Early short-rain snow

Snow conditions on Kibo have changed considerably over the past 10 days, as shown in the timelapse above. Very little seasonal snow was present on 16 October, nicely revealing the current distribution of glacier ice. Five days later the entire summit was blanketed by snow. A second-hand report from our friend Simon Mtuy indicates that the snowline on the 18th was below Kibo hut. (Simon's wonderful company is SENE).

Between the 21st and 26th, ablation of new snow appears to have dominated over additional accumulation. However, note extensive snow below the Western Breach on the 26 October image; this may have resulted from localized convection, typical on that side of the mountain. Simon was on the mountain last week, so it will be interesting to hear his observations. Low on the mountain (i.e., below 1800 m) he reports nearly non-stop rain since the beginning of October - an early beginning to the short-rains season!

Summit Snow

High elevations on Kibo received an early October dusting of snow, as shown in the Sentinel-2 image above, acquired Sunday. Until AWS data are recovered, we don't know whether this snow resulted from one event, or multiple; five days prior the summit was obscured by clouds, and it was snow-free ten days earlier.

This image reveals interesting information about ice, snow, and clouds. The brightest areas which are labeled are the remaining ice bodies. Increasing fragmentation of what was once the Southern Icefield is readily apparent. Within a few years the Heim and Decken Glacier will likely be gone, followed shortly thereafter by the Furtwängler.

Almost all other bright areas - of various sizes and shapes - are new snow (e.g., southeast of the Reusch Crater). In this scene, note how snowcover is distributed rather symmetrically on the mountain, which is typically not the case for individual snowfall events.

One large bright area to the southwest of Reusch Crater shows relatively-thick convective clouds rising above the Western Breach. Elsewhere, thin clouds appear darker and more variable in brightness, forming a annular pattern around Kibo. These clouds are low in elevation, as evidenced by the visible shadows. This annular pattern is quite common on Kibo, with clouds thickening during the day due to convection. Sometimes, the crater remains cloud-free yet encircled by clouds, if convection dominates over advection (which transports moisture laterally).

Early October snowcover usually persists for only days to weeks, with the short rains not getting underway for at least another month. Nonetheless, such events considerably influence mass balance, as snowcover greatly impacts radiative energy exchanges due, for example, to the higher reflectivity (albedo) of surfaces.

NIF shrinkage: 2015-2019

The right-hand image above depicts Kilimanjaro's Northern Icefield in mid-September (2 weeks ago). Although resolution is not ideal, minimal snowcover allows comparison with the same glacier four years earlier (July 2015). Note that the two images are not perfectly registered, so the following observations are qualitative.

Both the north and south remants of the icefield have decreased in area, especially relatively-thin portions at lower elevations. These include the northwest part of the north remnant, and the western margin of the southern part. A marginal meltwater lake is visible at the southern margin of the north portion on both images, and has been present for many years. At the eastern edge, we have observed shrinkage of several isolated blocks of ice over the years; these were present in 2017, but have now disappeared. On the south portion, thin areas and holes in the left-hand image are now ice free, including one location (southeast margin) where we have evidence that geothermal heat initiated hole formation.

The rate of glacier thinning was reduced during 2018, due to above-normal snow accumulation and the attendant increase in albedo. To illustrate, note the brighter, high-elevation portions of the glacier in the 2015 image; this is snow cover over old glacier ice.

We are hoping to visit the summit glaciers early in 2020 to measure ablation stakes, conduct GPS surveys, and photographically document changes to the glaciers since our last visit.