Meteorological satellite

A satellite Météorologique is an Artificial satellite which has like main mission of taking data for the monitoring of the time and of the Climat of the Ground. With each new generation, the sensors on board these satellites become more powerful and divide information into more of channels so that one can use them to differentiate the various weather phenomena: clouds, precipitations, winds, fog, etc

Several countries launch and maintain meteorological satellites: the United States, European countries with the European space agency (ESA), India, China, Russia and Japan. Together, all these satellites surround the sphere and give a total cover of the atmosphere.

History

The first meteorological satellite, the Vanguard 2, was launched the February 17th 1959 to measure the cloud cover. Unfortunately, during its orbiting, its axis of rotation was badly directed and it could give only little information.

TIROS-1 was the first success in this field. NASA launched it on April 1st 1960 and transmitted during 78 days. He was the ancestor of the program Nimbus which led to the development of the modern meteorological satellites launched by NASA and operated by NOAA.

Types

There are two types of meteorological satellites: geostationary and circumpolar.

Geostationary satellites

Located directly above the equator and with a distance such (35 880 km), they orbit in way Synchrone with the Earth. The geostationary satellites can thus take information uninterrupted of the same portion of the sphere, especially in the visible spectrums and infra-red S.

This information is used by the meteorologists to visually follow the weather systems in addition to extracting from the derived data (Température and Albédo) to know the structure of the atmosphere and the clouds, data which one will inject into the models of numerical forecast. The media also decorate their bulletins weather of animations in loop coming from these satellites.

The geostationary satellites have a maximum resolution at their under-point, the point of the equator to the vertical of which they are located. This resolution decreases while going towards the edges of the terrestrial disc because of the Parallaxe of the angle of sight more and more shaving. Thus, for example, with the top of 65 degrees of Northern latitude or in lower part of 65 degrees of Southern latitude, they become almost unusable.

The various countries referred to above maintain a fleet of these satellites:

the United States: The series GOES covering Americas and part of the Atlantic and the Pacific. The GOES-11 and GOES-12 are those active in 2006 but at the end of May, the GOES-N was put into orbit and will become GOES-13 once activated.
ESA: Europeans have the series Meteosat with numbers 6,7 and 8 covering the Atlantic and number 5, the Indian Ocean.
Japan: MTSAT -1R is positioned with 140°E and covers the Pacific.
India: METSAT -1/stabilized KALPANA-1 with 74°E.
Russia: With positioned GOMS with the longitude of Moscow.
China: Use the series Feng-Yun （風雲) of which most recent is the FY-2C with 105°E launched in October 2004.

Circumpolar satellites

For complémenter the geostationary satellites, satellites orbit around the Earth at low altitude (~720 - 800 km) according to a trajectory passing by the poles. They are heliosynchronous, i.e. their axis of rotation is perpendicular to the axis between the Sun and the Earth. They can thus pass twice above any point of the surface of the sphere to each day with a similar luminosity.

As they are brought closer to surface, these satellites have a better resolution. One can distinguish more easily the details there from temperature from the clouds and their visible form. Forest fires and the fog are much more obvious there. One can even extract some from information on the wind according to the shape and the displacement of the clouds. Unfortunately, as they do not cover same terrestrial surface continuously, they have a use more limited to supervise the weather in real-time. It are especially useful in this field in the polar regions where composite images coming from the various satellites are more frequent and make it possible to see what is almost invisible with the geostationary satellites.

However, for uses of longer breath, these satellites give important information. The data Infrarouge S and visible collected by these satellites make it possible to follow displacement to medium term of phenomena the such marine currents like the Gulf Stream and El Nino and the masses of air with a precision much larger.

The United States uses the series TIROS of NOAA in binomials on opposite orbits (worms north and the other towards the south). At present, the NOAA/TIROS 12 and 14 are in reserve in orbit whereas the 15,16,17 and 18 are used (2006). Russia has the series Meteor and RESURS . China and India also have circumpolar satellites.

Instrumentation

These satellites are provided originally with two types of sensors:

Of the Radiometer S to note the temperature of the atmosphere and the Hydrometeor S which are there. They operate in the spectrum Infrarouge. The first instruments “looked at” only some wavelengths whereas the new generations divide this spectrum into more than 10 channels
Of the radiometers in the visible one to note the brightness of the solar reflection on various surfaces. These data are corrected by the trace programs on the ground according to the angle of the sun to standardize information.

More recently, one added there:

a sounder which carries out an aerological survey of the remote terrestrial atmosphere to draw from it the structure of temperature and moisture.

Use

In addition to weather information on the temperature and the cover of the clouds one can mention:

Measurement of the Temperature of sea surface, the cover of ice in winter and displacements of the Iceberg S for the sailors and the climatological fishermen
Studies of the progression of the Glacier S, the Deserted S for the Hydrology
Evolution of smoke coming from the Forest fires, the volcanic ash (eruption of the Holy Mount Helens for example), from the sandstorms to the the Sahara, etc
Study of the atmospheric Pollution and the trails of Fuel oil at sea
To follow the evolution of the luminosity of the cities for studies of luminous pollution or to locate a night loss of current
the northern lights.

Information of these meteorological satellites can be complementary to other types of environmental satellites to follow the changes of vegetation, the state of the sea, the cast iron of the glaciers. Their data are also treated to draw the structure of the atmosphere from it (stability, temperature, winds and moisture) what supplements the data of ground stations and aerological to feed the numerical forecasting models.

The American ministry for defense has its own meteorological satellites within the framework of the program Defense Meteorological Satellite Program (DMSP). The latter have a resolution of a few hundred meters (size of a ship) and a luminous sensitivity which makes it possible to see in visible even the night. The blackout of 1977 in New York was particularly notable on these circumpolar satellites which can also locate the hearths of forest fire and even the sources brooding under surface.

See too

Internal bonds

Artificial satellite
Chronology of the artificial satellites and space probes
METEOSAT
European space agency
NOAA and NASA

External bonds

Questions and answers: Fair with the questions about the use of the satellite photographs by Environment Canada
the meteorological satellites, on the site of Weather-France
Excels site for the interpretation of the satellite photographs by EUMETSAT, DHMZ, the IMF, KNMI and ZAMG
space Applications for the development
Cactéristiques of the geostationary and circumpolar satellites
satellite Images in real-time by SE
Interprète the satellite images by Suomi Virtual Museum
Biographie of Dr. Verner Suomi (“the father of the meteorological satellite”)

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