Volcanic twilights again
For a few days since 13 Aug. 2011, observers in Germany have noticed colourful twilight phenomena like intense crepuscular rays, and thus were reminded of the volcanic twilights from the Kasatochi and Sarychev. An aerosol layer is presently verifiable in the entire northern hemisphere, indeed. At the moment, measurements from the Meteorological Observatory Hohenpeissenberg (Germany), Evora (Portugal), Mauna Loa (Hawaii), Ukraine and Russia, all record this layer at heights between 12 and 19 km.
Most probably, these volcanic aerosols can be traced back to the Nabro Volcano in Eritrea. Despite having undergone no historically reported eruptions, the Nabro Volcano erupted shortly after local midnight on 13 June 2011, after a series of earthquakes ranging up to magnitude 5.7 in the Eritrea-Ethiopia border region. Its ash plume was observed on satellite images and drifted to the west-northwest along the said border, spanning a width of about 50 km and extending for several hundred kilometers westward in the immediate hours following the onset of the eruption, while reportedly reaching a ceiling near 15 km of altitude. The ash cloud also disrupted air traffic, as United Arab Emirates based flights were cancelled along with Saudi Arabian Airlines flights. Egypt’s Luxor International Airport was placed in a state of emergency for a while.
This aerosol layer seems to have been present since 15 July 2011 as shown by the Lidar measurements from Hohenpeissenberg.
More pictures and plots of the measurements are summarized here (PDF download):
Link to the NASA-Website with further measurements.
Support for this documentation on behalf of the Meteorological Observatory Hohenpeissenberg is gratefully acknowledged.
Author: Claudia Hinz, Brannenburg, Germany
Posted on August 18, 2011, in observations, phenomena, twilight phenomena, volcanic eruption phenomena and tagged crepuscular rays, Nabro Volcano, purple light, volcanic twilight. Bookmark the permalink. 7 Comments.