Abstract
Lidar measurements of stratospheric aerosol layers over Nagano-shi (36.7°N, 138.2°E) have been made for 38 months since the volcanic eruption of Mt. Pinatubo in the Philippines on June 15, 1991. At the initial stage until September, 1991, the non-uniform volcanic aerosol layer above 20 km was observed, which moved slowly toward to high latitudes in the easterly wind region. The integrated backscattering coefficient (IBC) reached the maximum value in December, 1991 and then decreased gradually with the decay time of 7.5 months although the re-increase was observed in November, 1992. The time variation of temperature deviation from the averaged value calculated from rawinsonde data at Wajima shows that stratospheric warming and tropospheric cooling happened in April to May, 1992 and 1993. The comparison of the surface temperature between four cities, Nagano, Matsumoto, Shizuoka and Niigata, during those tropospheric cooling periods demonstrates that inland cities were 0.6-1.0 deg. cooler than coast cities.
