Long-term observations of the mid-latude stratospheric aerosol by the Langley 48-inch Lidar

The Langley 48-inch ground-based lidar system was developed at the NASA Langley Research Center in the early 1970s to measure aerosol backscatter profiles in the upper troposphere and lower stratosphere. The original version of the system employed a ruby laser, which transmitted energy at a single wavelength of 694 nm. As new technology became available, modifications and upgrades were made to the system, including the addition of a Nd:YAG laser in 1992. The system is currently capable of operating at three wavelengths, 1064 nm and 532 nm, transmitted by the YAG, and the 694nm transmitted by the ruby. Aerosol backscatter profiles have been measured with this system at the Hampton, Virginia site (37.1°N, 76.3°W) on a near-regular basis since 1974. This 25-year data set is one of the world’s longest continuous lidar records on mid-latitude aerosols. On a number of occasions during this 25-year period, the stratospheric aerosol was greatly enhanced by highly explosive volcanic eruptions. These perturbations and long recovery periods are reflected in the long-term record. This presentation will include a discussion on the Langley 48-inch lidar and its long-term record with emphasis on measurements obtained during periods following the eruptions of El Chichon in 1982 and Pinatubo in 1991.