Lidar data from Fukuoka, Japan and Hampton, Virginia showed little change in the remnants of the stratospheric cloud ejected by the March-April 1982 eruption of El Chichón.

Edward Brooks resumed dawn and twilight observations from Jeddah, Saudi Arabia in late August. Bright colors were seen during some dawns and dusks in late August but colors became more intense in early September. NNW-SSE bands of aerosols were seen low in the W sky during brilliant dusks 12 and 13 September. During the evening of the 14th, faint N-S aerosol bands were visible, but their rapid fading suggested that they were at relatively low altitudes. Aerosol bands, trending N-S and NNW-SSE, were seen in the E sky at dawn 18-19 September. Colors remained brilliant through 24 September. Brooks noted that the very late twilight illumination at high sky angles observed at times since April 1982 would require particles to be present at altitudes near 100 km if caused by primary scatter. He suggests instead that secondary scattering from aerosols near 25 km altitude was responsible for late, high angle illumination.

From Millville, New Jersey, Fred Schaaf observed moderate to strong early and late twilight colors during the first half of September. After the arrival of a northern air mass 15 September, both early and late colors became weak. Moderately strong early and late colors returned 6 October. Schaaf noted that if late colors were caused by direct illumination of high-altitude aerosols (timing of illumination would indicate altitudes in excess of 70 km), they should have been unaffected by the northern airmass; the near disappearance of late colors in mid-September suggests that they are the result of secondary scattering from lower-altitude material.

Information Contacts: E. Brooks, Saudi Arabia; F. Schaaf, Millville, NJ; W. Fuller, NASA; M. Fujiwara and M. Hirono, Kyushu Univ., Japan.