Stratospheric aerosol measurements over Mauna Loa Observatory, Hawaii

The stratospheric aerosol layer has been monitored above Mauna Loa Observatory (MLO) by lidar since late 1974. The original lidar used a ruby laser (694 nm) and since 1994 a Nd:YAG laser (532 nm and 1064 nm) has been in operation. MLO is one of four baseline stations operated by the NOAA/Climate Monitoring and Diagnostics Laboratory. At 19.6 degrees north, MLO is generally on the edge of the tropical atmosphere but experiences mid-latitude air masses as well. The observatory lay in the path of the two largest eruptions (in terms of stratospheric aerosol) in the past 35 years, El Chichon in 1982 and Mount Pinatubo in 1991. The aerosol backscatter has been integrated between 15.8 and 33 km. This altitude range covers the stratospheric layer in nearly all cases. The upper troposphere has very low aerosol levels and so the stratospheric layer is quite distinct. Several other smaller eruptions have also been observed during the 26 years of observations