Climate controls on the interseasonal and interannual variability of the
surface mass balance of a tropical glacier (Zongo Glacier, Bolivia,
16°S): new insights from the application of a distributed energy balance
model over 9 years
Abstract
The application of a distributed energy balance model over 9 years at an
hourly time step to a 20 x 20 m grid cell over Glacier Zongo (Bolivia,
16°S) enabled assessment of the climate factors that control the
interseasonal and interannual variability of its surface mass balance.
The model was validated by comparing the measured and simulated
discharge at the outlet, albedo at the AWS, surface types and annual
mass balance both glacier wide and as a function of the altitudinal
range. Analysis of the mean monthly energy fluxes highlighted the
importance of the meteorological conditions during the period between
September and November on the variability of the annual surface mass
balance. Two sensitivity analyses are presented, one of the distribution
of precipitation over time which maintains a physical coherence between
the different meteorological variables and one of the impact of
prolonged periods of intense cloud radiative forcing on the surface mass
balance. The distribution of precipitation events over time and their
associated amounts are the main drivers of the interannual variability
of the surface mass balance via an albedo feedback effect. Additionally,
prolonged periods of negative cloud radiative forcing, specifically over
the month of November, have notable ability to reduce the melt rate.