Tides & Currents - why isn't Puget Sound emptying?

Clearly I think too much ...

I've got an app on my phone (Android - Tides & Current) and iPad (USA Tides Free) which show graphical depictions of Tidal Height and Current.

http://tbone.biol.sc.edu/tide/tideshow.cgi?site=Edmonds%2C+2.7+wsW+of%2C+Washington+Current

If one goes to the URL above, then generates a graphic depiction of the current, you get the following plot:

Note that the blue portions are the flood and the green portions are the ebb.  Given that the chart is by speed and time, the area  of the various colored portions is proportional to the volume of water moving.  Note that the total areas in green are far larger than the total areas in blue.

Then why isn't Puget Sound emptying?

               Clearly I think too much ...


                Yup ,,,you do.

Hint: it has a lower salinity than the open ocean.

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One contribution to the variance might be due to the water ebbing or flooding via different routes.  Your current estimate appears to be for Edmonds.  Perhaps some portion of the flood volume passes more easily through a different part of the sound whereas the ebb drains more easily at Edmonds.  If I remember correctly from the San Juans, there are places where the ebb and flood are from different directions, which would skew the volumes if one only measured at a particular point. 

But then I too may be thinking too much.  Perhaps look at a different location where there is only one point of ebb and flood and see if the volume results are the same.

Bingo - Alpalmer!  There is another point in the Sound that is the opposite of the Edmonds site.  And on the overall the system is balanced.  Trust me, I'm a Dr. (Ph.D. in Physical Oceanography that is) and tides, currents, and ocean evaluations are what I do.

looks like it is emptying just fine... but having a harder time getting refilled 

it did always intrigue me out at neah bay that the ebbs always ran far harder than the floods.  probably some simple answer that will make me do a "doh!" palm to the face when i hear it.

Lee mentions salinity, and ocean water has somewhat higher salinity (more dense) than PS surface water.  And the deeper waters of PS have higher salinity than the surface. 

One contribution to the variance might be due to the water ebbing or flooding via different routes....

Bingo - Alpalmer!  There is another point in the Sound that is the opposite of the Edmonds site.  And on the overall the system is balanced.  Trust me, I'm a Dr. (Ph.D. in Physical Oceanography that is) and tides, currents, and ocean evaluations are what I do.

All the water that ebbs and floods through south Puget Sound goes past Edmonds.  There is no other way in or out. 

However, your comments have caused me more painful thinking and I have realized the current is measured at the surface or damn near.  There is no reason that the ebb and flood should occur at the same depth.  It may be that the flood comes in along the bottom and the ebb out along the surface in accord with the salinity gradient.  This would also explain why the current could be ebbing while the tide is rising.  I've lined up the current and tide charts for Edmonds over the same 48 hour period in the attachment.  In particular the slack current between ebb and flood is about 90 minutes later than the slack low tide.  To me this implies the flood current is coming in below the surface while the ebb current is still going out. 

Thanks!  I can sleep well knowing I'll not wake to a 3 mile wide ravine. 

Like many of life's mysteries Solomon provides the answer: Ecclesiates 1:7

Like many of life's mysteries Solomon provides the answer: Ecclesiates 1:7

IslandHoppa - gentleman and apparently a scholar:

"All the rivers run into the sea; yet the sea is not full; unto the place from whence the rivers come, thither they return again."