Tuesday, October 8, 2019

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.

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