NASA scientists and engineers have built an instrument powerful and accurate enough to gather around-the-clock global atmospheric carbon-dioxide (CO2) measurements from space. The CO2 Sounder Lidar operates by bouncing an infrared laser light off the Earth’s surface. Like all atmospheric gases, carbon dioxide absorbs light in narrow wavelength bands — in this case, the infrared. By tuning the laser to the infrared, scientists can detect and then analyze the level of carbon dioxide in that vertical path.
The laser also offers the ability to measure water vapor whose absorption lines lie next to CO2’s absorption lines.