<descriptor thcode="2"><thesaurus thcode="2" name="USGS Thesaurus" scope="Topics and methods of scientific study carried out by USGS, with product types, scientific disciplines, geologic time, and types of institutional structure and activities.  Broad and shallow, used to help people find scientific information." creator="U.S. Geological Survey" rights="Public domain" edition="2.0" date="2020-01-09" codetype="number" prefix="topic" uri="https://www2.usgs.gov/science/USGSThesaurus" tblname="term" nonpref="nonpref" relterm="relterm" root_code="1" contact="pschweitzer"><category><term thcode="25" code="29" name="distinct labels" parent="26" scope="Preferred labels (descriptor texts) are distinct within the thesaurus. A concept can be specified either by its unique identifier (code) or by the text of its descriptor."/><term thcode="25" code="16" name="hierarchical" parent="11" scope="Substantive broader-narrower relationships exist among the terms."/><term thcode="25" code="13" name="transitive" parent="12" scope="Narrower terms have an &quot;is a&quot; relationship with their broader terms, and generally can be described as part-of, type-of, or instance-of the broader term."/><term thcode="25" code="21" name="disciplines" parent="2" scope="Broad categories of human inquiry or activity, such as scientific disciplines."/><term thcode="25" code="20" name="methods" parent="2" scope="Actions taken to obtain or analyze information"/><term thcode="25" code="19" name="organizational functions" parent="2" scope="Things that organizations do, typically including various types of programs, projects, and services."/><term thcode="25" code="7" name="temporal" parent="2" scope="Terms indicate periods of time, such as chronostratigraphic units, named historical periods or intervals surrounding known historical events, or seasons."/><term thcode="25" code="5" name="theme" parent="2" scope="Terms indicate domains of human concern, such as scientific discipline, societal problems, or characteristics of earth, space, oceans, and living things."/><term thcode="25" code="29" name="distinct labels" parent="26" scope="Preferred labels (descriptor texts) are distinct within the thesaurus. A concept can be specified either by its unique identifier (code) or by the text of its descriptor."/><term thcode="25" code="16" name="hierarchical" parent="11" scope="Substantive broader-narrower relationships exist among the terms."/><term thcode="25" code="13" name="transitive" parent="12" scope="Narrower terms have an &quot;is a&quot; relationship with their broader terms, and generally can be described as part-of, type-of, or instance-of the broader term."/><term thcode="25" code="21" name="disciplines" parent="2" scope="Broad categories of human inquiry or activity, such as scientific disciplines."/><term thcode="25" code="20" name="methods" parent="2" scope="Actions taken to obtain or analyze information"/><term thcode="25" code="19" name="organizational functions" parent="2" scope="Things that organizations do, typically including various types of programs, projects, and services."/><term thcode="25" code="7" name="temporal" parent="2" scope="Terms indicate periods of time, such as chronostratigraphic units, named historical periods or intervals surrounding known historical events, or seasons."/><term thcode="25" code="5" name="theme" parent="2" scope="Terms indicate domains of human concern, such as scientific discipline, societal problems, or characteristics of earth, space, oceans, and living things."/></category><altlabel><altlabel>USGSThesaurus</altlabel><altlabel>USGSThesaurus</altlabel></altlabel></thesaurus><term thcode="2" code="375" name="field inventory and monitoring" parent="376" scope="Repeated observation or sampling at a site, on a scheduled or event basis, for study and analysis.  In general, this category excludes sampling programs in which materials are obtained in the field and brought back to a laboratory for study and analysis."/><uf><usefor name="baseline characterization"/><usefor name="field monitoring"/><usefor name="field observation"/><usefor name="inventory"/><usefor name="ocean current measurement"><usewith><term thcode="2" code="814" name="ocean currents" parent="816" scope="Recurrent strong flows of seawater generated by wind or variations in water density along a given path."/></usewith></usefor><usefor name="ocean monitoring"><usewith><term thcode="2" code="810" name="ocean characteristics" parent="287" scope="The attributes and process of seas and oceans."/></usewith></usefor><usefor name="ocean wave measurement"><usewith><term thcode="2" code="822" name="ocean waves" parent="816" scope="A periodic movement of seawater caused by wind, tide, and currents."/></usewith></usefor><usefor name="precipitation measurement"><usewith><term thcode="2" code="927" name="precipitation (atmospheric)" parent="63" scope="Any or all forms of water particles that fall from the atmosphere, such as rain, snow, hail and sleet."/></usewith></usefor><usefor name="rainfall measurement"><usewith><term thcode="2" code="927" name="precipitation (atmospheric)" parent="63" scope="Any or all forms of water particles that fall from the atmosphere, such as rain, snow, hail and sleet."/></usewith></usefor><usefor name="reconnaissance"/><usefor name="river discharge monitoring"/><usefor name="snowfall measurement"><usewith><term thcode="2" code="927" name="precipitation (atmospheric)" parent="63" scope="Any or all forms of water particles that fall from the atmosphere, such as rain, snow, hail and sleet."/></usewith></usefor><usefor name="volcano monitoring"><usewith><term thcode="2" code="1286" name="volcanic activity" parent="451" scope="Episodes during which gases, ash, and lava (molten rock) escape from vents in the earth's crust, accompanied by minor tremors."/></usewith></usefor><usefor name="weather monitoring"><usewith><term thcode="2" code="63" name="atmospheric and climatic processes" parent="101" scope="Phenomena affecting or occurring within the mass of gases that surrounds the earth, including its physics, chemistry, dynamics, and weather conditions."/></usewith></usefor><usefor name="weather observations"><usewith><term thcode="2" code="63" name="atmospheric and climatic processes" parent="101" scope="Phenomena affecting or occurring within the mass of gases that surrounds the earth, including its physics, chemistry, dynamics, and weather conditions."/></usewith></usefor></uf><bt><term thcode="2" code="376" name="field methods" parent="734" scope="Research procedures and instrumental means to measure, collect data and samples, and observe in the natural areas where the materials, phenomena, structures, or species being studied occur."/><term thcode="2" code="734" name="methods" parent="1" scope="Techniques, methods, procedures, or strategies for research, management, collection, or analysis of scientific information in USGS."/><term thcode="2" code="1" name="Categories" scope="Thematic terms for categorizing information resources.  This thesaurus is intended to support finding and understanding scientific information."/></bt><nt><term thcode="2" code="222" name="CTD measurement" parent="375" scope="Instrumental determination of conductivity, temperature, and pressure as a function of depth to determine the salinity of seawater."/><term thcode="2" code="1726" name="acoustic doppler current profiling" parent="375" scope="Field monitoring of water currents using the doppler effect with acoustic instruments."/><term thcode="2" code="1353" name="animal and plant census" parent="375" scope="Inventory of macroscopic animals and plants by observation in the field. Used to estimate population and distribution."/><term thcode="2" code="125" name="borehole logging" parent="375" scope="Method of recording the physical characteristics of the subsurface as a function of depth by observations during drilling of a well or borehole, studying the resulting core, or by lowering instruments into a drilled hole."/><term thcode="2" code="317" name="ecosystem monitoring" parent="375" scope="Recording, evaluating, and actively intervening over time in the interaction of living and nonliving elements in a specific environment."/><term thcode="2" code="326" name="electromagnetic surveying" parent="375" scope="Method of determining the shape and constituency of near-surface earth structures by variations of responses of the materials to electrical and magnetic fields. Use for ground-based methods of imaging."/><term thcode="2" code="1359" name="field monitoring stations" parent="375" scope="Locations where USGS scientists or their collaborators make measurements of natural phenomena."/><term thcode="2" code="1668" name="gravimeter measurement" parent="375" scope="Use of a specialized instrument for measuring the earth's gravity at a given location."/><term thcode="2" code="527" name="handheld field spectroscopy" parent="375" scope="Use of portable equipment to measure spectral reflectance of materials in the field."/><term thcode="2" code="1669" name="magnetometer measurement" parent="375" scope="Use of specialized instruments designed to measure the earth's magnetic field at a given location."/><term thcode="2" code="378" name="monitoring networks" parent="375" scope="An aggregation of field monitoring stations that fulfill a common purpose"/><term thcode="2" code="1672" name="optical methods" parent="375" scope="Measurement of light transmission or reflectance in the field to estimate, for example, the density of suspended sediment in water bodies."/><term thcode="2" code="1042" name="seismic methods" parent="375" scope="Procedures used to record and study earthquakes or earth vibrations including those that are artificially induced."/><term thcode="2" code="1083" name="sonar methods" parent="375" scope="SOund Navigation And Ranging techniques to detect submerged objects and to determine depths to the bottom of a water body using reflections of sound waves."/><term thcode="2" code="2024" name="statistical surveying" parent="375" scope="Information gathering by asking questions of selected people or organizations."/><term thcode="2" code="1116" name="stream-gage measurement" parent="375" scope="Use of specialized instruments designed for observing, checking, and recording the water discharge that occurs in a natural channel."/><term thcode="2" code="1148" name="telemetry" parent="375" scope="Field technique using instruments which measure heat, radiation, speed, or other property and transmit the data to a distant receiver."/><term thcode="2" code="1169" name="tiltmeter measurement" parent="375" scope="Determination of tiny changes in the slope angle or tilt of the ground in order to monitor deformation caused by moving magma. Instruments detect variations in a liquid level or in the position of a pendulum."/><term thcode="2" code="1716" name="tomography" parent="375" scope="Observation of the internal structure of an object or, as is more typical in USGS research, a cross section of the earth's crust by changing the relative orientation of a signal generator, a sensor, or both."/><term thcode="2" code="1273" name="video monitoring" parent="375" scope="Field study employing the use of filming or repeated photography with stationary optical or digital cameras to observe changes in a feature or organism."/><term thcode="2" code="1285" name="vocalization methods" parent="375" scope="Series of methods used to (a) record sonograms (sound spectrogram) of animal sounds which are analyzed to identify the presence of species in an area and to determine distinct sound patterns within a species, e.g., mating calls, danger alerts; (b) attract species to an area for inventory or monitoring by playing recorded animal sounds or mimicking them."/></nt><rt><term thcode="2" code="370" name="faunal and floral census (microscopic)" parent="619" scope="Records of counts of the different microscopic species in a core, soil, sediment, rock or water sample to determine geologic age or other characteristic of the sample.  Use for microscopic examinations."/></rt></descriptor>