Polar Mesospheric Cloud Particle Size Retrieval from GOMOS / ENVISAT Observations
Abstract
GOMOS (Global Ozone Monitoring by Occultation of Stars) is a stellar occultation
instrument, combining four spectrometers and two fast photometers, that flew on board the
European platform ENVISAT from 2002 to 2012. Polar mesospheric clouds (PMCs), that form
during summer in the polar upper mesosphere, could be detected using the photometers' signals.
Their main properties (occurrence frequency, peak altitude, radiance) have been retrieved from
2002 to 2010, leading to a 16-summer (in both hemispheres) database of more than 21000 clouds.
PMCs are very sensitive to changes in their environment. That makes them important
tracers for the complex mechanisms that control the summer mesopause region. A better
understanding of the microphysical processes going on in this atmospheric region is essential in order to
model of their growth, their transport mechanisms and their lifetime. To that purpose, the particle
size distribution is an important parameter.
This presentation will be focused on PMC particle sizes retrieved from GOMOS spectral
observations in the northern hemisphere. The retrieval method will be explained, and results based
on the obtained 8-year dataset will be described and compared to PMC particle sizes derived from
the measurements of other instruments.