Tuesday, February 22, 2011

Snow accumulation updates

A subset of Quelccaya AWS measurements are transmitted from the station to our Climate System Research Center at UMass, via the geostationary-orbit GOES East satellite. Among the most-interesting values to follow is snowfall, which principally governs Quelccaya Ice Cap mass balance and responds rather sensitively to conditions in the Tropical Pacific Ocean (e.g., ENSO).

The 2010-11 accumulation season began late - at the end of November - by which time 30-60 cm of snow typically blankets the summit. Through December, January and February to date, accumulation has been steady, and snow depth is now at ~1.5 meters. While slightly less than normal for the date, the rate of accumulation remains high - in contrast to other years when the rate tends to decrease about now.

With the Oceanic Enso Index still low (-1.4°C), snowfall over the next month or two is expected to be above normal at the station. Another 50 cm will bring 2010-11 to the mean depth (2004-09; cf. water equivalance, determined during fieldwork), and another 100 cm will make this the greatest accumulation for the period of record. Interannual variability of snow depth is remarkably low at Quelccaya!

[UPDATE 3/10:  As of 6 March, accumulation is approaching 1.9 meters. Snowfall to this date was only greater during the 2007-08 wet season (during our relatively brief period of record, 2003 to present).]

[UPDATE 4/27:  The rate of accumulation decreased notably after early March, coinciding with the lessening OEI anomaly, with the seasonal total now at ~2.2 meters. Although only 2007-08 saw greater accumulation to this date, the annual differences are small.]