Clouds and the Earth's Radiant Energy System

Clouds and the Earth's Radiant Energy System (CERES) is on-going NASA climatological experiment from Earth orbit.[1][2] The CERES are scientific satellite instruments, part of the NASA's Earth Observing System (EOS), designed to measure both solar-reflected and Earth-emitted radiation from the top of the atmosphere (TOA) to the Earth's surface. Cloud properties are determined using simultaneous measurements by other EOS instruments such as the Moderate Resolution Imaging Spectroradiometer (MODIS).[3] Results from the CERES and other NASA missions, such as the Earth Radiation Budget Experiment (ERBE),[4] could lead to a better understanding of the role of clouds and the energy cycle in global climate change.[1][5]

Incoming, top-of-atmosphere (TOA) shortwave flux radiation, shows energy received from the sun (Jan 26–27, 2012).
Outgoing, longwave flux radiation at the top-of-atmosphere (Jan 26–27, 2012). Heat energy radiated from Earth (in watts per square meter) is shown in shades of yellow, red, blue and white. The brightest-yellow areas are the hottest and are emitting the most energy out to space, while the dark blue areas and the bright white clouds are much colder, emitting the least energy.
Ceres-raps-scan
Artist representation of CERES instruments scanning Earth in Rotating Azimuth Plane mode.

Scientific goals

CERES experiment has four main objectives:

  • Continuation of the ERBE record of radiative fluxes at the top of the atmosphere (TOA) for climate change analysis.
  • Doubling the accuracy of estimates of radiative fluxes at TOA and the Earth's surface.
  • Provide the first long-term global estimates of the radiative fluxes within the Earth's atmosphere.
  • Provide cloud property estimates that are consistent with the radiative fluxes from surface to TOA.

Each CERES instrument is a radiometer which has three channels – a shortwave (SW) channel to measure reflected sunlight in 0.2–5 µm region, a channel to measure Earth-emitted thermal radiation in the 8–12 µm "window" or "WN" region, and a Total channel to measure entire spectrum of outgoing Earth's radiation (>0.2 µm). The CERES instrument was based on the successful Earth Radiation Budget Experiment which used three satellites to provide global energy budget measurements from 1984 to 1993.[6]

Ground absolute calibration

For a climate data record (CDR) mission like CERES, accuracy is of high importance and achieved for pure infrared nighttime measurements by use of a ground laboratory SI traceable blackbody to determine total and WN channel radiometric gains. This however was not the case for CERES solar channels such as SW and solar portion of the Total telescope, which have no direct un-broken chain to SI traceability. This is because CERES solar responses were measured on ground using lamps whose output energy were estimated by a cryo-cavity reference detector, which used a silver Cassegrain telescope identical to CERES devices to match the satellite instrument field of view. The reflectivity of this telescope built and used since the mid-1990s was never actually measured, estimated[7] only based on witness samples (see slide 9 of Priestley et al. (2014)[8]). Such difficulties in ground calibration, combined with suspected on-ground contamination events[9] have resulted in the need to make unexplained ground to flight changes in SW detector gains as big as 8%,[10] simply to make the ERB data seem somewhat reasonable to climate science (note that CERES currently claims[11] a one sigma SW absolute accuracy of 0.9%).

In-flight calibration

CERES spatial resolution at nadir view (equivalent diameter of the footprint) is 10 km for CERES on TRMM, and 20 km for CERES on Terra and Aqua satellites. Perhaps of greater importance for missions such as CERES is calibration stability, or the ability to track and partition instrumental changes from Earth data so it tracks true climate change with confidence. CERES onboard calibration sources intended to achieve this for channels measuring reflected sunlight include solar diffusers and tungsten lamps. However the lamps have very little output in the important ultraviolet wavelength region where degradation is greatest and they have been seen to drift in energy by over 1.4% in ground tests, without a capability to monitor them on-orbit (Priestley et al. (2001)[12]). The solar diffusers have also degraded greatly in orbit such that they have been declared unusable by Priestley et al. (2011).[13] A pair of black body cavities that can be controlled at different temperatures are used for the Total and WN channels, but these have not been proved stable to better than 0.5%/decade.[9] Cold space observations and internal calibration are performed during normal Earth scans.

Missions

First launch

The first CERES instrument Proto-Flight Module (PFM) was launched aboard the NASA Tropical Rainfall Measuring Mission (TRMM) in November 1997 from Japan. However, this instrument failed to operate after 8 months due to an on-board circuit failure.

CERES on the EOS and JPSS mission satellites

An additional six CERES instruments were launched on the Earth Observing System and the Joint Polar Satellite System. The Terra satellite, launched in December 1999, carried two (Flight Module 1 (FM1) and FM2) and the Aqua satellite, launched in May 2002, carried two more (FM3 and FM4). A fifth instrument (FM5) was launched on the Suomi NPP satellite in October 2011 and a sixth (FM6) on NOAA-20 in November 2017. With the failure of the PFM on TRMM and the 2005 loss of the SW channel of FM4 on Aqua, there are five of the CERES Flight Modules that are fully operational as of 2017.[14][15]

Radiation Budget Instruments

The measurements of the CERES instruments was to be furthered by the Radiation Budget Instrument (RBI) to be launched on Joint Polar Satellite System-2 (JPSS-2) in 2021, JPSS-3 in 2026, and JPSS-4 in 2031.[15] The project was cancelled on January 26, 2018; NASA cited technical, cost, and schedule issues and the impact of anticipated RBI cost growth on other programs.[16][17]

Operating modes

CERES operates in three scanning modes: across the satellite ground track (cross-track), along the direction of the satellite ground track (along-track), and in a Rotating Azimuth Plane (RAP). In RAP mode, the radiometers scan in elevation as they rotate in azimuth, thus acquiring radiance measurement from a wide range of viewing angles. Until February 2005, on Terra and Aqua satellites one of CERES instruments scanned in cross-track mode while the other was in RAP or along-track mode. The instrument operating in RAP scanning mode took two days of along-track data every month. However the multi-angular CERES data allowed to derive new models which account for anisotropy of the viewed scene, and allow TOA radiative flux retrieval with enhanced precision.[18]

See also

References

  1. ^ a b B. A. Wielicki; Harrison, Edwin F.; Cess, Robert D.; King, Michael D.; Randall, David A.; et al. (1995). "Mission to Planet Earth: Role of Clouds and Radiation in Climate". Bull. Am. Meteorol. Soc. 76 (11): 2125–2152. Bibcode:1995BAMS...76.2125W. doi:10.1175/1520-0477(1995)076<2125:MTPERO>2.0.CO;2.
  2. ^ Wielicki; et al. (1996). "Clouds and the Earth's Radiant Energy System (CERES): An Earth Observing System Experiment". Bulletin of the American Meteorological Society. 77 (5): 853–868. Bibcode:1996BAMS...77..853W. doi:10.1175/1520-0477(1996)077<0853:CATERE>2.0.CO;2.
  3. ^ P. Minnis; et al. (September 2003). "CERES Cloud Property Retrievals from Imager on TRMM, Terra and Aqua" (PDF). Spain. pp. 37–48.
  4. ^ Barkstrom, Bruce R. (1984). "The Earth Radiation Budget Experiment". Bulletin of the American Meteorological Society. 65 (11): 1170–1186. Bibcode:1984BAMS...65.1170B. doi:10.1175/1520-0477(1984)065<1170:TERBE>2.0.CO;2.
  5. ^ "Surface and Atmospheric Remote Sensing: Technologies, Data Analysis and Interpretation., International". Geoscience and Remote Sensing Symposium IGARSS '94. 1994.
  6. ^ NASA, Clouds and the Earth's Radiant Energy System (CERES) (accessed Sept. 9, 2014)
  7. ^ M. Folkman et al., "Calibration of a shortwave reference standard by transfer from a blackbody standard using a cryogenic active cavity radiometer", IEEE Geoscience and Remote Sensing Symposium, pp. 2298–2300, 1994.
  8. ^ Priestley, Kory; et al. (August 5, 2014). "CERES CALCON Talk".
  9. ^ a b Matthews (2009). "In-Flight Spectral Characterization and Calibration Stability Estimates for the Clouds and the Earth's Radiant Energy System (CERES)". Journal of Atmospheric and Oceanic Technology. 28: 3. Bibcode:2011JAtOT..28....3P. doi:10.1175/2010JTECHA1521.1.
  10. ^ Priestley, Kory (July 1, 2002). "CERES Gain Changes".
  11. ^ Wielicki; et al. (2013). "Achieving Climate Change Absolute Accuracy". Bulletin of the American Meteorological Society. 94 (10): 1519. Bibcode:2013BAMS...94.1519W. doi:10.1175/BAMS-D-12-00149.1.
  12. ^ Priestley; et al. (2001). "Postlaunch Radiometric Validation of the Clouds and the Earth's Radiant Energy System (CERES) Proto-Flight Model on the Tropical Rainfall Measuring Mission (TRMM) Spacecraft through 1999". Journal of Applied Meteorology. 39 (12): 2249. Bibcode:2000JApMe..39.2249P. doi:10.1175/1520-0450(2001)040<2249:PRVOTC>2.0.CO;2.
  13. ^ Priestley; et al. (2011). "Radiometric Performance of the CERES Earth Radiation Budget Climate Record Sensors on the EOS Aqua and Terra Spacecraft through April 2007". Journal of Atmospheric and Oceanic Technology. 28 (1): 3. Bibcode:2011JAtOT..28....3P. doi:10.1175/2010JTECHA1521.1.
  14. ^ "Joint Polar Satellite System - Launch Schedule". www.jpss.noaa.gov. Archived from the original on 19 January 2017. Retrieved 23 January 2017.
  15. ^ a b "Joint Polar Satellite System: Mission and Instruments". NASA. Retrieved 14 November 2017.
  16. ^ "NASA Cancels Earth Science Sensor Set for 2021 Launch". NASA.gov. Retrieved 28 January 2018.
  17. ^ "NASA Cancels Earth Science Sensor Set for 2021 Launch". NASA.gov. Retrieved 28 January 2018.
  18. ^ N. G. Loeb; Kato, Seiji; Loukachine, Konstantin; Manalo-Smith, Natividad; et al. (2005). "Angular distribution models for top-of-atmosphere radiative flux estimation from the Clouds and the Earth's Radiant Energy System instrument on the Terra Satellite. Part I: Methodology". J. Atmos. Ocean. Tech. 22 (4): 338–351. Bibcode:2005JAtOT..22..338L. doi:10.1175/JTECH1712.1.

External links

1997

1997 (MCMXCVII)

was a common year starting on Wednesday of the Gregorian calendar, the 1997th year of the Common Era (CE) and Anno Domini (AD) designations, the 997th year of the 2nd millennium, the 97th year of the 20th century, and the 8th year of the 1990s decade.

1997 in the United States

Events from the year 1997 in the United States.

Aqua (satellite)

Aqua (EOS PM-1) is a NASA scientific research satellite in orbit around the Earth, studying the precipitation, evaporation, and cycling of water. It is the second major component of the Earth Observing System (EOS) preceded by Terra (launched 1999) and followed by Aura (launched 2004).

The name "Aqua" comes from the Latin word for water. The satellite was launched from Vandenberg Air Force Base on May 4, 2002, aboard a Delta II rocket. Aqua is on a Sun-synchronous orbit. It flies as the third in the satellite formation called the "A Train" with several other satellites (OCO-2, the Japanese GCOM W1, CALIPSO, CloudSat, and Aura).

Atmospheric infrared sounder

The atmospheric infrared sounder (AIRS) is one of six instruments flying on board NASA's Aqua satellite, launched on May 4, 2002. The instrument is designed to support climate research and improve weather forecasting.Working in combination with its partner microwave instrument, the Advanced Microwave Sounding Unit (AMSU-A), AIRS observes the global water and energy cycles, climate variation and trends, and the response of the climate system to increased greenhouse gases. AIRS uses infrared technology to create three-dimensional maps of air and surface temperature, water vapor, and cloud properties. AIRS can also measure trace greenhouse gases such as ozone, carbon monoxide, carbon dioxide, and methane.

AIRS and AMSU-A share the Aqua satellite with the Moderate Resolution Imaging Spectroradiometer (MODIS), Clouds and the Earth's Radiant Energy System (CERES), and the Advanced Microwave Scanning Radiometer-EOS (AMSR-E). Aqua is part of NASA's "A-train," a series of high-inclination, Sun-synchronous satellites in low Earth orbit designed to make long-term global observations of the land surface, biosphere, solid Earth, atmosphere, and ocean.AIRS data is free and available to the public through the Goddard Earth Sciences Data Information and Services Center.

NASA's Jet Propulsion Laboratory in Pasadena, California, manages AIRS for NASA's Science Mission Directorate in Washington, D.C.

CLARREO

CLARREO (Climate Absolute Radiance and Refractivity Observatory) is a high-priority NASA decadal survey mission, originally selected as such by the National Research Council in 2007. The CLARREO mission is intended to provide a metrology laboratory in orbit to accurately quantify and attribute Earth's climate change (see List of climate research satellites). The mission is also designed to transfer its high accuracy to other spaceborne sensors. It would serve as a reference calibration standard in orbit, making climate trends apparent in their data sets within a 30-year time frame. These measurements may go on to enable testing, validation, and improvement of climate model prediction.

Due to funding cuts in announced for the 2012 budget, the CLARREO mission was significantly scaled back, while remaining spaceborne projects were eyed to fill the gap.In the President's FY16 budget request, a smaller CLARREO Pathfinder (CPF) mission was provided $76.9M to demonstrate essential measurement technologies of the CLARREO Tier 1 Decadal Survey mission. That funding will potentially support the flight of the Reflected Solar (RS) spectrometer, which is one piece of the full Decadal Survey-recommended mission, hosted on the International Space Station (ISS) in 2020 (although the Trump administration's budget proposal of March 2017 appears set to defund this mission).

Chesapeake Light

Chesapeake Light is an offshore lighthouse marking the entrance to the Chesapeake Bay. The structure was first marked with a lightship in the 1930s, and was later replaced by a "Texas Tower" in 1965. The lighthouse was eventually automated and was used for supporting atmospheric measurement sites for NASA and NOAA. Due to deteriorating structural conditions, the lighthouse was deactivated in 2016. At the time it was the last remaining "Texas Tower" still in use due to obsolescence.

Deep Space Climate Observatory

Deep Space Climate Observatory (DSCOVR; formerly known as Triana, unofficially known as GoreSat) is a NOAA space weather, space climate, and Earth observation satellite. It was launched by SpaceX on a Falcon 9 launch vehicle on February 11, 2015, from Cape Canaveral.It was originally developed as a NASA satellite proposed in 1998 by then-Vice President Al Gore for the purpose of Earth observation. It is in a Lissajous orbit at the Sun–Earth L1 Lagrangian point, 1.5 million km (930 thousand mi) from Earth, to monitor variable solar wind condition, provide early warning of approaching coronal mass ejections and observe phenomena on Earth, including changes in ozone, aerosols, dust and volcanic ash, cloud height, vegetation cover and climate. At this location it has a continuous view of the Sun and of the sunlit side of the Earth. The satellite is orbiting the Sun–Earth L1 point in a six-month period, with a spacecraft–Earth–Sun angle varying from 4 to 15 degrees. It takes full-Earth pictures about every two hours and is able to process them faster than other Earth observation satellites.DSCOVR started orbiting around L1 by June 8, 2015, just over 100 days after launch. After the spacecraft arrived on site and entered its operational phase, NASA began releasing near-real time images of Earth through the EPIC instrument's website.

Earth's energy budget

Earth's energy budget accounts for the balance between the energy Earth receives from the Sun, the energy Earth radiates back into outer space after having been distributed throughout the five components of Earth's climate system and having thus powered the so-called Earth’s heat engine. This system is made up of earth's water, ice, atmosphere, rocky crust, and all living things.Quantifying changes in these amounts is required to accurately model the Earth's climate.

Received radiation is unevenly distributed over the planet, because the Sun heats equatorial regions more than polar regions. "The atmosphere and ocean work non-stop to even out solar heating imbalances through evaporation of surface water, convection, rainfall, winds, and ocean circulation." Earth is very close to being in radiative equilibrium, the situation where the incoming solar energy is balanced by an equal flow of heat to space; under that condition, global temperatures will be relatively stable. Globally, over the course of the year, the Earth system—land surfaces, oceans, and atmosphere—absorbs and then radiates back to space an average of about 240 watts of solar power per square meter. Anything that increases or decreases the amount of incoming or outgoing energy will change global temperatures in response.However, Earth's energy balance and heat fluxes depend on many factors, such as atmospheric composition (mainly aerosols and greenhouse gases), the albedo (reflectivity) of surface properties, cloud cover and vegetation and land use patterns.

Changes in surface temperature due to Earth's energy budget do not occur instantaneously, due to the inertia of the oceans and the cryosphere. The net heat flux is buffered primarily by becoming part of the ocean's heat content, until a new equilibrium state is established between radiative forcings and the climate response.

Earth Radiation Budget Satellite

The Earth Radiation Budget Satellite (ERBS) was a NASA scientific research satellite within NASA's ERBE (Earth Radiation Budget Experiment) Research Program - a three-satellite mission, designed to investigate the Earth's radiation budget It also carried an instrument that studied stratospheric aerosol and gases.

ERBS was launched on October 5, 1984 by the Space Shuttle Challenger during the STS-41-G mission and deactivated on October 14, 2005.

Joint Polar Satellite System

The Joint Polar Satellite System (JPSS) is the latest generation of U.S. polar-orbiting, non-geosynchronous, environmental satellites. JPSS will provide the global environmental data used in numerical weather prediction models for forecasts, and scientific data used for climate monitoring. JPSS will aid in fulfilling the mission of the U.S. National Oceanic and Atmospheric Administration (NOAA), an agency of the Department of Commerce. Data and imagery obtained from the JPSS will increase timeliness and accuracy of public warnings and forecasts of climate and weather events, thus reducing the potential loss of human life and property and advancing the national economy. The JPSS is developed by the National Aeronautics and Space Administration (NASA) for the National Oceanic and Atmospheric Administration (NOAA), who is responsible for operation of JPSS. Three to five satellites are planned for the JPSS constellation of satellites. JPSS satellites will be flown, and the scientific data from JPSS will be processed, by the JPSS - Common Ground System (JPSS-CGS).

The first satellite in the JPSS is the Suomi NPP satellite, which launched on October 28, 2011. This was followed by JPSS-1, which was launched on November 18, 2017, three years later than stated when the contract was awarded in 2010. On November 21, 2017, after reaching its final orbit, JPSS-1 was renamed NOAA-20. Three more JPSS satellites will be launched between 2022 and 2031. In addition, the TSI Calibration Transfer Experiment was launched on the U.S. Air Force Space Test Program Satellite-3 (STPSat-3) on November 19, 2013. It is also part of JPSS.

NOAA-20

NOAA-20, designated JPSS-1 prior to launch, is the first of the United States National Oceanic and Atmospheric Administration's latest generation of U.S. polar-orbiting, non-geosynchronous, environmental satellites called the Joint Polar Satellite System. NOAA-20 was launched on November 18, 2017 and joined the Suomi National Polar-orbiting Partnership satellite in the same orbit. NOAA-20 operates about 50 minutes ahead of Suomi NPP, allowing important overlap in observational coverage. Circling the Earth from pole-to-pole, it crosses the equator about 14 times daily, providing full global coverage twice a day. This will give meteorologists information on "atmospheric temperature and moisture, clouds, sea-surface temperature, ocean color, sea ice cover, volcanic ash, and fire detection" so as to enhance weather forecasting including hurricane tracking, post-hurricane recovery by detailing storm damage and mapping of power outages.The project incorporates five instruments, and these are substantially upgraded since previous satellite equipment. The project's greater-detailed observations will provide better predictions and emphasize climate behavior in cases like El Niño and La Nina.The project's satellite bus and Ozone Mapping and Profiler equipment, was designed by Ball Aerospace. The Visible Infrared Imaging Radiometer Suite and the Common Ground System were built by Raytheon, and the Cross-track Infrared Sounder was by Harris. The Advanced Technology Microwave Sounder and the Clouds and the Earth’s Radiant Energy System instrument were built by Northrop Grumman Aerospace Systems.

Outgoing longwave radiation

Outgoing Longwave Radiation (OLR) is the energy radiating from the Earth as infrared radiation at low energy to Space.

OLR is electromagnetic radiation emitted from Earth and its atmosphere out to space in the form of thermal radiation. The flux of energy transported by outgoing longwave radiation is measured in W/m².

Over 99% of outgoing longwave radiation has wavelengths between 4 µm and 100 µm, in the thermal infrared part of the electromagnetic spectrum. Contributions with wavelengths larger than 40 µm are small, therefore often only wavelengths up to 50 µm are considered . In the wavelength range between 4 µm and 10 µm the spectrum of outgoing longwave radiation overlaps that of solar radiation, and for various applications different cut-off wavelengths between the two may be chosen.

Radiative cooling by outgoing longwave radiation is the primary way the Earth System loses energy. The balance between this loss and the energy gained by radiative heating from incoming solar shortwave radiation determines global heating or cooling of the Earth system (Energy budget of Earth’s climate). Local differences between radiative heating and cooling provide the energy that drives atmospheric dynamics.

Philip R. Goode

Philip R. Goode is an American theoretical physicist also working in observational astronomy and its instrumentation. He is a Distinguished Research Professor of Physics at New Jersey Institute of Technology (NJIT). His career divides into five overlapping periods as follows.

His earliest work in theoretical nuclear physics, 1967-1982.

Pioneering research in helioseismology (1981-2005).

He created, developed and directed (1995-2014) NJIT’s Center for Solar-Terrestrial Research (CSTR), which made NJIT one of the most important universities in the U.S. for observational solar physics, heliophysics, and solar-terrestrial physics.

The construction of, and scientific results from, the world’s most powerful solar telescope (2002–present) in Big Bear Solar Observatory (BBSO). In 2017, this ground-based telescope was renamed the Goode Solar Telescope (GST). Goode was director of BBSO from 1997, when the observatory was transferred from Caltech to NJIT, until 2013.

Sustained earthshine studies of Earth’s reflectance (1998–present).

Radiation Budget Instrument

The Radiation Budget Instrument (RBI) is a scanning radiometer capable of measuring Earth's reflected sunlight and emitted thermal radiation. The project was cancelled on January 26, 2018; NASA cited technical, cost, and schedule issues and the impact of anticipated RBI cost growth on other programs.RBI was scheduled to fly on the Joint Polar Satellite System 2 (JPSS-2) mission planned for launch in November 2021; the JPSS-3 mission planned for launch in 2026; and the JPSS-4 mission planned for launch in 2031. The one on JPSS-2 would have been the 14th in the series that started with the Earth radiation budget instruments launched in 1985, and would have extended the unique global climate measurements of the Earth's radiation budget provided by the Clouds and the Earth's Radiant Energy System (CERES) instruments since 1998.

Suomi NPP

The Suomi National Polar-orbiting Partnership or Suomi NPP, previously known as the National Polar-orbiting Operational Environmental Satellite System Preparatory Project (NPP) and NPP-Bridge, is a weather satellite operated by the United States National Oceanic and Atmospheric Administration. It was launched in 2011 and continues to operate.

Suomi was originally intended as a pathfinder for the NPOESS program, which was to have replaced NOAA's Polar Operational Environmental Satellites and the U.S. Air Force's Defense Meteorological Satellite Program. Suomi was launched in 2011 after the cancellation of NPOESS to serve as a stop-gap between the POES satellites and the Joint Polar Satellite System which will replace them. Its instruments provide climate measurements that continue prior observations by NASA's Earth Observing System.

The satellite is named after Verner E. Suomi, a meteorologist at the University of Wisconsin–Madison. The name was announced on January 24, 2012, three months after the satellite's launch.The satellite was launched from Space Launch Complex 2W at Vandenberg Air Force Base in California by a United Launch Alliance Delta II 7920-10C on October 28, 2011. The satellite was placed into a sun-synchronous orbit 824 km (512 miles) above the Earth.

Terra (satellite)

Terra (EOS AM-1) is a multi-national NASA scientific research satellite in a Sun-synchronous orbit around the Earth. It is the flagship of the Earth Observing System (EOS). The name "Terra" comes from the Latin word for Earth. A naming contest was held by NASA among U.S. high school students. The winning essay was submitted by Sasha Jones of Brentwood, Missouri. The identifier "AM-1" refers to its orbit, passing over the equator in the morning.

Tropical Rainfall Measuring Mission

The Tropical Rainfall Measuring Mission (TRMM) was a joint space mission between NASA and the Japan Aerospace Exploration Agency (JAXA) designed to monitor and study tropical rainfall. The term refers to both the mission itself and the satellite that the mission used to collect data. TRMM was part of NASA's Mission to Planet Earth, a long-term, coordinated research effort to study the Earth as a global system. The satellite was launched on November 27, 1997 from the Tanegashima Space Center in Tanegashima, Japan. TRMM operated for 17 years, including several mission extensions, before being decommissioned in April 2015. TRMM re-entered Earth's atmosphere on June 16, 2015.

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