EM 1110-2-2907
1 October 2003
El Nio
A warming of the surface waters of the eastern equatorial Pacific that
occurs at irregular intervals of 2-7 years, lasting 1-2 years. Along the
west coast of South America, southerly winds promote the upwelling of
cold, nutrient-rich water that sustains large fish populations that sustain
abundant sea birds, whose droppings support the fertilizer industry.
Near the end of each calendar year, a warm current of nutrient-pool
tropical water replaces the cold, nutrient-rich surface water. Because
this condition often occurs around Christmas, it was named El Nio
(Spanish for boy child, referring to the Christ child). In most years the
warming last only a few weeks or a month, after which the weather
patterns return to normal and fishing improves. However, when El Nio
conditions last for many months, more extensive ocean warming occurs
and economic results can be disastrous. El Nio has been linked to
wetter, colder winters in the United States; drier, hotter summers in
South America and Europe; and drought in Africa. See ENSO.
Emission
Process by which a body radiates electromagnetic energy. Emission is
determined by kinetic temperature and emissivity.
Emissivity (e )
Ratio of radiant flux from a body to that from a blackbody at the same
kinetic temperature and emissivity.
Emittance
A term for the radiant flux of energy per unit area emitted by a body.
(Now obsolete).
Emulsion
Suspension of photosensitive silver halide grains in gelatin that
constitutes the image-forming layer on photographic film.
Energy flux
Radiant flux.
Enhancement
Process of altering the appearance of an image so that the interpreter
can extract more information.
ENSO (El Nio-Southern
Interacting parts of a single global system of climate fluctuations. ENSO
Oscillation)
is the most prominent known source of interannual variability in weather
and climate around the world, though not all areas are affected. The
Southern Oscillation (SO) is a global-scale seesaw in atmospheric
pressure between Indonesia/North Australia, and the southeast Pacific.
In major warm events El Nio warming extends over much of the
tropical Pacific and becomes clearly linked to the SO pattern. Many of
the countries most affected by ENSO events are developing countries
with economies that are largely dependent upon their agricultural and
fishery sectors as a major source of food supply, employment, and
foreign exchange. New capabilities to predict the onset of ENSO event
can have a global impact. While ENSO is a natural part of the Earth's
climate, whether its intensity or frequency may change as a result of
global warming is an important concern.
EOSAT
The commercial company that took over operations of the Landsat
system in 1985.
Ephemeris
A table of predicted satellite orbital locations for specific time intervals.
The ephemeris data help to characterize the conditions under which
remotely sensed data are collected and are commonly used to correct
the sensor data prior to analysis.
ERBSS
Earth Radiation Budget Sensor System, carried by NOAA satellites.
EREP
Earth Resources Experiment Package, carried on Skylab and
consisting of cameras and multispectral scanner.
EROS
Earth Resources Observation System.
EROS Data Center (EDC)
Facility of the U.S. Geological Survey at Sioux Falls, South Dakota, that
archives, processes, and distributes images.
ERTS
Earth Resource Technology Satellite, now called Landsat.
ESA
European Space Agency, based in Paris. A consortium between
several European states for the development of space science,
including the launch of remote-sensing satellites.
Glossary-10
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