Washington, USA, 13 June 2006: NASA’s Cloud-Aerosol Lidar and Infrared Pathfinder Satellite Observation (CALIPSO) spacecraft has begun gathering data from the Earth’s atmosphere that are expected to become a key tool in unraveling just how much effect the reflectivity of clouds and tiny particles called aerosols are having on the planet’s changing climate.
Satellites for many years have produced pictures showing the Earth swathed in clouds. More recent instruments also identify aerosol plumes from dust storms, forest fires, industrial pollution and the like. While valuable, those data mainly provide a two-dimensional perspective, with no precise information about the altitude of the clouds and aerosols.
CALIPSO will use lidar to measure the specific altitudes of clouds and aerosols within about 100 feet. Also the satellite’s lidar equipment uses an eye-safe laser that actually might be glimpsed in a hazy sky or on snow cover. It would be visible as a row of green dots about 250 feet across and 800 feet apart, but it could only be seen at night in a very dark sky, most likely from an airplane looking down at snow cover or clouds. The satellite will pass at more than 15,000 miles per hour and at an altitude of more than 430 miles.
Such access to global data telling us the altitudinal location of clouds and haze plumes in the atmosphere is going to advance the space-based study of aerosol-and-cloud interactions since authoritative knowledge about whether the aerosol layer and the cloud layer are really at the same level in the atmosphere can be obtained.
The satellite also is equipped with other scientific instruments that will collect information about the structure of clouds and aerosols. All of the information gathered would be important to those using computer models in trying to understand the mechanics of climate change and how it is likely to play out in the future.