The temperature of ocean water varies by location – both in terms of latitude and from top to bottom, due to variations in solar radiation and the physical properties of water.

This squat lobster was seen during dive on Hutchinson Seamount within the Pacific Remote Islands Marine National Monument. The surface water temperature at the dive site was 29.6°C (85.6°F) when the Deep Discoverer remotely operated vehicle (ROV) was deployed. When the ROV arrived on bottom at 1,700 meters, the <em>in situ</em> temperature had decreased to a near-freezing 2.6°C (36.7F).

This squat lobster was seen during a dive on Hutchinson Seamount within the Pacific Remote Islands Marine National Monument. The surface water temperature at the dive site was 29.6°C (85.6°F) when the Deep Discoverer remotely operated vehicle (ROV) was deployed. When the ROV arrived on bottom at 1,700 meters, the in situ temperature had decreased to a near-freezing 2.6°C (36.7°F). Image courtesy of the NOAA Office of Ocean Exploration and Research, 2015 Hohonu Moana.

Our planet is heated by solar radiation, incoming energy from the sun. Because the Earth is round, the angle of the surface relative to the incoming radiation differs with latitude. At low latitudes (the tropics), direct overhead sunlight received all year warms surface waters. At high latitudes, ocean waters receive less sunlight – the poles receive only 40 percent of the heat that the equator does. Thus, the surface waters in the Arctic and Antarctic are not warmed much; in fact, they are very cold. So cold, in fact, that at times that the surface water freezes to form ice. In other areas, sunlight varies depending on the time of year, meaning surface waters in the ocean can fluctuate in temperature.

These variations in solar energy mean that the ocean surface can vary in temperature from a warm 30°C in the tropics to a very cold -2°C near the poles.

In the ocean, solar energy is rapidly absorbed or reflected in the upper surface, leaving little energy to penetrate deeper, and so deeper water is not heated (this also explains the lack of light deep in the ocean). Additionally, warm water is less dense than cold water, and so cold water will sink while warm water floats above it.

Thus, temperature of the ocean also varies from top to bottom, giving a vertical structure to most of the ocean. This vertical structure has a large impact on how life is distributed in the ocean.

 

For More Information:

Here in Hawaiian Waters It Is...Cold!Hohonu Moana: Exploring Deep Waters off Hawaiʻi

How is light distributed in the ocean?

Ocean Zones (pdf, 434 kb), Learning Science through Ocean Exploration

 

RSS Feeds Ocean Exploration Facts RSS Feed

 

Sign up for the Ocean Explorer E-mail Update List.