Satellite Sea Level Measurement
1993–2012 Sea level trends from satellite altimetry.Current rates of sea level rise from satellite altimetry have been estimated in the range of 2.9–3.4 ± 0.4–0.6 mm per year for 1993–2010. This exceeds those from tide gauges. It is unclear whether this represents an increase over the last decades; variability; true differences between satellites and tide gauges; or problems with satellite calibration. Knowing the current altitude of a satellite which can measure sea level to a precision of about 20 millimetres (e.g. the Topex/Poseidon system) is primarily complicated by orbital decay and the difference between the assumed orbit and the earth geoid . This problem is partially corrected by regular re-calibration of satellite altimeters from land stations whose height from MSL is known by surveying. Over water, the height is calibrated from tide gauge data which is needed to correct for tides and atmospheric effects on sea level.
Read more about this topic: Current Sea Level Rise
Famous quotes containing the words satellite, sea, level and/or measurement:
“Books are the best things, well used; abused, among the worst. What is the right use? What is the one end, which all means go to effect? They are for nothing but to inspire. I had better never see a book, than to be warped by its attraction clean out of my own orbit, and made a satellite instead of a system.”
—Ralph Waldo Emerson (18031882)
“I wouldnt think of asking you to lie; you havent the necessary diplomatic training.”
—John Farrow. Consul in Valparaiso, The Sea Chase (1955)
“Those who profess contempt for men, and put them on a level with beasts, yet wish to be admired and believed by men, and contradict themselves by their own feelingstheir nature, which is stronger than all, convincing them of the greatness of man more forcibly than reason convinces them of his baseness.”
—Blaise Pascal (16231662)
“Thats the great danger of sectarian opinions, they always accept the formulas of past events as useful for the measurement of future events and they never are, if you have high standards of accuracy.”
—John Dos Passos (18961970)