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meteorological tides original
dcterms created equal to or less than 2020-09-09T01:02:45.463Zequal to or more than 2020-09-09T01:02:45.463Z
definition Periodical or quasi-periodical changes in water level caused by the daily or seasonal variations in local meteorological conditions. They are recognised principally by Sa, Ssa, and S1 constituents, see also radiational tides.
radiational tides original
dcterms created equal to or less than 2020-09-09T01:02:45.470Zequal to or more than 2020-09-09T01:02:45.470Z
definition A quasi-periodic rise and fall of sea level caused by meteorological variability, hence also known as “meteorological tides”. Semi-diurnal radiational tides in the tropics are thought to be due to semi-diurnal fluctuations in surface barometric pressure forced at diurnal period at the top of the atmosphere (sometimes called "atmospheric tide"). Diurnal radiational tides are often caused by land/sea breezes or solar heating (note that neither of these forcing functions are purely sinusoidal in time). Monsoonal winds may cause semiannual radiational tides on some coastlines. Annual heating of the atmosphere and redistribution of air mass can both cause annual radiational tides.
quadrature original
dcterms created equal to or less than 2020-09-09T01:02:45.469Zequal to or more than 2020-09-09T01:02:45.469Z
definition The condition whereby the angle formed by the sun, earth, and moon is 90°. See also syzygy.
syzygy original
dcterms created equal to or less than 2020-09-09T01:02:45.481Zequal to or more than 2020-09-09T01:02:45.481Z
definition The condition whereby the sun, earth and moon are in alignment. See also quadrature.
Rayleigh criterion original
dcterms created equal to or less than 2020-09-09T01:02:45.471Zequal to or more than 2020-09-09T01:02:45.471Z
definition From the "Australian Hydrographic Office Glossary": A criterion used in tidal analysis, which requires that only constituents which are separated by at least one complete period from their neighbouring constituents over the length of data available should be included in the harmonic analysis of a given time series. See also synodic period.
synodic period original
dcterms created equal to or less than 2020-09-09T01:02:45.480Zequal to or more than 2020-09-09T01:02:45.480Z
definition From the "Australian Hydrographic Office Glossary": The minimum length of data necessary to separate a pair of constituents according to the Rayleigh criterion.
rectilinear currents original
dcterms created equal to or less than 2020-09-09T01:02:45.471Zequal to or more than 2020-09-09T01:02:45.471Z
definition From the "Australian Hydrographic Office Glossary": Also known as a reversing stream; a tidal stream which flows alternately in approximately opposite directions with slack water at each reversal of direction. Encountered mainly in straits and channels. See also streams
streams original
dcterms created equal to or less than 2020-09-09T01:02:45.480Zequal to or more than 2020-09-09T01:02:45.480Z
definition Same as tidal currents, although some hydrographic authorities use "streams" to refer exclusively to the tidal currents along the principal directions of ebb and flood (which may not differ by 180°, but usually do!). The set of the current is the direction in which it flows. On the incoming tide, the streams are said to be in flood; the outgoing streams are in ebb. The stand of the tide occurs near high and low water when the water level is unchanging. The analogous term for streams is the slack water that may or may not occur at the same time. Tidal streams which flow back and forth along a line are rectilinear, whereas those that follow an elliptical circuit (due to the coriolis force) are rotary (see also rotary flow). The ellipse traced out by a tidal current vector in a rotary flow regime is called a tidal ellipse.
rotary flow original
dcterms created equal to or less than 2020-09-09T01:02:45.474Zequal to or more than 2020-09-09T01:02:45.474Z
definition From the "Australian Hydrographic Office Glossary": A tidal stream that flows continually with the direction of flow changing through all points of the compass during a tidal cycle. Usually found offshore where there are no restricting barriers. This natural tendency of tidal flows (they become rectilinear only when restricted) has its origins in the Coriolis force and thus it tends to rotate counterclockwise in the southern hemisphere. See also streams.
secondary port original
dcterms created equal to or less than 2020-09-09T01:02:45.475Zequal to or more than 2020-09-09T01:02:45.475Z
definition In the context of tide tables, a port for which predictions are required, but for which insufficient data for a reliable harmonic analysis is available and hence, predictions from the nearest standard port (see standard port) must be used (with suitable corrections). Also called a subordinate port.