Ocean surface topography

The ocean is not flat. It has hills and valleys.

These hills and valleys move the water. They help us see how the water flows.

Scientists use satellites in space to see these shapes. The satellites send out pulses of light. They measure how long the light takes to come back. This tells us how high the water is. This helps us learn about the weather. It also helps us see how the world changes. We can learn a lot from looking down at our blue seas.

The ocean is not flat. It has hills and valleys on its surface.

Scientists call this ocean surface topography. These shapes help us understand how water moves. Large ocean currents flow around these hills and valleys. For example, water moves in circles around these shapes. This happens because of the Coriolis effect, which is a force caused by Earth's rotation.

How do we see these shapes from space? We use satellites. One way is called satellite altimetry.

These satellites send out microwave pulses toward the water. The pulses hit the ocean and bounce back. The satellite measures the time it takes for the pulse to return. This tells us the height of the sea surface.

By using this data, we can track heat in the ocean. This helps us study our climate and weather. We can also see if sea levels are rising. Many satellites, like Jason-3, help with this work. They help us learn how our blue planet changes over time.

The ocean surface is not flat like a tabletop. Instead, it has many hills and valleys across its surface.

Scientists call these shapes ocean surface topography. These highs and lows are important because they help us understand how water moves. Large ocean currents flow around these hills and valleys in predictable ways. In the northern hemisphere, water rotates clockwise around hills. It rotates counterclockwise around valleys. In the southern hemisphere, the rotation happens in the opposite way. This movement is caused by the Coriolis effect. Understanding these patterns helps us learn how the ocean moves heat around the world.

We can see these ocean shapes from space using special tools. One main method is called satellite altimetry. A satellite sends a microwave pulse down toward the ocean surface. The pulse hits the water and bounces back up to the satellite. The machine measures the round-trip time of the pulse. By knowing the time, scientists can calculate the sea surface height. They use a reference shape called an ellipsoid to help with these math steps. They also use a surface called the geoid to represent how water flows. This allows scientists to measure the height of the sea very precisely.

Humans have been studying these ocean patterns for a long time. For 100 years, people collected data from ships. However, space missions changed how much we can see. The TOPEX/Poseidon mission was the first to map these shapes with great accuracy. It orbited from 1992 until 2006. After that, the Jason series of satellites continued the work. Jason-1 was launched by a Boeing Delta II rocket in California in 2001. Jason-2 launched on June 20, 2008, from Vandenberg. Jason-3 launched on January 16, 2016, using a SpaceX Falcon-9 rocket.

Many different satellites help us study the ocean today. There are currently nine satellites calculating ocean topography. These include names like Cryosat-2, SARAL, and Sentinel-3A. Some satellites work together in a tandem rotation. For example, Jason-3 and Sentinel-6 Michael Freilich orbit about 330 kilometers apart. Scientists also use gravity missions like GRACE and GOCE. By combining gravity data with altimetry, they can see sea level rise. They can even measure ocean heat content. This data helps us understand weather, climate, and even how to manage fisheries.

These ocean maps are linked to many things we see every day. They help us predict weather and study the Earth's climate. The data shows us how the ocean changes during events like El Niño or La Niña. It also helps us monitor global warming by watching sea levels. Even the way we navigate ships can be helped by this science. A new mission called the Surface Water Ocean Topography Mission has been proposed. It aims to map all surface water, including lakes and rivers. This will give us a complete view of Earth's freshwater and oceans from space.

Ocean surface topography, also known as sea surface topography or ocean dynamic topography, refers to the hills and valleys on the ocean's surface.

While the ocean might look flat from a boat, it actually has many highs and lows. Scientists measure these variations as the average sea surface height (SSH) relative to the Earth's geoid. The geoid is a surface that represents how water flows across the planet. Understanding these shapes is vital because they help us study large-scale ocean circulation. By mapping these features, researchers can see how the ocean moves heat around the entire globe.

To map these features, scientists use a process called satellite altimetry. A satellite sends a microwave pulse down toward the ocean surface. The pulse travels to the water and then bounces back up to the satellite. By measuring the round-trip time of this pulse, the satellite calculates the distance to the surface. This measurement is compared to the satellite's own orbit altitude. The satellite uses a reference shape called an ellipsoid to help with these calculations. Because the ellipsoid is not an equipotential surface of Earth's gravity, scientists must transform the data to the geoid. This ensures the measurements accurately reflect the actual water flow.

Ocean topography is directly linked to how water moves through currents. Currents flow around these surface hills and valleys in predictable patterns. This movement is influenced by the Coriolis effect, which is a force caused by Earth's rotation. In the northern hemisphere, water rotates in a clockwise direction around hills. It rotates in a counterclockwise direction around valleys. In the southern hemisphere, these patterns are reversed. These currents are essential for transporting heat and carbon throughout the world's oceans.

Many different factors cause the sea surface height to change over time. Short-term changes are often caused by the tidal forces of the Moon and the seasonal cycle of the Sun. Other factors include changes in temperature, salinity, waves, tides, and winds. On much longer timescales, the patterns in SSH are influenced by ocean circulation. Slower, larger variations can occur due to changes in Earth's gravitational field. This might happen because of melting ice, the rearrangement of continents, or the formation of sea mounts. Scientists can combine altimetry with satellite gravimetry from missions like GRACE to monitor sea level rise.

Our ability to map the ocean has improved greatly through space missions. For 100 years, scientists relied on observations collected by ships. The TOPEX/Poseidon mission changed this in 1992 by providing the first highly accurate maps. This mission allowed scientists to study large-scale current systems for the first time. Following TOPEX/Poseidon, the Jason series of satellites continued this important work. Jason-1 was launched in 2001 by a Boeing Delta II rocket. Jason-2 launched in 2008, and Jason-3 launched in 2016 using a SpaceX Falcon-9 rocket.

Today, a network of satellites works together to monitor our oceans. There are currently nine different satellites calculating ocean topography. These include Cryosat-2, SARAL, Jason-3, Sentinel-3A, Sentinel-3B, CFOSat, HY-2B, HY-2C, and Sentinel-6 Michael Freilich. Some of these satellites work in a tandem rotation. For example, Jason-3 and Sentinel-6 Michael Freilich orbit about 330 kilometers apart. These missions help scientists monitor phenomena like El Niño, La Niña, and the North Atlantic oscillation. They also track planetary waves that cross the oceans over several months.

This data is incredibly useful for many different parts of science. It helps researchers understand weather patterns and the long-term effects of Earth's climate. The information is also used for navigation, fisheries management, and offshore operations. By observing the ocean, we can better predict short-term and long-term weather changes. Scientists also use this data to study how much heat the ocean contains. This is a critical piece of information for understanding global warming. Looking forward, a new mission called the Surface Water Ocean Topography Mission has been proposed. It aims to provide a global survey of all surface water, including lakes and rivers.