• upwelling
    Upwelling usually results in rich fisheries.

    Photograph by Bates Littlehales

    Artificial Upwelling
    Scientists and businesses are working to create areas of "artificial upwelling" to pump cold water to the surface. Researchers hope artificial upwelling will increase fish crops from the Gulf of Mexico to southwest Australia.

    Artificial upwelling involves complex technology using the motion of waves to bring cold, nutrient-rich water from the deep ocean to the surface. Experiments in artificial upwelling have been tried in the Pacific Ocean near the Hawaiian Islands.

    Upwelling is a process in which currents bring deep, cold water to the surface of the ocean. Upwelling is a result of winds and the rotation of the Earth.

    The Earth rotates on its axis from west to east. Because of this rotation, winds tend to veer right in the northern hemisphere and left in the southern hemisphere. This is known as the Coriolis effect and is largely responsible for upwelling in coastal regions.

    The Coriolis effect also causes upwelling in the open ocean near the Equator. Trade winds at the Equator blow surface water both north and south, allowing upwelling of deeper water.

    The wind patterns generated during slow-moving cyclones can also blow surface water aside, causing upwelling directly beneath the eye of the cyclone. The colder water eventually helps to weaken the cyclone.

    Effects of Upwelling
    Biodiversity and productivity
    Because the deep water brought to the surface is often rich in nutrients, coastal upwelling supports the growth of seaweed and plankton. These, in turn, provide food for fish, marine mammals, and birds.

    Upwelling generates some of the world’s most fertile ecosystems. A 25,900-square-kilometer (10,000-square-mile) region off the west coast of Peru, for example, undergoes continual coastal upwelling and is among the richest fishing grounds in the world. Overall, coastal upwelling regions only cover 1 percent of the total area of the world’s oceans, but they provide about 50 percent of the fish harvest brought back to shore by the world’s fisheries.

    During El Niño, a weather phenomenon that typically occurs every three to seven years, the Pacific Ocean’s climate changes dramatically. The transition zone between warm surface water and cold deep water deepens. Trade winds are also weak during El Niño. The combination of weak winds and deeper water limits upwelling. The reduction in nutrient-rich water leads to a lower fish population in the area, and therefore to a smaller fish crop.

    Animal movement
    Upwelling affects the movement of animal life in the area. Tiny larvae—the developing forms of many fish and invertebrates—can drift around in ocean currents for long periods of time. A strong upwelling event can wash the larvae far offshore, endangering their survival.

    Coastal climate
    The cold water welling up to the surface cools the air in the region. This promotes the development of sea fog. The city of San Francisco, California, is famous for its chilly, foggy summers, brought on by seasonal upwelling in the area.


    Downwelling is a kind of reverse upwelling. Instead of deeper water rising up, warm surface water sinks down. Upwelling and downwelling patterns often alternate seasonally. The West Coast of the United States, for example, experiences summer upwelling and winter downwelling, as the winds change directions with the seasons.

  • Term Part of Speech Definition Encyclopedic Entry
    artificial upwelling Noun

    process of bringing cold water from the deep ocean to the surface.

    axis Noun

    an invisible line around which an object spins.

    Encyclopedic Entry: axis
    biodiversity Noun

    all the different kinds of living organisms within a given area.

    Encyclopedic Entry: biodiversity
    bird Noun

    egg-laying animal with feathers, wings, and a beak.

    chilly Adjective

    slightly cold.

    climate Noun

    all weather conditions for a given location over a period of time.

    Encyclopedic Entry: climate
    coast Noun

    edge of land along the sea or other large body of water.

    Encyclopedic Entry: coast
    complex Adjective


    Coriolis effect Noun

    the result of Earth's rotation on weather patterns and ocean currents. The Coriolis effect makes storms swirl clockwise in the Southern hemisphere and counterclockwise in the Northern Hemisphere.

    Encyclopedic Entry: Coriolis effect
    crop Noun

    agricultural produce.

    Encyclopedic Entry: crop
    current Noun

    steady, predictable flow of fluid within a larger body of that fluid.

    Encyclopedic Entry: current
    cyclone Noun

    weather system that rotates around a center of low pressure and includes thunderstorms and rain. Usually, hurricanes refer to cyclones that form over the Atlantic Ocean.

    downwelling Noun

    movement of seawater from the surface to the deep.

    Earth Noun

    our planet, the third from the Sun. The Earth is the only place in the known universe that supports life.

    Encyclopedic Entry: Earth
    east Noun

    direction in which the sun appears to rise, to the right of north.

    ecosystem Noun

    community and interactions of living and nonliving things in an area.

    Encyclopedic Entry: ecosystem
    El Nino Noun

    irregular, recurring weather system that features a warm, eastern-flowing ocean current in the eastern Pacific Ocean.

    Encyclopedic Entry: El Niño
    Equator Noun

    imaginary line around the Earth, another planet, or star running east-west, 0 degrees latitude.

    Encyclopedic Entry: equator
    fertile Adjective

    able to produce crops or sustain agriculture.

    fishery Noun

    industry or occupation of harvesting fish, either in the wild or through aquaculture.

    fog Noun

    clouds at ground level.

    Encyclopedic Entry: fog
    invertebrate Noun

    animal without a spine.

    larva Noun

    a new or immature insect or other type of invertebrate.

    marine mammal Noun

    an animal that lives most of its life in the ocean but breathes air and gives birth to live young, such as whales and seals.

    Northern Hemisphere Noun

    half of the Earth between the North Pole and the Equator.

    nutrient Noun

    substance an organism needs for energy, growth, and life.

    Encyclopedic Entry: nutrient
    ocean Noun

    large body of salt water that covers most of the Earth.

    Encyclopedic Entry: ocean
    plankton Plural Noun

    (singular: plankton) microscopic aquatic organisms.

    reduction Noun


    rotation Noun

    object's complete turn around its own axis.

    Encyclopedic Entry: rotation
    seaweed Noun

    marine algae. Seaweed can be composed of brown, green, or red algae, as well as "blue-green algae," which is actually bacteria.

    Southern Hemisphere Noun

    half of the Earth between the South Pole and the Equator.

    technology Noun

    the science of using tools and complex machines to make human life easier or more profitable.

    trade wind Noun

    winds that blow toward the Equator, from northeast to southwest in the Northern Hemisphere and from southeast to northwest in the Southern Hemisphere.

    transition zone Noun

    area between two natural or artificial regions.

    upwelling Noun

    process by which currents bring cold, nutrient-rich water to the ocean surface.

    Encyclopedic Entry: upwelling
    veer Verb

    to lean or change direction.

    west Noun

    direction in which the sun appears to set.

    wind Noun

    movement of air (from a high pressure zone to a low pressure zone) caused by the uneven heating of the Earth by the sun.

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