When was any one liter of Long Island Sound water last in the Atlantic Ocean? The Sound for this model is:
Area: 1,268 mi²
Mean depth: 63 feet
Length 110 miles
Eastern opening into the Atlantic is 9 miles wide
An average tide of 6 feet, twice a day.
As a sailor and swimmer in the Sound, I picture it as a relatively closed polluted body refreshed by the Atlantic. But I started wondering just how often the water near me, 50 miles from Plum Gut, turns over. Tidal currents are 1 knot, or about a mile an hour. In other words, each day the water at my location flows west for 6 hours as the tide rises, then back east for 6 miles as it drains, at the rate of one mile an hour.
The most simple model in my mind pictures a “plug” of Atlantic Ocean water traveling 6 miles west into the Sound before draining out - but of course, there’s turbulence and mixing – but how much mixing? And how much mixing at any one place lengthwise along the body? My hope is that someone here commands a better understanding of how to model this.