Active Layer Dynamics at Four Borehole Sites in Western Dronning Maud Land, Antarctica A dissertation submitted in fulfilment of the requirements for the degree of MASTER OF SCIENCE of Rhodes University by Camilla Kotzé December, 2015 Supervisor Professor K.I. Meiklejohn (Department of Geography, Rhodes University) Abstract Permafrost and active layer dynamics in the Antarctic play an important role within terrestrial landscapes and ecosystems and as a climate change indicator. However, they remain less thoroughly researched than their Northern-Hemispheric counterpart. Despite advancements made by ANTPAS on the permafrost and active layer monitoring network in the Antarctic, observational gaps still exist. Western Dronning Maud Land (WDML) has been identified as one of these gaps, necessitating further research on permafrost dynamics and the influence of climate parameters thereon. Such elucidation is critical to both the cryospheric and life sciences. Variations in the surface climate of Antarctica can be seen as a result of inter-annual variations in atmospheric circulation, enhancing permafrost degradation and active layer thickening which directly affects soil processes, such as sorting and cryoturbation. Ground temperatures from four permafrost boreholes from WDML were analysed from 2007 to 2014. The study sites exhibit seasonal freezing, periglacial landforms, and altitudinal variation, ranging between ca. 450masl to ca. 1300masl. Using ground thermal regime and regional climate data, the spatial and temporal variability of the active layer in the Ahlmannryggen and Jutulsessen areas of WDML were characterised. 137Cs tracing has revealed that the active layer and associated landforms have been active over the past half century. Further results show that active layer depths at each site vary inter-annually and are particularly influenced by snow cover, altitude and distance to the ice-shelf. Moreover, a correlation between the SAO (Semi-Annual Oscillation) and measured ground temperatures was found, principally during the transitional season of the SAO in May and September. The relationship between climate and ground thermal regimes, especially the influence of teleconnections thereon, is essential to improving the understanding of permafrost dynamics and landform morphology in continental Antarctica. Keywords: Antarctic, Western Dronning Maud Land, active layer, ground thermal regime, soil moisture, SAO i Acknowledgements The author would firstly like to thank her parents and David Cousins for continual support and encouragement throughout her academic career. Thanks and appreciation to Professor Ian Meiklejohn for guidance during the undertaking of this two-year endeavour. Sincerest gratitude is expressed to the NRF (National Research Foundation) whose financial support made the completion of this M.Sc. possible. DEA (Department of Environmental Affair) and SANAP (South African National Antarctic Programme) are thanked for providing logistical support during the fieldwork seasons conducted in the Antarctic. Thanks to SAWS (South African Weather Service) for the provision of data, as well as to the members of the 2009/10, 2010/11, 2011/12, 2012/13, 2013/14, 2013/14 Austral summer relief voyages to SANAE IV that assisted during the fieldwork data collection process. Christel Hansen is especially thanked for her guidance and expertise in the field. Rosie Dwight and Liezel Rudolph are thanked for the provision of some of the data used in this dissertation. Last but not least, Rhodes University is acknowledged for their support throughout the M.Sc. studies. ii Table of Contents Abstract .............................................................................................................................................. i Acknowledgements ........................................................................................................................... ii Table of Contents ............................................................................................................................ iii Table of Figures ............................................................................................................................... vi Table of Tables ................................................................................................................................ iii Table of Equations .......................................................................................................................... xi List of Abbreviations ...................................................................................................................... xii CHAPTER 1: Introduction ............................................................................................................. 1 1.1. Background, Context and Motivation ............................................................................ 1 1.2. Aims and Objectives......................................................................................................... 6 1.3. Setting and Study Sites .................................................................................................... 7 CHAPTER 2: Literature Review .................................................................................................. 16 2.1. Progress and Current Status of TSP and CALM-S Sites ........................................... 16 2.2. Active Layer and Permafrost Occurrence and Properties ......................................... 18 2.3. Surface Manifestations of Permafrost and the Active Layer ..................................... 24 2.3.1. Patterned Ground ........................................................................................................... 24 2.3.2. Viscous-flow Features .................................................................................................... 29 2.4. Teleconnections............................................................................................................... 31 2.4.1. Semi-Annual Oscillation ................................................................................................ 32 CHAPTER 3: Materials and Methods ......................................................................................... 34 3.1. Field Methods ...................................................................................................................... 35 3.1.1. Automated Logging Stations .......................................................................................... 35 3.1.2. Soil Moisture Calibration ............................................................................................... 39 3.1.3. 137Cs Analysis ................................................................................................................. 40 3.1.4. Landscape Mapping ....................................................................................................... 43 3.2. Laboratory Methods ...................................................................................................... 43 iii 3.2.1. Soil Moisture Calibrations ............................................................................................. 43 3.2.2. 137Cs Analysis ................................................................................................................. 45 3.2.2.1. Sample Preparation ................................................................................................. 45 3.2.2.2. Radionuclides .......................................................................................................... 46 3.2.2.3. Organic Enrichment and Particle Size Corrections ................................................ 46 3.3. Statistical Analysis and Preparation ............................................................................ 48 3.3.1. Data Preparation ............................................................................................................. 48 3.3.2. Statistical Methods ......................................................................................................... 49 3.3.2.1. Descriptive Statistics ............................................................................................... 49 3.3.2.2. Statistical Inference ................................................................................................. 51 3.3.2.3. Mapping .................................................................................................................. 52 CHAPTER 4: Results and Discussion of Findings ...................................................................... 53 4.1. Objective 1: Active Layer Dynamics ............................................................................ 53 4.1.1. Soil Moisture Regimes ................................................................................................... 53 4.1.1.1. Soil Physical Analysis ............................................................................................. 54 4.1.1.2. Soil Moisture and Air Temperature......................................................................... 56 4.1.2. Annual Ground Thermal Regimes ................................................................................. 59 4.1.2.1. Active Layer Depth .................................................................................................. 64 4.1.2.2. Active Layer Depth and Air Temperature ............................................................... 72 4.1.2.3. Active Layer Temperature at the four sites, 2014 ..................................................