S. during January to March?

8. What general affect does the change of the jet stream during an El Niño phase have on climate conditions in the northern U.S. during the January to March.?

9. What happens to the Pacific jet stream during a La Niña phase during January to March?

10. What general affect does the change of the jet stream during a La Niña phase have on climate conditions in the southern U.S. during January to March?

11. What general affect does the change of the jet stream during a La Niña phase have on climate conditions in the northern U.S. during January to March?

12. Understand the figure in the readings concerning the jet stream and climate variability across the U.S. Sketch the figure.

El Nino Conditions La Nina Conditions

After completing the questions above you are an expert on U.S. climate variability associated with ENSO. Your job is to explain this event to your new partners tomorrow. You should study your information and answers for homework and be ready to explain this process to your classmates tomorrow.

ENSO Jigsaw Worksheet - Pacific Ocean Aspects

Under the normal conditions provide a definition of the physical aspect, whereas under El Nino and La Nina note the Pacific Ocean anomaly (difference from normal) for the phase. Be sure you understand the pictures and are able to sketch them. Hint: conditions are usually opposite between the two conditions.

Anomaly from Normal Physical AspectDefinition / Importance

Anomaly from Normal

Warm Pool of Water - importance

Thermocline

Trade Winds / Walker Circulation

Jet Stream

Another Phase NameNo Definition

Southern Oscillation

Upwelling - Biological

ENSO Jigsaw Worksheet – U.S. Climate Variability Aspects

1. This page pertains to ENSO affects on climate, especially during January to March period. For the two different phases, mark (a circle would work) with a red pencil the areas of the U.S. that have warmer than normal temperatures. With a blue pencil, mark areas that have cooler than normal temperatures. In green, mark the areas that have higher than normal precipitation. Finally, in brown mark the areas that have lower than normal precipitation. Draw in the changes in the jet stream between the two phases. Be Neat!

La Nina – Cold Phase El Nino – Warm Phase

2. What is a teleconnection?

3. Recall, Joe Soccer lives in Southern U.S. What is the typical anomaly associated with El Niño phase for precipitation and temperature in Texas?

4. What is the typical anomaly associated with La Niña phase for precipitation and temperature in Texas?

5. Do these anomalies always occur as you answered in questions 2 and 3 for El Niña and La Niña phases? Yes No

6. Discuss in your group how Joe might use the above information.

ENSO Jigsaw Worksheet – Worldwide Climate Variability Aspects - Optional

This page pertains to ENSO affects on climate. For the two different phases, mark (a circle would work) with a red pencil the areas that have warmer than normal temperatures. With a blue pencil, mark areas that have cooler than normal temperatures. In green, mark the areas that have higher than normal precipitation. Finally, in brown mark the areas that have lower than normal precipitation. On one of the maps, mark the location of the Niño 3.4 region. Be Neat! One may need to refer back to the “Becoming an Expert on ___” reading materials.

La Nina – Cold Phase El Nino – Warm Phase

1. Do these anomalies you colored put in the maps always occur as you answered for El Niña and La Niña phases? Yes No

2. Why do you think the anomalies are stronger in the equator region of the world than in the rest of the world?

3. Why do you think much of the research into ENSO has originated in Australia?

ENSO Crossword Puzzle - Optional

1 2 3

4

5 6 7

8

9

10 11

12

13

14

15

Constructed using Crossword Weaver

Across

2 Upper level winds that create storm tracks.

4 First scientist to rigorous study ENSO5 precipitation and temperature over a

period longer than two weeks7 El Nino phase is sometimes know as

this because of hotter than normal sea surface temperatures

8 Relationship between the ocean and atmosphere

11 The boundary between cold deep water and warmer upper layer of water in an body of water.

12 precipitation and temperature over a period of two weeks or less

14 Linkage between physical process in one region and climate variability in another region.

15 Walker _____ is the vertical and horizontal movement of the trade winds, which form a circular pattern

Down

1 Changes in climate between years is an example of this

3 changes from the normal or a base6 Imaginary line around the middle of

the world.9 ____ Oscillation refers to the seesaw

pattern of air pressure between the western and eastern Pacific Ocean.

10 ____ winds cause the sea level to be higher in the western Pacific Ocean

13 La Nina phase is sometimes known as this because of cooler than normal sea surface temperatures

Other Effects of ENSO - Optional

There is evidence of ENSO having an effect on the occurrence of forest fires, floods, and hurricanes, along with impacts on human health. But, what are these effects? As with ENSO, scientists are still learning about links between climate and other physical, biological, and human aspects. The following paragraphs provide brief explanations to how ENSO may affect these different aspects. Answer the following questions after reading the associated paragraphs.

Forest Fires / Floods

As you learned in the science module, ENSO impacts precipitation in various areas of the world. Changes in precipitation can lead to other changes in the environment. One such change is a change in the number of wildfires, both brush and forest fires. As you have learned previously, the different ENSO phases may cause some areas to be drier than normal. Decreased precipitation may lead to an increase in wildfires. For example, during some El Niño years, increased number and severity of forest fires have been reported in Indonesia (country northwest of Australia) and Australia. The most predominant year for forest fires in Indonesia was the El Nino of 1982 and 1983. The 1997- 1998 year also saw an increased number of forest fires. These years saw particularly strong El Niño phases. Similarly, increased precipitation associated with an ENSO phase in a particular area may cause an increase in flooding. But, not all years see an increase in fires or floods. 1. Why is there a greater risk of increased forest fires during an El Niño year in Australia?

2. During what El Niño season were forest fires most predominant?

3. What country has suffered the most recently from the effects of forest fires associated with the El Niño phase?

4. Why do some areas see an increased probability of flooding during an El Niño year?

Hurricanes

Hurricanes (also known as tropical cyclones or typhoons depending on the area of the world they occur) need warm ocean water to develop. Hurricanes occur during all ENSO phases. However, changes in the warm pool of water cause by the different ENSO phase have implications for location and development of hurricanes. In the western Pacific Ocean, El Niño phases decreases tropical cyclone activity. This is expected as the warm pool of water moves eastward. Activity in the central and eastern Pacific increases during El Niño phase. Hurricane activity in the Atlantic basin is affected by ENSO through changes in the Atlantic atmospheric circulation. El Niño phases contribute to a decreased numbers of Atlantic tropical storms and hurricanes. La Niña phases generally have opposite conditions, increased storms in the western Pacific and Atlantic Oceans and decreased storms in the central and eastern Pacific Ocean. Bove et al. (http://www.aoml.noaa.gov/hrd/Landsea/elnino/) give the average number of U.S. Atlantic hurricanes during El Niño years is 1.04, 1.61 during neutral years, and 2.23 during La Niña.

5. Why does a La Niña event increase the risk for of a hurricane in Australia?

6. How does an El Niño event affect the number of hurricanes affecting the U.S.? Hint: consider both Atlantic and Pacific Oceans.

7. How does a La Niña event affect the number of hurricanes affecting the U.S.? Hint: consider both Atlantic and Pacific Oceans.

8. During an El Niño phase 1.04 hurricanes always hit the U.S. True or false and why?

Human Health

The World Health Association notes a pattern between the different ENSO events and outbreak of diseases. However, generalizing the relationship between disease outbreaks and ENSO events is not easy. Local health delivery systems affect the incident of diseases. In addition, local ecological conditions, along with humidity, timing of precipitation, and temperature changes, affect the transmission of diseases. To illustrate the complex relationship between ENSO and diseases consider the case of malaria. Malaria is a mosquito borne disease. In countries that are normally relatively warm with low precipitation levels (such as countries in southern Africa), an ENSO phase that increases precipitation may be associated with increased cases of malaria. This occurs because increased precipitation causes increases in standing water necessary for mosquitoes to reproduce. More mosquitoes mean a higher chance for disease outbreak. Increased precipitation leads to increased cases of malaria.

In countries that are normally warm and have high precipitation levels (such as Venezuela, Columbia, and Sri Lanka), an ENSO phase that decreases precipitation may lead to an outbreak of malaria. Decreased precipitation may turn normal flowing rivers into stagnant ponds. These stagnant ponds provide the breeding grounds for the mosquitoes which flowing rivers could not provide. Here, decreased precipitation leads to increased cases of malaria. In addition to malaria, researchers have found approximately 21 infectious diseases that may have a relationship with ENSO. Other diseases that may have a relationship with ENSO events include Dengue, Australian Encephalitis, Rift Valley Fever, and valley fever. Much more research is necessary to understand the relationship between health and ENSO events.http://www.who.int/mediacentre/factsheets/fs192/en/

9. Malaria is transmitted by what insect?

10. Besides ENSO what other factors are important in determining if a disease outbreak occurs.

11. Countries that normally have high precipitation levels may see an increase in malaria during ENSO phases that bring decreased precipitation. Why?

12. Countries that normally have low precipitation levels may see an increase in malaria during ENSO phases that bring increased precipitation. Why?

13. Optional Question: ENSO impacts other physical and biological phenomenon in addition to the ones discussed here. Write a short paragraph on other potential ENSO impacts by conducting web-based research. Suggested topics, but not limited to, are fish production in the eastern Pacific, western U.S. snow pack, tornados in the U.S., droughts in Australia, and salmon production in the U.S. and British Columbia.

For additional information see

Forest Fireshttp://ess.geology.ufl.edu/usra_esse/ENSO_Impacts.htmlhttp://iri.columbia.edu/climate/ENSO/societal/impact/methods/BasicQuestions.html

Human Healthhttp://image.thelancet.com/extras/02art5336web.pdfhttp://www.who.int/mediacentre/factsheets/fs192/en/http://www.ispe.arizona.edu/climas/research/vf/background.html

Hurricaneshttp://www.aoml.noaa.gov/hrd/Landsea/lanina/http://www.aoml.noaa.gov/hrd/Landsea/elnino/http://www.aoml.noaa.gov/hrd/tcfaq/G2.html

Tornadoshttp://www.spc.noaa.gov/publications/schaefer/el_nino.htm