HR: 14:30h
AN: A43D-04 INVITED     [Abstracts]
TI: Physical Properties of the Ash from El Chichon Eruptions and Solar Radiation Extinction as a Measure of its Climate Impact
AU: * Galindo, I
EM: igalindo@ucol.mx
AF: Centro Universitario de Investigaciones en Ciencias del Ambiente, Revolucion #427, Colima, Col 28000, Mexico
AB: The eruptions of El Chichon Volcano in southern Mexico in late March and April 1982 and Pinatubo in the Philippines in June 1991 provided the greatest volcanic clouds in the stratosphere in the last century, perhaps indeed the greatest since the Krakatau eruption (Indonesia) on 27 August 1883. Curiously enough it was almost the hundredth anniversary of the great explosive Krakatau eruption when we experienced the El Chichon eruptions. Today 25 years later we shall meet and discuss the main aspects of the El Chichon eruption and what we have learned from this historical event. Here we shall concentrate on some of the observed effects on climate. The experimentally determined refractive index n = 1.53 - 0.001i of the ash particles shows a very small aerosol absorption expressed as the imaginary component of the refractive index (0.001) which implies that the aerosol scattering is quite high. These results provide the physical basis to understand the atmospheric impact from sea level up to the stratosphere of the aerosol cloud all over the world: Regional increases of air temperature and solar radiation depletion with large and variable aerosol optical depths while the resultant stratospheric dust cloud traveled completely around the Earth. Finally it is shown that the tropical atmosphere was already perturbed even before the El Chichon eruption due to the so-called "Mystery Cloud" (Nyamuragira´s Volcano eruption in December 1981)
UR: http:www.ucol.mx
DE: 0305 Aerosols and particles (0345, 4801, 4906)
DE: 0360 Radiation: transmission and scattering
DE: 0370 Volcanic effects (8409)
SC: Atmospheric Sciences [A]
MN: 2007 Joint Assembly