UC Research Repository
Nau mai, haere mai, welcome to the UC Research Repository
The UC Research Repository collects, stores and makes available original research from postgraduate students, researchers and academics based at the University of Canterbury.
Communities
Select a community to browse its collections.
- Items from Journals and Conferences hosted by the University of Canterbury
- University of Canterbury Research Centres
Recent Submissions
The role of avalanche deposition on the mass balance of Rolleston Glacier, Arthur’s Pass, New Zealand.
(2024) Spera, Alison
Avalanches are a crucial source of nourishment for cirque mountain glaciers, supplementing their accumulation
and delaying melt. However, their role in glacier mass balance is highly under-studied and overlooking their
influences may inaccurately assess glacier health. This thesis investigates the role of avalanches on the Rolleston
Glacier mass balance using an Energy Balance Model (EBM) coupled to a mass transport and deposition
(MTD) algorithm. A 12-year climate record (2010 – 2022) was used as model input with precipitation factors
and temperature lapse rates as tuning parameters. Annual (Bn) and winter balances (Bw) were compared for the
glaciological years 2010/11, 2012/13 and 2018/19 with and without the MTD algorithm. The MTD performed
better for positive balance years, with optimum precipitation factors and lapse rates applied for different years.
To quantify the proportion of winter balance attributed to avalanches, the model was run over the 12-year
period. Excluding gravitational processes produced results that were within 1.81 m w.e of directly measured
mass balance, while activating the MTD yielded estimates within 0.64 m w.e of the observed. In general, the
spatial distribution of the winter balance was improved under the MTD, contributing an additional 1.47 m w.e to
the average winter balance across 2010 – 2022. A comparison against probe measurements showed more bias was
incurred (2.04 m w.e) when discarding the MTD from the model. The model was validated against cumulative
mass balance measurements showing strong R2 relationships when coupled to the MTD (R2 = 0.9) as opposed
to scenarios without the MTD (R2 = 0.65). Future work should incorporate a comprehensive sensitivity analysis
and parameter optimisation procedures to advance the applications of mass transport algorithms to mass balance
models. The results demonstrate that including the MTD has useful applications to simulating more accurate
mass balance estimates to avalanche-fed glaciers like Rolleston Glacier and enhances understanding of local-scale
alpine processes.
Simulating Solar Storms via Active DC Injection from the HVDC Link
(2023) Lapthorn, Andrew; Hardie , Stewart; Agger , Paul; Subritzky , Soren; Dalzell , Mike; Clilverd , Mark; Cobbett , Neil; Beggan , Ciaran; Huebert , Juliane; Eaton , Eliot; Brundell, James; Rodger , Craig
As part of the MBIE Endeavour programme “Solar Tsunamis: Space-Weather Prediction and
Risk Mitigation for New Zealand’s Energy Infrastructure,” we are interested in the effects of
geomagnetically induced currents (GICs) on New Zealand’s electrical infrastructure. GICs
appear as quasi-dc currents on the power system and can lead to problems in the network as a
result of transformer saturation such as increased reactive power demand, increased harmonics,
and even overloading of the transformers. Studies have shown that, depending on the severity
of the solar storm, these effects could potentially be widespread.
Different transformer designs behave differently under these quasi-dc conditions, with single phase designs the worst, and three-limb core designs proving the most resilient. Furthermore,
several transformers in New Zealand have neutral earthing resistors (NERs) installed.
Therefore, it is difficult to say at what point do GICs start becoming a problem, and how much
current is too much current.
In January 2023, with the support of Transpower, we were able to utilise New Zealand’s high
voltage DC (HVDC) link to inject current directly into the ground at Haywards substation and
monitor the effects on two 216 MVA, 220/110 kV autotransformers, along with monitoring of
associated transmission lines. Over the span of nine days, six injection tests were carried out
lasting between one and two hours each time. The peak current injected into the ground was
about 621 A. This paper provides an overview of the testing plan, procedure, and initial results
from the collected data.
Transport and equity: Anticipate the unintended, plan for the marginalised
(2024) Kingham, Simon
Central Bank Stabilisation Policy when Capital Flows Matter: Instruments, Targets, and Trade-offs
(2024) Guender, Alfred
This paper examines how policy instruments shape the trade-off between core
macroeconomic and financial stability in an open economy where speculative
capital flows affect financial market conditions. We derive and contrast the target
rules that underpin optimal discretionary policy in four different instrument
scenarios, each of which involves one, two or three of the following instruments:
the policy rate, an interest rate equalisation tool, and intervention in the foreign
exchange market. The analysis reveals a one-to-one correspondence between the
policy instruments deployed and the number of target rules that guide the optimal
policy. Using more instruments leads to simpler target rules, sharper trade-offs, and
increased welfare. The three-instrument case produces the same output-inflation
trade-off as the canonical closed-economy New Keynesian model and ensures
complete insulation from foreign monetary policy and other demand-side shocks.
OCHT pilot in Ōtautahi
(2024) Kingham, Simon; Curl , Angela; Carroll, Liam