Extensive lidar observations of the Pinatubo aerosol layers at Tsukuba (36.1°N), Naha (26.2°N), Japan and Lauder (45.0°S), New Zealand

Abstract

Since the explosive volcanic eruption of Mt. Pinatubo on June 15, 1991, extensive lidar observations at a wavelength of 532 nm have been made at Tsukuba and Naha in the northern hemisphere and Lauder in the southern hemisphere. The first increase of the aerosols from the Pinatubo eruption was observed at 15.7 km over Tsukuba on June 28, 1991. From fall 1991, the Pinatubo aerosol particles were effectively transported from the tropical region into the northern mid‐latitude. The maximum scattering ratios observed were 14.1 at 22.7 km on November 29, 1991 at Tsukuba and 22.5 at 25.9 km on December 4, 1991 at Naha respectively. The Lauder measurements started in November 1992, too late to pick up the Pinatubo maximum. The maximum values of integrated backscattering coefficient (IBC) above the tropopause were 5.4×10−3 sr−1 over Naha on November 18, 1991 and 7.1×10−3 sr−1 over Tsukuba on February 22, 1992 respectively. The IBC over Tsukuba showed clear seasonal variation with a maximum in winter and early spring and a minimum in summer. The IBC over Tsukuba in winter of 92/93 decreased only about 26 percent compared with the IBC in 91/92 winter, but the IBC in winter of 93/94 decreased largely. The IBC over Lauder was significantly larger than those over Tsukuba and Naha from June 1993 to August 1993.