| The Rip | ||
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| The Tasman Sea and the Pacific Ocean meet at Cape Reinga. The vectors of the bodies' wave fronts meet at an angle. When the waves meet, sometimes they cancel each other, sometimes they compound with spectacular results. | ||
| What's happening here? | ||
| The Royal Australian Navy's Directorate of Oceanography and Meteorology prepared this chart showing the intersection of the East Australian Current (EAC) of the Tasman Sea and the South Subtropical Current of the Pacific Ocean. Did you see Finding Nemo? Remember the 'Superhighway' that Marlin and Dory took to Sydney? That's the EAC. | ||
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The EAC heads down the East coast of Oz; some of it loops back across the Tasman Sea, reaching as far as NZ, located in the lowest right portion of the chart. This is also known as the Tasman Current or as part of the South Pacific Gyre. Vector #8 shows the direction of this flow. It's heading north-north-east. Look immediately above this at vectors 12 and 13. These are part of the South Subtropical Current, and they head to the west. They collide at Cape Reinga, which is at the #9 and #10. | |
| That's the Ocean currents. There are also tidal currents, which cycle twice a day. | ||
| The National Institute of Water and Atmospheric research created this excellent .gif showing tidal currents around the North Island. Keep in mind these are just the tidal currents, caused by the rotation of the moon around the earth. There's also the effects of wind, solar heating, gravity, and Coriolis. | ||
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"Twice-daily M2
tidal currents around the North Island of New Zealand based on a TIDE2D
model. The currents at a model grid point are represented by a vector with
its length scaled to the current speed and the arrow points in the direction
of flow. Every 4th model grid point is plotted at ~1 hour intervals. Cape
Reinga is at the top of the North Island." To simplify a bit, the longer the arrow, the faster the water is moving. Look at what's happening at the very top of the North Island. |
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| NIWA home page: | ||
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| Page of origin for this graphic: | ||
"Physical Hazards Affecting Coastal Margins and the Continental Shelf - North Island Currents" |
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| Here's one way of figuring out where the currents go. | ||
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| Waves crashing to create spray | ||
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| a video of the waves from Cape Reinga. Wave 1 is from the Pacific side. Wave 2, from the Tasman side, crests shortly after wave 1 passes. Wave 3 appears after wave 2 crests. Another collision appears at 4, creating a big plume. | ||
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