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Glossary of ENSO Terms
- anomaly
- The difference between the value of a variable (for example temperature) at a given location and its long term average at that location.
- circulation
- The flow or motion of a fluid.
- climatology
- A quantitative description of climate showing the characteristic values of climate variables over a region. Climate refers to the statistical collection of weather conditions over a specified period of time. Note that the climate taken over different periods of time (30 years, 1000 years) may be different.
- convection
- Mass motions in a field resulting in transport and mixing of the field. More specifically, it refers to motion associated with a rising current of air.
- coupled model (or coupled atmosphere-ocean model).
- In the context of climate modeling this usually refers to a numerical model which simulates both atmospheric and oceanic motions and temperatures and which takes into account the effects of each component on the other.
- cumulonimbus
- A cloud type that is dense and vertically developed and is associated with rain (particularly of a convective nature).
- composite
- An average that is done according to a specific criteria. For example, one could composite the rainfall at a station for all years where the temperature was much above average.
- jet stream
- Strong winds concentrated within a narrow zone in the atmosphere. Often used in reference to the axis of maximum mid-latitude westerlies located in the high troposphere.
- monsoons
- Seasonal winds. They are caused primarily by the greater annual variation in air temperature over large land surfaces compared to ocean surfaces though other factors like land-relief are important.
- stationary waves
- Waves (flow patterns with periodicity in time and/or space) that are fixed relative to Earth.
- storm track
- The path followed by the center of a low (of atmospheric pressure). In many cases, multiple storms follow the same storm track.
- teleconnection
- A strong statistical relationship between weather in different parts of the globe. For example, there appears to be a teleconnection between the tropics and North America during El Niño.
- thermocline
- As one descends from the surface of the ocean the temperature remains nearly the same as it was at the surface. Soon, however, one encounters a zone in which temperature starts decreasing rapidly with depth. This zone is called the thermocline. The thermocline is important because it can support large scale waves which play a major role in ENSO. In studying the tropical Pacific Ocean, the depth of 20C water ("the 20C isotherm") is often used as a proxy for the depth of the thermocline. Along the equator, the 20C isotherm is typically located at about 50m depth in the eastern pacific, sloping downwards to about 150 m in the western Pacific.
- upwelling
- In ocean dynamics, the upward motion of sub-surface water toward the surface of the ocean. This is often a source of cold, nutrient-rich water. Strong upwelling occurs along the equator where easterly winids are present. Upwelling also can occur along coastlines, and is important to fisheries in California and Peru.