An Extreme Case of Cooling

Published: 29 July 2016

Editor’s note: Brett Borchardt, a data quality analyst in the ARM Data Quality Office at the University of Oklahoma at Norman, sent this update.

I’ve been investigating an impressive temperature drop at the ARM deployment on the southern tip of Antarctica’s Ross Ice Shelf.

On July 4, ARM’s Surface Meteorological Instrumentation (MET) instrumentation captured an extreme case of in situ cooling at the ARM West Antarctic Radiation Experiment, or AWARE, at McMurdo Station.

Over 21 minutes, temperatures dropped 12.2 degrees C (21.9 degrees F), and then raised 10.3 degrees C (18.5 degrees F) over 30 minutes.

The wind arithmetic mean dropped to 0 around the same time indicating little to no vertical mixing, and the instrument reported clear skies. The temperature and winds rebound just after 2026 UTC, which is when the visibility also takes a big hit. According to the site manager, freezing fog moved in at that time.

Regardless, the temperature fluctuation over such a short period is impressive.

Click on the images to enlarge them.