An international satellite tracking the impacts of small ocean currents

Although climate change is driving sea level rise over time, scientists say differences in surface height from place to place in the ocean can affect Earth’s climate. These ups and downs are associated with currents and eddies, swirling rivers in the ocean, that influence how it absorbs atmospheric heat and carbon.

The Surface Water and Ocean Topography mission will explore how the ocean absorbs atmospheric heat and carbon, moderating global temperatures and climate change.

Mission will study ocean currents from a satellite

The Surface Water and Ocean Topography (SWOT) mission is a joint effort between NASA and the French space agency Center National d’Études Spatiales (CNES), with contributions from the Canadian Space Agency (CSA) and the UK Space Agency. United.

Launched in November 2022, the SWOT mission will collect data on ocean heights to study currents and eddies up to five times smaller than previously detected. You will also collect detailed information about freshwater lakes and rivers.

Observing the ocean at relatively small scales will help scientists assess its role in moderating climate change. The largest store of atmospheric heat and carbon on the planet, the ocean has absorbed more than 90% of the heat trapped by human-caused greenhouse gas emissions.

Much of the ongoing absorption of that heat, and the excess carbon dioxide and methane that produced it, is thought to occur around currents and eddies less than 100 kilometers wide. These flows are small relative to currents like the Gulf Stream and California Current, but the researchers estimate that together they transfer up to half of the heat and carbon from surface waters to the deep ocean.

Better understanding this phenomenon may be key to determining whether there is a ceiling on the ocean’s ability to absorb heat and carbon from human activities.

Existing satellites cannot detect smaller-scale currents and eddies, limiting research into how those features interact with each other and with larger-scale flows.

In addition to helping researchers study the climate impacts of small currents, SWOT’s ability to “see” smaller areas of the Earth’s surface will allow it to collect more accurate data along coastlines, where increased ocean level and current flow can have immediate impacts on terrestrial ecosystems and human activity.

Higher seas, for example, can push storm surges farther inland. Additionally, currents intensified by sea level rise can increase saltwater intrusion into deltas, estuaries, and wetlands, as well as into groundwater supplies.

Measuring the height of the ocean will lead to a better understanding of currents and eddies. Precisely, the researchers use the differences in height between the points, known as the slope, to calculate the movement of the currents. The math explains the force of Earth’s gravity, which pulls water up and down, and the planet’s rotation, which, in the Northern Hemisphere, bends the flow clockwise around high points. and counterclockwise around the single crochets. The effect is the opposite in the south.

By measuring ocean heights down to 0.4-centimeter increments, as well as their slopes, SWOT’s two Ka-Band Radar Interferometer (KaRIn) antennas, researchers will be able to discern currents and eddies as small as 12 miles (20 kilometers) across. wide.

SWOT will also employ a nadir altimeter, older technology that can identify currents and eddies approximately 100 kilometers wide. Where the nadir altimeter will point down and take data in one dimension, the KaRIn antennas will tilt. This will allow the KaRIn antennas to scan the surface in two dimensions and, working in tandem, collect data more accurately than the nadir altimeter alone.