If you’ve followed any of the media on the “garbage patch” you’ve
probably seen this area of marine debris concentration in the North
Pacific Ocean referred to also as “the gyre”. A bit confusing given that
there is a Subtropical Gyre in the N. Pacific Ocean. Are these features
one and the same? No. Let us help to demystify these terms for you.
First, “the gyre”: A gyre is a large-scale circular feature made up of
ocean currents that spiral around a central point, clockwise in the
Northern Hemisphere and counter-clockwise in the Southern Hemisphere.
Worldwide, there are five major subtropical oceanic gyres: the North and
South Pacific Subtropical Gyres, the North and South Atlantic
Subtropical Gyres, and the Indian Ocean Subtropical Gyre. The North
Pacific Subtropical Gyre is the one most notable because of its tendency
to collect debris. It is made up of four large, clockwise-rotating
currents — North Pacific, California, North Equatorial, and Kuroshio.
It is very difficult to measure the exact size of a gyre because it is a
fluid system, but the North Pacific Subtropical Gyre is roughly
estimated to be approximately 7 to 9 million square miles—not a small
area! This, of course, is a ballpark estimate. This is equivalent to
approximately three times the area of the continental United States (3
million square miles).
Now, the “garbage patch”: It appears that the main “garbage patch” (aka
eastern garbage patch) referred to in the media is within the North
Pacific Subtropical High, an area between Hawaii and California. Due to
limited marine debris samples collected in the Pacific it is still
difficult to predict its exact content, size, and location. However,
marine debris has been quantified in higher concentrations in the calm
center of this high-pressure zone compared to areas outside this zone.
It should be noted that the North Pacific Subtropical High is not a
stationary area, but one that moves and changes.
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NOTE: This map is an oversimplification of ocean currents and features
in the Pacific Ocean. There are numerous factors that affect the
location, size, and strength of all of these features throughout the
year, including seasonality and El Nino/La Nina. Depicting that on a
static map is very difficult.