Satellite temperature measurements are

inferences Inferences are steps in reasoning, moving from premises to logical consequences; etymologically, the word ''infer'' means to "carry forward". Inference is theoretically traditionally divided into deduction and induction, a distinction that in ...

of the

temperature Temperature is a physical quantity that expresses quantitatively the perceptions of hotness and coldness. Temperature is measured with a thermometer. Thermometers are calibrated in various temperature scales that historically have relied on ...

of the

atmosphere An atmosphere () is a layer of gas or layers of gases that envelop a planet, and is held in place by the gravity of the planetary body. A planet retains an atmosphere when the gravity is great and the temperature of the atmosphere is low. ...

at various altitudes as well as sea and land surface temperatures obtained from

radiometric Radiometry is a set of techniques for measuring electromagnetic radiation, including visible light. Radiometric techniques in optics characterize the distribution of the radiation's power in space, as opposed to photometric techniques, which ch ...

measurements by

satellites A satellite or artificial satellite is an object intentionally placed into orbit in outer space. Except for passive satellites, most satellites have an electricity generation system for equipment on board, such as solar panels or radioisotop ...

. These measurements can be used to locate

weather fronts A weather front is a boundary separating air masses for which several characteristics differ, such as air density, wind, temperature, and humidity. Disturbed and unstable weather due to these differences often arises along the boundary. For i ...

, monitor the

El Niño-Southern Oscillation EL, El or el may refer to: Religion * El (deity), a Semitic word for "God" People * EL (rapper) (born 1983), stage name of Elorm Adablah, a Ghanaian rapper and sound engineer * El DeBarge, music artist * El Franco Lee (1949–2016), American ...

, determine the strength of

tropical cyclones 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 ...

, study

urban heat island An urban heat island (UHI) is an urban or metropolitan area that is significantly warmer than its surrounding rural areas due to human activities. The temperature difference is usually larger at night than during the day, and is most apparen ...

s and monitor the global climate.

Wildfires A wildfire, forest fire, bushfire, wildland fire or rural fire is an unplanned, uncontrolled and unpredictable fire in an area of combustible vegetation. Depending on the type of vegetation present, a wildfire may be more specifically identi ...

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 ...

s, and industrial hot spots can also be found via thermal imaging from weather satellites. They can also be used as part of instrumental temperature records of Earth's climate system.

Weather satellite A weather satellite or meteorological satellite is a type of Earth observation satellite that is primarily used to monitor the weather and climate of the Earth. Satellites can be polar orbiting (covering the entire Earth asynchronously), or ...

s do not measure temperature directly. They measure

radiance In radiometry, radiance is the radiant flux emitted, reflected, transmitted or received by a given surface, per unit solid angle per unit projected area. Radiance is used to characterize diffuse emission and reflection of electromagnetic radiatio ...

s in various

wavelength In physics, the wavelength is the spatial period of a periodic wave—the distance over which the wave's shape repeats. It is the distance between consecutive corresponding points of the same phase on the wave, such as two adjacent crests, tr ...

bands. Since 1978

microwave sounding unit The microwave sounding unit (MSU) was the predecessor to the Advanced Microwave Sounding Unit (AMSU). The MSU was first launched aboard the TIROS-N satellite in late 1978 and provided global coverage (from Pole to Pole). It carries a 4-channel micr ...

s (MSUs) on

National Oceanic and Atmospheric Administration The National Oceanic and Atmospheric Administration (abbreviated as NOAA ) is an United States scientific and regulatory agency within the United States Department of Commerce that forecasts weather, monitors oceanic and atmospheric conditi ...

polar orbit A polar orbit is one in which a satellite passes above or nearly above both poles of the body being orbited (usually a planet such as the Earth, but possibly another body such as the Moon or Sun) on each revolution. It has an inclination of abo ...

ing satellites have measured the intensity of upwelling microwave radiation from atmospheric

oxygen Oxygen is the chemical element with the symbol O and atomic number 8. It is a member of the chalcogen group in the periodic table, a highly reactive nonmetal, and an oxidizing agent that readily forms oxides with most elements as we ...

, which is related to the temperature of broad vertical layers of the atmosphere. Measurements of

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

radiation pertaining to sea surface temperature have been collected since 1967. Satellite datasets show that over the past four decades the

troposphere 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 ...

has warmed and the

stratosphere The stratosphere () is the second layer of the atmosphere of the Earth, located above the troposphere and below the mesosphere. The stratosphere is an atmospheric layer composed of stratified temperature layers, with the warm layers of air ...

has cooled. Both of these trends are consistent with the influence of increasing atmospheric concentrations of

greenhouse gases A greenhouse gas (GHG or GhG) is a gas that absorbs and emits radiant energy within the thermal infrared range, causing the greenhouse effect. The primary greenhouse gases in Earth's atmosphere are water vapor (), carbon dioxide (), meth ...

such as rising carbon dioxide in Earth's atmosphere.

Measurements

Satellite A satellite or artificial satellite is an object intentionally placed into orbit in outer space. Except for passive satellites, most satellites have an electricity generation system for equipment on board, such as solar panels or radioiso ...

s do not measure temperature directly. They measure radiances in various wavelength bands, which must then be mathematically inverted to obtain indirect inferences of temperature. The resulting temperature profiles depend on details of the methods that are used to obtain temperatures from radiances. As a result, different groups that have analyzed the satellite data have produced differing temperature datasets. The satellite time series is not homogeneous. It is constructed from a series of satellites with similar but not identical sensors. The sensors also deteriorate over time, and corrections are necessary for orbital drift and decay. Particularly large differences between reconstructed temperature series occur at the few times when there is little temporal overlap between successive satellites, making intercalibration difficult.

Infrared measurements

Surface measurements

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

radiation can be used to measure both the temperature of the surface (using "window" wavelengths to which the atmosphere is transparent), and the temperature of the atmosphere (using wavelengths for which the atmosphere is not transparent, or measuring cloud top temperatures in infrared windows). Satellites used to retrieve surface temperatures via measurement of thermal infrared in general require cloud-free conditions. Some of the instruments include the

Advanced Very High Resolution Radiometer The Advanced Very-High-Resolution Radiometer (AVHRR) instrument is a space-borne sensor that measures the reflectance of the Earth in five spectral bands that are relatively wide by today's standards. AVHRR instruments are or have been carried b ...

(AVHRR), Along Track Scanning Radiometers (AASTR), Visible Infrared Imaging Radiometer Suite (VIIRS), the Atmospheric Infrared Sounder (AIRS), and the ACE Fourier Transform Spectrometer (ACE‐FTS) on the Canadian SCISAT-1 satellite. Weather satellites have been available to infer

sea surface temperature Sea surface temperature (SST), or ocean surface temperature, is the ocean temperature close to the surface. The exact meaning of ''surface'' varies according to the measurement method used, but it is between and below the sea surface. Air ma ...

(SST) information since 1967, with the first global composites occurring during 1970. Since 1982,

satellite A satellite or artificial satellite is an object intentionally placed into orbit in outer space. Except for passive satellites, most satellites have an electricity generation system for equipment on board, such as solar panels or radioiso ...

s have been increasingly utilized to measure SST and have allowed its

spatial Spatial may refer to: *Dimension *Space *Three-dimensional space Three-dimensional space (also: 3D space, 3-space or, rarely, tri-dimensional space) is a geometric setting in which three values (called ''parameters'') are required to determ ...

and temporal variation to be viewed more fully. For example, changes in SST monitored via satellite have been used to document the progression of the

since the 1970s. Over land the retrieval of temperature from radiances is harder, because of inhomogeneities in the surface. Studies have been conducted on the

effect via satellite imagery. Use of advanced very high resolution infrared satellite imagery can be used, in the absence of cloudiness, to detect

density Density (volumetric mass density or specific mass) is the substance's mass per unit of volume. The symbol most often used for density is ''ρ'' (the lower case Greek letter rho), although the Latin letter ''D'' can also be used. Mathematicall ...

discontinuities (

weather front A weather front is a boundary separating air masses for which several characteristics differ, such as air density, wind, temperature, and humidity. Disturbed and unstable weather due to these differences often arises along the boundary. For ...

s) such as

cold front A cold front is the leading edge of a cooler mass of air at ground level that replaces a warmer mass of air and lies within a pronounced surface trough of low pressure. It often forms behind an extratropical cyclone (to the west in the Northern ...

s at ground level. 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 intensities ...

, infrared satellite imagery can be used to determine the temperature difference between the

eye Eyes are organs of the visual system. They provide living organisms with vision, the ability to receive and process visual detail, as well as enabling several photo response functions that are independent of vision. Eyes detect light and conv ...

and the

cloud In meteorology, a cloud is an aerosol consisting of a visible mass of miniature liquid droplets, frozen crystals, or other particles suspended in the atmosphere of a planetary body or similar space. Water or various other chemicals may ...

top temperature of the

central dense overcast The central dense overcast, or CDO, of a tropical cyclone or strong subtropical cyclone is the large central area of thunderstorms surrounding its circulation center, caused by the formation of its eyewall. It can be round, angular, oval, or i ...

of mature tropical cyclones to estimate their

maximum sustained wind The maximum sustained wind associated with a tropical cyclone is a common indicator of the intensity of the storm. Within a mature tropical cyclone, it is found within the eyewall at a distance defined as the radius of maximum wind, or RMW. U ...

s and their minimum central pressures. Along Track Scanning Radiometers aboard weather satellites are able to detect wildfires, which show up at night as pixels with a greater temperature than . The

Moderate-Resolution Imaging Spectroradiometer The Moderate Resolution Imaging Spectroradiometer (MODIS) is a satellite-based sensor used for earth and climate measurements. There are two MODIS sensors in Earth orbit: one on board the Terra ( EOS AM) satellite, launched by NASA in ...

aboard the Terra satellite can detect thermal hot spots associated with wildfires, volcanoes, and industrial hot spots. The Atmospheric Infrared Sounder on the Aqua satellite, launched in 2002, uses infrared detection to measure near-surface temperature.Harvey, Chelsea (18 April 2019)
"It's A Match: Satellite and Ground Measurements Agree on Warming"
, ''Scientific American''. Retrieved 8 January 2019.

Stratosphere measurements

Stratospheric temperature measurements are made from the Stratospheric Sounding Unit (SSU) instruments, which are three-channel infrared (IR) radiometers. Since this measures infrared emission from carbon dioxide, the atmospheric opacity is higher and hence the temperature is measured at a higher altitude (stratosphere) than microwave measurements. Since 1979 the Stratospheric sounding units (SSUs) on the NOAA operational satellites have provided near global stratospheric temperature data above the lower stratosphere. The SSU is a

far-infrared Far infrared (FIR) is a region in the infrared spectrum of electromagnetic radiation. Far infrared is often defined as any radiation with a wavelength of 15 micrometers (μm) to 1 mm (corresponding to a range of about 20 THz to ...

spectrometer employing a pressure modulation technique to make measurement in three channels in the 15 μm carbon dioxide absorption band. The three channels use the same frequency but different carbon dioxide cell pressure, the corresponding weighting functions peaks at 29 km for channel 1, 37 km for channel 2 and 45 km for channel 3. The process of deriving trends from SSUs measurement has proved particularly difficult because of satellite drift, inter-calibration between different satellites with scant overlap and gas leaks in the instrument carbon dioxide pressure cells. Furthermore since the radiances measured by SSUs are due to emission by

carbon dioxide Carbon dioxide ( chemical formula ) is a chemical compound made up of molecules that each have one carbon atom covalently double bonded to two oxygen atoms. It is found in the gas state at room temperature. In the air, carbon dioxide is t ...

the weighting functions move to higher altitudes as the carbon dioxide concentration in the stratosphere increase. Mid to upper stratosphere temperatures shows a strong negative trend interspersed by transient volcanic warming after the explosive volcanic eruptions of El Chichón and

Mount Pinatubo Mount Pinatubo is an active stratovolcano in the Zambales Mountains, located on the tripoint boundary of the Philippine provinces of Zambales, Tarlac and Pampanga, all in Central Luzon on the northern island of Luzon. Its eruptive histo ...

, little temperature trend has been observed since 1995. The greatest cooling occurred in the tropical stratosphere consistent with enhanced Brewer-Dobson circulation under greenhouse gas concentrations increase. Lower stratospheric cooling is mainly caused by the effects of ozone depletion with a possible contribution from increased stratospheric water vapor and greenhouse gases increase. There has been a decline in stratospheric temperatures, interspersed by warmings related to volcanic eruptions.

Global Warming In common usage, climate change describes global warming—the ongoing increase in global average temperature—and its effects on Earth's climate system. Climate variability and change, Climate change in a broader sense also includes ...

theory suggests that the

should cool while the

warms.

The long term cooling in the lower stratosphere occurred in two downward steps in temperature both after the transient warming related to explosive volcanic eruptions of El Chichón and

, this behavior of the global stratospheric temperature has been attributed to global ozone concentration variation in the two years following volcanic eruptions. Since 1996 the trend is slightly positive due to ozone recovery juxtaposed to a cooling trend of 0.1K/decade that is consistent with the predicted impact of increased greenhouse gases. The table below shows the stratospheric temperature trend from the SSU measurements in the three different bands, where negative trend indicated cooling.

Microwave (tropospheric and stratospheric) measurements

Microwave Sounding Unit (MSU) measurements

From 1979 to 2005 the

s (MSUs) and since 1998 the Advanced Microwave Sounding Units on NOAA polar orbiting

weather satellite A weather satellite or meteorological satellite is a type of Earth observation satellite that is primarily used to monitor the weather and climate of the Earth. Satellites can be polar orbiting (covering the entire Earth asynchronously), or ...

s have measured the intensity of upwelling

microwave radiation Microwave is a form of electromagnetic radiation with wavelengths ranging from about one meter to one millimeter corresponding to frequencies between 300 MHz and 300 GHz respectively. Different sources define different frequency rang ...

from atmospheric

. The intensity is proportional to the temperature of broad vertical layers of the

. Upwelling radiance is measured at different frequencies; these different frequency bands sample a different weighted range of the atmosphere. Figure 3 (right) shows the atmospheric levels sampled by different wavelength reconstructions from the satellite measurements, where TLS, TTS, and TTT represent three different wavelengths.

Other microwave measurements

A different technique is used by the Aura spacecraft, the Microwave Limb Sounder, which measure microwave emission horizontally, rather than aiming at the nadir.M. J. Schwartz et al.
Validation of the Aura Microwave Limb Sounder temperature and geopotential height measurements
, ''JGR: Atmospheres, Vol. 113'', No. D15, 16 August 2008. https://doi.org/10.1029/2007JD008783 . Retrieved 9 January 2020. Temperature measurements are also made by

occultation An occultation is an event that occurs when one object is hidden from the observer by another object that passes between them. The term is often used in astronomy, but can also refer to any situation in which an object in the foreground blocks ...

of GPS signals.Remote Sensing Systems
Upper Air Temperature
. Retrieved 12 January 2020. This technique measures the refraction of the radio signals from

GPS satellites GPS satellite blocks are the various production generations of the Global Positioning System (GPS) used for satellite navigation. The first satellite in the system, Navstar 1, was launched on 22 February 1978. The GPS satellite constellatio ...

by the Earth's atmosphere, thus allowing vertical temperature and moisture profiles to be measured.

Temperature measurements on other planets

Planetary science missions also make temperature measurements on other planets and moons of the solar system, using both infrared techniques (typical of orbiter and flyby missions of planets with solid surfaces) and microwave techniques (more often used for planets with atmospheres). Infrared temperature measurement instruments used in planetary missions include surface temperature measurements taken by the Thermal Emission Spectrometer (TES) instrument on

Mars Global Surveyor ''Mars Global Surveyor'' (MGS) was an American robotic space probe developed by NASA's Jet Propulsion Laboratory and launched November 1996. MGS was a global mapping mission that examined the entire planet, from the ionosphere down through t ...

and the

Diviner Diviner, also referred to as the Diviner Lunar Radiometer Experiment (DLRE), is an infrared radiometer aboard NASA's Lunar Reconnaissance Orbiter, part of the Lunar Precursor Robotic Program which is studying the Moon. It has been used to create ...

instrument on the

Lunar Reconnaissance Orbiter The Lunar Reconnaissance Orbiter (LRO) is a NASA robotic spacecraft currently orbiting the Moon in an eccentric polar mapping orbit. Data collected by LRO have been described as essential for planning NASA's future human and robotic missions to ...

; and atmospheric temperature measurements taken by the composite infrared spectrometer instrument on the NASA Cassini spacecraft.NASA/JPL/GSFC/Univ. Oxford (19 May 2011)
Taking the Temperature of a Saturn Storm
, retrieved 10 January 2020. Microwave atmospheric temperature measurement instruments include the

Microwave Radiometer A microwave radiometer (MWR) is a radiometer that measures energy emitted at one millimeter-to-metre wavelengths (frequencies of 0.3–300 GHz) known as microwaves. Microwave radiometers are very sensitive receivers designed to measure thermally- ...

on the

Juno Juno commonly refers to: * Juno (mythology), the Roman goddess of marriage and queen of the gods * ''Juno'' (film), 2007 Juno may also refer to: Arts, entertainment and media Fictional characters *Juno, in the film ''Jenny, Juno'' *Juno, in the ...

mission to Jupiter.

References

External links

A graph comparing of the surface, balloon and satellite records(2007 archive)
CCSP Synthesis and Assessment Product 1.1

{{DEFAULTSORT:Satellite Temperature Measurements Satellite meteorology Articles containing video clips Temperature