Logo link to homepage

Report on Atmospheric Effects (1980-1989) — March 1987

Scientific Event Alert Network Bulletin, vol. 12, no. 3 (March 1987)
Managing Editor: Lindsay McClelland.

Atmospheric Effects (1980-1989) Ruiz aerosols persist; optical effects seen from England

Please cite this report as:

Global Volcanism Program, 1987. Report on Atmospheric Effects (1980-1989) (McClelland, L., ed.). Scientific Event Alert Network Bulletin, 12:3. Smithsonian Institution.

Atmospheric Effects (1980-1989)

All times are local (unless otherwise noted)

Stratospheric aerosol layers observed from Fukuoka, Japan, have been significantly disturbed since late February (figure 39). Additional layers were detected at higher altitudes and backscattering ratios increased. February and March lidar data from Garmisch-Partenkirchen, Germany, generally showed peaks at higher altitudes than in January, but backscattering ratios remained similar. At Mauna Loa, Hawaii, a progressive depletion of aerosols in the lower stratosphere continued through March, but increased concentration between 21 and 25 km compensated for declines from 16 to 21 km, yielding the same average integrated backscatter as in February.

Figure with caption Figure 39. Lidar data from various locations, showing altitudes of aerosol layers. Note that some layers have multiple peaks. Backscattering ratios from Fukouka, Japan, are for the Nd-YAG wavelength of 1.06 µm; all others 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.

H. H. Lamb has continued to monitor twilight optical effects from Holt, England (53°N, 1°E). No remarkable evening colors were observed through late spring and most of the summer of 1986. On 8 September at 1850 GMT (20 minutes after sunset), the W sky was a cold yellow color. During the next 10 minutes a purplish patch of light developed, to 23° elevation at 1855 and 19° at 1900, suggesting that the illuminated layer was at 18-20 km altitude. By 1905, the sky near the horizon was a fiery red. Similar phenomena were observed 17-18 September, the last 5 days of October, and 15 November. Abnormal yellow color was visible in the evening sky on 14 and 20 December, and on the 20th a purple patch developed above the yellow, grading into white. A purple patch was seen again at dawn on the 21st, with a crepuscular ray to beyond 20° elevation at 0730 GMT, about 40 minutes before sunrise.

These observations suggested an aerosol layer at an altitude of 20 km or more. None of the effects were as intense as those observed between 1982 and 1984-5, produced by the El Chichón aerosols. Lidar in Italy, Germany, Japan, and the USA had begun to detect additional aerosol layers between late September and early November, and aerosol material, probably in the upper troposphere, was visible in daylight from Fairbanks, Alaska in early October. However, satellite data suggested that these apparent new aerosols may have been older material seasonally transported from lower to higher latitudes.

Information Contacts: H.H. Lamb, Climatic Research Unit, School of Environmental Sciences, University of East Anglia, Norwich NR4 7TJ England; Thomas DeFoor, Mauna Loa Observatory, P.O. Box 275, Hilo, HI 96720 USA; Motowo Fujiwara, Physics Department, Kyushu University, Fukuoka 812, Japan; Horst Jäger, Fraunhofer-Institut für Atmosphärische Umweltforschung, Kreuzeckbahnstrasse 19, D-8100 Garmisch-Partenkirchen, West Germany.