27 August at N 85 21' W08 09' drifting westward

One part of the ASCOS observations is launching of "weather balloons" -
helium-filled balloons sent up on a regular schedule every six hours
from the helipad, carrying a sonde measuring pressure, temperature and
humidity with sensors on the sonde itself. Winds are calculated from how
the sensor package moves using differential GPS; a GPS receiver on the
sonde records the position of the instruments and compares those to the
position of the ground station. The height of the sonde can be
calculated from the observed pressure and temperature. The results from
the soundings provide a picture of the time-varying vertical structure
of the atmosphere up to about 25 kilometers. They are also used as
"first guess" profiles for some retrieval algorithms used to interpret
different remotes sensing instruments. Every so often the sounding is
augmented by sensors measuring either radioactivity or ozone; we try and
time these so that they are done on days when the Sodankylä monitoring
station in norther Finland does similar launches.

Ozone sounding being launchedOzone sounding being launched