42

There are two ways this problem needs to be looked at. The first is more astronomy than Earth science. The Earth as an entire system is largely contained. Its gravity and magnetic field retains nearly all of its elements. Earth does lose hydrogen and helium and cosmic rays will split water molecules leading to a loss of an impressive amount of ...


39

"Sea" versus "lake" versus "just part of the ocean" is a bit fuzzy, but there are two things that are universal about seas: They are saline. They are either endorheic or have a sea-level (tidally-influenced) connection to the ocean. Now, let's see how the Great Lakes look under these criteria. Saline? No, salinity is 0, give or take measurement error. ...


35

When dissolved in water, salt breaks up into sodium and chlorine ions, which combine with water molecules so they cannot easily sink. However, there is a tendency for streams of fresh water to float on salt water and rise to the top. This caused problems for British submarines in the Dardanelles Straits during WW1. Moving from almost fresh water to the ...


33

There are many "uncharted waters". Nautical charts have information about water depths, dangers to navigation, aids to navigation, anchorages, and other features. You can see here what might be included in a nautical chart: U.S. Chart No. 1 The area in question is a shallow sea... so boats of different sizes may or may not be able to take certain routes ...


33

The area is experiencing post-glacial isostatic rebound. Much of Canada was covered in an extensive ice sheet in the last glacial period (the 'Ice Age'), from about 110 ka until 12 ka. The ice in the Hudson Bay area was among the last to melt: A thick ice sheet depresses the crust (the lithosphere), making a small dent in the uppermost mantle (the ...


29

Your assumption that there is not a lot of water elsewhere in the solar system is incorrect. According the this article on NASA's website; Missions in recent years have overturned our view of a dry solar system, returning mounting evidence of ample water from a vast array of locations. Comets from the remote corners of our solar system are made of water ...


27

In the case of Río de la Plata, part of it is history and politics, and part of it is oceanography. Most of Argentina and Uruguay considers Río de la Plata as a river (thus, the name, río) and as such it is the widest river in the world (maximum width >200km). Río de la Plata is formed as the confluence of the Paraná and Uruguay rivers and results in a ...


26

There are lots of controls on sea level, not just the volume of water in the world ocean. These controls operate on different time and spatial scales, and interact in nonlinear ways. As a result, both global ('absolute') sea level and local ('relative') sea level can rise in some places and fall in others. For example, absolute sea-level is currently rising,...


26

Sea level has a strong seasonal signal. The annual variability is less than the daily changes associated with tidal forcing in most locations, but still can be on the order of 5-10 cm (maximum values about 15 cm). The causes of the seasonal fluctuations are mostly associated with seasonal changes in wind intensity and patterns, changes in temperature that ...


26

Why does the salt in the oceans not sink to the bottom? Because there isn't any "salt", per se, in the ocean. Salt, as the compound sodium chloride (NaCl) does not exist as a solid in the ocean. It is dissolved into sodium and chloride ions (charged atoms) that exist within the ocean as a homogenous phase (that is, a "thing"). That said, water with sodium ...


24

The water was already present when the Earth assembled itself out of the accretionary disk. Continued outgassing of volcanoes transferred the water into the atmosphere which was saturated with water. And rain transferred the water onto the surface. Compared to other planets and smaller solar system object Earth has a big advantage. It is large enough to ...


24

Ocean waves (and also in mediterranean type seas and larger lakes, but on a smaller scale) are generated by two processes: locally generated waves ("wind waves"), which follow the direction of the wind; waves generated further out in the sea (i.e. "swell waves"), which do not necessarily follow the direction of the wind. During the night, you are probably ...


23

In a nutshell: The instrument measures microwave radiances (after calibration) If we know the sea surface temperature, we can use radiances to calculate emissivity. The emissivity at 1.4 GHz is itself a function of near-surface ocean salinity. However, in reality, it's more complicated, because there are other factors that come into the equation, such as ...


23

Yes, there are lots of other factors. Factors affecting sea levels are no different from other natural processes: there is a large number of coupled, non-linear effects, operating on every time scale, and at every length scale, and across many orders of magnitude. The Wikipedia page Current sea level rise lists many of the known processes. And I wrote a ...


21

Why doesn't 71% water of the earth dry or evaporate? The simple answer: Because it rains. The not so simple answer: By some estimates, the Earth has already lost about a quarter of its water, and it is predicted to lose almost all of its water in a billion or so years from now. It rains because temperature decreases with altitude. This lapse rate means ...


21

No. As it is, many hurricanes never make landfall. In an oceanic world I could see three fates happening: Hurricanes that dissipate due to dynamical features or climatological features. By dynamical features, I mean things like two hurricanes that shear each other out or produce an environment that can't be sustained. An example of the latter is upwelling, ...


19

For very quick visual comparison I would use Cube Browser or ncview together with a command line tool like the Climate Data Operators. For quick production of nice looking graphics (and animations) Panoply really makes good job. For further analysis or special graphics keep following your approach and script with things like MATLAB, Python (e.g. with Iris), ...


18

Theoretically, I agree that there should be one instable equilibrium point between the two stable equilibrium points when we have a 2D current field. However, there are some additional components of the problem: Ocean currents are not 2D but 3D currents. Considering only the sea surface might lets field lines disappear. The wind has an additional forcing. ...


18

Yes, you're right, there should be (at least one) saddle point in the middle of the loop. And indeed, if you search for illustrations of Pacific ocean circulation, you can see the saddle point in some of them, like this one: Source: Introduction to Tropical Meteorology, 2nd ed., chapter 3.3.1, fig. 3.20. Now, in a lot of other maps, the saddle region is ...


17

The writers of netCDF, UNIDATA, maintain a pretty extensive list of visualisation software on the netCDF website. It even mentions an Excel add-in, for the masochistic, presumably. Over the years, I've found Ferret to be reliable with CF compliant files (and non-compliant ones, for that matter) and useful for interactive quick looks and simple ...


17

In a 1983 Journal of Geology paper by Milliman and Meade, "World-Wide Delivery of River Sediment to the Oceans" (link) it is estimated that the world's rivers carry about $13.5\times 10^9$ tonnes of sediment per year. If we assume an average density of $2.5~\rm{g/cm^3}$, this corresponds to a volume of 8.8 cubic kilometers. The total surface area of the ...


15

The easiest way this is measured is via Argo floats. They're probes which periodically dive into the sea, and measure the ocean heat content. This is done by calculating the formula. According to the European Environmental Agency, this formula is: Ocean heat content is defined as the integrated temperature change times the density of seawater, times ...


15

Here is an estimate from Beauchamp and Baud (2002), for parts of the ocean around Pangea, for the latter parts of it's existence (~300-250mya). It is based on various previous papers that looked at deposits of carbonates and phosphate deposits, and made a few assumptions, including a sufficient supply of silica and nutrient inputs, and environments suitable ...


15

Yes, there are many. According to the seafloor topographic data of ETOPO (1 arc second resolution), and the Exclusive Economic Zones (EEZ) database of marineregions.org. There are at least 157 seafloor features higher than -100 m (closer than 100 m to the sea surface). With that data, I made the following figure that shows: ETOPO topographic data All EEZ ...


15

What is possible in a low-friction world is illustrated by the Great Red Spot on Jupiter, an anticyclonic storm that has has been continuously observed that fluid planet's surface at least since 1878 (142 years). Though it has shrunk a bit from its biggest size, it's still big enough to cover the Earth. The Great Red Spot may have had a longer history, ...


14

I don't know about the size of land masses, but their distribution and the shape of ocean basins definitely play a big role. When considering the ideal case of an all-ocean globe, i.e. one with no land masses (equilibrium tidal theory), the combined effect of sun and moon give a theoretical tidal range of less than 1 m(1). As tidal ranges can be much larger ...


14

First, inhomogeneities in the ocean are in fact quite common. There are density gradients in both horizontal and vertical directions and those gradients result in the baroclinic circulation of the ocean. The density gradients in the ocean are caused by salinity and temperature differences. Rossby waves are common in the ocean. They propagate along lines of ...


14

Meddies are anticyclonic (rotating clockwise) lenses of warm salty Mediterranean Water that travel through the North Atlantic between ∼500 and 1500 m depth. They are observed as large temperature, salinity and velocity anomalies (Richardson et al., 2000). Meddies are typically 40–100 km in diameter with their core being 500–1000 m thick. Meddies separate ...


14

Because of post glacial rebound. The asthenosphere was pressed down under Laurentide ice sheet during last ice age and is now finding a new balance, without the weight of the ice. Note that around the ice sheet, the land is actually sinking today, like when ones partner gets up from a waterbed mattress.


13

I'm not familiar with land-based methods, but for global measurements, one method is to use satellite altimetry (I'm more familiar with the geodesy side, but many of the same satellites are used). I think many of the current methods interpolate global or regional currents from a sparse network of buoys. As more radar satellites are launched, however, ...


Only top voted, non community-wiki answers of a minimum length are eligible