<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="816" name="ocean processes" parent="101" scope="Recurrent natural changes that are physical, biological, or chemical, actively affecting the seas and oceans."/><uf><usefor name="marine sediment transport"><usewith><term thcode="2" code="1034" name="sediment transport" parent="451" scope="Transport of solid particles of unconsolidated rock and mineral fragments, chemical precipitates, or biological materials."/></usewith></usefor><usefor name="ocean hazards"><usewith><term thcode="2" code="531" name="hazards" parent="1174" scope="Potential dangers from both natural processes (e.g., earthquakes, floods, and climate change) and human impacts on the environment."/></usewith></usefor><usefor name="oceans"><usewith><term thcode="2" code="810" name="ocean characteristics" parent="287" scope="The attributes and process of seas and oceans."/></usewith></usefor></uf><bt><term thcode="2" code="101" name="biological and physical processes" parent="1174" scope="All continuing activities, functions, and phenomena associated with organisms and non-living matter."/><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="812" name="ocean circulation" parent="816" scope="Movement of large masses of water within an ocean."/><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."/><term thcode="2" code="822" name="ocean waves" parent="816" scope="A periodic movement of seawater caused by wind, tide, and currents."/><term thcode="2" code="1168" name="tides (oceanic)" parent="816" scope="The periodic rise and fall of the level of the sea due to the gravitational attraction of the moon and sun. Occurs twice each day."/></nt><rt><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="2058" name="ocean acidification" parent="435" scope="Decrease in the pH of ocean waters as a result of the increase in atmospheric carbon dioxide concentration."/><term thcode="2" code="810" name="ocean characteristics" parent="287" scope="The attributes and process of 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="823" name="ocean-atmosphere interaction" parent="63" scope="Processes, including momentum, heat, gas and other exchanges, which result in profound effects on climate and interactions between the air in the lowest part of the atmosphere and the oceans."/><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."/></rt></descriptor>