Lidar in Hawaii, Virginia, and Germany continued to detect stratospheric aerosols from the November 1985 eruption of Ruiz (figure 40). Data from Mauna Loa, Hawaii showed a continuing gradual decline in both total backscatter and the thickness of the zone of enhanced aerosols. From Hampton, VA, the aerosol layer was quite uniform from the tropopause upward, with little sublayering evident. Altitudes of peak backscattering measured from Garmisch-Partenkirchen, Germany, which had increased slightly in February and March, returned to January levels. Backscattering ratios have remained stable.

Figure 40. Lidar data from various locations, showing altitudes of aerosol layers. Note that some layers have multiple peaks. Backscattering ratios are for the ruby wavelength of 0.69 µm. Integrated values show total backscatter, expressed in steradians-1, integrated over 300-m intervals from 16-33 km at Mauna Loa. Altitudes of maximum backscattering ratios and coefficients are shown for each layer at Mauna Loa.

Information Contacts: Thomas DeFoor, Mauna Loa Observatory, P. O. Box 275, Hilo, HI 96720 USA; Horst Jäger, Fraunhofer-Institut für Atmosphärische Umweltforschung, Kreuzeckbahnstrasse 19, D-8100 Garmisch-Partenkirchen, West Germany; William Fuller, NASA Langley Research Center, Hampton, VA 23665 USA.