What is the master reference for sea level. Surely, all the oceans are not at the same level.
2006-11-11 11:49:38 · 6 answers · asked by Philip 1 in Science & Mathematics ➔ Earth Sciences & Geology
Traditionally sea level is defined as: 'The time averaged (mean) sea level relative to a fixed land based bench mark'. Here the time over which the water level is averaged must be long enough to smooth out the effects of local wind, waves, tides, atmospheric variations and seasonal effects. The UK ordinance datum bench mark is situated at Newlyn in Cornwall. The tide gauge at Newlyn is a simple devise called a stilling well. This devise is a well that is built into the harbour arm and is open to the ocean at a level below that of the lowest astronomic tide. The well has the effect of damping out water surface fluctuations due to wind and waves. Measurement of water level within the well was traditionally achieved by an elaborate system of floats and pulleys. Such systems (although fairly accurate) have now been replaced pressure sensors or other electrical methods (resistance / capacitance) of sensing the sea surface position.
International data on sea level change is archived at the Proadman Oceanographic Office (POL) in Bidston, UK. Here data from the Global Sea Level Observing System (GLOSS) is archived. These data comprise nearly 300 primary tide gauges located in coastal areas all over the world. POL has been nominated as the Permanent Service for Mean Sea Level (PSMSL).
2006-11-11 11:54:13 · answer #1 · answered by Martha P 7 · 0⤊ 0⤋
Due to gravity, all interconnected seas and oceans are at the same level. variability occurs due to the gravitational effects of the moon and weather but the average is the same
2006-11-11 11:56:51 · answer #2 · answered by jezmek 2 · 1⤊ 0⤋
Good question that made me think. On Navigational Charts the reference is to LAT Lowest Astronomical Tide. This is the lowest point that the tide 'should' reach and subsequent measurements are made from this level.
2006-11-11 11:52:53 · answer #3 · answered by Anonymous · 0⤊ 0⤋
actually there is a slight differential in elevations but sea level is calculated on the average (including tides)
2006-11-11 11:55:52 · answer #4 · answered by Ralph 5 · 0⤊ 0⤋
don't all large bodies of water meet at the shoreline
at sea level??
they cannot be above it/ or below it - they are all at
sea level - which rises and falls with the tide
2006-11-11 11:52:03 · answer #5 · answered by tomkat1528 5 · 0⤊ 0⤋
aren't they all the same?
2006-11-11 11:51:38 · answer #6 · answered by ? 7 · 0⤊ 0⤋