Snow!

A 3-day snowy interval was underway at this time last week, bringing over 50 cm of snow on Tuesday to Lava Tower camp at the 4,600m level - and ending an extended dry period. This snow required some climbers to turn back, according to Simon Mtuy at Summit Expeditions, as continuing up the mountain became too difficult. We hope to post photos of the event here shortly.

At the summit, snow began accumulating on Sunday the 13th and continued into the 16th. Telemetry indicates that the event brought somewhere between ~19 and 28cm to the glaciers. Through noon today (local time) the new snow had settled and ablated by 5-10cm, over the past ~5 days.

Hopefully this snowfall brought much-needed rainfall to northern Tanzania. Perhaps the "long rains" are beginning, a bit early?

[UPDATE 3/4:  Below are a couple images as the event was beginning. The first illustrates slight accumulation around the two stations on the first day of snowfall. The lower image is a view of Birafu Camp on the second day. The heaviest snowfall came the next day, which some guides describe as the most they can recall in ~4 years. Both images courtesy of Clavery Tungaraza]

Weather station images

Here is a link to October images of Kilimanjaro's weather stations. Penitentes were present at the time on most glacier surfaces, and these appear in the images. Depending upon their size, penitentes can make glacier travel rather difficult. On Kibo it is unusual to find them greater than about 0.5m in height, but in the dry Andes they develop to heights of several meters. Currently the glacier surface is likely to be much flatter, as ablation continued through what normally are the wet months of November and December.

Little snowfall to the Solstice

The 'short rains' typically bring snowcover to the summit crater by the Solstice, but not this December. One event during the second week resulted in ~10 cm of accumulation on the glacier. This was followed by drier weather, so quite likely the crater is now largely snowfree. Any first-hand observations from the summit during the holidays are welcome!

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 Furtwängler 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.

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.

Success!

Back safely from fieldwork at the summit. Thanks to Simon (above) and the SENE crew (Summit Expeditions & Nomadic Experiences), as well as the Marangu Hotel team, this was a fun and productive trip. Over the course of 6 busy days amidst the penitentes, we accomplished just about every objective on the list; details will be posted soon.

Upcoming fieldwork

I haven't been on the mountain for 11 months now, and am anxious to get back. Telemetry indicates that the rate of ablation during the current dry season has been unprecedented in the 10-year record - which is somewhat perplexing. Snow accumulation began on the glaciers within a few weeks of our October 2009 fieldwork and continued without much interruption until the very end of May, bringing a net accumulation of 70 cm to the Northern Ice Field. Ablation then began, and although measurements from the two sensors differ, most of this snow appears to have now ablated. Visiting the glaciers will allow evaluation of the extent to which melting, evaporation, and superimposed ice formation is responsible.

So, we depart later this month for the summit glaciers with an ambitious program and a collaborative team, including personnel from the Univ. of Massachusetts, Innsbruck University, and NASA JPL. Simon Mtuy and Summit Expeditions are again providing logistical support on the mountain. One of my objectives will be to add reference-quality instrumentation developed by the U.S. CRN (Climate Reference Network), establishing the first CRN station outside the Americas. Operating CRN instruments alongside those which have been on Kilimanjaro since February 2000 will provide an intercomparison with which the long-term data can be adjusted. Measuring air temperature in that environment, on snow and with solar radiation typically exceeding 1,200 W/m^2, is far more difficult than might be expected.

Accompanying work at the weather station will be measurement of how ablation on the glacier has varied spatially, while NASA team members investigate microbiological diversity in the ice. And we're optimistic about getting some dates soon on ice samples collected last October. Stay tuned!

-Doug Hardy, UMass Geosciences