In the Northern Hemisphere, the most northern system, the polar cell, blows air in a consistent southwestern direction toward a pocket of low pressure along the 60-degree latitude line. A combination of Earth’s rotation, the fact that Earth is tilted on an axis, and the placement of most continents in the Northern Hemisphere, create pressure systems that divide each hemisphere into three distinct wind patterns or circulation cells. It would make intuitive sense that the hot air and cool air would meet in the middle of the equator and the North or South pole, however, in reality it is much more complicated. The clashing of hot air originating at the equator and cold air originating at the poles creates regions of high atmospheric pressure and low atmospheric pressure along specific latitude lines. Likewise, cold air from the poles sinks and moves towards the equator. The hot air over the equator rises and moves away from the equator. This uneven distribution of heat causes air to move. The Sun’s radiation is strongest at the equator and dissipates the closer you get to the poles. These wind patterns (convection cells) are created by radiation from the Sun beating down on Earth and generating heat. Surface ocean currents are driven by consistent wind patterns that persist throughout time over the entire globe, such as the jet stream. When air moves across the ocean’s surface, it pulls the top layers of water with it through friction, the force of resistance between two touching materials moving over one another. Wind is a major force in propelling water across the globe in surface currents. Gravity pulls the water away from hills and toward valleys and Earth’s rotation steers the moving water. The Sun’s radiation creates prevailing wind patterns, which push ocean water to bunch in hills and valleys. Climate change is altering the processes that propel water across the globe, and should this alter ocean currents, it would likely lead to a cascade of even more change.Īt the surface, currents are mainly driven by four factors-wind, the Sun’s radiation, gravity, and Earth’s rotation. While the ocean as we know it has been in existence since the beginning of humanity, the familiar currents that help stabilize our climate may now be threatened. This planetary movement has a strong effect on how oceans move. Though it appears we live on a stable and stationary planet, we are, in fact, whipping through space around the Sun in an orbit and spinning on an axis. It also requires a shift in perspective to encompass the movement of planets, the Moon, and the Sun. Ocean motion is influenced by occurrences here on Earth that are familiar, like heat changes and wind. Friction, drag, and density all come into play when describing the nature of a wave, the movement of a current, or the ebb of a tide. Ocean movement is created by the governing principles of physics and chemistry. Water is propelled around the globe in sweeping currents, waves transfer energy across entire ocean basins, and tides reliably flood and ebb every single day. But this is far from the truth-the ocean is constantly in motion. Any reuse without express permission from the copyright owner is prohibited.Looking toward the sea from land, it may appear that the ocean is a stagnant place. CC BY-NC-ND 3.0Įxcept where otherwise noted, images are subject to copyright. Mulligan, Editor, Journal of Geophysical Research: Oceans Text © 2023. Journal of Geophysical Research: Oceans, 127, e2022JC018925. Global climatology of extratropical cyclones from a new tracking approach and associated wave heights from satellite radar altimeter. The results reveal the effects of EC characteristics, including cyclone translational speed and maximum winds, on wave growth and wave height variability on a global scale.Ĭitation: Lodise, J., Merrifield, S., Collins, C., Rogowski, P., Behrens, J., & Terrill, E. The new approach accurately locates and efficiently tracks these storms, enabling seasonal and longer-term regional trends in storm occurrence to be directly related to wave generation. The method uses atmospheric pressure from a global database of data-assimilated weather forecasts over a period of 42 years from 1979 to 2020 and a record of significant wave height observations measured using satellite radar altimeters. develop a new algorithm for identifying and tracking ECs and describe the analysis of surface waves heights generated in the North Atlantic, North Pacific, and Southern Ocean regions. These storms, which occur more frequently than hurricanes, form in the mid- to northern latitudes and are not well studied. Source: Journal of Geophysical Research: OceansĮxtratropical cyclones (ECs) are large storms with very strong winds that can cause hazardous ocean conditions with large waves than can exceed 10 meters in height. Editors’ Highlights are summaries of recent papers by AGU’s journal editors.
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