Lidar data from the USSR showed aerosols at similar altitudes as those observed at other Northern Hemisphere locations (figure 60), but data from Obninsk (55°N, 38°E) on 30 June included a higher altitude layer. Integrated backscattering returned to 3 April/27 May values after a substantial decline in late May and early June. No evidence of material from the 29 July eruption of Makian (Indonesia) had been detected by lidar stations as of early August. Lidar data from Mauna Loa, Hawaii has documented a a continuing irregular decline in integrated aerosol backscattering since late 1986. No large explosive eruptions are known to have produced significant stratospheric aerosols since the Ruiz eruption of November 1985.

Figure 60. Lidar data from various locations, showing altitudes of aerosol layers during April-August 1988. Note that some layers have multiple peaks. Backscattering ratios from Obninsk and Teplokluchenka, USSR, are for the Nd-YAG wavelength of 0.53 µm; all others are for the ruby wavelength of 0.69 µm. Integrated values show total backscatter, expressed in steradians-1, integrated over 500-m intervals from 15-30 km at Obninsk and Teplokluchenka, and from the tropopause to 30 km at Hampton, Virginia. Altitudes of maximum backscattering ratios and coefficients are shown for each layer at Mauna Loa.

Information Contacts: Sergei Khmelevtsov, Institute of Experimental Meteorology, Lenin St. 82, Obninsk, Kaluga Reg., USSR; 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 and Mary Osborn, NASA Langley Research Center, Hampton, VA 23665 USA.