<p><a href="http://earth.usc.edu/~stott/Catalina/Oceans.html" rel="noreferrer">This</a> is a good overview of ocean surface currents, which includes a schematic like this one:</p>

<p><img src="https://i.sstatic.net/O6Icf.jpg" alt="Surface currents"></p>

<p>In the mid-latitudes, you get gyre circulations that move poleward along the eastern coasts of continents (the western edges of the ocean), bringing warm water. The water off the east coasts of these places is thus warmer than you would expect for that latitude. The return flow on the eastern edges of ocean basins (west coast of continents) brings cold water from poleward of that latitude.</p>

<p>There are a few things to note about this circulation, though, since that analysis applies to the mid-latitudes only. There are opposite gyres closer to the poles that make the east coasts much colder than expected. (Compare the Alaska current to the Labrador, which is off the east coast of Canada.) The circulation near the equator is a lot more complex and interesting, especially where it meets up with other gyres.</p>

<p>There are some strange and fascinating reasons why the circulation is the way it is, but <em>that</em> answer is the result of an entire oceanography course...</p>

CC BY-SA 3.0
2015-07-07T09:18:36.693Z
I'm going to throw this out there.  That looks a lot like the Coriolis effect, (cept for at the poles and the Equatorial Counters), https://upload.wikimedia.org/wikipedia/commons/6/69/Coriolis_effect14.png    You probobly knew that.  :-)
userLTK
CC BY-SA 3.0
2015-07-07T13:06:40.967Z
@userLTK It's related to that! [Sverdrup balance](https://en.wikipedia.org/wiki/Sverdrup_balance) says that the torque that winds exert on a column of water -- which would normally change its angular momentum -- is balanced by the water moving poleward or equatorward to adjust the Coriolis component of its angular momentum. Thus total angular momentum is roughly conserved, until the flow meets a [western boundary current](https://en.wikipedia.org/wiki/Boundary_current#Western_boundary_currents) and friction takes over.
Jareth Holt
CC BY-SA 3.0
2015-07-20T09:35:41.047Z
@JarethHolt You should also consider coastal upwelling that is related to Ekman transport and which brings deeper (and therefore) colder water to the surface. The Humboldt current at the Peruan coats is one good example. Deep and cold water is also nutrient-rich which turns this regions into flourishing marine environments.
makra
CC BY-SA 3.0
2015-07-05T10:46:02.663Z
2015-07-05T10:46:02.663Z
Jareth Holt
<p>Even at similar latitudes they appear to be quite different from one another.</p>

CC BY-SA 3.0
2015-07-05T07:41:44.047Z
Which country are you asking about? This is an international site.
Fred
CC BY-SA 3.0
2015-07-05T18:58:33.063Z
That statement is true in most continents! That is the awesome part about it. Just look at the Namibia, Perú, California, west Africa upwellings!
arkaia
CC BY-SA 3.0
2015-07-06T03:37:23.050Z
Australia has to be different! The Leeuwin current is a *warm* ocean current which flows southwards near the western coast of Australia [https://en.wikipedia.org/wiki/Leeuwin_Current]
Fred
CC BY-SA 3.0
2015-07-06T15:16:56.223Z
@Fred That's true! The Leeuwin current actually shields Australia from the West Australia current...which flows equatorward and would otherwise bring cold water northward. I don't know much about the Leeuwin current, but I'd guess that it's trapped to the continental shelf, fed by the Indonesian Throughflow water that doesn't connect to the equatorial Indian Ocean currents. Shelves are important, and I clearly don't know enough about them >.>
Jareth Holt
CC BY-SA 3.0
2015-07-08T13:48:57.780Z
The ocean at Newfoundland (Canada east coast) freezes in winter, but the ocean at British Columbia certainly doesn't.  So it's not universally true; in Canada it isn't.
gerrit
<ocean><temperature>
Why is the Ocean water on the west Coast so cold comparing to the East coast?
reddit
# Why is the Ocean water on the west Coast so cold comparing to the East coast?

(Asked by: username_0 on 2015-07-05)

Even at similar latitudes they appear to be quite different from one another.

**Tags:** ocean, temperature

> **Comments:**
> **username_1**: Which country are you asking about? This is an international site.  
> **username_2**: That statement is true in most continents! That is the awesome part about it. Just look at the Namibia, Perú, California, west Africa upwellings!  
> **username_1**: Australia has to be different! The Leeuwin current is a *warm* ocean current which flows southwards near the western coast of Australia [https://en.wikipedia.org/wiki/Leeuwin_Current]  
> **username_3**: @username_1 That's true! The Leeuwin current actually shields Australia from the West Australia current...which flows equatorward and would otherwise bring cold water northward. I don't know much about the Leeuwin current, but I'd guess that it's trapped to the continental shelf, fed by the Indonesian Throughflow water that doesn't connect to the equatorial Indian Ocean currents. Shelves are important, and I clearly don't know enough about them >.>  
> **username_4**: The ocean at Newfoundland (Canada east coast) freezes in winter, but the ocean at British Columbia certainly doesn't.  So it's not universally true; in Canada it isn't.  

---

## 1 answers

### Answer by username_3 on 2015-07-05. Score: 15 | Accepted answer

[This](http://earth.usc.edu/~stott/Catalina/Oceans.html) is a good overview of ocean surface currents, which includes a schematic like this one:

![Surface currents](https://i.sstatic.net/O6Icf.jpg)

In the mid-latitudes, you get gyre circulations that move poleward along the eastern coasts of continents (the western edges of the ocean), bringing warm water. The water off the east coasts of these places is thus warmer than you would expect for that latitude. The return flow on the eastern edges of ocean basins (west coast of continents) brings cold water from poleward of that latitude.

There are a few things to note about this circulation, though, since that analysis applies to the mid-latitudes only. There are opposite gyres closer to the poles that make the east coasts much colder than expected. (Compare the Alaska current to the Labrador, which is off the east coast of Canada.) The circulation near the equator is a lot more complex and interesting, especially where it meets up with other gyres.

There are some strange and fascinating reasons why the circulation is the way it is, but *that* answer is the result of an entire oceanography course...

> **Comments:**
> **username_5**: I'm going to throw this out there.  That looks a lot like the Coriolis effect, (cept for at the poles and the Equatorial Counters), https://upload.wikimedia.org/wikipedia/commons/6/69/Coriolis_effect14.png    You probobly knew that.  :-)  
> **username_3**: @username_5 It's related to that! [Sverdrup balance](https://en.wikipedia.org/wiki/Sverdrup_balance) says that the torque that winds exert on a column of water -- which would normally change its angular momentum -- is balanced by the water moving poleward or equatorward to adjust the Coriolis component of its angular momentum. Thus total angular momentum is roughly conserved, until the flow meets a [western boundary current](https://en.wikipedia.org/wiki/Boundary_current#Western_boundary_currents) and friction takes over.  
> **username_6**: @username_3 You should also consider coastal upwelling that is related to Ekman transport and which brings deeper (and therefore) colder water to the surface. The Humboldt current at the Peruan coats is one good example. Deep and cold water is also nutrient-rich which turns this regions into flourishing marine environments.  

---

