Those of us who live on Earth – including ocean scientists – focus on wind at the planet’s surface. Wind affects our daily lives by driving weather patterns and ocean circulation, both of which are related to climate. Many well-known phenomena such as hurricanes, monsoons, and El Niño/La Niña – which impact us on the surface – reach high into the atmosphere. For example, an Indian Ocean cyclone seen in surface winds (yellow circle) also appears in at levels up to 10 km (6 mi) above Earth’s surface (yellow ovals).
High-level winds can be very fast! Commercial airlines can take advantage of jet streams at the top of the troposphere when they blow in a favorable direction. Newsworthy events such as volcanic ash plumes, ozone holes, and the polar vortex can be driven by stratospheric winds. Get to know the connections among atmospheric layers in the following examples.
For decades, NASA has kept an eye on our ocean from space. Today’s technologies detect ocean wind, sea surface salinity, sea level, and color as an indicator of ocean health. Satellite data is fed into computer models that capture the motion of ocean currents at the surface and, in the case of Estimating the Circulation and Climate of the Ocean (ECCO), all the way to the seafloor! These models help us better understand how ocean currents transport heat, salinity, debris, and seaweed such as Sargassum that can impact Caribbean beaches.
Earth’s uneven surface exerts a frictional drag on the air blowing just above it. This friction can act to change the wind's direction and slow it down. Compare this movie to the Surface Winds example (above) and you’ll notice that wind speeds are generally faster. Detecting wind at this at this level is useful for analyzing atmospheric rivers and interactions between hurricane and tiny airborne particles known as aerosols. This includes nutrient-laden dust from the Sahara that helps to fertilize microscopic ocean algae – phytoplankton – and the Amazon rainforest.
At this level in the atmosphere, wind moves smaller-scale features, like thunderstorms, and larger systems, like hurricanes, around the Earth. A key type of convection associated with El Niño / La Niña cycles – known as Walker Circulation – is centered around this atmospheric level. Likewise, atmospheric carbon dioxide can be mixed and transported at this altitude as it fluxes between the troposphere and Earth’s surface. During monsoon seasons, steering winds play a critical role in determining the direct and intensity of monsoon rains.
Jet streams are relatively narrow bands of strong wind in the upper levels of the atmosphere, typically occurring around 9 kilometers (30,000 feet) altitude. Within jet streams, the winds blow from west to east, but the band often shifts north and south because jet streams follow the boundaries between hot and cold air. When a hurricane reaches the jet stream, it can accelerate significantly, especially if when traveling over a warm ocean waters. Jet streams can transport aerosols such as smoke, and gases such as ozone, very long distances.
The ozone hole is a large area of the stratosphere with extremely low amounts of ozone that forms over Antarctica in August to October. Its size is partly controlled by strong winds that encircle and isolate the region, known as the polar vortex. On the other side of the planet, the polar vortex can expand in winter, sending cold air southward toward North America and Europe. In spring and early summer, stratospheric ozone intrusions can raise ground-level ozone concentrations in some areas to potentially unhealthy levels.
The stratosphere is the altitude limit of jets because air is roughly a thousand times thinner there than in the troposphere. Thus, scientific balloons are often used to investigate the stratosphere. During major volcanic explosive eruptions, huge amounts of ash can be injected into the stratosphere. Similarly, a dust plume from a 2013 meteor event circled the globe in the stratosphere. Interestingly, scientists have linked low temperatures in the United States to unusual wind cycles in the Arctic stratosphere which, in turn, were connected to even higher atmosphere levels in the Antarctic.
