Oceanography Surface Current Patterns

Earth's Ocean Surface Current Patterns And How They Are Produced

The major ocean surface currents vary in speed, size, and depth by location, but generally help to dictate much of the weather patterns coming from the ocean's surface. This is due to the transfer of heat from one location to another on the planet. These current patterns create larger swirls of mixing currents in some locations called gyres. One of the largest gyres in the world, the Pacific Gyre is located in the waters between the cost of California and Hawai'i (McWilliams and Restrepo, 1999). In other locations, currents form a connective band of moving water between oceans and seas where creatures are carried. Many of these currents mix downward and influence deeper currents as well (Mills, 2011).

Surface currents move and are created by the sun due to unequal heating of the Earth's surface. More specifically, these patterns are produced primarily by wind. This means that the prevailing winds, which are generally clock-wise in the northern hemisphere and counter-clockwise in the southern hemisphere help to dictate the surface flows. These rotational characteristics are the result of the Coriolis Force (Mills, 2011). Currents that are specifically created by wind are called Ekman flow. Other forces that influence surface current can also include geostrophic currents, which flow from areas of high to low pressure under the ocean's surface. These typically occur in the Polar Regions where water is cooled enough to gain a higher density than its mixing currents, sending it downward (McWilliams and Restrepo, 1999). This is another example of how surface currents can influence currents at deeper levels.

The Gulf Stream also influences the world's ocean currents at the surface by creating major flows of current many times larger than the Mississippi or Amazon rivers (McWilliams and Restrepo, 1999). There are many different specific currents, namely the North Atlantic and the Canary in the Atlantic, both of which are influenced by the flows of the Gulf Stream. Surface currents are generally measured as the top 10% of the ocean's currents and extend from the surface to around 400 meters in depth (Mills, 2011). Below this depth currents are dictated by other forces such as temperature, salinity, the moon and the Earth's rotation. These currents can also affect and be affected by deeper water eddies and upwellings, which sailors and commercial boats often plan rips around due to higher or lower fuel costs specific to these areas in the ocean and their related currents (Mills, 2011). The study of currents and their effects on sea life as well as other aspects of life on Earth is relatively new, having been just recently undertaken as a direct result of the commercial and recreational actions of sailors (Mills, 2011). Currents and their side effects are not completely understood even today, as new discoveries are still being made.