Mass balance of a slope glacier on Kilimanjaro and its sensitivity to climate

Abstract

Meteorological and glaciological measurements obtained at 5873 m a.s.l. on Kersten Glacier, a slope glacier on the southern flanks of Kilimanjaro, are used to run a physically-based mass balance model for the period February 2005 to January 2006. This shows that net shortwave radiation is the most variable energy flux at the glacier-atmosphere interface, governed by surface albedo. The majority of the mass loss (∼65%) is due to sublimation (direct conversion of snow/ice to water vapour), with melting of secondary importance. Sensitivity experiments reveal that glacier mass balance is 2-4 times more sensitive to a 20% precipitation change than to a 1°C air temperature change. These figures also hold when the model is run with input data representative of a longer term mean period. Results suggest that a regional-scale moisture projection for the 21st century is crucial to a physically-based prediction of glacier retention on Africa's highest mountain.

Evaluation of a Coupled Snow and Energy Balance Model for Zhadang Glacier, Tibetan Plateau, Using Glaciological Measurements and Time-Lapse Photography

“…4, part d). Model results are in strong correlation with this variability and an RMSE of 2.12 K is within the measurement uncertainties that range in the order of 2-2.5 K due to the dependency on emitted radiation as also mentioned by Mölg et al (2008Mölg et al ( , 2012. Similar good results are evident for T sub (Fig.…”

Impact of debris cover on glacier ablation and atmosphere–glacier feedbacks in the Karakoram

“…The original basis of the glacier CMB model is the processbased model of (Mölg et al, 2008(Mölg et al, , 2009. The model solves the full energy balance equation to determine the energy for snow and ice ablation.…”

“…Initial test simulations with WRF-CMB over the Karakoram gave unrealistically low surface temperatures as a result of excessive nighttime damp- ing of the turbulent fluxes, in particular the sensible heat flux (QS) over debris-free glacier surfaces at high elevations. The stability corrections are based on the bulk Richardson number (specifically, those provided in Braithwaite, 1995) and have been used previously in glacier CMB modeling (e.g., Mölg et al, 2008Mölg et al, , 2009Reid et al, 2012). In the most stable conditions, the turbulent fluxes are fully damped, which resulted in decoupling of the surface and the atmosphere and excessive radiative cooling.…”

Measuring and Modeling the Retreat of the Summit Ice Fields on Kilimanjaro, East Africa

“…We examine temporal and spatial variation in retreat rates, highlighting findings obtained from detailed surveys of the south-facing ice cliff on the NIF and quantifying mean recession rates in this area. We compare our estimates with others obtained through modeling and measurement (Mölg et al, 2003b(Mölg et al, , 2008Winkler et al, 2010). In addition, we also examine the interseasonal variation of retreat rates, which allows an examination of the forcing factors responsible.…”

“…Although the relative importance of both land-use change and global climate forcings are still being researched (Pepin et al, 2010;Fairman et al, 2011;Mölg et al, 2012), there is a growing consensus that whatever the cause(s), drying of the summit climate-resulting in lower humidity, less frequent cloud cover and enhanced daytime solar radiation input, increasing ablation on the one hand, and reduced precipitation decreasing accumulation on the other-has encouraged a long-term negative mass balance of the summit ice fields (Mölg et al, 2003b;Kaser et al, 2004;Mölg et al, 2008Mölg et al, , 2009aMölg et al, , 2009b, as is the case in other parts of tropical Africa (Mölg et al, 2003a).…”