INCREASE IN THE STRATOSPHERIC BACKGROUND SULFURIC-ACID AEROSOL MASS IN THE PAST 10 YEARS

Data obtained from measurements of the stratospheric aerosol at Laramie, Wyoming (41°N), indicate that the background or nonvolcanic stratospheric sulfuric acid aerosol mass at northern mid-latitudes has increased by about 5 ±2 percent per year during die past 10 years. Whether this increase is natural or anthropogenic could not be determined at this time because of inadequate information on sulfur sources, in particular, carbonyl sulfide, which is thought to be the dominant nonvolcanic source of stratospheric sulfuric acid vapor. An increase in stratospheric sulfate levels has important climatic implications as well as heterogeneous chemical effects that may alter the concentration of stratospheric ozone.