UPDATE with fuller description here:
Satellite derived temperature of the lower stratosphere (TLS) shows a strong signal from the two stratospheric volcanic eruptions that occurred during the sample period (El Chichon and Mt Pinatubo).
The material ejected into the stratosphere blocks incoming solar, warming the stratosphere and cooling the troposphere and surface temperatures. When the particulate matter has dropped out there is a long-term depletion of stratospheric ozone ( 5 to 8% less after Pinatubo ) that lets more energy reach the lower atmosphere. 
In each case the perturbation lasted less that five years.
What is notable is that, in both instances, TLS settled at a significantly lower level than before the eruption. Each event leading to a definative drop of around 0.5 kelvin in globally averaged TLS.
A 365 day, low-pass filter was used to remove the annual signal.
Details of the filter and a script to implement it are provided here: