Glacial melt under a porous debris layer

In this paper we undertake a quantitative analysis of the dynamic process by which ice underneath a dry porous debris layer melts. We show that the incorporation of debris-layer airflow into a theoretical model of glacial melting can capture the empirically observed features of the so-called Østrem curve (a plot of the melt rate as a function of debris depth). Specifically, we show that the turning point in the Østrem curve can be caused by two distinct mechanisms: the increase in the proportion of ice that is debris-covered and/or a reduction in the evaporative heat flux as the debris layer thickens. This second effect causes an increased melt rate because the reduction in (latent) energy used for evaporation increases the amount of energy available for melting. Our model provides an explicit prediction for the melt rate and the temperature distribution within the debris layer, and provides insight into the relative importance of the two effects responsible for the maximum in the Østrem curve. We use the data of Nicholson and Benn (2006) to show that our model is consistent with existing empirical measurements

Hysteretic regime switching diffusions and resource extraction

We calculate the probability that an extraction project will be abandoned, directly from a real options model closely related the seminal work of Brennan and Schwartz (1985). We assume that the resource is extracted at two alternative rates, with a capital cost for switching, and with an option to abandon due to unsatisfactory market prices. The abandonment probability is expressed as a hitting probability for a regime switching diffusion with hysteresis, which is shown to be the unique solution of a system of coupled boundary value problems. Our work lends itself to use as a quantitative and easily interpreted measure of risk in the planning of extraction projects. Numerical results show that the abandonment probability may be non-monotone with respect to the volatility of the price process, in contrast with project valuations. In the one-dimensional stationary case, the stochastic process is a hysteretic system with noise in the sense of Freidlin et al. (2000), and we obtain a closed-form expression for the hitting or abandonment probability in this case

Design and construction of a bespoke system for the detection of buried, iron-rich meteorites in Antarctica.

Iron-rich meteorites are significantly underrepresented in collection statistics from Antarctica. This has led to a hypothesis that there is a sparse layer of iron-rich meteorites hidden below the surface of the ice, thereby explaining the apparent shortfall. As standard Antarctic meteorite collecting techniques rely upon a visual surface search approach, the need has thus arisen to develop a system that can detect iron objects under a few tens of centimetres of ice, where the expected number density is of the order one per square kilometre. To help answer this hypothesis, a large-scale pulse induction metal detector array has been constructed for deployment in Antarctica. The metal detector array is 6 m wide, able to travel at 15 km h-1 and can scan 1 km2 in ~11 hours. This paper details the construction of the metal detector system with respect to design criteria, notably the ruggedization of the system for Antarctic deployment. Some preliminary results from UK and Antarctic testing are presented. We show that the system performs as specified and should reach the pre-agreed target of the detection of a 100 g iron meteorite at 300 mm when deployed in Antarctica

Overview of The Lost Meteorites of Antarctica Field Campaigns

The Lost Meteorites of Antarctica project was the first UK-led Antarctic meteorite recovery expedition. The project has successfully confirmed two new high-density meteorite stranding zones in the Hutchison Icefield and Outer Recovery Icefields areas and investigated the geology of three previously unvisited Antarctic nunataks (Turner Nunatak, Pillinger Nunatak, Halliday Nunatak). The project undertook meteorite searching on the ice surface via skidoo reconnaissance and systematic searching and developed a novel pulse induction metal detection system to search for englacial iron-rich meteorites trapped within the upper one meter of ice. In total, 121 meteorites have been recovered from the ice surface searching activities, which are now curated in the United Kingdom at the Natural History Museum London and are available for scientific analysis