3 ms·
I'd wager that gravity isn't 100% equal over the whole globe, the pull of the moon's gravity also isn't equal over the globe, and that the circulation of water
by Mikeb85 11y ago
I'd wager that gravity isn't 100% equal over the whole globe, the pull of the moon's gravity also isn't equal over the globe, and that the circulation of water across the world's oceans also isn't 100% (so there's different salinity, water pressure, various prevailing 'currents', temperature, etc...). Of course I don't study this, so I don't know the exact reasons, but I'm sure there is a reason...
- mturmon 11y agoYes, it's all of that. Tides, temperature variations, ocean surface winds, and circulation all go in to changing sea surface height, at various time scales. It amounts to order of a couple of meters, peak-to-peak, in a weekly average. Sea surface height (SSH) has been measured from space with great accuracy, using radar altimetry, since 1992. We can now also measure sea surface temperature (SST), salinity (SSS), and surface winds. The winds are knowable because wind ruffles the water surface and this changes the radar scatter properties. Therefore, somewhat surprisingly, we know more about the ocean than the land. For more: https://en.wikipedia.org/wiki/Ocean_surface_topography; https://en.wikipedia.org/wiki/Ocean_surface_topography; the data is at http://podaac.jpl.nasa.gov/CoreMeasurements http://podaac.jpl.nasa.gov/CoreMeasurements