The below glossary contains a list of terms relevant to the JPL Physical Oceanography DAAC and its data holdings. A more extensive listing is available in the EOSDIS Glossary.
A B C D E F G H I J K L M N O P Q R S T U V W X Y Z
ACTIVE LONG TERM ARCHIVE (ALTA):A facility that provides permanent active archive functions for EOSDIS Archived Holdings during and beyond the scope of the EOS mission, receiving responsibility for these holdings and providing long-term access to users. An ALTA is funded independently of the EOS budget. ALTAs include the NASA/National Space Science Data Center (NSSDC), the USGS/Earth Resources Observation System (EROS) data center, and the NOAA/National Environmental Satellite, Data, and Information Service (NESDIS) data centers. Source: EPO.
AEROSOL: A gaseous suspension of fine particles. Source: EPO.
ALBEDO: The fraction of the total solar radiation incident on a body that is reflected by it. Source: EPO.
ALGORITHM: Software delivered to the SDPS by a science investigator (PI, TL, or II) to be used as the primary tool in the generation of science products. The term includes executable code, source code, job control scripts, as well as documentation. A prescription for the calculation of a quantity; used in Earth system science to derive physical or biological properties from observations and to facilitate calculation of state variables in models. Source: ECS.
ANCILLARY DATA: Data other than instrument data required to perform an instrument's data processing. They include orbit data, attitude data, time information, spacecraft engineering data, calibration data, data quality information, and data from other instruments. Source: EPO.
ARCHIVED HOLDINGS: All EOS and non-EOS data and data products, as well as supporting information, that are archived by EOSDIS. This includes models, algorithms, documentation, and level 0 data or higher level data products from which level 0 may be recovered. Source: EPO.
ATMOSPHERE: The envelope of gases surrounding the Earth and bound to it by the Earth's gravitational attraction. Studies of the chemical and radiative properties, dynamic motions, and physical processes of this system constitute the field of meteorology. Source: EPO.
ATTITUDE: The orientation of the sensor along with information about the accuracy and precision with which this orientation is known. This data is required to perform proper calibration of instrument data. The attitude is usually stored in Euler angle or quaternion form and may be calculated by the on-board computer and telemetered to the ground or calculated by ground processing facilities using a variety of attitude sensor data.
ATTITUDE SENSOR DATA: Attitude Sensor data is that subset of the telemetry data that is used to determine the pointing of the spacecraft axes, calibration and alignment data, Euler angles or quaternions, rates and biases, and associated parameters.
BIOLOGICAL PRODUCTIVITY: The amount of organic matter, carbon, or energy content that is accumulated during a given time period. Source: EPO.
BIOSPHERE: The portion of Earth and its atmosphere that can support life. The part (reservoir) of the global carbon cycle that includes living organisms (plants and animals) and life-derived organic matter (litter, detritus). The terrestrial biosphere in-cludes the living biota (plants and animals) and the litter and soil organic matter on land; the marine biosphere includes the biota and detritus in the oceans. Source: EPO.
BROWSE: A representation of a dataset or data granule used to pre-screen data as an aid to selection prior to ordering. A data set, typically of limited size and resolution, created to rapidly provide an understanding of the type and quality of available full resolution data sets. It may also enable the selection of intervals for further processing or analysis of physical events. For example, a browse image might be a reduced resolution version of a single channel from a multi-channel instrument. Note: Full resolution data sets may be browsed. Source: SPSO, ESADS.
BROWSE DATA PRODUCT: Subsets of a larger data set generated for the purpose of allowing rapid interrogation (i.e., browse ) of the larger data set by a potential user. For example, the browse product for an image data set with multiple spectral bands and moderate spatial resolution might be an image in two spectral channels, at a degraded spatial resolution. The form of browse data is generally unique for each type of data set and depends on the nature of the data and the criteria used for data selection within the relevant scientific disciplines. Source: EPO.
CALIBRATION: The activities involved in adjusting an instrument to be intrinsically accurate, either before or after launch. The process of collecting instrument characterization information (scale, offset, nonlinearity, operational, and environmental effects), using either laboratory standards, field standards, or modeling, which is used to interpret instrument measurements.
CALIBRATION DATA: The collection of data required to perform calibration of the instrument science and engineering data, and the spacecraft or platform engineering data. It includes pre-flight calibrator measurements, calibration equation coefficients derived from calibration software routines, and ground truth data that are to be used in the data calibration processing routine. Source: ECS.
CARBON CYCLE: All reservoirs and fluxes of carbon; usually thought of as a series of the four main reservoirs of carbon interconnected by pathways of exchange. The four regions of the Earth in which carbon behaves in a systematic manner are the atmosphere, terrestrial biosphere (usually includes freshwater systems), oceans, and sediments (includes fossil fuels). Each of these global reservoirs may be subdivided into smaller pools ranging in size from individual communities or ecosystems to the total of all living organisms (biota). Carbon exchanges from reservoir to reservoir by various chemical, physical, geological, and biological processes. Source: EPO.
CLIMATE: The statistical collection and representation of the weather conditions for a specified area during a specified time interval, usually decades, together with a description of the state of the external system or boundary conditions. The properties that characterize the climate are thermal (temperatures of the surface air, water, land, and ice), kinetic (wind and ocean currents, together with associated vertical motions and the motions of air masses, humidity, cloudiness and cloud water content, groundwater, lake winds, and water content of snow on land and sea ice), and static (pressure and density of the atmosphere and ocean, composition of the dry air, salinity of the oceans, and the geometric boundaries and physical constants of the system). These properties are interconnected by various physical processes such as precipitation, evaporation, infrared radiation, convection, advection, and turbulence. Source: EPO.
The long-term fluctuations in temperature, precipitation, wind, and all other aspects of the Earth's climate. External processes, such as solar- irradiance variations, variations of the EarthUs orbital parameters (eccentricity, precession, and inclination), lithosphere motions, and volcanic activity, are factors in climatic variation. Internal variations of the climate system, e.g., changes in the abundance of greenhouse gases, also may produce fluctuations of sufficient magnitude and variability to explain observed climate change through the feedback processes interrelating the components of the climate system. Source: EPO.
CLOUD: A visible mass of condensed water vapor particles or ice suspended above the Earth's surface. Clouds may be classified by their visual appearance, height, or form. Source: EPO.
CLOUD ALBEDO: Reflectivity that varies from less than 10 to more than 90 percent of the insolation and depends on drop sizes, liquid water content, water vapor content, thickness of the cloud, and the sun's zenith angle. The smaller the drops and the greater the liquid water content, the greater the cloud albedo, if all other factors are the same. Source: EPO.
COMMANDING: Process of scheduling and issuing instructions for actions to be carried out by a space-based instrument or spacecraft. Source: EPO.
CORRELATIVE DATA: Scientific data from other sources used in the interpretation or validation of instrument data products, e.g. ground truth data and/or data products of other instruments. These data are not utilized for processing instrument data. Source: ESADS, EPO.
COVERAGE MAP: The footprint coverage of a remote sensing sensor projected on a surface (i.e. A graphical representation of the coverage of data or a granule located on the Earth. Source: ESDIS IMS Lexicon.
DATA: The representative forms of information, including facts, concepts, rules, or any other kind of knowledge. Source: ESADS.
DATA ARCHIVE: A facility providing indefinitely long storage, preservation, disposition, and distribution of data sets and associated metadata. Source: ESADS.
DATA CENTER: An institutionally supported facility providing convenient access to, manipulation of, and/or distribution of data sets (including supporting information and expertise) for a wide community of users. It has a long term charter (not tied to the lifetime of a specific project). A data center can create Special Data Products when needed. A facility storing, maintaining, and making available data sets for expected use in ongoing and/or future activities. Data centers provide selection and replication of data and needed documentation and, often, the generation of user tailored data products. Source: ESADS, EPO.
DATABASE: A collection of data sets with supporting metadata related to a system, project or facility. A collection of integrated data serviced by a Data Base Management System (DBMS); often organized for quick search and retrieval. Source: ESAD.
DATA PRODUCT: A collection of parameters packaged with associated ancillary and labeling data. Uniformly processed and formatted. Typically uniform temporal and spatial resolution. (Often the collection of data distributed by a data center or subsetted by a data center for distribution.) Source: SPSO
DATA PRODUCT LEVEL: Data levels 1 through 4 as designated in the Product Type and Processing Level Definitions document. Source: SPSO.
Raw Data: Data in their original packets, as received from the observer, unprocessed by EDOS.
Level 0: Raw instrument data at original resolution, time ordered, with duplicate packets removed.
Level 1A: Reconstructed unprocessed instrument data at full resolution, time referenced, and annotated with ancillary information, including radiometric and geometric calibration coefficients and georeferencing parameters (i.e., platform ephemeris) computed and appended, but not applied to Level 0 data.
Level 1B: Radiometrically corrected and geolocated Level 1A data that have been processed to sensor units.
Level 2: Derived geophysical parameters at the same resolution and location as the Level 1 data.
Level 3: Geophysical parameters that have been spacially and/or temporally re-sampled (i.e., derived from Level 1 or Level 2 data).
Level 4: Model output and/or results of lower level data that are not directly derived by the instruments.
DATA SET: A logically meaningful grouping or collection of similar or related data. Data having mostly similar characteristics (source or class of source, processing level and algorithms, etc.) Source: SPSO
DISCIPLINE: A field of study (e.g., oceanography, meteorology, geology, land biology). Source: ESADS.
DISTRIBUTED ACTIVE ARCHIVE CENTER (DAAC): An EOSDIS facility that generates, archives, and distributes EOS Standard Data Products, and related information, for the duration of the EOS mission. An EOSDIS DAAC is managed by an institution such as a NASA field center or a university, under terms of an agreement with NASA. Each DAAC contains functional elements for processing data [the Product Generation System (PGS)], for archiving and disseminating data (the DADS), and for user services and information management (elements of the IMS). Other (non-NASA) agencies may share management and funding responsibilities for the active archives under terms of agreements negotiated with NASA. Source: EPO.
EOS DATA AND INFORMATION SYSTEM (EOSDIS:) A facility that will manage the data resulting from NASA's Earth science research satellites and field measurement programs, and other data essential for the interpretation of these measurements. It will also provide access to data held in the archives of other government agencies, organizations, and countries. EOSDIS will generate user-defined data products, and will facilitate the combination and manipulation of data from all sources as well as their incorporation into models of the environment. Source: EPO.
EOS OPERATIONS CENTER (EOC): The facility responsible for EOS mission operations, including command and control of EOS spacecraft, mission planning and scheduling, and coordination of EOS instrument planning and scheduling. All commands for EOS spacecraft and instruments go through the EOC for integration and validation before transmission to space. Source: EPO.
EOS PROGRAM: The activity that provides the long-term observations and the supporting information system necessary to develop a comprehensive understanding of the way the Earth functions as a natural system. The EOS Program Office and the EOS Project are included in the EOS Program. Source: EPO.
EPHEMERIS: A tabular statement of the spatial coordinates of a celestial body or a spacecraft as a function of time. Source: EPO.
FACILITY INSTRUMENT: An instrument defined by NASA as having broad significance to the EOS Program that is provided by a designated NASA center or foreign agency. Source: EPO.
FLIGHT HARDWARE All active mission hardware in orbit about the Earth. For EOS, flight hardware includes all EOS spacecraft and EOS instruments on International Platforms and other spacecraft. Source: EPO.
GLOBAL: Modifier which can denote total or nearly total coverage of the Earth, land, ocean or both.
GRANULE: The smallest aggregation of data which is independently managed (i,e., described, inventoried, retrievable). Granules may be managed as logical granules and/or physical granules. Source: ESADS, EPO.
GREENHOUSE GASES: Those gases, such as water vapor, carbon dioxide, tropospheric ozone, nitrous oxide, methane, and CFCs, that are largely transparent to solar radiation but opaque to outgoing longwave radiation. Their action is similar to that of glass in a greenhouse. Some of the longwave (infrared) radiation is absorbed and reemitted by the greenhouse gases. The effect of this is to warm the surface and the lower atmosphere of the earth. Source: EPO.
GROUND NETWORK: The network of ground stations that support near-Earth spacecraft primarily in the launch or early mission phase. The Ground Network is the successor to the NASA Satellite Tracking and Data Acquisition Network (STADAN). Source: EPO.
GROUND TRUTH: Geophysical parameter data, measured or collected by other means than by the instrument itself, used as correlative or calibration data for that instrument data. It includes data taken on the ground or in the atmosphere. Ground truth data are another measurement of the phenomenon of interest; they are not necessarily more "true" or more accurate than the instrument data. Source: EPO.
HEFT (High Efficency File Transfer): HEFT is a file transfer technology provided commercially from Aspera© that provides a reliable and faster data transfer solution. This new approach overcomes the challenge of large data set transfers over any Internet Protocol (IP) network, regardless of network conditions and geographic distance. Most of PO.DAACâ€™s data products are accessible via HEFT.
INFORMATION MANAGEMENT SYSTEM (IMS): The user interface for EOSDIS. It provides information about data, both in EOSDIS and in external archives, on a 24-hour basis; accepts user orders for EOS data; provides information about future data acquisition and processing schedules; accepts and forwards data acquisition and processing requests; and maintains information on system status, management, and coordination. Source: EPO.
INFRARED RADIATION: Electromagnetic radiation lying in the wavelength interval from 0.7 5m to 1000 5m (micrometers). Its lower limit is bounded by visible radiation, and its upper limit by microwave radiation. Most of the energy emitted by the Earth and its atmosphere is at infrared wavelengths. Infrared radiation is generated almost entirely by large-scale intramolecular processes. The tri-atomic gases, such as water vapor, carbon dioxide, and ozone, absorb infrared radiation and play important roles in the propagation of infrared radiation in the atmosphere. Source: EPO.
IN-SITU DATA: Data associated with reference to measurements made at the actual location of the object or material measured, by contrast with remote sensing (i.e., from space). Source: EPO.
INSTRUMENT: An integrated collection of hardware containing one or more sensors and associated controls designed to produce data on an environment. Source: ESADS.
INSTRUMENT CONTROL CENTER (ICC): An EOS facility dedicated to a specific instrument that plans and schedules instrument operations, generates and validates command sequences, provides the capability to forward commands and to store them for later transmission, monitors the health and safety of the instrument, and provides instrument controllers with status information of their instrument. Source: EPO.
INSTRUMENT CONTROL FACILITY (ICF): A facility containing one or more EOS ICCs. Source: EPO.
INSTRUMENT ENGINEERING DATA: Data produced by the engineering sensor(s) of an instrument that is used to determine the physical state of an instrument in order to operate it, monitor its health, or aid in processing its science data. Source: EPO.
INSTRUMENT SCIENCE DATA: Data produced by the science sensor(s) containing the primary observables of an instrument, usually constituting the mission of that instrument. Source: ESADS, EPO.
INTERDISCIPLINARY SCIENTIST: An individual selected by the project and/or the peer review process who is responsible for conducting investigations requiring analysis, interpretation, and use of data which crosses instrument and discipline boundaries. Source: ESADS.
INVENTORY: A uniform set of descriptions of granules from one or more data sets with information required to select and obtain a subset of those granules. Granule descriptions typically include temporal and spatial coverage, data quality indicators, and physical storage information. An inventory may describe physical granules, logical granules, or both, including a mapping between them if they are not identical. Source: IWGDMGC, ESADS, EPO.
IONOSPHERE: Rarefied, ionized region of the Earth's atmosphere, between approximately 60 and 400 km. Source: EPO.
LEVEL: See DATA PRODUCT LEVEL.
LOGICAL GRANULE: The smallest aggregation of data which is independently identified (i.e., described, inventoried). Source: ESADS.
LOGICAL RECORD: A collection of data whose location and extent are defined in terms of the information it contains and not in terms related to the physical medium on which it is stored. Portions of the same logical record may be located in different physical records, or several logical records may be located in one physical record. Source: ESADS.
MESOSPHERE: Region of the atmosphere between approximately 50 and 85 km. Source: EPO.
METADATA: Information about a data set which is provided by the data supplier or the generating algorithm and which provides a description of the content, format, and utility of the data set. Metadata provide criteria which may be used to select data for a particular scientific investigation. Information describing a data set, including data user guide, descriptions of the data set in directories, and inventories, and any additional information required to define the relationships among these.
Source: ESADS, EPO, IWGDMGC.
MODELING: An investigative technique that uses a mathematical or physical representation of a system or theory that accounts for all or some of its known properties. Models are often used to test the effects of changes of system components on the overall performance of the system. Source: EPO.
NADIR: Direction toward the center of the Earth. Opposite of zenith. Source: EPO.
NEAR REAL-TIME DATA: Data from the source that are available for use within a time that is short in comparison to important time scales in the phenomena being studied. Source: ESADS.
NEAR-LINE: Near-line refers to tapes or other archive media that are typically stored for very quick access and loading on the computer system for use (i.e. robotic tape silos or optical disc jukeboxes). Source: EDC/ESDIS.
OCEAN MIXING: Processes that involve rates of advection, upwelling/downwelling, and eddy diffusion and that determine, for example, how rapidly excess atmospheric carbon dioxide can be taken up by the oceans. Source: EPO.
OFF-LINE: Access to information by mail, telephone, facsimile, or other non- direct interface. Source: EPO.
ON-LINE: Access to information by direct interface to an information data base via electronic networking. Source: EPO.
OPERATIONS: Within EOSDIS, those activities di-rectly related to the acquisition, archiving, distribution, and processing of mission-related information. Source: EPO.
ORBIT DATA: Data that represent spacecraft locations. Orbit (or ephemeris) data include: Geodetic latitude, longitude and height above an adopted reference ellipsoid (or distance from the center of mass of the Earth). Source: EPO.
OZONE: A molecule made up of three atoms of oxygen. In the stratosphere, it occurs naturally and provides a protective layer shielding the Earth from ultraviolet radiation and subsequent harmful health effects on humans and the environment. In the troposphere, it is a chemical oxidant and major component of photochemical smog. Ozone is an effective greenhouse gas especially in the middle and upper troposphere and lower stratosphere.Source: EPO.
PACKAGE: A set of data granules organized for distribution by a DAAC. Source: ESDIS IMS Lexicon.
PARAMETER: A measurable or derived variable representedby the data (e.g. air temperature, snow depth, relative humidity). Source: SPSO.
PATHFINDER DATA SET: A long-term, global Earth science data set produced from non-EOS data using community consensus algorithms as part of the EOSDIS Program. Selection of Pathfinder Data Sets is made by the EOS Program Office (in consultation with the IWG and the science community). Source: EPO.
PAYLOAD: The complement of instruments that are accommodated on a spacecraft. Source: EPO.
PHYTOPLANKTON: That portion of the plankton community in a body of water made up of tiny plants (e.g., algae and diatoms). Source: EPO.
PLANETARY ALBEDO: The fraction of incident solar radiation that is reflected by a planet and returned to space. The planetary albedo of the Earth-atmosphere system is approximately 30 percent, most of which is due to backscatter from clouds in the atmosphere. Source: EPO.
PLAYBACK DATA: Data that are stored on a spacecraft, platform, or other carrier that are transmitted at a later time. Source: ESADS.
PRIMARY PRODUCTIVITY: The rate of carbon fixation by marine photosynthetic organisms (phytoplankton). Primary productivity results in the reduction of dissolved inorganic carbon to form organic carbon, with concomitant release of oxygen. Source: EPO.
PRINCIPAL INVESTIGATOR (PI): The individual selected by proposal review, who has primary responsibility for preparing the proposal, selecting the investigation team, carrying out the scientific investigation, and reporting the results. Responsibilities often include supplying an instrument. Source: ESADS, EPO.
PROCESSING LEVEL: See Data Product Level.
PROTOTYPE INSTRUMENT: An instrument primarily intended as a prototype for developing an operational instrument capability. The instrument may be replaced by an operational model, or declared operational after the functional utility of the instrument is understood. Source: ESADS.
QUICK-LOOK DATA: Data available for examination within a short time of receipt, where completeness of processing is sacrificed to achieve rapid availability. Source: ESADS.
RAW DATA: Numerical values representing the direct observations output by a measuring instrument transmitted as a bit stream in the order they were obtained. Also see DATA PRODUCT LEVEL.
REAL-TIME DATA: Data that are acquired and transmitted immediately to the ground (as opposed to playback data). Delay is limited to the actual time (propagation delays) required to transmit the data. Source: ESADS, EPO.
RETROGRADE ORBIT: An orbit with an inclination of more than 90 degrees. Satellites with a retrograde orbit move in a direction opposite to the rotation of the Earth. In other words, the subsatellite track moves from East to West.
SCIENCE COMPUTING FACILITY (SCF): A facility supplied by the EOS Program to an EOS TL, TM, or PI (Instrument or Interdisciplinary) for the following purposes: developing and maintaining the algorithms and software used to generate Standard Data Products; quality control of Standard Data Products; in-flight instrument calibration and data set validation; scientific analysis, modeling, and research; generation of Special Data Products; and use as an interface to the investigatorUs institutional facility. Source: EPO.
SENSOR: A device which transmits an output signal in response to a physical input stimulus (as radiance, sound, etc.). Science and engineering sensors are distinguished according to the stimuli to which they respond. Source: ESADS.
SIGNAL-TO-NOISE RATIO (S/N): The ratio of the level of the information-bearing signal power to the level of the noise power. Source: EPO.
SOURCE/PLATFORM: The observational environment, entity or structure which holds the data collection device (usually an instrument). It may be a satellite, aircraft, ground station, buoy, ship, person (in the case of human observations or hand-held instruments), computer (in the case of computer model data), or a questionaire (in the case of a paper survey (e.g. CIESIN's Census data).
SPACECRAFT: The spacecraft is the EOS space or orbiting component composed of the payload and mission-unique equipment required to support the EOS mission. It includes propulsion, separation springs, and user interface equipment not unique to the launch vehicle. Source: EPO.
SPACECRAFT ENGINEERING DATA: Data produced by the engineering sensor(s) of a spacecraft that are used to determine the physical state of the spacecraft, in order to operate it or monitor health and safety. Source: EPO.
STRATOSPHERE: Region of the atmosphere between the troposphere and mesosphere, having a lower boundary of approximately 8 km at the poles to 18 km at the equator and an upper boundary of approximately 50 km. Depending upon latitude and season, the temperature in the lower stratosphere can increase, be isothermal, or even decrease with altitude, but the temperature in the upper stratosphere generally increases with height due to absorption of solar radiation by ozone. Source: EPO.
SUN-SYNCHRONOUS ORBIT: In a sun-synchronous orbit, the satellite passes over the same part of the Earth at approximately the same local time each day. The satellite's orbital plane appears to be fixed with respect to the sun. For example, the satellite will pass over the Great Lakes at the same local time for each ascending pass and at the same local time of day for each descending pass. The times are different for ascending and descending passes, however.
TELEMETRY: A space-to-ground data stream of measured values (including instrument science data, instrument engineering data, and spacecraft engineering data) that does not include command, tracking, computer memory transfer, audio, or video signals. Source: EPO.
THERMOSPHERE: Outermost layer of the atmosphere, above the mesosphere. Source: EPO.
TRACE GAS: A minor constituent of the atmosphere. The most important trace gases contributing to the greenhouse effect are water vapor, carbon di-oxide, ozone, methane, nitrous oxide, and chloro-fluorocarbons. Other trace gases include ammonia, nitric oxide, ethylene, sulfur dioxide, methyl chloride, carbon monoxide, and carbon tetrachloride. Source: EPO.
TRACKING AND DATA RELAY SATELLITE SYSTEM (TDRSS): A constellation of NASA satellites and ground stations that track and relay data to and from low-altitude, Earth-orbiting satellites (including the Space Shuttle). This NASA system includes specialized communications satellites located in geosynchronous orbit both east and west of the continental U.S. (providing coverage of virtually the whole globe) and a TDRSS Ground Terminal at White Sands, New Mexico. Source: EPO.
TROPOPAUSE: Boundary between the upper troposphere and the lower stratosphere that varies in altitude between approximately 8 km at the poles to 18 km at the equator. Source: EPO.
TROPOSPHERE: Lowest atmospheric layer, between the surface and tropopause. Source: EPO.
UPWELLING: The vertical motion of water in the ocean by which subsurface water of lower temperature and greater density moves toward the surface of the ocean. Upwelling occurs most commonly along the western coastlines of continents, but may occur anywhere in the ocean. Upwelling results when winds blowing nearly parallel to a continental coastline transport the light surface water away from the coast. Subsurface water of greater density and lower temperature replaces the surface water, and exerts a considerable influence on the weather of coastal regions. Carbon dioxide is transferred to the atmosphere in regions of upwelling. This is especially important in the Pacific equatorial regions, where 1 to 2 gigatons of carbon per year may be released to the atmosphere. Upwelling also re-sults in increased ocean productivity by transporting nutrient-rich waters to the surface layer of the ocean. Source: EPO.
USER: Any person accessing the EOSDIS. AUTHORIZED USERS are users who have viable EOSDIS accounts, and who may therefore make EOSDIS data requests. These users may be Affiliated or Unaffiliated. AFFILIATED USERS are those who are sponsored by one of the parties to the Earth Observations ICWG (EO-ICWG) data policy. (Source: EPO.)