Sea-surface height (SSH) is the height (or topography or relief) of the ocean's surface. On a daily basis, SSH is most obviously affected by the tidal forces of the Moon and the Sun acting on the Earth. Over longer timescales, SSH is influenced by ocean circulation. Typically, SSH anomalies resulting from these forces differ from the mean by less than ±1 m (3 ft) at the global scale. The slowest and largest variations are due to changes in the Earth's gravitational field (geoid) due to the rearrangement of continents, formation of sea mounts and other redistribution of rock.
Since the Earth's gravitational field is relatively stable on decadal to centennial timescales, ocean circulation plays a more significant role in the observed variation of SSH. Across the seasonal cycle changes in patterns of warming, cooling and surface wind forcing affect circulation and influence SSH. Variations in SSH can be measured by satellite altimetry (e.g. TOPEX/Poseidon) and used to calculate determine sea level rise and properties such as ocean heat storage.
See also Eddy (fluid dynamics).
Famous quotes containing the words sea, surface and/or height:
“For she has made me the laily worm
That lies at the fit o’ the tree,
An’ my sister Masery she’s made
The machrel of the sea.”
—Unknown. The Laily Worm and the Machrel of the Sea (l. 5–8)
“All the aspects of this desert are beautiful, whether you behold it in fair weather or foul, or when the sun is just breaking out after a storm, and shining on its moist surface in the distance, it is so white, and pure, and level, and each slight inequality and track is so distinctly revealed; and when your eyes slide off this, they fall on the ocean.”
—Henry David Thoreau (1817–1862)
“It would be naive to think that peace and justice can be achieved easily. No set of rules or study of history will automatically resolve the problems.... However, with faith and perseverance,... complex problems in the past have been resolved in our search for justice and peace. They can be resolved in the future, provided, of course, that we can think of five new ways to measure the height of a tall building by using a barometer.”
—Jimmy Carter (James Earl Carter, Jr.)