Earth Atmosphere Processes

Globally glaciers are rapidly retreating. As ice volume shrinks, slopes that surround a glacier destabilise, making them more prone to rockfall. In addition, changing surface morphology of a thinning glacier can alter the distance that rocks can travel out onto the surface.

Glacier tourism is an important contributor to the regional economy of the west coast of the South Island, where over 400,000 tourists visit the glacier region each year.

Rockfall is a hazard to glacier tourism operations, so increased knowledge about the processes and feedbacks that impact the spatial distribution of rockfall is important.

Our research is exploring the physical implications of rapid retreat at Fox Glacier by modelling potential rockfall distribution, and providing the local community with increased knowledge and understanding of the rapid changes occurring.

We are using unmanned aerial vehicles (UAVs) to digitally photograph the slopes surrounding the glacier. These photographs are combined in a structure from motion (SfM) software to create a digital elevation model from which rockfall run-out distances can be estimated. In addition, surface surveys and photographic analysis are being used to quantify change in surface debris cover – as amount of debris on the glacier surface influences ice melting and consequently surface topography.

This research is being supported by the Brian Mason Science and Technical Trust

Publications:
Purdie, H., Gomez, C. & Espiner, S. In Press. Glacier retreat and increased rockfall hazard: implications for glacier tourism.New Zealand Geographer

Purdie, H., Wilson, J., Gomez, C., Stewart, E. J. & Espiner, S. 2014. The physical and social implications of rapid glacial retreat: A case study from Fox and Franz Josef Glaciers, South Westland, New Zealand. Snow and Ice Research Group, New Zealand, Annual Workshop. Unwin Lodge, Aoraki Mount Cook Village, 2 July - 4 July.

Purdie, H. 2013. Glacier retreat and tourism: Insights from New Zealand. Mountain Research and Development, 33, 463-472.

Staff involved:

• Dr Heather Purdie
• Paul Bealing

Geospatial Science is changing the way that we examine and understand coasts. The aims of this research cluster are to examine applications of Geographic Information Systems (GIS) and Remote Sensing (RS) to coastal management, monitoring and hazard assessment.

Research into novel GIS-based techniques for quantifying tsunami hazard vulnerability is ongoing and has informed the Christchurch coastal evacuation plan. The techniques applied to this plan are now informing the development of national policy on tsunami evacuation. In addition, staff and graduate students in the School are or have been involved in:

• applying shoreline mapping and analysis techniques to modified estuarine ecosystems and eroding beaches,
• using GIS to create novel monitoring protocols for use in the management of beaches and coastal sediment extractions,
• using RS to study rhythmic topography, and beach and river mouth dynamics on coarse-sediment coasts,
• using GIS to analyse patterns of sediment reduction between river mouths and cliff coasts.

Staff involved:

• Dr Deirdre Hart

Selected publications and theses:

• Eikaas, HS and Hemmingsen, MA (2006) A GIS approach to model sediment reduction susceptibility of mixed sand and gravel beaches. Environmental Management 37: 816-825
• Griffiths, N. (2005) The effect of tsunami hazard on the Avon-Heathcote Estuary Area. Honours dissertation (Geography), University of Canterbury , 39pp.
• Hart, DE and Knight, GA ( Submitted ). Geographic information system assessment of tsunami vulnerability on a dune coast. Journal of Coastal Research
• Jupp, K; Partridge, TR; Hart, DE and Marsden, ID (2007) Ecology of the Avon-Heathcote Estuary: Comparative salt marsh survey 2006-2007. Estuarine Research Report 34, University of Canterbury, for the Avon-Heathcote Ihutai Trust and Christchurch City Council.
• Knight, G.A (2005) Tsunami vulnerability on the Christchurch coast. Honours dissertation (Geography), University of Canterbury , 46pp.
• New Zealand Police (2006) Operation Pacific Wave: Coastal Evacuation Plan Canterbury. Canterbury District Police, Christchurch.

Join the Southern Ocean Swell Facebook Group

Lakeshores 
The coastal group has a long association with lakeshore management being involved since the early 1970s at Lakes Manapouri and Te Anau. Management of issues on the shorelines of lakes used in hydro-electric power schemes is a speciality, including investigations of hazards and their mitigation, prediction of shoreline development on new and changing lakes such as Lake Dunstan, studies on longshore transport at Lake Colleridge, and information on lakeshore processes and morphologies for resource consents at Lakes Mahinerangi, Manapouri, Monowai, Pukaki, Te Anau and Waikaremoana.

Shore Platforms 
The coastal group also has a 30+ year record of erosion of shore platforms at Kaikoura. The network of erosion bolt sites was installed in 1973 by Bob Kirk and updated in 1993 by Wayne Stephenson (now at University of Melbourne). This work has been extended by Anna Taylor for her Ph.D. thesis (2003), which included studies of shore platform development at Akaroa and Lake Waikaremoana, comparing limestone, 'hard' mudstone, greywacke, basalt and 'soft' mudstone lithologies in a variety of wave environments. The Lake Waikaremoana work is part of an ongoing monitoring program to examine shore change to assess the effects of lake level management.

Fast Ferry Wakes 
Martin Single is involved with ongoing studies as to the effects of wake waves from fast ferries travelling through Tory Channel and Queen Charlotte Sound. This is a very public issue as these vessels form part of the transport link between the North and South Islands and have been considered an essential service. However the effects of the wakes have been perceived by some as damaging to the environment and as a danger to users of the area. Of particular interest are the actual effects to the physical coastal environment, the sustainability of the activity, and the possible consequences of slowing these ferries. Martin is a member of the PIANC technical working group (WG41) which has recently completed a publication on guidelines for management of high speed craft.

Staff Involved:

• Dr Deirdre Hart

Selected publications and theses:

• Allan, JC (1998) Shoreline development at Lake Dunstan , South Island , New Zealand . PhD Thesis, University of Canterbury (Geography), 461pp.
• Dawe, IN (2006) Longshore Sediment Transport on a Mixed Sand and Gravel Lakeshore. PhD Thesis, University of Canterbury (Geography), 364pp.
• James, M, Mark A, Single MB (2002) Lake Manager's Handbook: Lake Level Management. Ministry for the Environment: Wellington, 87pp.
• Stephenson, WJ (1997) Development of shore platforms on Kaikoura Peninsula, South Island, New Zealand. PhD Thesis, University of Canterbury (Geography), 350pp.
• Taylor , AJ (2003) Change and processes of change on shore platforms. PhD Thesis, University of Canterbury (Geography), 387pp.
• Single, MB and Kirk, RM (1998) Coastal change and human processes in Tory Channel, Marlborough Sounds. Proceedings of the eighteenth conference of the New Zealand Geographical Society 27-30 August, 1995. New Zealand Geographical Society: Hamilton, pp118-121.

Join the Southern Ocean Swell Facebook Group

The close proximity of these distinct coarse-sediment coastal types has facilitated a long history of research on mixed sand and gravel and composite beaches at the University of Canterbury. Of particular interest are the mix, distribution and loss of sediments within these systems, their high-energy wave and swash processes, and interactions with fluvial environments.

Present research in this area includes:

• research on the dynamics and management of mixed sand and gravel river mouth lagoons, locally called hapua (Hart),
• investigations into cusp formation and dynamics on mixed sand and gravel beaches in high energy environments (Pitman)

Research spotlight:

The colocation of sand and gravel sediments on MSG beaches make them the most hydrodynamically complex unconsolidated shorelines in the world. Gravel sediments typically require much higher energies to initiate transport than sand sediments, and so the distribution and proportion of sand versus gravel on the beach face is in a constant state of flux. Research on pure gravel beaches show longshore sediment transport processes to be important in controlling storm response. Conversely, the response of a sand beach to storm activity is controlled primarily by cross-shore (on and offshore) sediment movements. In a storm, sand is moved offshore where it accumulates in a bar. The waves begin to break on this bar, which in turn protects the beach from further erosion, and under subsequent calm conditions the sand can move back onshore.

So what happens when both sediments co-exist in a beach matrix? Does the sand move offshore and form a submerged bar that protects the gravel that is left on the beach? Is the rate of gravel erosion increased once the sand has been transported away? How long does the beach take to recover, and do both types of sediment return together? These are the most basic questions for understanding and predicting beach response to storms, but we currently only have the answers for pure sand or pure gravel beaches. This is an increasingly untenable position for both coastal managers but also Cantabrians living and working along the coast who risk losing land and livelihoods to the sea if these MSG dynamic environments remain poorly understood, and therefore risk being inappropriately managed.

Pitman, Hart, and Shulmeister are currently investigating how these individual factions of sediment on a beach respond to wave forcing. The project, kindly funded by the Brian Mason Trust, uses state of the art LiDAR sensors to track changes and movement in the beach.

This research is kindly funded by the Brian mason Scientific and Technical Trust https://brianmasontrust.org/

Staff involved:

• Dr Deirdre Hart

Selected publications and theses:

• Dawe, IN (2006) Longshore Sediment Transport on a Mixed Sand and Gravel Lakeshore. PhD Thesis, University of Canterbury (Geography), 364pp.
• Hart, DE (2007) River-mouth lagoon dynamics on mixed sand and gravel barrier coasts. Journal of Coastal Research SI50: 927-931.
• Hart, DE; Marsden, I and Francis, M (2007 in press ) Coastal Systems. In : Natural History of Canterbury (3 rd edn). Canterbury University Press. 30pp
• Hart, DE and Single, MB (2004) Evolution, dynamics and management of Waikoriri Lagoon, Boldhead, Westland, New Zealand. Westland District Council Report. 23pp.
• Hemmingsen , MA (2004) Reduction of greywacke sediments on the Canterbury Bight coast, South Island , New Zealand . PhD Thesis, University of Canterbury (Geography), 323pp v1.
• Eikaas, HS and Hemmingsen, MA (2006) A GIS approach to model sediment reduction susceptibility of mixed sand and gravel beaches. Environmental Management 37: 816-825
• Ishikawa, R (2006) Beach and Nearshore Morphology at Amberley Beach , Pegasus Bay . Honours dissertation (Geography), University of Canterbury , 55pp.
• Single MB and Hemmingsen MA (2000) Mixed sand and gravel barrier beaches of South Canterbury , New Zealand . In: Packham, JR et al. (eds) Ecology and Geomorphology of Coastal Shingle. Otley : Westbury, pp261-276.
• Single, MB (2006) Timaru to Banks Peninsula coastal report : status of gravel resources and management implications. Report to Environment Canterbury: Christchurch, 7p.

Join the Southern Ocean Swell Facebook Group

This research cluster concerns the physical and biological processes operating in estuaries, harbours and other coastal water bodies. Current investigations include:

• modelling ocean current and algal bloom dynamics in the South Sea of Korea (Hart in association with Byun),
• development of techniques for mapping and monitor macro algae in the Avon-Heathcote Estuary (Hart, Marsden and Park in association with the Avon-Heathcote Ihutai Estuary Trust), and
• investigation of links between physical conditions and salt marsh communities to inform restoration frameworks (Cochrane, Hart, Marsden, Partridge and Shulmeister, in association with the Avon-Heathcote Ihutai Estuary Trust).

Staff involved:

• Dr Deirdre Hart 
• Dr Jamie Shulmeister

Selected publications and theses:

• Byun DS, Wang XH, Hart DE, Cho YK. 2005. Modeling the effect of freshwater inflows on the development of spring blooms in an estuarine embayment. Estuarine and Coastal Shelf Science 65: 351-360
• Byun DS, Cho YK , Huh IA, Hart DE. 2005. Runoff-induced vertical thermal dynamics in a canyon-shaped reservoir during the summer monsoon. Marine and Freshwater Research 56: 959-968
• Hart DE. 2004. Sedimentation in the Upper Lyttelton Harbour. Environment Canterbury Report. 18pp.
• Jupp, K; Partridge, TR; Hart, DE and Marsden, ID (2007) Ecology of the Avon-Heathcote Estuary: Comparative salt marsh survey 2006-2007. Estuarine Research Report 34, University of Canterbury, for the Avon-Heathcote Ihutai Trust and Christchurch City Council.

Join the Southern Ocean Swell Facebook Group

This project examines how reef islands are built and maintained via the sediment systems that nourish their beaches. It concerns the eco-sedimentological links between reef system and reef island sediments, ecology and hydrodynamics, as well as the implications of understanding reef island-system linkages for reef resource management.

Tropical reef island environments appear acutely vulnerable to anticipated sea-level rise, climate shifts, and changes in the patterns and intensity of coastal resource use. Determining how islands have formed, are nourished, and whether they are continuing to accumulate sediment is essential for their sustainable management.

Students wishing to pursue a MSc or PhD in this area are expected to bring their own field and laboratory analysis funding as well as independently gaining a full stipend-type scholarship.

Objectives:

The broad objective of this project is to understand reef sediment systems, in particular, how these systems build and nourish islands. Sub-aims include examining how reef sediment systems respond to changes in climate, sea level, and anthropogenic influences such as pollution and destructive reef uses. A new part of this project involves the creation of a fully photographically illustrated guide to carbonate sediment identification.

Results:

Progress to date includes the improvement of census-based approaches to determining carbonate budgets (Hart & Kench 2007), research into the hydraulic nature of carbonate sediments (current), and improving techniques for determining reef island accumulation sequences (Woodroffe et al. 2007). In addition, graduate students have researched sustainable options for the management of resources in tropical reef, mangrove and marine protected area (MPA) environments in Indonesia and the Maldives (Idrus; Mohamed), and links between regional climate phenomena and the vulnerability of Maldivian atolls to coastal, meteorological and water-resource hazards (Zahid).

Publications:

• http://en.wikipedia.org/wiki/Cay
• Hart, DE and Kench, PS (2007) Carbonate production of an emergent reef platform, Warraber Island , Torres Strait , Australia . Coral Reefs 26:53-68.
• Idrus, R. (2009) Hard Habits to Break: Investigating Coastal Resource Utilisations and Management Systems in Sulawesi, Indonesia. PhD (Environmental Science), University of Canterbury. 
• Woodroffe, CD; Samosorn, B; Hua, Q and Hart, DE (2007) Incremental accretion of a sandy reef island over the past 3000 years indicated by component-specific radiocarbon dating. Geophysical Research Letters 34, L03602, doi:10.1029/2006GL028875, 2007.
  
• Zahid (2011) The influence of Asian monsoon variability on precipitation patterns over the Maldives. PhD (Geography), University of Canterbury.
• Economic valuation of coral reefs: a case study of the costs and benefits of improved management of Dhigali Haa, a marine protected area in Baa atoll, Maldives
• Changing Reef Values: An Inquiry into the Use, Management and Governances of Reef Resources in Island Communities of the Maldives

Staff involved and completed graduate students:

• Dr Deirdre Hart
• Professor Colin Woodroffe (University of Wollongong)
• Dr Zahid Zahid
• Dr Rijal Idrus
• Dr Mizna Mohamed

Join the Southern Ocean Swell Facebook Group

Glaciers form in locations where more snow and ice accumulates each year than is lost by summer melting; the balance between these gains and losses is referred to as the mass balance of the glacier. Scientists are very interested in monitoring mass balance as this provides information about the ‘health’ of the glacier, and how glaciers respond to changing climate.

Although New Zealand has over 3100 glaciers, very few are monitored on a regular basis. In 2010, Tim Kerr and Heather Purdie reinvigorated a previously sporadic mass balance monitoring programme on the Rolleston Glacier. Rolleston Glacier is a small cirque glacier in the Arthurs Pass region, situated on the south-eastern flank of Mt Philistine. Field work is undertaken at the end of each winter (November), and again at the end of the following summer (March), order to determine how much mass the glacier has either gained or lost.

We use a combination of direct measurement (e.g. snowpits, probing and stakes), with remote surveying techniques (e.g. ground penetrating radar, oblique repeat photography) and modelling, to develop a better understanding how a small alpine glacier responds to changing climate and the role that avalanche deposition has to overall glacier health.

Publications:

Purdie, H., Rack, W., Anderson, B., Kerr, T., Chinn, T. J., Owens, I. & Linton, M. 2015. The impact of extreme summer melt on net accumulation of an avalanche fed glacier, as determined by ground-penetrating radar. Geografiska Annaler. Series A: Physical Geography,97, 779-791.

Purdie, H. & Rack, W. 2014. The role of avalanche on snow accumulation on small alpine glaciers. Crystal Ball, New Zealand Mountain Safety Council, 25, 29-30.\

Staff involved:

Heather Purdie (University of Canterbury)
Tim Kerr (Aqualinc)
Wolfgang Rack (Gateway Antarctica).

The global wine-producing industry is highly sensitive to variations in weather and climate, which can significantly affect both quantity and quality of the wine. It is also an important economic activity in many developing parts of the world, resulting in significant exports of high quality wine. The wine-climate research conducted in the School of Earth & Environment aims to improve knowledge of the climate processes that affect the main wine-producing areas of New Zealand and other countries through collaboration with an international research group (led by French colleagues) working in some of the main vineyard areas of the world (e.g. France, Spain, Italy, Portugal, Chile, Argentina, Uruguay, Bolivia, South Africa, and the US). Collaboration of our research group with french researchers started in 2011 via a project led by Dr Hervé Quénol (CNRS, University of Rennes, France), which was followed by the ‘Development of advanced weather and climate modelling tools to help vineyard regions adapt to climate change’ project led by Professor Sturman and funded by the Ministry of Primary Industries in New Zealand (2013-15) This project involved researchers from CNRS and University of Rennes (France), Plant and Food Research (Blenheim and Lincoln), NIWA and the atmospheric research group in the School of Earth & Environment. The international collaboration is continuing via the five-year LIFE-ADVICLIM project (2014-2019) tha includes researchers from several European countries. The research programme involves application of climate monitoring and modelling at very local scales in different vineyard regions of the world in order to provide advice and software tools to help vineyard owners adapt to existing and future climate variability in order to ensure the long term sustainability of the industry.

Research strategy:

In New Zealand, we initially selected two case study areas for intensive analysis – Marlborough and Waipara, while the research has involved four main components:

1. A statistical analysis of climate variability in the main New Zealand wine-producing areas using existing data to evaluate the significance of periodic variations, random events and longer term trends.

1. Application of advanced 3-D atmospheric modelling techniques to provide a high resolution (~1 km) assessment of spatial and temporal climate variability in the two case study areas. Meteorological data (temperature, humidity, rainfall, wind speed and direction) from a high resolution climate monitoring network installed in the Marlborough region has been used to validate model results. The model results is being used to identify areas of particular risk in the context of climate variability (e.g. marginally located grape varieties and frost effects).

1. Application of a combination of Geographic Information System (GIS) and geo-statistical techniques to downscale the climate model results to vineyard scale (~50 m) to evaluate the effects of such factors as soil, land use and topography on small scale climate variability, also incorporating the meteorological data collected in the two areas.
2. The impacts of possible future climate change on the long term viability of vineyards and specific vine varieties in these areas are also being assessed, based on the IPCC scenarios for the rest of this century.

Staff involved:

• Assoc. Prof.Peyman Zawar-Reza
• Dr Marwan Katurji

Project rationale and overview:

The floating ice shelves that fringe 45% of Antarctica (Fig. 1) are potentially highly sensitive indicators of climate change, because they are thought to have an abrupt limit of thermal viability that, when exceeded, leads to their collapse. However, understanding and interpreting ice shelf change is difficult because the processes that control ice shelf response to external effects, including the nature of their interaction with the surrounding ocean, are not well understood.

The aim of this research is to examine the behaviour of the McMurdo Ice Shelf (Figure 2) in the Ross Sea Sector of Antarctica, and to find out how it has changed over the last century. In particular, we want to establish how sensitive the extent, thickness and flow of the ice shelf are to changes in climate inputs. The current state of the ice shelf will be determined from a combination of field-based data collection, analysis of information derived from satellite images, and mathematical modelling. We will compare our present-day measurements of ice shelf area, thickness and velocity with historical data to see how the situation has changed over the last century, and to predict how it may change in the future.

Research goals and approach:

The overall goals of this research are: (1) to establish the current state of the McMurdo Ice Shelf; (2) to determine the nature of changes through the last century, since measurements were first made there; and (3) to determine the response relationship between measured changes and the climate record. The emphasis of the work is on process-based understandings of environmental change behaviour, with an IPCC-type timescale view of 101-102 years. The research is interdisciplinary, involving glaciologists, sedimentologists, and oceanographers.

The overall methodological approach combines field data collection with remote sensing analysis and numerical modelling. Satellite radar interferometry will be used to calculate velocities, which will be ground truthed with field measurement. Melt and accretion rates at the base of the ice shelf will be calculated using numerical modelling.

Progress to date (as at June 2004):

The first fieldwork season was successfully completed in the Antarctic during the period November 2003-January 2004. A network of 53 stakes was established across the ice shelf in November, from Koettlitz Glacier in the west, to the boundary with the Ross Ice Shelf in the east. The changing position of these markers was monitored through the summer. Preliminary processing of the GPS data indicates that short term summer velocity varies from more than 160 m a-1, to less than 5 m a-1 across the ice shelf. Thickness measurements suggest that there has been some thinning of the ice shelf since thickness was measured in the 1960s.

Detailed analysis of the results of the first field season, remote sensing analysis of velocity, and analysis of information derived from debris characteristics on the ice surface are all under way.

Resourcing:

This research is supported by various organisations. Key support is currently received from:

• University of Canterbury
• Antarctica New Zealand
• Leverhulme Trust UK
• NASA

Papers in draft:

Glasser N F, Goodsell B, Copland L and Lawson W, forthcoming, Debris transport and despotion on the McMurdo Ice Shelf, Antarctica, Arctic Antarctic and Alpine Research.

Clendon P, Lawson W and Spronken-Smith R, forthcoming, Surface energetics of the debris-covered ice on the McMurdo Ice Shelf, Antarctica, Annals of Glaciology.

Researchers Involved:

• Wendy Lawson, Principle Investigator
• Luke Copland, post-doctoral research fellow
• Becky Goodsell, postdoctoral research fellow
• Michael Williams, NIWA Wellington
• Neil Glasser, Centre for Glaciology, University of Aberystwyth
• Sean Fitzsimons, University of Otago
• Penny Clendon, PhD student

Supported by Glacier Explorers:

Global glacier recession is increasing the number of glaciers that terminate in proglacial lakes, yet knowledge about the processes that drive ice-berg calving are still poorly understood. This knowledge-gap is in part due to the challenge of obtaining good data sets in a highly dynamic and dangerous environment.  We are using emerging remote technologies, in the form of a remote controlled jet boat to survey bathymetry, and Structure from Motion (SfM) to characterise terminus morphology, to better understand relationships between lake growth and terminus evolution.

In addition to learning more about the processes operating in this dynamic environment, our research also helps to inform local tourism company Glacier Explorers about the changing characteristics of Tasman Lake which can assist them with day-to-day operational decisions.

Publications:

Purdie, H., Bealing, P., Tidey, E. & Gomez, C. in preparation. Use of a remote-controlled jet boat to survey bathymetry at the terminus of a calving glacier: Tasman Glacier, New Zealand. Journal of Glaciology.

Purdie, H., Bealing, P., Tidey, E. & Gomez, C. 2015. Bathymetric and terminus evolution as determined by remote-sensing techniques: Tasman Glacier, New Zealand. New Zealand Snow and Ice Research Group Annual Workshop. Cass, Canterbury, 2-4 July.

Purdie, H., Bealing, P., Tidey, E. & Gomez, C. 2015. Use of a remote-controlled jet boat to survey bathymetry at the terminus of a lake-calving glacier: Tasman Glacier, New Zealand. New Zealand Region of the Australasian Hydrographic Society Annual Seminar: Our seas and oceans - still to be explored and charted. Wellington, 22 June. 

Staff involved:

• Heather Purdie
• Paul Bealing
• Christopher Gomez
• In collaboration with the Otago School of Surveying Emily Tidey

STABX is a research field campaign setup in the Cass Basin in the middle of the Southern Alps of New Zealand to study atmospheric boundary layers in mountainous environments.

This campaign is primarily designed to answer research questions related to atmospheric boundary layer flows in complex terrain with emphasis on quiescent and cold climate dynamics, but also has an educational and teaching outreach for courses given within the School of Earth & Environment.

STABX is planned to run for several years.

Location:

The Cass Basin forms part of the mid-Waimakariri inter-mountain river basin in the central South Island and provides a wide range of atmospheric environments that reflect the complex topography (slopes, valleys, ridges, hills, terrain gaps) and diverse surface types (lakes, streams, grass, swamp, forest). Within the basin lies the University of Canterbury Cass field station
See map for location of the research field site.

Atmospheric Stable Boundary Layers:

When the sun sets and the shadow is cast over the terrain the same physical processes that created the warm, relatively windy daytime atmosphere starts acting in reverse to cool down the surface in the absence of solar incoming radiation. The process of surface cooling starts early in the evening and continues throughout the night up till sunrise. In the absence of regional scale pressure gradients (lack of strong winds), the local scale effects start to take over. Air density responds to temperate, so nighttime cold surfaces cool the air above it and creates a denser air layer that sinks due to gravity. This process continues and deepens the stable boundary layer above the valley floor.

The stable boundary layer is that layer that is characterized by colder temperatures than the air layers above it. Winds are very weak and some times do not exist. Vertical mixing is inhibited due to the gravity driven subsidence. Inside this layer wave motions start to dominate with periods of intermittent turbulence as wave structures break. Small terrain and land use features like trees, rivers, terraces play a role in effecting the flow patterns.

Below is a picture for a typical stable boundary layer streamlined by an injection of hot smoke form a chimney. The wave patterns on top of the layer resemble the oscillations depicted by the boundary layer of soap bubble (main page banner, credit to Fabian Oefner) although the forcing is different. The top of this layer pierced by the hot rising smoke plume marks the top of a temperature inversion.

STABX will aim to understand the driving phenomenon behind the conditions yielding to, maintaining and eventually breaking the stable boundary layer.

The research targets specifically the micro-scale environment down to the resolution of slopes, trees, small lakes, terrain gaps, and surface types. Effects of larger scale forcing such as drainage winds, mountain waves, weather fronts, will also be considered but in context of the stable boundary layer dynamics.

STABX extensive observation network and design will permit probing into the details of the stable boundary layer features with aims to understand this complex phenomena, which still needs to be studied due to its spatial variability and sensitivity to small scale topography and vegetation cover.

STABX research objectives are the following. These will be achieved through observation data analysis and atmospheric numerical modeling.

Given the time, observational density included, and the variety of mountain meteorological phenomena to be observed in this work the objectives are the following.

1. Identify modes of oscillations excited by the surface (1-3 meters above the surface) in strongly stratified boundary layer.
2. Investigate the interaction between ridge-top level winds on modifying near surface wave-forms eventually leading to the intermittent break up of the inversion.
3. Investigate the ability of numerical weather models in predicting the stable boundary layer dynamics
4. Utility of weather models for prediction of frost in complex terrain.

The Dry Valleys are dry! Antarctica is the driest continent on earth, which ironically is 98% covered in ice. The Dry Valleys receive around 50mm of precipitation per year at the valley mouths and almost nothing at the head of the valleys. Why? Because of the rain shadow effect from the Transantarctic mountains. Very simplistically the weather in the Dry Valleys is as follows: In the summer under 24hour sun, when there is regionally calm weather, the winds are driven by thermal circulations which causes up valley winds during the day. During the few hours when the low sun casts shadow into the valleys, the temperature drops a few degrees and there is a weak down valley wind. The major weather comes from the outside, in summer low-pressure systems bring strong winds into the valley, and if dense with moisture, snow will fall. In the winter when the circumpolar vortex strengthens, low-pressure systems cause hurricane strength warm foehn winds to funnel down into the valleys. These are the strong winds that pick up sand and blast and erode the rocks causing sculpted ventifacts. 

To understand the biocomplexity of the Dry Valleys ecosystems, it is critical to understand the microclimate. Temperature and water are critical for life. I know that I require water and warmth to live in the Dry Valleys, and a few cinnamon scones! So what causes surface temperature to rise above freezing? And what causes precipitation? 

Marwan and Peyman are also looking at finer scale climate questions. They are interested in the atmosphere very close to the surface - below 500m. Specifically wind interaction with topography, turbulence, waves, and the forces behind them. The Dry Valleys represent a simplified system with no vegetation, which is ideal for theory and hypothesis testing.

They have some serious gadgets, 700 kilos of gadgets in fact. There is the SODAR (sound detection and ranging), and a RASS (radio acoustic sounding system), a surface automatic weather station, and a kite. The SODAR and RASS instruments measure wind speed, wind direction and temperature in a vertical profile from the ground up to 500m every 10 minutes.

But the most fun, was flying the kite. A beautiful bright yellow and red 4m kite is attached to a hand winch and flown with instruments attached to validating the temperature profiles taken by the RASS up to 300m. It is labour intensive but necessary for checking the remote sensing gear. Kites work better than weather balloons in windy environments, such as the Dry Valleys. 

Staff involved:

• Assoc Prof Peyman Zawar-Reza
• Dr Marwan Katurji