Carbon satellites: "sniffing out" carbon from afar, accurately monitoring global carbon emissions.

With the rapid development of atmospheric sounding and modeling technologies, tracing carbon emissions through atmospheric carbon dioxide concentration observation is considered an effective method for assessing greenhouse gas emission reduction achievements. On December 22, 2016, my country launched its first carbon dioxide observation scientific experimental satellite, TanSat, becoming the third country in the world to provide carbon satellite data.

Monitoring global CO2 concentrations, with observations and simulations conducted simultaneously.

The carbon satellite, officially named the "Global Carbon Dioxide Monitoring Scientific Experiment Satellite," monitors global CO2 concentrations using atmospheric carbon dioxide concentration measurement methods. It relies on simultaneous observation and simulation, aiming to address global climate change and monitor the global distribution of carbon dioxide concentrations.

In terms of observation, satellite remote sensing can play a significant role in global carbon dioxide observation due to its unique observation locations and methods, especially in high-resolution global coverage observations, where it can see a wide range and clearly. Simulation, on the other hand, mainly uses atmospheric transport models and high-performance computers to simulate the atmospheric carbon dioxide transport process and the atmospheric carbon dioxide content at every moment and every place, and coordinates with satellite observations to obtain a carbon flux value that is closest to the truth.

Equipped with a specially designed "long-range vision" system, it provides crucial data support.

Currently, there are only a few hundred ground-based carbon dioxide observation stations worldwide, which is insufficient to meet monitoring needs. Carbon satellites offer a solution to this problem to some extent, as they can acquire global carbon dioxide monitoring data.

Identifying which gases are carbon dioxide from the thick atmosphere that surrounds the Earth, and even creating "dynamic maps"—China's carbon satellite is equipped with a specially designed "long-range vision."

The TanSat carbon satellite carries a hyperspectral and high spatial resolution carbon dioxide detector. This detector works by using molecular absorption lines in the visible and near-infrared spectral bands to detect carbon dioxide concentration, accurately and in real-time monitoring changes in global atmospheric carbon dioxide concentration. The carbon satellite orbits the Earth approximately 14 times per day, with a detection width of 20 kilometers. While orbiting the Earth's poles, it acquires global carbon dioxide concentration information to accurately demonstrate how human activities and natural systems emit and absorb this greenhouse gas.

By analyzing the global column concentration sequence and using a series of models from the data assimilation system, the global CO2 flux change (the total amount of CO2 passing through a unit area per unit time) can be deduced, which is the core data foundation for carbon cycle research.

△ Compare the data returned by the carbon satellite,

It can calculate the carbon dioxide levels in different regions of the world.

In addition to its core capabilities, the carbon satellite carries another powerful tool—a multispectral cloud and aerosol polarization imager. This imager measures auxiliary information such as clouds and atmospheric particulate matter, helping scientists accurately reverse-engineer carbon dioxide concentrations by eliminating interfering factors. It also assists meteorologists in improving the accuracy of weather forecasts and provides crucial data support for research into the causes of air pollution such as PM2.5. Carbon satellite data is updated daily. Users can customize and download global data from the carbon satellite by date and region.

First global map of atmospheric carbon dioxide distribution from a Chinese carbon satellite

△Through repeated observations,

Carbon satellites can provide a complete map of global carbon dioxide distribution.

As a standard near-polar sun-synchronous satellite, the carbon satellite orbits the Earth's North and South Poles at an altitude of 700 kilometers, completing 14 to 15 orbits per day. Its global carbon dioxide monitoring instrument collects hyperspectral resolution information of the Earth's atmosphere over a 20-kilometer east-west radius per orbit. Therefore, the carbon satellite can acquire data covering an area of ​​approximately 300 kilometers per day, spanning (14 to 15) × 20 kilometers. Given that the Earth's equator has a circumference of about 40,000 kilometers, theoretically, obtaining observation data from approximately 140 days and 2,000 orbits would allow for the creation of a seamless, globally covered carbon dioxide monitoring map.

△China's first global carbon dioxide distribution map from its carbon satellite

In September 2017, the first global carbon dioxide distribution map was released, with an average accuracy of 2.11 ppm. The map shows a pattern of high carbon dioxide concentrations in the Northern Hemisphere and low concentrations in the Southern Hemisphere during spring, due to anthropogenic emissions. Comparing the distribution maps from April and July 2017, a clear trend of decreasing carbon dioxide concentrations in the Northern Hemisphere from spring to summer is shown, indicating the seasonal carbon sequestration function of ecosystems. The map also reflects the high carbon dioxide concentrations in areas with frequent human activity.

Global carbon flux dataset

△Schematic diagram of global carbon sources and sinks monitored by China's carbon satellite (TanSat)

On August 15, 2021, researchers from the Institute of Atmospheric Physics, Chinese Academy of Sciences, and other institutions used an advanced carbon flux calculation system to obtain the first global carbon flux dataset from the China Carbon Satellite, my country's first global carbon dioxide monitoring scientific experimental satellite. This is a milestone result, marking that my country has the spatial quantitative monitoring capability of global carbon balance, making it the third country in the world, after Japan and the United States, to possess this technology.

Global inventory helps to understand the impact of actions such as carbon dioxide emission reduction and carbon sequestration on climate change trends, and satellite remote sensing will play a significant role in global, unified, and unbiased carbon accounting.

China's carbon satellite is the country's first-generation dedicated greenhouse gas monitoring satellite and the third global "carbon-sniffing" satellite after Japan and the United States. Its successful development has enabled high-precision space-based greenhouse gas monitoring from scratch. Its subsequent stable operation in orbit will fill the technological gap in my country's greenhouse gas detection capabilities. Its achievements are of great significance for my country to understand the changing patterns of global warming and the distribution of global carbon emissions, and to enhance my country's international voice in addressing global climate change.
In the future, based on the research results of carbon satellites, my country will develop a new generation of greenhouse gas monitoring satellites to serve the realization of global and national dual carbon goals.

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