Definitions & Causes of Upwelling and Downwelling in Oceans

Upwelling Definition

Upwelling is the process by which colder, denser water from deep in the ocean rises to replace warmer surface waters. Upwelling is the process of water from below rising to the surface. It occurs when the wind blows onshore, pushing up cooler deep water and replacing it with warmer surface water.

Upwelling zones

Upwelling zones are regions in the ocean where cold water from below rises to the surface. This process is called upwelling, and it occurs when wind or other physical forces push surface waters away, allowing this colder water to rise up. Upwelling zones can be found worldwide, but they are most common near coasts that have strong winds, like in Southern California.

The Upwelling zone is a region of the ocean that contains cold, nutrient-rich water. The upwelling process occurs when winds or currents push surface waters away from a coastline and bring colder, deeper waters to the surface. This brings nutrients and oxygen closer to shore, where fish can thrive.

 Types of Upwelling

Upwelling is a process by which deep-water masses are pushed to the ocean surface. It happens because when upwelling occurs, warmer water is brought closer to the freezing point because of heat conduction from the atmosphere. This results in a surface layer of colder water with a higher density than the denser, heavier waters below it, so it sinks downwards.

There are three types of upwelling on Earth:

• Coastal Upwelling Currents

• Open-Ocean Upwelling Currents

• Deep-Water Upwelling Currents

Coastal Upwelling Currents

Coastal upwelling occurs when winds push surface waters toward the land, cooling them in the process. The cold water then sinks to the bottom of the water body, taking with it nutrients that had been at or near the surface before movement.

Open-Ocean Upwelling Currents

Open-ocean upwelling occurs when cold water from the ocean’s depths is pushed to the surface by winds. This can occur near the equator in the tropics, mountains, or other areas with strong wind circulation.

Deep-Water Upwelling

Deep-water upwelling occurs around areas with intense upwelling forces, including wind patterns and steep continental slopes. Deep-water upwelling is possible because warm water flows upward along deep ocean trenches as part of a global circulation system called the thermohaline circulation. Because of this, nutrient and gas-building nutrients do not sit still within the ocean ecosystem. When the water returns to the surface, these resources are brought back in as well.

Some upwelling takes place along mountain ranges and other ocean features that affect wind patterns. These features can cause deep water to be pushed up toward the surface, pushing nutrient resources toward the land. They can also push down cold water into deeper areas of the ocean. The ocean upwells along with areas with landmass. 

What Causes upwelling

Upwelling happens because there’s less density in cold water than in warm water.  The colder, denser waters rise to replace warmer and lighter waters that have risen up from below.

The Earth’s rotation causes water currents to flow away from the equator and towards the poles due to density differences between warm and cold water. This creates a large area of low pressure near the equator that pulls up cooler, denser water from below.

The wind is another factor that can cause upwelling; convergence zones in which different currents meet and the volume of water pushes from all directions are another factor. Wind-driven upwelling is more likely to create vertical stratification.

How to Measure Upwelling

There are many ways that upwelling can be measured. Some of these include temperature, salinity, chlorophyll concentrations, and light penetration.

Temperature readings can determine how warm the water is that has been pushed to the surface from greater depths of the ocean; this can affect sunlight penetration within the ocean.

Salinity can determine how salty the water is, and it can also be used to measure how deep the water originated from.

Chlorophyll levels can be used to determine the amount of phytoplankton in an area of the ocean.

 Light penetration is important because phytoplankton need sunlight to grow.

Major Oceans with Upwelling

The three major oceans on Earth are all subject to upwelling.

Atlantic Ocean

The Atlantic Ocean is subject to both coastal and deep-water upwelling. Coastal upwelling along the eastern seaboard of North America pushes nutrient-rich cold surface water away from the coast and towards Europe, Africa, and South America. Deep-water upwelling takes place along deep trenches near the Mid-Atlantic Ridge. There are also a number of other areas where there is open-ocean upwelling in the Atlantic Ocean.

Indian Ocean

The Indian Ocean has both coastal and deep-water upwelling. It is subject to both types of upwelling along the coastline of Africa and Asia. Coastal upwelling also takes place in the Persian Gulf. Deep-water upwelling is common in the Indian Ocean as well. There are three areas where deep-water upwelling can occur and create nutrient-rich water that is pushed toward the surface: near Australia, near India, and near Indonesia.

Pacific Ocean

The Pacific Ocean is subject to coastal upwelling as a result of its geography. The West Pacific side of the Pacific Ocean experiences coastal upwelling due to the Humboldt Current. The East Pacific side is affected by coastal upwelling because of the California Current. Upwelling also takes place on the Pacific Ocean’s open-ocean side, including along deep trenches in places such as Peru and Chile and near Alaska.

Along landmasses, two types of upwelling can take place:

• Frontally forced

• Cabbeling driven.

Frontally forced upwelling

Frontally forced upwelling is a type of upwelling that takes place when warm water moves away from the coast (or any landmass) and toward colder regions that are located farther away. Frontally forced upwelling is common near islands, mountains, and landmasses in general.

Cabbeling driven upwelling

Cabbeling-driven upwelling takes place when cool water is pushed to the surface by relatively warm water. This type of upwelling occurs behind islands, under ice shelves, or within fjords.

Why is upwelling important

Upwelling is important because it brings nutrients back to the surface, such as nitrogen and phosphorous. The nutrients are used to support the growth of organisms in the ocean.

Nutrients are essential for a healthy ocean ecosystem. They are necessary for life. Because of this, upwelling is important because it brings nutrients back to the surface, such as nitrogen and phosphorous.

Nitrogen is an essential nutrient used by many organisms within the oceanic ecosystem. When it is brought to the surface, it can be used by organisms. Phosphorous is an essential nutrient, too. It is used by marine plants and microscopic animals known as phytoplankton.

Upwelling is a process that brings cold, nutrient-rich water to the surface. This can lead to blooms of phytoplankton and other marine life.

Upwelling creates a unique environment in which nutrients can be brought to the surface. These nutrients are then used by organisms that live on the ocean’s surface for food. Upwelling is essential to creating an environment that is rich with nutrients; otherwise, many organisms would not be able to survive.

Upwelling is used by the ocean’s inhabitants to create a rich environment. This can also be helpful in terms of seasonal changes when an area of the ocean experiences upwelling, more nutrients, phytoplankton, and other organisms are brought to the surface.

As a result, there is a significant increase in plankton production. These organisms are then eaten by some animals, and parts of their bodies are excreted as waste. The waste then sinks into the water and is used as a source of nutrients by other organisms.

The upwelled water also has more oxygen than the surrounding waters.  As a result, fish populations can grow quickly in these areas.  This process can bring nutrients to the surface that would otherwise not be available for plants and animals.

 This process allows for the transfer of oxygen throughout the ocean via “the biological pump,” which certain creatures use to travel from the ocean’s surface to its depths. For this system to work properly, upwelling must occur simultaneously with nutrient depletion at the surface.

These events are essential in terms of keeping an ecosystem stable. When upwelling occurs, it brings nutrients to life forms that would not be able to survive without it. Upwelling can also cause an increase in the amount of phytoplankton that is available for organisms to eat.

As a result of eating more phytoplankton and other tiny creatures, larger organisms have the opportunity to grow and flourish, while smaller ones are able to feed off of them. This can lead to a larger population of organisms within the same area.

Because of upwelling in the Ocean, there is a great number of nutrients available for organisms to use in order to survive. As a result, that area will be rich in nutrients. However, a single downwelling event could alter an entire ecosystem because the nutrients may not always be available to every organism.

When the water moves through the gastropod, it passes its body and opens up its shell. It then uses water current movement to force water into its shell and then withdraws it from its body.

As a result of the upwelling of water, the gastropod will go from being rich in nutrients to have a lack of them. If it is not able to find food in the area, it will eventually die. The upwelling and subsequent downwelling create an effect that causes major changes within an ecosystem.

The winds also create waves that can break down coastal cliffs, creating new coastlines.

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Downwelling

Downwelling refers to a process by which cold and salty waters sink downward towards the seafloor. Downwelling and upwelling are important ocean currents because they transport nutrients and gases throughout the oceanic ecosystem.

As previously said, an organism’s ability to survive and eat involves the ability to draw water in from outside itself and out of its body. If the organism is unable to keep up with these demands, it will not be able to maintain its survival. The biological pump essentially keeps this cycle going because organisms would cease to exist without it in a given area.

Aquatic Turbulence and Downwelling

One of the biological pumps’ main components is the significant amount of turbulence that occurs in the open ocean waters. This turbulence provides a large amount of energy for organisms that reside in this area that come together to form an ecosystem. Through this turbulence, organisms can get food and also be transported to new areas of the ocean. All these effects are one of the reasons why the biological pump is so important in maintaining conditions for life in open ocean regions. In order for this process to continue, there must be a continuous flow of energy from the upper layers of the oceans to the lower layers, where organisms exist.

Downwelling in Oceans

Downwelling is a type of circulation pattern that occurs in the ocean, whereby the net movement of water is from the surface to the bottom. Downwelling can be due to many different factors such as wind or thermocline conditions. It can also occur in cascading form, where there are two or more layers of downwelling in sequence. This blog post will explore these different factors and how they affect the ocean’s levels and currents.

Downwelling is often attributed to the influence of winds but is actually a term describing the process that waters travel from higher, cooler layers to lower, warmer layers. It is a common process in both oceans and seas.

Downwelling (in the context of this blog) refers to the net movement of water from the surface to the bottom. This can be caused by various factors, one being wind currents that migrate water towards the surface.

What are the Cause of Downwelling in Oceans

Downwelling is often referred to as a thermohaline current, which is defined as “a steady and time-integrated (or long-term) movement of water in the pycnocline of the ocean caused by differences in salinity or density.” Due to these density/salinity differences, water will slowly sink.

Vertical temperature gradients can also affect the temperature of surface waters. This is due to the difference between air and water temperatures.

Downwelling currents can be caused by many factors. The primary factors are:

• Wind
• Thermocline
• Density conditions.

Although the main factor is typically wind, it can occur with other types of currents, such as thermohaline patterns.

Downwelling currents are created by differences in salinity or temperature between water layers within an ocean or other body of water (sea). Downwelling currents are often controlled by the wind, which drives them.

Downwelling Examples

Downwelling currents exist in most oceans and could be considered a “universal” feature of the ocean system.

Examples include:

• North Atlantic Deep Water
• Central Equatorial Counter Current
• South Pacific Subtropical Annular Mode
• Indian Ocean Dipole Mode
• South Pacific Mode
• North Atlantic Subtropical Gyre
• Benguela Current.

 

Wind and temperature play a role in downwelling circulation patterns. In the Northern Pacific, warm currents move northward, such as the North Equatorial Current, carrying warm water to regions north of the Equator. As they do this, they lose heat and eventually begin to sink.

North of Japan, these waters then move eastward, forming warm North Pacific Intermediate Water. This water moves east until it reaches the Aleutian Islands, where it is cooled by winds blowing from land to sea and becomes part of an ocean conveyor belt. This cycle is known as the North Pacific Gyre.

In the Southern Ocean, the Antarctic Circumpolar Current moves around Antarctica, bringing cold water to lower latitudes. The polar front is located near Antarctica between the subtropical and subpolar gyres.

Downwelling can be caused by thermocline conditions in oceans and seas which are regions of rapid change in temperature at various depths. Due to this temperature change, there is a change in density which can cause a vertical movement of water.

Downwelling occurs in all oceans and seas. It is a process that involves water moving from the surface to the depths of the ocean. In an ocean, downwelling can be caused by wind circulation patterns. These include thermohaline currents as well as eddy current flows. Wind can carry water from higher, colder layers to lower, warmer ones.

Downwelling currents can also occur in a cascading form, which is where there are several layers of downwelling in sequence.

Downwelling in the oceans can be caused by vertical temperature gradients, which are the difference in temperature between the surface and deeper levels of water. If a water body is warm at the top and cool at the bottom, this will cause a vertical heat distribution, causing water to move from where it is warmer to where it is cooler.

Related:

• Supralittoral Zone and Sublittoral Zone Animal Ecosystems

• Intertidal Zone Characteristics | Intertidal Zone Animals & Plants Ecosystems