Scarab is a 4-channel radiometer (visible light, solar, total, and infrared radiation). It was developed by the French Laboratoire de Météorologie Dynamique (dynamic meteorology laboratory, LMD) and CNES to measure Earth’s radiation budget.
The radiation budget is the difference between solar radiation absorbed by our planet and its atmosphere and the infrared radiation it emits back into space. These flows are the only energy exchanges between Earth and space, and they are essential components of its climate. Earth’s radiation budget is balanced on a global scale over the course of a year, but seasonal imbalance exists on a regional scale. It is therefore essential to map the radiation budget’s components and monitor its variations over time in order to better understand how our climate evolves, because any climate change (due to human activity for example) will necessarily involve a change in the radiation budget.
The very first estimations of Earth’s radiation budget were made at the beginning of the 20th century. But the last thirty years of satellite development gave us the first quantitative observations.