Everything about Weather Satellite totally explained
A
weather satellite is a type of
satellite that's primarily used to monitor the
weather and
climate of the
Earth. These meteorological
satellites, however, see more than
clouds and cloud systems. City lights,
fires, effects of
pollution,
auroras, sand and dust storms,
snow cover,
ice mapping, boundaries of
ocean currents,
energy flows, etc., are other types of environmental information collected using weather satellites.
Weather satellite images helped in monitoring the volcanic ash cloud from
Mount St. Helens and activity from other volcanoes such as
Mount Etna. Smoke from
fires in the western
United States such as
Colorado and
Utah have also been monitored.
Other environmental satellites can detect changes in the Earth's vegetation, sea state, ocean color, and ice fields. For example, the 2002 oil spill off the northwest coast of
Spain was watched carefully by the European ENVISAT, which, though not a weather satellite, flies an instrument (ASAR) which can see changes in the sea surface.
El Niño and its effects on weather are monitored daily from satellite images. The Antarctic ozone hole is mapped from weather satellite data. Collectively, weather satellites flown by the U.S., Europe, India, China, Russia, and Japan provide nearly continuous observations for a global weather watch.
Observation
Observation is typically made via different 'channels' of the
Electromagnetic spectrum, in particular, the
Visible and
Infrared portions.
Some of these channels include
:
- Visible and Near Infrared: 0.6 μm - 1.6 μm - For recording cloud cover during the day
- Infrared: 3.9 μm - 7.3 μm (Water Vapour), 8.7 μm, - 13.4 μm (Thermal imaging)
History
The first weather satellite,
Vanguard 2, was launched on
17 February 1959. It was designed to measure cloud cover and resistance, but a poor axis of rotation kept it from collecting a notable amount of useful data.
The first weather satellite to be considered a success was
TIROS-1, launched by NASA on
1 April 1960. TIROS operated for 78 days and proved to be much more successful than Vanguard 2. TIROS paved the way for the
Nimbus program, whose technology and findings are the heritage of most of the Earth-observing satellites NASA and NOAA have launched since then.
Types
There are two basic types of meteorological satellites:
geostationary and
polar orbiting.
Geostationary weather satellites orbit the Earth above the
equator at
altitudes of 35,880 km (22,300 miles). Because of this
orbit, they remain stationary with respect to the rotating Earth and thus can record or transmit images of the entire hemisphere below continuously with their visible-light and infrared sensors. The
news media use the geostationary photos in their daily weather presentation as single images or made into movie loops.
Several geostationary meteorological spacecraft are in operation. The
United States has two in operation;
GOES-11 and GOES-12. GOES-12 is designated GOES-East, over the
Amazon River and provides most of the U.S. weather information. GOES-11 is GOES-West over the eastern
Pacific Ocean. The
Japanese have one in operation;
MTSAT-1R over the mid Pacific at 140°E. The
Europeans have
Meteosat-8 (3.5°W) and Meteosat-9 (0°) over the
Atlantic Ocean and have Meteosat-6 (63°E) and Meteosat-7 (57.5°E) over the
Indian Ocean. The
Russians operate the
GOMS over the equator south of
Moscow.
India also operates geostationary satellites which carry instruments for meteorological purposes.
China operates the
Feng-Yun（風雲) geostationary satellites, FY-2C at 105°E and FY-2D at 86.5°E.
Polar orbiting weather satellites circle the Earth at a typical altitude of 850 km (530 miles) in a north to south (or vice versa) path, passing over the poles in their continuous flight. Polar satellites are in
sun-synchronous orbits, which means they're able to observe any place on Earth and will view every location twice each day with the same general lighting conditions due to the near-constant local
solar time. Polar orbiting weather satellites offer a much better resolution than their geostationary counterparts due their closeness to the Earth.
The United States has the
NOAA series of polar orbiting meteorological satellites, presently NOAA 17 and NOAA 18 as primary spacecraft, NOAA 15 and NOAA 16 as secondary spacecraft, NOAA 14 in standby, and NOAA 12. Europe has the Metop-A satellite. Russia has the
Meteor and RESURS series of satellites. China and India have polar orbiting satellites as well.
Visible-light images from weather satellites during local daylight hours are easy to interpret even by the average person; clouds, cloud systems such as fronts and tropical
storms,
lakes,
forests,
mountains, snow ice, fires, and pollution such as smoke,
smog, dust and haze are readily apparent. Even
wind can be determined by cloud patterns, alignments and movement from successive photos.
The thermal or infrared images recorded by sensors called scanning radiometers enable a trained analyst to determine cloud heights and types, to calculate land and surface water temperatures, and to locate ocean surface features. These infrared pictures depict ocean eddies or vortices and map currents such as the Gulf Stream which are valuable to the shipping industry.
Fishermen and
farmers are interested in knowing land and water temperatures to protect their crops against frost or increase their catch from the sea. Even El Niño phenomena can be spotted. Using color-digitized techniques, the gray shaded thermal images can be converted to color for easier identification of desired information.
Snowfield monitoring, especially in the
Sierra Nevada, can be helpful to the hydrologist keeping track of how much snow is available for runoff vital to the water sheds of the western United States. This information is gleaned from existing satellites of all agencies of the U.S. government (in addition to local, on-the-ground measurements). Ice floes, packs and bergs can also be located and tracked from weather space craft.
Even pollution whether it's nature-made or man-made can be pinpointed. The visual and infrared photos show effects of pollution from their respective areas over the entire earth.
Aircraft and
rocket pollution, as well as
condensation trails, can also be spotted. The ocean current and low level wind information gleaned from the space photos can help predict oceanic oil spill coverage and movement. Almost every
summer, sand and dust from the
Sahara Desert in
Africa drifts across the equatorial regions of the Atlantic Ocean. GOES-EAST photos enable meteorologists to observe, track and forecast this sand cloud. In addition to reducing visibilities and causing respiratory problems, sand clouds suppress
hurricane formation by modifying the
solar radiation balance of the tropics. Other
dust storms in
Asia and
mainland China are common and easy to spot and monitor, with recent examples of dust moving across the Pacific ocean and reaching
North America.
The
United States Department of Defense's Meteorological Satellite (
DMSP) can "see" the best of all weather vehicles with its ability to detect objects almost as 'small' as a huge
oil tanker. In addition, of all the weather satellites in orbit, only DMSP can "see" at night in the visual. Some of the most spectacular photos have been recorded by the night visual sensor; city lights,
volcanoes, fires, lightning,
meteors, oil field burn-offs, as well as the
Aurora Borealis and
Aurora Australis have been captured by this 450-mile-high space vehicle's low moonlight sensor.
At the same time, energy monitoring as well as city growth can be accomplished since both major and even minor cities, as well as highway lights, are conspicuous. This informs
Astronomers of
light pollution. The
New York City Blackout of 1977 was captured by one of the night orbiter DMSP space vehicles.
In addition to monitoring city lights, these photos are a life saving asset in the detection and monitoring of fires. Not only do the satellites see the fires visually day and night, but the thermal and
infrared scanners on board these weather satellites detect potential fire sources below the surface of the Earth where smoldering occurs. Once the fire is detected, the same weather satellites provide vital information about wind that could fan or spread the fires. These same cloud photos from space tell the
firefighter when it'll rain.
In remote areas of the world with few local observers, fires could rage out of control for days or even weeks and consume millions of acres before authorities are alerted. Weather satellites can be a tremendous asset in such situations. Nighttime photos also clearly show the burn-off in the gas and oil fields of the
Middle East and African countries. This burn-off throws large amounts of
carbon dioxide into the
atmosphere.
Dramatic photos are provided by all the weather satellites, but even more definitive were the DMSP night visible-light pictures of the 700 oil well fires that
Iraq started on
23 February 1991 as they fled
Kuwait. These fires were vividly illustrated as huge flashes in the night photos, far outstripping the glow of large populated areas. The fires consumed millions of gallons of oil; the last was doused on
November 6.
Further Information
Get more info on 'Weather Satellite'.
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