June snowfall

Don't expect to see bare glacier ice on Kilimanjaro's glaciers anytime soon - at least not on horizontal surfaces at the summit. Higher than normal snowfall has continued into June, with ~7 cm accumulation on the Northern Ice Field June 9th and 10th and another event beginning June 22nd. Snowfall this late is quite unusual, as the long rains typically finish by the end of May.

For the glaciers, additional new snow will keep albedo high and reduce the absorption of incoming solar radiation. Less absorption will result in less ablation during the forthcoming dry season. No, this does not mean that recession of Kilimanjaro glaciers has ended; 2011-12 snowfall merely demonstrates the expected interannual variability (which our measurements seek to quantify and understand). For travel on the glaciers, the amount of accumulation since November (~75 cm) will likely result in extensive penitentes towards the end of the dry season (i.e., Sep - Oct).

Telemetry data from Kilimanjaro have been examined only to June 24th due to other fieldwork obligations. Stay tuned for an update towards the end of July!

A Fairy Tale comes true!

After more than 12 years of meteorological measurements on Kibo's Northern Ice Field, the most-recent period October through May has - for the first time - followed the expected pattern:  'short rains' during November and December, a brief dry interval into February, substantial and prolonged 'long rains' in March-April-May, and then commencement of an extended dry season by June. The figure above details this pattern through increases in glacier surface height (snowfall) as well as decreases (ablation).

Typically, only a June beginning of the dry season has been reliable, as noted in an entry yesterday. In some years Masika brings only minimal accumulation to the glaciers (e.g., 2001, 2005, 2009 or 2011), sometimes it is Vuli which fails (e.g., 2005 or 2010), sometimes Vuli snowfall exceeds that of Masika (e.g. 2006-07), and sometimes nearly-constant-yet-modest accumulation occurs from November to June (e.g., 2009-10).

Variability in the seasonal timing and magnitude of precipitation at Kilimanjaro's summit is the norm, despite an annual cycle of humidity which follows the 'expected' pattern rather closely. Both small- and large-scale aspects of atmospheric circulation modulate the humidity pattern and influence snowfall, and the timing and amount of snowfall is hugely important to glacier mass balance there. Documenting the inter-annual variability of precipitation on Kilimanjaro and measuring the impact on glaciers is why we keep the AWS going!

2012 dry season begins

One of the most consistent elements of climate on the Northern Ice Field has been cessation of Masika (long rains) by the beginning of June. This year was no exception, with accumulation of snow ending ~17 May. Another extended dry season has begun on Kilimanjaro.

Don't expect to see glacier ice exposed at the surface anytime soon however, as considerable snowfall occurred in the 6+ weeks prior. This followed a notable event in early March, and a snowy short rains (especially November). Indeed, there has been 75 cm of net snow accumulation on the glacier surface since early-October fieldwork! During the forthcoming dry season this clean, relatively-bright snowcover will reflect much more solar radiation than the underlying, decades-old ice surface would, effectively reducing ablation of horizontal surfaces. As a result, large areas of the glaciers are likely to remain snow covered through the dry season.

By September, penitentes could be well developed on the glaciers. Although both beautiful and fascinating, these will render glacier travel more difficult during September fieldwork.

More on April precipitation

"The rains this year began promptly on the 1st of April." So begins a column by Gareth Jones on 11 May, titled "Kenya:  Wet in the Wild" and published by AllAfrica Global Media.

At the summit of Kilimanjaro, seasonal precipitation in the form of snow began at exactly the same time, as the screen shot below illustrates. Four-hourly data by telemetry are shown here as circles, from 2 different sensors. The red line simply smooths out a diurnal cycle, and y-axes units are meters of snow accumulation.

If snowfall on the mountain continues through the rest of May, as the Kenya Meteorological Department is forecasting for rains to the north, the 2012 long rains will be one of the snowiest on the Northern Ice Field since our measurements began in 2000.

Snowy, calm April 2012

 Snowfall continued through the final week of April, bringing total accumulation to 44 cm. This is the most snow for any April since our records began in 2000. Humidity was high, incoming solar radiation was low, and April 2012 established a new record for the lowest mean monthly wind speed, at only 10.2 km/hr! All monthly values are provided here.
[UPDATE 5/7: The photo above was taken on 1 May, clearly illustrating the late-April snow (courtesy Simon Mtuy).]

Archival video

Here is a clip produced by New York Times Science Times. The feature was filmed in June 2001 for broadcast on the National Geographic Channel, and recently turned up on YouTube. Director of Photography John Hazard was fun to have along, joining Georg Kaser, Tharsis Hyera, Erick Masawe and others!

Snowy April

As of yesterday, 30 cm of snow has accumulated on the Northern Ice Field this month. Not since 2006 has there been this much during April.

Any photographs of snowcover in the crater or at the summit would be appreciated!

 [UPDATE 5/1:  See above... snowfall continued.]