Lidar observations of Eyjafjallajokull ashes outbreak
April 20, 2010 The Napoli Earlinet Lidar observed ash from Eyjafjallajokull starting in the morning of April 20, 2010, at around 3km height. Ash layer seeped into PBL in the eveningThe peak value of backscattering coefficient at 355nm (found at 18:50 UT, ~2 Km) increases from 2.2·10-6 sr-1 m-1 to 5·10-6 sr-1 m-1, and from 1.3·10-6 sr-1 m-1 to 3·10-6 sr-1 m-1 at 532nm.
April 21, 2010 Eyjafjallajokull ashes layer is present between 2 and 3 km in the first part of measurements. Night time data show the presence of ashes at high altitudes (5-8 Km) as well.
April 22, 2010 Ash is detected at 2-3 Km and between 4 and 6 Km. Linear volume depolarization is always 1-3%.
April 23, 2010 Low clouds and rain prevent performing lidar measurements. Measurements will restart as soon as possible.
April 24, 2010 Low clouds and rain prevent performing lidar measurements. Measurements will start as soon as weather conditions will allow it.
April 25, 2010 Due to the presence of low clouds, measurements have been performed only between 14:37 and 17:00.
Aerosol layers are visible below 3 km and between 4 and 5.5 km ( clearly visible in the depolarization map). Backtrajectories indicate that the origin is in the Sahara region.
In Napoli the event is clearly visible. A strong depolarizing layer (linear volume depolarization about 10%) is at 4 km. Several other layers not depolarizing are visible at 2Km, 3Km and 5 Km.
This morning the strongly depolarizing layer at 4 km is no longer present over Napoli. The most intense layer is at 2.5- 3 km( linear volume dep about 2%). Other layers are present below the main layer, they are well distinguishable from the PBL, at least for now.