Scientists use several different types of satellite imagery to detect the presence of an El Niño. Imagery from the Topex/Poseidon satellites measures height of the sea surface, allowing researchers to look for increased water height in the western Pacific Ocean during an El Niño year. This body of water is also warmer than the surrounding water, so the satellites that measure sea surface temperature are also used in studies of El Niño.
Finally, the changes in wind patterns can help identify an El Niño as the normal easterly breeze shifts around and sometimes ceases entirely. Information on wind direction and strength is gathered from buoys placed in the Pacific Ocean. The shift or cessation of the trade winds allows the tongue of warm water to move towards the United States.
Determine if this year is an El Niño year or not
- Discuss with students the different means of detecting an El Niño using satellite imagery in conjunction with information from buoys stationed in the Pacific.
- Orient students to the different scales used in the satellite images.
- From the NOAA AVHRR imagery locate the areas of warmer water.
- From the TOPEX/POSEIDON imagery locate the areas of higher sea level. In general where are the areas of higher water located? (nearer to the equator than the poles) How do the areas with higher water compare to the areas with increased average water temperature?
- Discuss how the weakening of the trade winds is an important factor in the growth of an El Niño.
- Give students two different years of data from the buoys in the Pacific Ocean and ask them to characterize each one in terms of average wind speed and direction.
- Given all of this information, which year do you think represents an El Niño year?
Fisheries Impacted by El Niño
Many traditional fisheries are impacted by the presence of an El Niño. Fisheries depend on upwelling conditions to provide food for the fish they are collecting. In an El Niño year upwelling ceases along the eastern Pacific. Research the locations and types of fisheries in the Pacific Ocean. Determine which areas and fisheries are likely to be most impacted by El Niño.
Societal Impacts of Flooding
Weather forecasters often refer to severe storms as a 50-year storm or a 100-year storm. What do they mean by that? For comparison, geologist Ken Fink averaged data from most of the 20th century for Portland, Maine. The average elevation of water above the national geodetic vertical data established in 1929 for a 100-year storm is 2.92 meters. For a 50-year storm it is 2.86 meters and for a 10 year storm it is 2.60 meters.
Mark these heights on a stake or pole and hold it vertically against the school building to envision the effect of those storms. What would happen to your neighborhood or town if one of these storms struck?