PhD Student: Sarah Wheaton
A climatology is defined as the mean state for a given time of year of an atmospheric parameter.
The problem with this is that the amount of aerosol in the stratosphere is not constant. Approximately once every 6 years or so there is a volcanic eruptionpowerful enough to inject sulphur dioxide directly into the stratosphere where it is rapidly converted into aerosol. This excess aerosol decays away over the course of several years.
This large interannual variability coupled with the unpredictability of volcanic eruptions means that it is difficult and probably meaningless to define a standard climatology of aerosol loading. Although it would be quite possible to take a mean aerosol loading for any time of year over several years this would not be usefully representative of the actual state of the atmosphere for any but very short and unpredictable periods of time.
In this history, on the other hand, we hope to preserve the wide range of aerosol loading states from the high concentrations immediatly after the eruption of Mt Pinatubo, to the present mimimum.