NASA's Cloud-Aerosol Lidar and Infrared Pathfinder Satellite Observations (CALIPSO) satellite watches Eyjafjallajökull's plume drift over northern Europe. Credit: NASA/Kurt Severance and Tim Marvel
On Saturday, Apr. 17 around 02:00 UTC (9:00 p.m. EDT), the CALIPSO (Cloud-Aerosol Lidar and Infrared Pathfinder Satellite Observations) satellite collected observations across Europe and captured this image of the Eyjafjallajokull ash cloud as it continued to drift over the continent. Unlike other satellites that provide a bird's-eye view of the ash cloud's horizontal spread, CALIPSO provides a unique vertical profile of a slice of the atmosphere. In this image, the ash cloud is seen as a thin, wispy layer of particles ranging in altitude from about 5,000 to 22,000 feet. To compare its altitude and breadth, see the clouds over Northern Europe, some of which are so thick that they block the penetration of light from CALIPSO's lidar to the surface. The yellow layer near the surface over France is believed to be primarily air pollution.
Highlighting its ability to capture high-resolution profile data of the atmosphere, CALIPSO on Apr. 15 detected remnants of the Eyjafjallajokull cloud drifting near Iceland at about 30,000 feet. CALIPSO uses an innovative lidar to see aerosols (small particles such as dust, smoke and pollution) and thin clouds that are often invisible to radar, and sometimes to human eye.
CALIPSO's lidar sends a series of short pulses of laser light down through the atmosphere, and measures light reflected back to the satellite. The strength of the returned signal reveals the characteristics of the cloud and aerosol layers that lie below. The time required for the signal to travel down through the atmosphere and return to the satellite is used to construct a vertical map showing locations of clouds and aerosols.
CALIPSO is joint research mission between NASA and CNES, the French space agency. It has been in operation for almost four years.
Text Credit: Patrick Lynch, NASA Langley Research Center
Image and text from: http://www.nasa.gov/topics/earth/features/iceland-volcano-plume.html