Satellites and moored instruments in the Pacific provide the measurements we need to keep track of El Niño.
Three types of satellites are used to watch El Niño:
The National Oceanic and Atmospheric Administration's Pacific Marine Environmental Laboratory in Seattle, with the help of oceanographers in other countries, operates around 70 moorings in the tropical Pacific. A mooring is a steel or plastic rope that goes from a float on the surface to an anchor on the sea floor. The moorings holds instruments that measure surface winds, air temperature, relative humidity, sea surface temperature, and underwater temperatures. Data from the mooring are sent to Seattle by special satellite links.
Here are the conditions in the Pacific measured by the ATLAS moorings in December 1997. The maps show temperatures in the east 6°C warmer than normal. Winds in the west are weaker than normal. Arrows pointing toward the east indicate winds weaker than normal trade-winds, which have arrows that point west.
Questions that come to mind are:
1. What is El Niño?
2. How has it come to be called El Niño (the [male] child)?
3. What causes El Niño?
4. What's the big deal? What does El Niño mean to me?
5. What do scientists know about El Niño and how do they know what they know?
6. Where and when does El Niño occur and how often?