<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="810" name="ocean characteristics" parent="287" scope="The attributes and process of seas and oceans."/><uf><usefor name="ocean mixed-layer depth"/><usefor name="ocean monitoring"><usewith><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."/></usewith></usefor><usefor name="ocean surface characteristics"/><usefor name="oceans"><usewith><term thcode="2" code="816" name="ocean processes" parent="101" scope="Recurrent natural changes that are physical, biological, or chemical, actively affecting the seas and oceans."/></usewith></usefor><usefor name="sea surface reflectance"/></uf><bt><term thcode="2" code="287" name="earth characteristics" parent="1174" scope="The measurable, definable properties and features of the earth."/><term thcode="2" code="1174" name="topics" parent="1" scope="Themes, subjects, and concerns for which USGS information resources are relevant."/><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="817" name="ocean salinity" parent="810" scope="Measure of the percentage of dissolved salts in seawater."/><term thcode="2" code="819" name="ocean temperature" parent="810" scope="Distribution of heat in the oceans, including surface water, thermocline and mode waters, and deep waters.  Includes discussion and measures of both in-situ and potential temperature."/><term thcode="2" code="1025" name="sea-floor characteristics" parent="810" scope="Geomorphic features and geographic, compositional, and textural variation in the materials composing the ocean floor. Includes both large-scale structures (such as seamounts and rises) and fine-scale variations in rocks and deposits on the sea floor."/><term thcode="2" code="1028" name="sea-level change" parent="810" scope="Variation in the relative vertical position of land and ocean waters. Caused globally by changes in the distribution of ice masses and the shape of the oceans, and locally by the rate of uplift or subsidence of the land surface.  Includes both global (eustatic) and local (relative) sea-level variations."/></nt><rt><term thcode="2" code="74" name="AVHRR" parent="588" scope="Advanced Very High Resolution Radiometer or broad-band, four or five channel scanner, sensing in the visible, near-infrared, and thermal infrared portions of the electromagnetic spectrum. This information is used to estimate characteristics of the land and sea surface such as temperature and overall health of vegetation."/><term thcode="2" code="703" name="marine chemistry" parent="1298" scope="Branch of chemistry that deals with the properties, composition, structure, and interaction of substances in the seas and oceans."/><term thcode="2" code="707" name="marine geophysics" parent="470" scope="Branch of earth sciences concerned with the physical processes of the oceans and continental margins.  We include here studies of large bodies of brackish and fresh water, such as lakes and rivers."/><term thcode="2" code="816" name="ocean processes" parent="101" scope="Recurrent natural changes that are physical, biological, or chemical, actively affecting the seas and oceans."/><term thcode="2" code="818" name="ocean sciences" parent="291" scope="Sciences involved in the study of geological, biological, chemical, and physical characteristics and processes of the oceans."/><term thcode="2" code="824" name="oceanic lithosphere" parent="667" scope="The solid outer zone of the earth, covered by seawater, and comprised of the crust and the upper layer of the mantle."/><term thcode="2" code="1722" name="sea ice concentration" parent="1072" scope="Proportion of ocean area in a given region that contains or is covered by floating ice."/><term thcode="2" code="1124" name="surface water (non-marine)" parent="1308" scope="Open bodies of water, such as lakes, rivers, or streams.  All non-marine waters on the  surface of the earth, including fresh, brackish, and salt water."/><term thcode="2" code="2264" name="water column reflectivity" parent="1304" scope="A measure of the strength of reflection from small particles suspended in water. It is usually measured by sending a pulse of sound or light through the water and measuring the sound or light that is returned. Water column reflectivity can be used to measure the concentration of suspended particles."/><term thcode="2" code="1308" name="water resources" parent="777" scope="Stocks of water, the liquid derived from precipitation. A constituent of living matter and necessity for all life, it covers a large proportion of the earth's surface."/></rt></descriptor>