Thursday, November 18, 2010

Timelapse: watch 129 days in 11 seconds

In early 2005 we installed a timelapse camera system near the weather station, with objectives of visually documenting the variability of weather (esp. clouds), glacier surface texture & roughness, accumulation & ablation, and crater snowcover. Images demonstrate the pronounced and typical diurnal cycle of convection on southwestern slopes, as well as interesting variability within the seasonal cycles.

A movie of 129 days worth of images is available here, spanning 8 Oct. 2009 to 14 Feb. 2010. To provide consistent lighting, these images are all from 6 PM local time, when the upper Breach Wall and the Furtw√§ngler Glacier are illuminated. To fully appreciate the day-to-day variability of weather and snowcover depicted, try watching just one portion of the image (e.g., convection to the South, glacier in foreground).

The two images below are from the same time interval, illustrating dry conditions on a clear day, and fresh 'short rains' snowcover (respectively). Note the white ablation stake in the foreground; 42 cm was exposed in early October of 2009 (shortly prior to date of upper image), increasing a year later (8 Oct. 2010) to 120 cm.

Wednesday, November 3, 2010

2010 dry season ablation

June through October is typically an extended dry period at the summit of Kilimanjaro, with ablation of horizontal glacier surfaces often increasing once the seasonal snow cover is gone. During September and October this year, ablation was especially pronounced on the Northern Ice Field, despite above-average snow cover at the end of May. Ablation will continue at this pace in November until the 'short rains' begin and snow cover is restored.

To illustrate, average net surface lowering at the weather station (2 sensors) was 30 cm in both October and September, following 19 and 22 cm in August and July, respectively. New records were established for net ablation over 2-, 3-, and 4-month intervals (since 2002).

Analysis of October 2010 field measurements is just getting underway, including those from a network of ablation stakes, but it appears that surface ablation may have been more normal on the southern glaciers. With our Innsbruck colleague's full instrumentation on that side, it will be fascinating to further investigate these spatial patterns of mass and energy flux.