Why does the current not flow to the gyre's center but instead flows in a clockwise circular path about a gyre in the the Northern Hemisphere
The pattern of ocean currents in gyres is influenced by a combination of factors, including the Earth's rotation, wind patterns, and the shape of the coastline. In the Northern Hemisphere, the Coriolis effect, which is caused by the rotation of the Earth, plays a significant role in determining the direction of the currents.
To understand why the currents flow in a clockwise circular path around a gyre in the Northern Hemisphere, let's break it down into a step-by-step explanation:
1. Coriolis Effect: Due to the Earth's rotation, a freely moving mass (like water or air) is deflected to the right in the Northern Hemisphere and to the left in the Southern Hemisphere. This effect is known as the Coriolis effect.
2. Trade Winds: In the tropics, near the equator, the trade winds blow from east to west. These easterly winds create a surface current that flows towards the west.
3. Ekman Transport: As the trade winds blow the surface layer of water towards the west, the Coriolis effect comes into play. It causes the water to be deflected to the right, creating a transport of water at an angle to the wind direction. This phenomenon is known as Ekman transport.
4. Convergence: The combination of winds and Ekman transport causes the surface waters to pile up in certain areas, resulting in the accumulation of water in the center of the gyre.
5. High Pressure: In the Northern Hemisphere, the center of the gyre tends to have higher atmospheric pressure compared to the surrounding regions. This high-pressure system acts as a force that directs the water away from the center.
6. Geostrophic Current: The balance between the pressure gradient force (caused by the high pressure in the center and lower pressure at the edges) and the Coriolis effect creates a geostrophic current. In the Northern Hemisphere, this current flows clockwise around the center of the gyre.
So, in summary, the combination of the Coriolis effect, trade winds, Ekman transport, pressure gradients, and the Earth's rotation all contribute to the clockwise circular flow of currents around a gyre in the Northern Hemisphere.