Meteoric smoke and H2SO4 aerosols in the upper stratosphere and mesosphere

Smoke extinction measured by the Solar Occultation For Ice Experiment, however, shows that while this is true in the middle to upper mesosphere (pressure <similar to 0.2hPa), it is not true near the stratopause. Here the expected winter increase begins 3months earlier than in models.

We suggest that the autumn extinction increase is due to H2SO4 condensing above the nominal stratospheric aerosol layer (similar to 5hPa). This is possible due to lowering of the H2SO4 saturation vapor pressure when the acid is neutralized through combination with meteoric metals. The appearance of neutralized H2SO4 aerosol in autumn is associated with the seasonal decrease in temperature.