Studies of Glacial and Periglacial Environments on Mars

This thesis presents the development and application of a grid-based mapping approach that provides an efficient solution to the problems of mapping small landforms over large areas. The approach allows the cataloguing of landform classes, of multiple sizes, efficiently in a single pass. The speed at which the data could be recorded allowed for the first continuous, full resolution mapping of decametre-scale landforms in CTX images on hemispherical-scale maps. The discrete, tabular nature of grid mapping opens up the possibility of citizen science meaning the grid mapping approach could have considerable future use and impact. The main scientific goal of this thesis was to determine the distribution and origins of ice-related landforms in the northern plains, and provide insight as to whether these landforms are related to distinct geological or geomorphological units. To accomplish this, I used the grid mapping approach to explore a large tract covering the Arcadia Planitia region of the northern plains of Mars. In addition, I was able to compare these results to two other sister studies performed in the Utopia and Acidalia Planitia regions of Mars. To explore possible sources of ice I performed a detailed study of the Rahway Vallis system. This found an assemblage of terraces, channels and sinuous ridges in Rahway Vallis that are topographically and morphologically consistent with either a draining lake, or a melting, once liquid, ice-body, and is indicative of a flow of volatiles into the northern plains and large scale shifts in ground ice stability. Overall, this thesis demonstrates the dominant effects of the deposition and sublimation of the Latitude Dependent Mantle in shaping recent landscapes on the northern plains of Mars. There was little evidence for thaw-related landforms, and evidence for a fluvial origin for ice in the near surface is circumstantial, or has been erased or covered

Gridmapping the northern plains of Mars: Geomorphological, Radar and Water-Equivalent Hydrogen results from Arcadia Plantia

A project of mapping ice-related landforms was undertaken to understand the role of sub-surface ice in the northern plains. This work is the first continuous regional mapping from CTX (“ConTeXt Camera”, 6 m/pixel; Malin et al., 2007) imagery in Arcadia Planitia along a strip 300 km across stretching from 30°N to 80°N centred on the 170° West line of longitude. The distribution and morphotypes of these landforms were used to understand the permafrost cryolithology. The mantled and textured signatures occur almost ubiquitously between 35° N and 78° N and have a positive spatial correlation with inferred ice stability based on thermal modelling, neutron spectroscopy and radar data. The degradational features into the LDM (Latitude Dependent Mantle) include pits, scallops and 100 m polygons and provide supporting evidence for sub-surface ice and volatile loss between 35-70° N in Arcadia with the mantle between 70-78° N appearing much more intact. Pitted terrain appears to be much more pervasive in Arcadia than in Acidalia and Utopia suggesting that the Arcadia study area had more wide-spread near-surface sub-surface ice, and thus was more susceptible to pitting, or that the ice was less well-buried by sediments. Correlations with ice stability models suggest that lack of pits north of 65-70° N could indicate a relatively young age (~1Ma), however this could also be explained through regional variations in degradation rates. The deposition of the LDM is consistent with an airfall hypothesis however there appears to be substantial evidence for fluvial processes in southern Arcadia with older, underlying processes being equally dominant with the LDM and degradation thereof in shaping the landscape

The UKC2 regional coupled environmental prediction system

It is hypothesized that more accurate prediction and warning of natural hazards, such as of the impacts of severe weather mediated through various components of the environment, require a more integrated Earth System approach to forecasting. This hypothesis can be explored using regional coupled prediction systems, in which the known interactions and feedbacks between different physical and biogeochemical components of the environment across sky, sea and land can be simulated. Such systems are becoming increasingly common research tools. This paper describes the development of the UKC2 regional coupled research system, which has been delivered under the UK Environmental Prediction Prototype project. This provides the first implementation of an atmosphere–land–ocean–wave modelling system focussed on the United Kingdom and surrounding seas at km-scale resolution. The UKC2 coupled system incorporates models of the atmosphere (Met Office Unified Model), land surface with river routing (JULES), shelf-sea ocean (NEMO) and ocean waves (WAVEWATCH III). These components are coupled, via OASIS3-MCT libraries, at unprecedentedly high resolution across the UK within a north-western European regional domain. A research framework has been established to explore the representation of feedback processes in coupled and uncoupled modes, providing a new research tool for UK environmental science. This paper documents the technical design and implementation of UKC2, along with the associated evaluation framework. An analysis of new results comparing the output of the coupled UKC2 system with relevant forced control simulations for six contrasting case studies of 5-day duration is presented. Results demonstrate that performance can be achieved with the UKC2 system that is at least comparable to its component control simulations. For some cases, improvements in air temperature, sea surface temperature, wind speed, significant wave height and mean wave period highlight the potential benefits of coupling between environmental model components. Results also illustrate that the coupling itself is not sufficient to address all known model issues. Priorities for future development of the UK Environmental Prediction framework and component systems are discussed

Abstracts from the NIHR INVOLVE Conference 2017

n/