A weather satellite or meteorological satellite is a type of Earth observation satellite that is primarily used to monitor the

weather Weather is the state of the atmosphere, describing for example the degree to which it is hot or cold, wet or dry, calm or stormy, clear or cloudy. On Earth, most weather phenomena occur in the lowest layer of the planet's atmosphere, the ...

and

climate Climate is the long-term weather pattern in an area, typically averaged over 30 years. More rigorously, it is the mean and variability of meteorological variables over a time spanning from months to millions of years. Some of the meteorologi ...

of the Earth. Satellites can be polar orbiting (covering the entire Earth asynchronously), or geostationary (hovering over the same spot on the

equator The equator is a circle of latitude, about in circumference, that divides Earth into the Northern and Southern hemispheres. It is an imaginary line located at 0 degrees latitude, halfway between the North and South poles. The term can also ...

). While primarily used to detect the development and movement of storm systems and other cloud patterns,

meteorological Meteorology is a branch of the atmospheric sciences (which include atmospheric chemistry and physics) with a major focus on weather forecasting. The study of meteorology dates back millennia, though significant progress in meteorology did not ...

satellites can also detect other phenomena such as city lights, fires, effects of pollution, auroras, sand and

dust storm A dust storm, also called a sandstorm, is a meteorological phenomenon common in arid and semi-arid regions. Dust storms arise when a gust front or other strong wind blows loose sand and dirt from a dry surface. Fine particles are transp ...

s, snow cover, ice mapping, boundaries of

ocean current An ocean current is a continuous, directed movement of sea water generated by a number of forces acting upon the water, including wind, the Coriolis effect, breaking waves, cabbeling, and temperature and salinity differences. Depth conto ...

s, and energy flows. Other types of environmental information are 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 Colorado (, other variants) is a state in the Mountain West subregion of the Western United States. It encompasses most of the Southern Rocky Mountains, as well as the northeastern portion of the Colorado Plateau and the western edge of the ...

and

Utah Utah ( , ) is a state in the Mountain West subregion of the Western United States. Utah is a landlocked U.S. state bordered to its east by Colorado, to its northeast by Wyoming, to its north by Idaho, to its south by Arizona, and to its ...

have also been monitored. 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.

History

As early as 1946, the idea of cameras in orbit to observe the weather was being developed. This was due to sparse data observation coverage and the expense of using cloud cameras on rockets. By 1958, the early prototypes for TIROS and Vanguard (developed by the Army Signal Corps) were created. The first weather satellite, Vanguard 2, was launched on February 17, 1959. It was designed to measure cloud cover and resistance, but a poor axis of rotation and its elliptical orbit kept it from collecting a notable amount of useful data. The Explorer VI and VII satellites also contained weather-related experiments. The first weather satellite to be considered a success was TIROS-1, launched by NASA on April 1, 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. Beginning with the Nimbus 3 satellite in 1969, temperature information through the

tropospheric The troposphere is the first and lowest layer of the atmosphere of the Earth, and contains 75% of the total mass of the planetary atmosphere, 99% of the total mass of water vapour and aerosols, and is where most weather phenomena occur. From t ...

column began to be retrieved by satellites from the eastern Atlantic and most of the Pacific Ocean, which led to significant improvements to weather forecasts. The ESSA and NOAA polar orbiting satellites followed suit from the late 1960s onward. Geostationary satellites followed, beginning with the ATS and SMS series in the late 1960s and early 1970s, then continuing with the GOES series from the 1970s onward. Polar orbiting satellites such as QuikScat and TRMM began to relay wind information near the ocean's surface starting in the late 1970s, with microwave imagery which resembled radar displays, which significantly improved the diagnoses of

tropical cyclone A tropical cyclone is a rapidly rotating storm system characterized by a low-pressure center, a closed low-level atmospheric circulation, strong winds, and a spiral arrangement of thunderstorms that produce heavy rain and squalls. Dep ...

strength, intensification, and location during the 2000s and 2010s. The DSCOVR satellite, owned by NOAA, was launched in 2015 and became the first deep space satellite that can observe and predict space weather. It can detect potentially dangerous weather such as solar wind and geomagnetic storms. This is what has given humanity the capability to make accurate and preemptive space weather forecasts since the late 2010s.

Observation

Observation is typically made via different 'channels' of the

electromagnetic spectrum The electromagnetic spectrum is the range of frequencies (the spectrum) of electromagnetic radiation and their respective wavelengths and photon energies. The electromagnetic spectrum covers electromagnetic waves with frequencies ranging fro ...

, in particular, the visible and

infrared Infrared (IR), sometimes called infrared light, is electromagnetic radiation (EMR) with wavelengths longer than those of Light, visible light. It is therefore invisible to the human eye. IR is generally understood to encompass wavelengths from ...

portions. Some of these channels include:EUMETSAT – MSG Spectrum
(PDF) *''Visible and Near Infrared:'' 0.6–1.6 μmfor recording cloud cover during the day *''Infrared:'' 3.9–7.3 μm (water vapor), 8.7–13.4 μm (thermal imaging)

Visible spectrum

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.

Infrared spectrum

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.

Infrared Infrared (IR), sometimes called infrared light, is electromagnetic radiation (EMR) with wavelengths longer than those of Light, visible light. It is therefore invisible to the human eye. IR is generally understood to encompass wavelengths from ...

satellite imagery can be used effectively for

s with a visible eye pattern, using the

Dvorak technique The Dvorak technique (developed between 1969 and 1984 by Vernon Dvorak) is a widely used system to estimate tropical cyclone intensity (which includes tropical depression, tropical storm, and hurricane/typhoon/intense tropical cyclone intensiti ...

, where the difference between the temperature of the warm eye and the surrounding cold cloud tops can be used to determine its intensity (colder cloud tops generally indicate a more intense storm). 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.

Types

First Full Disk Image from GOES-17 as GOES West (40118037553)

Each meteorological satellite is designed to use one of two different classes of orbit: geostationary and polar orbiting.

Geostationary

Geostationary weather satellites orbit the Earth above the

at altitudes of 35,880 km (22,300 miles). Because of this

orbit In celestial mechanics, an orbit is the curved trajectory of an object such as the trajectory of a planet around a star, or of a natural satellite around a planet, or of an artificial satellite around an object or position in space such as ...

, 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. These are also available on the city forecast pages of www.noaa.gov (example Dallas, TX). Several geostationary meteorological spacecraft are in operation. The United States' GOES series has three in operation:

GOES-15 GOES-15, previously known as GOES-P, is an American weather satellite, which forms part of the Geostationary Operational Environmental Satellite (GOES) system operated by the U.S. National Oceanic and Atmospheric Administration. The spacecraft was ...

GOES-16 GOES-16, formerly known as GOES-R before reaching geostationary orbit, is the first of the GOES-R series of Geostationary Operational Environmental Satellites (GOES) operated by NASA and the National Oceanic and Atmospheric Administratio ...

and GOES-17. GOES-16 and-17 remain stationary over the Atlantic and Pacific Oceans, respectively. GOES-15 was retired in early July 2019. The satellite GOES 13 that was previously owned by the National Oceanic and Atmospheric Association (NOAA) was transferred to the

U.S. Space Force The United States Space Force (USSF) is the space service branch of the U.S. Armed Forces, one of the eight U.S. uniformed services, and the world's only independent space force. Along with its sister branch, the U.S. Air Force, the Space ...

in 2019 and renamed the EWS-G1; becoming the first geostationary weather satellite to be owned and operated by the U.S. Department of Defense.

Russia Russia (, , ), or the Russian Federation, is a transcontinental country spanning Eastern Europe and Northern Asia. It is the largest country in the world, with its internationally recognised territory covering , and encompassing one-ei ...

's new-generation weather satellite

Elektro-L No.1 Elektro-L No.1 (russian: Электро-L), also known as Geostationary Operational Meteorological Satellite No.2 or GOMS No.2, is a Russian geostationary weather satellite which was launched in 2011. The first Elektro-L spacecraft to fly, it beca ...

operates at 76°E over the Indian Ocean. The Japanese have the MTSAT-2 located over the mid Pacific at 145°E and the Himawari 8 at 140°E. The Europeans have four in operation,

Meteosat The Meteosat series of satellites are geostationary meteorological satellites operated by EUMETSAT under the Meteosat Transition Programme (MTP) and the Meteosat Second Generation (MSG) program. The MTP program was established to ensure the ope ...

-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. China currently has four

Fengyun Fēngyún (FY, ) are China's meteorological satellites. Launched since 1988 into polar sun-synchronous and geosynchronous orbit, each three-axis stabilized Fengyun satellite is built by the Shanghai Academy of Spaceflight Technology ( SAST) and ...

(风云) geostationary satellites (FY-2E at 86.5°E, FY-2F at 123.5°E, FY-2G at 105°E and FY-4A at 104.5 °E) operated.

India India, officially the Republic of India (Hindi: ), is a country in South Asia. It is the List of countries and dependencies by area, seventh-largest country by area, the List of countries and dependencies by population, second-most populous ...

also operates geostationary satellites called INSAT which carry instruments for meteorological purposes.

Polar orbiting

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 orbiting weather satellites are in

sun-synchronous orbit A Sun-synchronous orbit (SSO), also called a heliosynchronous orbit, is a nearly polar orbit around a planet, in which the satellite passes over any given point of the planet's surface at the same local mean solar time. More technically, it is ...

s, which means they are 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-15, NOAA-18 and NOAA-19 ( POES) and NOAA-20 ( JPSS). Europe has the Metop-A, Metop-B and Metop-C satellites operated by EUMETSAT. Russia has the

Meteor A meteoroid () is a small rocky or metallic body in outer space. Meteoroids are defined as objects significantly smaller than asteroids, ranging in size from grains to objects up to a meter wide. Objects smaller than this are classified as mi ...

and RESURS series of satellites. China has FY-3A, 3B and 3C. India has polar orbiting satellites as well.

DMSP

The

United States Department of Defense The United States Department of Defense (DoD, USDOD or DOD) is an executive branch department of the federal government charged with coordinating and supervising all agencies and functions of the government directly related to national sec ...

'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 An oil tanker, also known as a petroleum tanker, is a ship designed for the bulk transport of oil or its products. There are two basic types of oil tankers: crude tankers and product tankers. Crude tankers move large quantities of unrefined ...

. 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,

volcano A volcano is a rupture in the crust of a planetary-mass object, such as Earth, that allows hot lava, volcanic ash, and gases to escape from a magma chamber below the surface. On Earth, volcanoes are most often found where tectonic plates ...

es, fires, lightning,

meteor A meteoroid () is a small rocky or metallic body in outer space. Meteoroids are defined as objects significantly smaller than asteroids, ranging in size from grains to objects up to a meter wide. Objects smaller than this are classified as mi ...

s, oil field burn-offs, as well as the Aurora Borealis and

Aurora Australis An aurora (plural: auroras or aurorae), also commonly known as the polar lights, is a natural light display in Earth's sky, predominantly seen in high-latitude regions (around the Arctic and Antarctic). Auroras display dynamic patterns of bri ...

have been captured by this space vehicle's low moonlight sensor. At the same time, energy use and city growth can be monitored since both major and even minor cities, as well as highway lights, are conspicuous. This informs

astronomer An astronomer is a scientist in the field of astronomy who focuses their studies on a specific question or field outside the scope of Earth. They observe astronomical objects such as stars, planets, moons, comets and galaxies – in either ...

s of

light pollution Light pollution is the presence of unwanted, inappropriate, or excessive use of artificial lighting. In a descriptive sense, the term ''light pollution'' refers to the effects of any poorly implemented lighting, during the day or night. Light po ...

. 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

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 A firefighter is a first responder and rescuer extensively trained in firefighting, primarily to extinguish hazardous fires that threaten life, property, and the environment as well as to rescue people and in some cases or jurisdictions als ...

when it will rain. Some of the most dramatic photos showed the 600 Kuwaiti oil fires that the fleeing Army of Iraq started on February 23, 1991. The night photos showed huge flashes, far outstripping the glow of large populated areas. The fires consumed millions of gallons of oil; the last was doused on November 6, 1991.

Uses

NOAA Shares First Infrared Imagery from GOES-17 (43904870711)

Snowfield monitoring, especially in the

Sierra Nevada The Sierra Nevada () is a mountain range in the Western United States, between the Central Valley of California and the Great Basin. The vast majority of the range lies in the state of California, although the Carson Range spur lies primar ...

, can be helpful to the hydrologist keeping track of available

snowpack Snowpack forms from layers of snow that accumulate in geographic regions and high elevations where the climate includes cold weather for extended periods during the year. Snowpacks are an important water resource that feed streams and rivers as t ...

for runoff vital to the watersheds 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 spacecraft. Even pollution whether it is 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 A rocket (from it, rocchetto, , bobbin/spool) is a vehicle that uses jet propulsion to accelerate without using the surrounding air. A rocket engine produces thrust by reaction to exhaust expelled at high speed. Rocket engines work entir ...

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 A tropical cyclone is a rapidly rotating storm system characterized by a low-pressure center, a closed low-level atmospheric circulation, strong winds, and a spiral arrangement of thunderstorms that produce heavy rain and squalls. Dep ...

formation by modifying the

solar radiation Solar irradiance is the power per unit area ( surface power density) received from the Sun in the form of electromagnetic radiation in the wavelength range of the measuring instrument. Solar irradiance is measured in watts per square metre ...

balance of the tropics. Other

s in Asia and

mainland China "Mainland China" is a geopolitical term defined as the territory governed by the China, People's Republic of China (including islands like Hainan or Chongming Island, Chongming), excluding dependent territories of the PRC, and other territorie ...

are common and easy to spot and monitor, with recent examples of dust moving across the Pacific Ocean and reaching North America. 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 show the burn-off in gas and oil fields. Atmospheric temperature and moisture profiles have been taken by weather satellites since 1969.

Non-imaging sensors

Not all weather satellites are direct

imager An image sensor or imager is a sensor that detects and conveys information used to make an image. It does so by converting the variable attenuation of light waves (as they pass through or reflect off objects) into signals, small bursts of cur ...

s. Some satellites are ''sounders'' that take measurements of a single

pixel In digital imaging, a pixel (abbreviated px), pel, or picture element is the smallest addressable element in a raster image, or the smallest point in an all points addressable display device. In most digital display devices, pixels are the ...

at a time. They have no horizontal spatial resolution but often are capable or resolving vertical atmospheric layers. Soundings along the satellite ground track can still be gridded later to form maps.

International regulation

According to the

International Telecommunication Union The International Telecommunication Union is a specialized agency of the United Nations responsible for many matters related to information and communication technologies. It was established on 17 May 1865 as the International Telegraph Unio ...

(ITU), a meteorological-satellite service (also: meteorological-satellite radiocommunication service) is – according to ''Article 1.52'' of the

ITU Radio Regulations The ITU Radio Regulations (short: RR) is a basic document of the International Telecommunication Union (ITU) that regulates on law of nations scale radiocommunication services and the utilisation of radio frequencies. It is the supplementatio ...

(RR) – defined as ''« An earth exploration-satellite service for

purposes.» ''

Classification

This ''radiocommunication service'' is classified in accordance with ''ITU Radio Regulations'' (article 1) as follows:
Fixed service (article 1.20) * Fixed-satellite service (article 1.21) * Inter-satellite service (article 1.22) * Earth exploration-satellite service (article 1.51) **Meteorological-satellite service

Frequency allocation

The allocation of radio frequencies is provided according to ''Article 5'' of the ITU Radio Regulations (edition 2012).''ITU Radio Regulations, CHAPTER II – Frequencies, ARTICLE 5 Frequency allocations, Section IV – Table of Frequency Allocations'' In order to improve harmonisation in spectrum utilisation, the majority of service-allocations stipulated in this document were incorporated in national Tables of Frequency Allocations and Utilisations which is with-in the responsibility of the appropriate national administration. The allocation might be primary, secondary, exclusive, and shared. *primary allocation: is indicated by writing in capital letters (see example below) *secondary allocation: is indicated by small letters *exclusive or shared utilization: is within the responsibility of administrations ; Example of

frequency allocation Frequency allocation (or spectrum allocation or spectrum management) is the allocation and regulation of the electromagnetic spectrum into radio frequency bands, normally done by governments in most countries. Because radio propagation does ...

References

External links

;Theory *
Cooperative Institute for Meteorological Satellite Studies
** ttp://profhorn.meteor.wisc.edu/wxwise/museum/a3/a3example1.html Interpreting Satellite Images – Suomi Virtual Museumbr>Physical Characteristics of Geostationary and Polar-Orbiting weather satellites

NOAA Economics & Social Benefits of POES
;Data
Near realtime composite of satellite image of the Earth
by ''Intellicast''
International weather satellite viewer
Online geostationary weather satellite viewer with 2 months of archived data.
Earth at night
by NASA
EUMETSAT – the European Organisation for the Exploitation of Meteorological Satellites
Near real-time and archived satellite imagery and cloud products. *ISCCP Global ISCCP B1 Browse System (GIBBS) http://www.ncdc.noaa.gov/gibbs/ ;Government policy
Geostationary Weather Satellites: Progress Made, but Weaknesses in Scheduling, Contingency Planning, and Communicating with Users Need To Be Addressed: Report to the Committee on Science, Space, and Technology, House of Representatives
Government Accountability Office
Polar Weather Satellites: NOAA Identified Ways to Mitigate Data Gaps, but Contingency Plans and Schedules Require Further Attention: Report to the Committee on Science, Space, and Technology, House of Representatives
Government Accountability Office {{DEFAULTSORT:Weather Satellite American inventions 1959 introductions *