Lidar instruments in Germany, Virginia, and Hawaii continued to detect stratospheric aerosols that were probably from the 13 November 1985 eruption of Ruiz. No new layers from the late March explosive activity of Augustine were apparent as of late April. At Mauna Loa, Hawaii, lidar continued to detect a strong layer at about 21 km altitude, accompanied by a weaker layer at about 27 km on 1 and 22 April (figure 24). High-altitude layers had previously been observed at Mauna Loa two weeks after the Ruiz eruption and in late February. April backscattering ratios at Garmisch-Partenkirchen, West Germany were similar to those of late February. At Hampton, VA, stratospheric layers were centered at about 19-20 km altitude. Enhanced backscattering, perhaps from large forest fires in the eastern United States, continued down into the troposphere.

Figure 24. 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 and from the tropopause to 30 km at Hampton. Altitudes of maximum backscattering ratios and coefficients are shown for each layer at Mauna Loa.

Further Reference. DeFoor, T., and Robinson, E., 1987, Stratospheric Lidar Profiles from Mauna Loa Observatory, Winter 1985-1986: GRL, v. 14, p. 618-621.

Information Contacts: Thomas DeFoor, Mauna Loa Observatory, P.O. Box 275, Hilo, HI 96720 USA; William Fuller, NASA Langley Research Center, Hampton, VA 23665 USA; H. Jäger, Fraunhofer-Institut fur Atmosphärische Umweltforschung, Kreuzeckbahnstrasse 19, D-8l00 Garmisch-Partenkirchen, West Germany.