Glossary
Terms
The percent of the sun’s electromagnetic energy reflected by the surface of an object back into space |
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Atolls |
Seamounts or guyots that have broken the surface with coral deposits built up around the rim |
Average wave height |
The average height of all the waves present, from the smallest ripple to the largest wave |
Bathythermograph |
Temperature versus depth profile |
Bergy bit |
A medium-sized fragment of glacier ice about the size of a small cottage |
Broaching |
Occurs when a landing craft gets turned parallel to the wave train |
Calve |
When the leading edge of a glacier breaks off |
Coastal current system |
A relatively uniform drift that flows roughly parallel to shore that may be composed of tidal currents, wind-driven currents, or local, density-driven currents |
Composite products |
Products composed of more than one day’s data |
Compressibility |
The ability of water to be compacted under pressure |
Continental rise |
Found seaward of the continental slope, in approximately 500 fathoms of water, made up of thick sediment deposits that cover irregular relief features |
Continental shelf |
The first province of the five major bottom provinces. The average width of the shelf is approximately 40 miles and comprise about 7.5 percent of the total ocean bottom |
Crest |
Peak or highest part of a wave |
Current |
The horizontal movement of water |
Deep-water layer |
The bottom layer of water, below 1,200 meters in the middle latitudes, characterized by fairly constant cold temperatures, generally less than 4°C |
Density current |
Current caused by density differences, or gravity differences between currents |
Drift |
The speed of a current measured in terms of knots |
Duration-limited sea |
Occurs when the wind is in contact with the sea for too short a time and it doesn’t have enough time to impart the maximum energy to the sea |
Ebb tide |
A falling, or outgoing, tide |
Fast ice |
Ice that forms along the shorelines |
Fathom |
6 feet |
Fetch areas |
Areas of constant wind speed and direction over a time |
Fetch-limited sea |
Occurs when the fetch length is too short and the wind is not in contact with the waves over a distance sufficient to impart the maximum energy to the waves |
First-year ice |
Reasonably unbroken level of ice of not more than one winter’s growth that starts as young ice. The thickness is from 30 centimeters to 2 meters (1 foot to 6 ½ feet) |
Flood tide |
A rising or incoming tide |
Forced waves |
Waves that are maintained by a periodic force |
Fracture |
Any break through sea ice |
Frazil crystals |
Thin plates of ice on the sea surface |
Free waves |
Waves caused by a sudden underwater impulse such as seismic activity |
Freeboard |
The portion of an iceberg above the water |
Fully developed sea |
When dissipation is equal to input energy and the waves stop growing |
Geopotential current |
See density current |
Grease ice |
Sea-surface ice showing a thick soupy consistency |
Growler |
A small fragment of glacier ice about the size of a grand piano |
Guyots |
Submerged, isolated, flat-topped mountains rising 3,000 feet or more above the sea floor |
Gyres |
Large oval, or circular, currents formed in the ocean basins by the combined effects of the winds, and the position of the continents |
Heat budget |
The temperature balance established in the ocean between heat gain and heat loss mechanisms |
Highest 1/10th wave height |
The average height of the highest 1/10th of all waves used to indicate the extreme roughness of the sea |
Hummock ice |
Ice topography piled haphazardly into mounds or hillocks |
Hydraulic currents |
Small-scale thermohaline subsurface circulations caused by the differences in sea level between two water bodies |
Ice rind |
Sea-surface ice showing a brittle crust forming with a shiny appearance |
Island arcs |
Groups of volcanic islands |
Isobaths |
Lines of equal water depth |
Lead |
A long, narrow open or refrozen break or passage through sea ice; a navigable fracture |
Littoral |
Shore |
Littoral current |
Current occurring in the surf zone caused by waves approaching the beach at an angle |
Long waves |
Waves that exist in water depths that are less than one-half of their wavelength |
Longshore current |
See littoral current |
Main thermocline |
The central layer of the ocean generally between 1,000 and 3,000 feet |
Mean range |
The difference, in height, between the high tides and the low tides |
Mean tide level |
The plane between mean low water and mean high water |
Mixed layer |
The upper layer of the three-layered ocean model |
Neap tide |
Tide that occurs when the moon is in its first- and third-quarter phases, the sun and the moon are at right angles to each other producing a lower-than-normal high tide and higher-than-normal low tide |
Nearshore current system |
Composed of shoreward moving water in the form of waves at the surface, a return flow or drift along the bottom in the surf zone, nearshore currents that parallel the beach (longshore or littoral), and rip currents |
Nil’s |
Sea-surface ice showing an elastic crust forming with a matte appearance |
Ocean basin |
Accounts for 76 percent of the ocean floor with depths ranging from 1,500 to 3,000 fathoms |
Ocean currents |
Organized, coherent belts of water in horizontal motion |
Ocean eddies |
A circular movement of water formed by the cutting off of meandering currents |
Oceanic fronts |
Lines of temperature and/or salinity discontinuity between two water masses |
Old ice |
Extremely heavy sea ice that has survived at least one summer’s melt and occurs primarily in the arctic and Antarctic polar packs |
Pack ice |
Sea ice covering more than half of the visible sea surface |
Plunging breakers |
Violently breaking waves that gain height rapidly as they first feel the bottom |
Polynya |
Any sizable area of sea water enclosed by sea ice |
Progressive waves |
Waves that are evident by the progressive movement of the wave form |
Puddle |
A depression in sea ice usually filled with melted water caused by warm weather |
Rafted ice |
Ice topography that occurs when wind forces ice cakes or ice floes to override one another |
Rams |
Protrusions of ice beneath the surface of irregular icebergs |
Refraction |
The bending of a wave that occurs when one portion of the wave moves slower than another portion |
Ridged ice |
Ice topography that is much rougher than rafted ice and occurs with first-year ice |
Rip currents |
Current caused by the return flow of water from the beach |
Salinity |
The total amount of dissolved solids in sea water |
Sea waves |
A complicated mix of superimposed waves and ripples that develop in a storm |
Seamounts |
Submerged, isolated, pinnacled mountains rising 3,000 feet or more above the sea floor |
A wave generated by a submarine (underwater) earthquake or volcanic event commonly called tsunamis |
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Set |
The direction in which the current is moving (toward) |
Shelf break |
Located at the seaward edge of the continental shelf with an average slant ratio roughly 20 times greater than that of the continental shelf |
Short waves |
Waves that exist in water depths greater than one-half of the wavelength |
Significant wave height |
The average height of the highest 1/3rd of all the waves present |
Sills |
Elevated parts of the ocean floor that partially separate ocean basins restricting the movement of bottom water masses resulting in their partial, and in some cases nearly total, isolation |
Slack water |
The period between an ebb tide and a flood tide when there is no appreciable horizontal movement of water |
Solvent |
The ability to dissolve other substances |
Specific heat |
The amount of heat needed to raise the temperature of one gram of a substance 1C° |
Spicules |
Minute ice needles on the sea surface |
Spilling breakers |
Waves that break very gradually as they move through the surf zone |
Spring range |
The annual average of the highest semi-diurnal range, which occurs twice a month, when the moon is in its new or full phase |
Spring tide |
Tide that occurs when the moon is in its new and full phases and the high tides are higher than normal and the low tides are lower than normal |
Stand |
The period between an ebb tide and a flood tide when there is no appreciable vertical movement of water |
Standing waves |
Waves made up of two progressive waves traveling in opposite directions |
Steady state |
Occurs when all the wind’s energy is imparted to the sea within the fetch |
Storm surges |
Occurs when tropical storms generating strong winds and low central pressures raise the sea level just before coming ashore |
Surf |
Swell that breaks on the shore |
Surf boarding |
Occurs when a craft is overtaken by a spilling breaker that carries the craft along, causing it to get out of control, broach, collide with another craft or hit some personnel |
Surf zone |
The horizontal distance in yards or feet between the outer most breaker and the limit of wave uprush on the beach |
Surface tension |
The ability to support heavier objects |
Surging breakers |
Waves that increase in height very slowly, the crest peaks but does NOT break as with other types, instead it continues to move up on to the beach |
Swamping |
Occurs when a craft is overtaken by a plunging breaker, and the wave "breaks" into and/or over the craft, causing it to fill with water, sink, turn over, shift out of position, or incur some other hazardous ordeal |
Swell waves |
Long, smooth, regular waves outside the generating area |
Swell waves |
Occurs as wind waves move beyond the fetch or when the wind over the fetch dies off |
Tablemounts |
See guyot |
Thaw holes |
Holes in sea ice that are caused by the melting associated with warm weather |
Thermocline |
The part of the ocean where temperature decreases rapidly with depth |
Tidal current |
The horizontal movement of water caused by tide changes |
Tidal day |
The daily tidal effect caused by the moon revolving around earth once every 24 hours and 50 minutes |
Tidal range |
The changes or difference in feet between high tide and low tide |
Tide |
Gravitational waves that have lengths in hundreds of miles and heights ranging up to 50 feet and are a consequence of the simultaneous action of the moon’s, the sun’s, and the earth’s gravitational forces, and the revolution about one another |
Trenches |
Long, narrow, and relatively steep-sided depressions that comprise the deepest portions of the oceans normally found on the seaward side of island arcs |
Trough |
Lull or lowest part of a wave |
Upwelling |
The rising of water toward the surface from subsurface layers of a body of water |
Viscosity |
Resistance to flow |
Wave amplitude |
One-half of the wave height, or the vertical displacement of a particle from the "at rest" position (sea level), to the top of the wave crest or base of the trough |
Wave frequency |
The number of waves passing a given point during a one-second interval |
Wave period |
The time interval between successive wave crests or troughs as they pass a fixed point |
Wave speed |
The rate at which the wave moves through the water measured in knots |
Wavelength |
The horizontal distance between two successive crests or troughs |
Wind waves |
Waves which result from the energy of the wind being imparted to the sea |
Wind-driven current |
Current initiated and sustained by the force of the wind exerting stress on the sea surface |
Young ice |
Ice that forms in one year or less with a thickness range from 10 to 30 centimeters (4 to 12 inches) |
Abbreviations and Acronyms
‰ |
Symbol denoting the measurement of salinity in parts per thousand by weight |
AOA |
Area of operations |
ASW |
Antisubmarine warfare |
AUTODIN |
Automatic Digital Network |
C |
Wave speed |
cm |
Centimeter |
Cwh |
Combined wave height |
ELF |
Extremely low frequency |
f |
Wave frequency |
FLIROUT |
Forward looking infrared forecast |
FNMOC |
Fleet Numerical Meteorology and Oceanography Center |
GFMPL |
Geophysics Fleet Mission Program Library |
h |
Hour |
IR |
Infrared |
ITWS |
International Tsunami Warning System |
km |
Kilometer |
km/hr |
Kilometer per hour |
L |
Wavelength |
LD |
Layer depth |
m |
Minute |
METSAT |
Meteorological satellite |
MLD |
Mixed-layer depth |
MOSS |
Mobile Oceanography Support Facility |
mph |
Mile per hour |
NAVEASTOCEANCEN |
Naval Eastern Oceanography Center |
NAVOCEANCOM |
Naval Oceanography Command |
NAVOCEANO |
Naval Oceanographic Office |
NAVPOLAROCEANCEN |
Naval Polar Oceanography Center |
NAVWESTOCEANCEN |
Naval Western Oceanography Center |
nm |
Nautical mile |
NODDS |
Navy Oceanographic Data Distribution System |
NOGAPS |
Naval Operational Global Atmospheric Prediction System |
NORAPS |
Naval Operational Regional Atmospheric Prediction System |
OPAREA |
Operational area |
OPARS |
Optimum Path Aircraft Routing System |
SST |
Sea-surface temperature |
sw |
Swell waves |
T |
Wave period |
TESS |
Tactical Environmental Support System |
ww |
Wind waves |