<descriptor thcode="62"><thesaurus thcode="62" name="Coastal and Marine Ecological Classification Standard" scope="Categories of ecosystems for coastal, estuarine, and marine environments." creator="FGDC" rights="public domain" date="2017-05-10" codetype="alpha" prefix="cmecs" uri="https://www2.usgs.gov/science/CMECS" tblname="cmecs" root_code="root" contact="pschweitzer"><category><term thcode="25" code="16" name="hierarchical" parent="11" scope="Substantive broader-narrower relationships exist among the terms."/><term thcode="25" code="16" name="hierarchical" parent="11" scope="Substantive broader-narrower relationships exist among the terms."/></category><altlabel><altlabel>CMECS</altlabel><altlabel>CMECS</altlabel><altlabel>Coastal and Marine Ecological Classification Standard (CMECS)</altlabel><altlabel>Coastal and Marine Ecological Classification Standard (CMECS)</altlabel></altlabel></thesaurus><term thcode="62" code="WC-627" name="Current" parent="WC-C012" scope="Hydroform Class: Water that is undergoing coherent mass movement, either as laminar or turbulent flow, relative to surrounding waters and fixed structural, landform or geologic features. ..."/><bt><term thcode="62" code="WC-C012" name="Hydroform" parent="WC-C001"/><term thcode="62" code="WC-C001" name="Water Column" parent="root"/><term thcode="62" code="root" name="CMECS" scope="Coastal and Marine Ecological Classification Standard: Category terms encompassing waters from the head of tide or inland incursion of ocean salinity to the splash zone of the coasts to the deepest portions of the oceans and the deep waters of the Great Lakes."/></bt><nt><term thcode="62" code="WC-628" name="Boundary Current" parent="WC-627" scope="Hydroform: The portion of an ocean gyre that moves along the continental boundary."/><term thcode="62" code="WC-629" name="Buoyancy Flow" parent="WC-627" scope="Hydroform: Current flow created by discontinuity in buoyancy of two juxtaposed water masses of different density, causing one to flow relative to the other toward buoyancy equilibrium."/><term thcode="62" code="WC-630" name="Current Meander" parent="WC-627" scope="Hydroform: A current that deviates from a straight line flow, which is often the result of incursion by lateral currents or the presence of a physical or density barrier. Meanders can pinch off from the main current flow and form rings."/><term thcode="62" code="WC-631" name="Deep Boundary Current" parent="WC-627" scope="Hydroform: A current that connects high-latitude ocean waters (where deep water is formed) with upwelling regions. ..."/><term thcode="62" code="WC-632" name="Deep Circulation" parent="WC-627" scope="Hydroform: The mass circulation of the oceans that carries cold polar surface water to depth, sinking due to higher density and wind forcing. ..."/><term thcode="62" code="WC-633" name="Deep Convection" parent="WC-627" scope="Hydroform: Large mass flows of water in the deep ocean that form critical parts (and return paths) of the great ocean circulation."/><term thcode="62" code="WC-634" name="Density Flow" parent="WC-627" scope="Hydroform: Flow caused by differential density between two convergent water masses?or by a parcel of denser water flowing along a sloping bottom under a column of less-dense water."/><term thcode="62" code="WC-635" name="Ekman Flow" parent="WC-627" scope="Hydroform: The flow of water at 90&#xC2;&#xB0; to the direction of the wind, at steady state, due to Earth's rotational effect."/><term thcode="62" code="WC-636" name="Inertial Current" parent="WC-627" scope="Hydroform: Currents that continue motion through inertia. Due to the rotation of the Earth, inertial currents tend to form circular gyres."/><term thcode="62" code="WC-637" name="Langmuir Circulation" parent="WC-627" scope="Hydroform: Rotational oscillatory motion of surface waters induced by wind and Coriolis deflection. ..."/><term thcode="62" code="WC-638" name="Mean Surface Current" parent="WC-627" scope="Hydroform: The time-averaged steady state ocean surface current pattern responsible for mean oceanic water motions."/><term thcode="62" code="WC-639" name="Mesoscale Eddy" parent="WC-627" scope="Hydroform: A rotational feature that (a) breaks off of an ocean gyre or large current (such as the Gulf Stream) and (b) persist autonomously for some period (from days to months) at sizes of 20 kilometers to 500 kilometers. ..."/><term thcode="62" code="WC-640" name="Residual Current" parent="WC-627" scope="Hydroform: Current movement resulting from asymmetry in tidal flow?notably within a partially enclosed estuary or embayment?that results in characteristic estuarine circulation patterns."/><term thcode="62" code="WC-641" name="Sub-mesoscale Eddy" parent="WC-627" scope="Hydroform: A reverse current with rotational movement created when fluid flows past an obstacle. Sub-mesoscale eddies are of size scale smaller than 20 kilometers."/><term thcode="62" code="WC-642" name="Thermohaline Eddy" parent="WC-627" scope="Hydroform: Eddy formation due to the interaction of temperature and salinity differences between two water masses initiating convective flow."/><term thcode="62" code="WC-643" name="Tidal Flow" parent="WC-627" scope="Hydroform: Advective flow resulting from of tidal movement, often amplified in velocity when moving through an inlet, pass or channel. ..."/><term thcode="62" code="WC-644" name="Turbidity Flow" parent="WC-627" scope="Hydroform: A flow of water down slope carrying a dense suspension of fluid mud or unconsolidated material."/><term thcode="62" code="WC-645" name="Wave-driven Current" parent="WC-627" scope="Hydroform: Residual current caused by asymmetrical force created by wave motion."/><term thcode="62" code="WC-646" name="Wind-driven Current" parent="WC-627" scope="Hydroform: Current caused by wind shear as distinguished by those caused by density differences, which result in thermohaline circulation. ..."/></nt></descriptor>