Glaciers and ice sheets play a crucial role in regulating Earth’s climate by reflecting solar radia-

tion and storing fresh water, with their retreat contributing to sea level rise and impacting water

resources and ecosystems. Glacial melt in the McMurdo Dry Valleys (MDV) is the dominant

source of water for streams, lakes and ecosystems. The MDV climate is sensitive to extreme

weather events, and understanding the meteorological factors influencing glacial melt and accu-

mulation is essential for predicting future changes to this fragile environment. This thesis aims

to investigate the meteorological controls on spatial and temporal variability in ablation and

accumulation of glaciers within the MDV to ultimately anticipate how global warming-induced

changes in weather patterns might impact MDV hydrology and ecosystems.

To address this aim, three research questions are answered by applying methods across multi-

ple scales. The first objective centeres on understanding the impact of foehn wind events on

glacial surface energy balance and melt (Chapter 2). By integrating observations from automatic

weather stations (AWS) with surface energy balance (SEB) modeling and regional weather fore-

casting outputs, the research identifies foehn winds as drivers of enhanced melt rates on glaciers.

Foehn winds increase energy gain through sensible heating but this is largely compensated for

by energy loss due to increased sublimation. The enhanced melt rates are driven by the lowering

of albedo during foehn events, which primes the glacier surface for melt. This chapter also

enhances knowledge on the mechanisms leading to foehn wind signature in the MDV. We show

that isentropic drawdown is responsible for foehn warming at Joyce Glacier and wider southern

MDV, compared to the gap-flow mechanism that was previously found for the northern MDV.

Chapter 3 uses 22 years of AWS data and SEB modelling to further study the impact of foehn

events and other meteorological factors on melt variability. We compare two sites in Taylor

Valley, the coastal Commonwealth Glacier and further inland Taylor Glacier, to study valley-

scale variation in melt environments. At both sites, foehn winds are important in explaining

inter-annual variability in melt. However, especially at Commonwealth Glacier, fluctuations in

albedo are driving melt variability through snow presence and changing ice albedo. Melt at

Taylor Glacier happens mostly with positive air temperatures, often due to foehn winds, while

at Commonwealth Glacier melt happens with negative air temperatures but large net shortwave

radiation. We hypothesise that future melting at Taylor Glacier is sensitive to changes in foehn

wind activity, whereas Commonwealth is influenced by coastal weather modifications affecting

snowfall and albedo.

Because of the importance of snowfall on glacial mass balance, albedo variability and melt, the

snowfall dynamics of the MDV and wider coastal Victoria Land (VL) are examined in Chapter

4. To investigate the moisture origins of precipitation and their connection to weather patterns,

Self-Organizing-Maps (SOM) are combined with Lagrangian moisture source analysis. Moisture

for snowfall in VL primarily originates from the Southern Ocean near Australia and New Zealand,

with increased local sources in the Ross Sea during summer when sea ice is reduced. We show

there is a distinct contrast in moisture sources, with northern VL receiving precipitation from

the west, driven by marine air from lower latitudes, and southern VL obtaining moisture from the

east, transported by cyclonic disturbances in the Ross Sea. Extreme precipitation in northern VL

occurs during anomalous meridional moisture transport, sometimes in the form of atmospheric

rivers. Such strong marine air intrusions do not affect the more isolated western Ross Ice Shelf

and southern VL located further in the Ross Sea embayment.

This thesis highlights the key role of atmospheric events, such as foehn winds and extreme

snowfall events, on glacial ablation and accumulation in the MDV. In the Synthesis (Chapter

5) we discuss the contribution of this thesis to our understanding of the weather and climate

that drives surface melt across Antarctica. We discuss avenues of research to predict the future

climate of the MDV. Future work should study how the synoptic patterns driving extreme events

might change with global warming, as well as the impact of reduced Antarctic sea ice cover on

the MDV through enhanced moisture availability. Furthermore, research gaps remain on the

mesoscale interactions between sea ice and atmosphere in the Ross Sea region that can impact

the MDV climate and glaciers.