Satellites Could Help Quantify, Monitor Ocean Carbon Levels

Satellite-based Earth observation is key to globally monitoring oceanic carbon absorption levels, according to a study led by researchers at the University of Exeter.

Satellites originally launched to study the wind also have the capability to observe how rain, wind, waves, foam, and temperature combine to control the movement of heat and carbon dioxide (CO₂) between the ocean and the atmosphere. Satellites launched to remotely sense gas emissions over the land are also able to measure CO₂ emissions as they disperse over the ocean. Finer spatial resolution remote-sensing observations have been particularly useful for studying processes and fluxes in CO₂ values in areas that have commonly been omitted in global-scale flux calculations, for example within coastal oceans, upwelling zones, and near the ice edge. Satellite-based biological production and sea-surface temperature data have enabled preliminary identification of the drivers of variability in the ocean CO₂ sink.

Coral reefs of Tonga viewed from space. Courtesy of Copernicus Sentinel data processed by ESA.

Today, multiple long-term satellite programs exist and commercial operators are promoting a plethora of satellite services. Examples of commercial activity include more than 150 optical CubeSats already in orbit for monitoring changes on land and the planned launch of 40 passive microwave CubeSats for monitoring weather. This is occurring in parallel with the emergence of routine image and pattern recognition, artificial intelligence, and commercial availability of cloud computing, meaning that nonspecialists can use a laptop computer to remotely access and analyze global satellite observations. For example, Google Earth Engine now provides free access and computing for scientific analysis of global satellite observation data sets.

Future satellite missions offer potential for new knowledge, including the ability to study the internal circulation of the oceans. The researchers believe that increased exploitation of existing satellites could help climatologists fill gaps in their knowledge of global CO₂ absorption by the oceans. They suggest the formation of a network that could routinely observe the oceans by combining data from many different satellites with information from automated instruments on ships, autonomous vehicles, and floats that routinely measure surface water CO₂, and using these in situ and satellite-based Earth observations to quantify the atmosphere-ocean exchange of climate-relevant gases.

The research was published in Frontiers in Ecology and the Environment (www.doi.org/10.1002/fee.2129).