Ocean energy research: understanding the ocean's climate code

As a major driving force of the global economy, the ocean carries more than 90% of world trade and supports 40% of the world's human life within 100 kilometers of the coast. The movement of ocean currents and the thermal difference between land and sea have shaped the earth's diverse natural landscapes and complex and diverse weather and climate phenomena. As the impact of climate change becomes increasingly serious, it is more important than ever to observe the ocean more accurately and gain a deeper understanding of the ocean's climate code.

How does the deep ocean obtain energy?

Professor Lin Xiaopei, Dean of the School of Ocean and Atmosphere at Ocean University of China, said that the energy of the ocean actually comes mainly from the sun, which can be divided into two types: one is the heat energy brought by solar radiation, which is the largest. The second is the mechanical energy injected into the ocean by the wind when the sun shines on the earth, forming the kinetic energy that makes the ocean move. In addition, the energy that drives ocean circulation also includes tidal movement, which mainly comes from the moon and the sun, as well as geothermal heat inside the earth.

Data analysis found that wind can input energy into the ocean through ocean circulation and mechanical energy into the ocean through waves. When the energy input into the ocean by wind changes, ocean circulation will change accordingly, causing changes in the distribution of heat in the ocean, which ultimately manifests as abnormal temperatures in the sea water, especially on the sea surface.

How is ocean energy transferred from the ocean surface to the deep ocean?

The process of heat penetrating into the ocean is mainly through mixing within the ocean. This mixing process actually stirs heat from the upper ocean to the deep ocean. This is one way. The second way is the kinetic energy input into the ocean through wind. At the beginning, it also mainly acts on the surface and upper layers of the ocean. It is mainly concentrated in the upper 100 meters of the ocean. Then below 100 meters, it also needs to go through some special processes, such as mesoscale eddies, combined with some downward waves in the upper ocean. They are like a channel that can transfer this energy from the upper layer to the deep ocean, and ultimately drive changes in the deep ocean.

What causes the variation in heat transport brought about by the circulation?

Since wind is one of the main driving forces of ocean circulation, the acceleration of sea surface wind leads to the acceleration of average ocean circulation. The analysis results also show that this acceleration of ocean circulation extending to the deep sea is mainly caused by the acceleration of sea surface wind on a planetary scale.

First, the acceleration of ocean circulation means that the ocean's process of redistributing heat is accelerated. Stronger tropical currents can bring more warm seawater to high latitudes, which may accelerate the melting of Arctic glaciers. Warming in high latitudes may also change weather patterns and affect regional climate. Secondly, the acceleration of ocean circulation may lead to enhanced vertical heat exchange, more heat entering the deep sea, increasing heat storage in the deep ocean, and helping to slow down land warming. In addition, since carbon dioxide has a low solubility in warm water, it may weaken the ocean's absorption of atmospheric carbon dioxide. Finally, the acceleration of ocean circulation may have an important impact on marine ecosystems, fishery resources, etc.

China Association for Science and Technology Department of Science Popularization

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