Publicly accessible
URL: http://nzetc.victoria.ac.nz/collections.html
copyright 2011, by Victoria University of Wellington
Some keywords in the header are a local Electronic Text Collection scheme to aid in establishing analytical groupings.
The ongoing aim of this project is to understand the origin and paleoenvironmental significance of relict ice from glaciers and lakes, which now lies buried by surficial sediments in many parts of the Dry Valleys. This phase of the project focuses on relict ice, buried in Lower Victoria Valley, which will be used as an analogue for relict ice in Beacon Valley. Of particular value will be the independent dating of sediments covering the ice using a new method of atmospherically derived beryllium-10.
Studies have shown that the use of atmospheric Be-10 to date Antarctic soil profiles gives equivocal results, and an independent test is needed. This requires sampling of a soil profile in a deposit of a known age. Such a deposit was sampled near the Hart Glacier in the Wright Valley.
In this field season, we also sampled the modern environments and stratigraphically recent ice deposits in Lower Victoria Valley as well as the modern and buried ice deposits in Beacon Valley. The main aim will be to analyse the ice for percentages of O2, N2 and Ar in the occluded gas bubbles. Ratios of these gases can be used to distinguish glacial and lake ice. The gas analyses will be used in conjunction with standard chemical (6 cations and 3 anions) and stable isotopic analyses to help characterize the ice. Results from this study will not only help with interpreting the origin of the buried ice but also test Hall's (2002) lake model for Victoria Valley.
Application process
The application process was organised in a professional and efficient manner. While the review process of the Antarctic Research Committee is rigorous and unbiased, the ranking/grading system lacks accountability, as the ranking results are not provided to the applicant. This also leaves the applicant without a clear understanding for several months of whether or not his/her event will have logistical support for the coming season.
Communications with Antarctica New Zealand staff
Generally good
Provision of maps and aerial photographs
Need for additional LIDAR data
Pre-season information
Generally good
Medicals, documentation and flights to Antarctica
Excellent
Reception and planning for your event
Availability and condition of equipment received
All equipment needs to be thoroughly checked out by event personel before leaving for the field. There should now be enough resources in the HFC to allow event personel to select from a variety of equipment.
Field training
For those with previous Antarctic field experience, the AFT refresher is a reminder (in case people have short memories) of Antarctic conditions. However, Antarctica NZ should consider whether AFT is a beneficial and an efficient use of funds for personnel with continuous Antarctic field experience. As I understand, AFT was set up in 1995 for event personnel who had no Antarctic field experience within the last 5 years. It is not clear why this has changed to one of mandatory AFT every 3 years.
Field party equipment 'shakedown' journey
All equipment was functional.
Delays at Scott Base, whatever the cause
Weather
Safety and Risk Management processes
I have considerable concern regarding the 'new' safety and risk management processes. It is not clear how these procedures contribute to improved safety in the field, which essentially relies on the equipment and judgment of event personnel in the field. These new proceedures should take into account previous experiences of the field party. Implementing these proceedures contributes to a substantial increase in the work load of both the science and base personel without, in my view, clear advances in field safety.
General comments about Scott Base
Scott Base staff were generally up to the usual high standards of 'can-do' and help that I have received in previous years.
Other comments
Comments such at those found on the BM report (11 Dec. 2005) were unwarrented.
Generally good for field work in the Dry Valleys
None to report.
Quality, suitability and performance of field clothing
All new parkas and wind jackets should be a bright colour (yellow). Black, blue and green simply do not show up in the Dry Valley landscapes.
Performance and design of field equipment such as tents, technical climbing equipment, kitchen gear, primus boxes, sleep kits and sledges
Lots of new gear coming on line, but proceed with caution. The old stuff works well and is tried and tested. Field parties were given choices on the new gear which is a good way to proceed. The new Macpac dome tents should not have been taken into the field without the modified flys.
20 person day ration box system
OK for some uses but generally need to be repacked in to breakfeast, lunch and dinner for longer duration events; Field support people need to be flexible on this; Rationing of certain foods for field parties does not seem appropriate in some cases.
Other comments
Iridium is cheap comms for areas that cannot get VHF; Suggest HF be used as backup. However, the new HF radios are good.
Numerous items have purchased by K047 over the years, but this past season there were 2 issues; 1) A solar panel kit for charging computers in the field was promised by Antarctica NZ, and this piece of kit never arrived. Prudently, I brought my own solar panel charging kit, but this added 40 lbs of cargo to SB. 2) Because of past experience in trying to cram 4 people into a Scott tent for cooking and evening discussion, I purchased an Arctic Oven (AO) tent, which has been used sucessfully for winter camping on the north slope of Alaska. The tent has about the same floor space as an Endura but is half the weight and much easier to set up. Modifications were made to the AO tent to make it more wind resistant, but the tent was deemed to be unsafe for Dry Valley conditions. I was faced with not using the AO and taking an Endura, a situation which would put us over the allowable helio weight. A compromise was reached in that a Scott tent, which just put us under allowable weight, would be used as a backup. The AO tent weathered 40-50kt gusts in Beacon and Kennar valleys without problems.
The 8 Ma relict ground ice in Beacon Valley, Antarctica has been the topic of much debate since Sugden and others reported it in 1995 (Sugden et al. 1995). There is little debate about the age of the volcanic ash, which dates the ice, but the emplacement of this ash and origin of the ice continues to be a matter of contention. The occurrence of relict ice is not unique to Beacon Valley, with a range of occurrences now reported throughout the Dry Valleys (Dickinson et al. 2003a). Such ice is likely to be much older than even the oldest ice in the present ice sheet, making it important because of the paleoenvironmental and paleobiological record it may contain. The ice also represents a terrestrial analogue for ice that is thought to exist on Mars. Thus, the overall aim of this ongoing project is to understand all aspects of relict ice in the Dry Valleys and the information that it can provide. The specific aim of this proposal is to obtain observations and materials for establishing the setting of these ice bodies and dating the length of time they have been in their present situation. The latter can be achieved by a new method that is based on the undisturbed accumulation of 10Be in the rock debris overlying the ice.
In addition to Beacon Valley, relict ice has now been confirmed to exist in Pearse, Columnar, Kennar, and Victoria Valleys, and is thought to be widespread throughout the Dry Valleys (Fig. 1). Studies associated with this project suggest that relict ground ice in the Dry Valleys can originate from either stranded remnants of glaciers (Marchant et al. 2002; Sugden et al. 1995) or buried glacial lakes (Hall et al. 2002; Kelly et al. 2002). Ground ice that is not relict may also result from a variety of in situ processes (Dickinson et al. 2003a; Dickinson and Rosen 1999; Dickinson and Rosen 2003). Relict ground ice appears to have been stranded in valley bottoms and is found as a continuum between two end-members: 1) massive clear ice with bubbles and trace amounts of debris to 2) highly deformed, debris-rich ice. The massive ice may derive from lake ice or ice cored moraines of wet-based glaciers pre-dating the present valley floors or ice cored moraines from the margins of the more recent cold-based glaciers. Highly deformed debris-rich ice may result from accumulated strain of multiple advances and retreats of cold-based glaciers (Fitzsimons et al. 1999). Clues to these origins may be determined from the chemistry and stable isotopic ratios of the ice as well as gas analysis of its bubbles. Such studies will need to be complemented with descriptions and analyses of the surrounding glacial sediments.
The age of the relict ice is critical to its value as a record of past climate. The difficulties in dating it are best exemplified by the numerous and conflicting ages, which range from 0.5 to 8Ma, published for Beacon Valley ice (Schafer et al. 2000; Stone et al. 2002; Sugden et al. 1995; Tschudi 2000; Ng et al. 2005). We have collected samples of relict ice and its overlying sediment for use in a new and evolving dating technique that involves the use of atmospherically-derived 10Be. This technique has been used with limited success for over a decade in dating soils from temperate areas. Recently, it has been applied to Antarctic soils (Graham et al. 1995; Graham et al. 2002) and sediments
Our approach to dating the surface of the relict ice uses 10Be produced in the upper atmosphere, which in Antarctica, accumulates in the salt components of the soil surface through snowmelt and evaporation (see method section for more detail). Atmospherically-derived 10Be differs in concentration by 1-2 orders of magnitude from the 10Be produced in situ that is used for surface exposure dating. In soils and sediments from three other areas in Antarctica (Dickinson et al. 2003b; Graham et al. 1995; Graham et al. 2002), we have
9Be/10Be ratio is fixed at the surface, and we think it is locked into clays and salts. We found that the 10Be/9Be ratio of the fines decreased systematically with depth to yield a decay age for the soil and sediment. The decay with depth suggests that Be is somehow infiltrating into the ground, by a process we do not fully understand. Nevertheless, the decay ages that we have obtained are reasonable for the soils and sediment analysed. We believe that this method should be applicable to dating the soils and ice-cemented sediments that overlie relict ice in the Dry Valleys, and indeed other parts of the Transantarctic Mountains.
Sampling sites were selected for the occurrence of massive relict ice. At each site, a 1.5 square metre pit was dug into the ice free soil or sediment above the relict ice. In some areas ice cemented sediment was above the relict ice. This was sampled by means of a small gasoline powered hammer drill with a diamond or carbide core bit. Once into the relatively sediment-free relict ice, a sipre auger with carbide cutters was used to core to a depth of about one metre.
Ian Graham and co-workers at GNS, Lower Hutt, will carry out the dating method using atmospheric 10Be. The procedure will be similar to that used in previous studies (Dickinson et al. 2003b; Graham et al. 1995; Graham et al. 2002). To streamline the method, we will only process the >62 micron fraction of sediment which we believe contains most of the Be.
Samples of granite used for fingerprinting will be cut (1-2 cm2 slabs) and rough polished. These will be placed in a laser ablate chamber attached to a multi-collector mass spectrometer. Lead isotopes 204,206 and 207 will be measured in the feldspars of each sample. Plots of 207Pb/204Pb vs 206Pb/204Pb will show areas of feldspar genesis which are unique to the magma bodies where granitic rocks crystallize. The Lead isotopic composition of feldspars are incorporated at the time of crystallization and form distinctive signatures which can be used for tracing the origin of the feldspar.
Three members of the event spent 7 days in Lower Victoria Valley from 14 - 21 Nov and 4 days near the Meserve Glacier in the Wright Valley from 21 - 25 Nov. Ron Sletten joined the event in for 8 days in Beacon Valley (25 Nov – 3 Dec) and 5 days (3 - 8 Dec) in Kennar Valley. All totalled we collected 35 kg of surface sediments and about 40kg of granite. Preliminary mapping of granite clasts in Beacon Valley show they are concentrated in the northeastern part of the valley. There appears to be about 5 different types of granites which can be identified in hand sample. Further results will have to wait for laboratory analysis.
Future research by this investigator will centre on the geochemistry and dating of relict ice and permafrosted sediments obtained from shallow cores. Based on the outcome of the proposed work, the intention for the 2007/08 season will be to core areas of relict ice. Experience has shown that two drilling areas per
In two years, we hope to have funds available to drill Beacon Valley in a joint project (Chris McKay) with NASA. Beacon Valley contains an undertermined thickenss of debris-laden ice. The present shallow coring system provides the technical development and expertise that will be necessary to drill Beacon Valley, but the system will need to be scaled up in size. The McKay proposal calls for the development of a 'smart' drill head that is capable of obtaining aseptic samples and has sensors to determine the presence of organic material and conduct microbiological assays through non-destructive methods.
This past season, is part of an on-going project that utilises shallow drilling technology in the Dry Valleys to study permafrost and relict ice. The project has numerous collaborations and linkages but one collaboration occurred for this season. Ron Sletten of the University of Washington provided expertise in the Beacon and kennar valleys and he will provide chemical and stable isotopic analyses of the relict ice samples.
A paper on landscape modification by meltwater from the Packard Glacier has been submitted to Boreas in Dec 2005. Results from OSL sampling of Victoria Valley sediments will be published as a paper in Holocene in May 2005. Results from the 10Be anaysis will first be published as an MSc thesis at Victoria University in 2006. Results from granite fingerprinting will be first published as an Hons Thesis at VUW. Copies of these will be sent to Antarctica NZ.
Further publications of the scientific results will be published in international peer-reviewed scientific journals. Copies of this work will also be sent, when available, to Antarctica NZ.
Prof Peter Barrett, (Director, Antarctic Research Centre, VUW)
Dean Peterson, Paul Woodgate and Steve Brown (Antarctica NZ)
All of the Scott Base personnel (Nov-Dec 2005)
Websters Drilling, for equipment preparation and cargo handling
Antarctica New Zealand; University Grants Committee, VUW; Foundation of Research and Technology, NZ
Seven key locations were identified for the NZ ITASE (International Transantarctic Scientific Expedition) programme. The analyses on the ice core from the first site, Victoria Lower Glacier in the McMurdo Dry Valleys, have been completed. During the 2003/04 field season we carried out a detailed reconnaissance of sites 2 and 3: Evans Piedmont Glacier (EPG) and Mt Erebus Saddle (MES) and determined the most suitable locations of the ice core recovery. During the 2004/05 field season we recovered to intermediate length ice cores (180m and 200m, respectively) from these locations and conduct further in-situ measurements, such as borehole temperature and light penetration characteristics, snow density and stratigraphy and its geographical variability. Furthermore, we installed a weather station and mass balance devices at EPG and cased the borehole at MES for future measurements. During the 2005/06 field season we re-visited VLG and EPG to conduct GPS measurements of the submerge velocity devices and to sample shallow snow pits. Furthermore, we retrieved the meteorological data and carried out maintenance work on the automatic weather station at EPG. Lastly we deployed 6m snow stakes at the high accumulation site at Mt Erebus Saddle.
The NZ ITASE programme has five objectives:
The focus of the New Zealand ITASE group is to provide information from the climate sensitive, low altitude, coastal sites. This will capture the climate signature of the troposphere, which represents a regional account on the Ross Sea climate. The ice core data are expected to provide a record of air temperature, snow accumulation, precipitation source, atmospheric circulation strength, storm frequency, sea ice variation, ocean productivity, and anthropogenic influences. The results will help to decide whether the Ross Sea region is currently cooling or warming with a longer-term prospective, taking low frequency climate variability (100 to 1000 year cycles) into account. Furthermore, proposed tele-connections such as the Amundsen Low-ENSO correlation [Bertler et al. 2004; Meyerson et al. 2002] or the Southern Hemisphere Annual Mode [Thompson and Solomon 2002] can be further constrained. The project is expected to contribute substantially to the Latitudinal Gradient Project, as it can provide a history of temperature, humidity, sea ice cover, precipitation source, atmospheric circulation, and ocean productivity along the Victoria Coast for the last 200 to 10,000 years. Furthermore, the timing and velocity of the Ross Ice Shelf retreat some 9 to 5ka years ago is still discussed controversially [Hall and Denton 2000; Steig et al. 1998; Steig et al. 2000]. The ice core locations 2 and 3 (Evans Piedmont Glacier and Mt. Erebus Saddle) are in the vicinity of planned ANDRILL coring locations (Granite Harbour and Windless Bight). The ice core records will provide a high resolution climate dataset, which serves as a reference for the younger part of marine record recovered through ANDRILL. During the 1999/2000 season mass balance measurement devices (submergence velocity method [Hamilton and Whillans 2000; Hamilton et al. 1998]) have been deployed at Victoria Lower Glacier. The device has since been revisited during season 2000/2001 and 2001/2002. The measurements show that the glacier has a slightly negative mass balance, losing around
New Zealand's future economic and social development, environmental sustainability, and infrastructural planning critically relies upon the accurate assessment of the impact of "global warming" in our sector of the planet. Future climate change is a result of both natural variability and anthropogenic influence. A joint programme between IGNS, University of Maine, Victoria University is investigating ice core records from New Zealand (Tasman Glacier and Mt. Ruapehu ice field). The comparison between our NZ and Antarctic ice core records will provide much needed data for the development of realistic regional climate models to predict NZ climate in the 21
ITASE-ObjectiveLatitudinal Gradient Project ObjectiveANDRILL ObjectiveLonger-Term Mass Balance ObjectiveThe Antarctic – New Zealand Connection Objectiveth Century [Mullan et al. 2001].
Application process
The application process was organised in a professional and efficient manner. While we feel that the review process of the Antarctic Research Committee is rigorous and unbiased, the ranking/grading system lacks accountability, as the ranking results are not provided to the applicant. This also prevents the applicant to improve future applications.
Communications with Antarctica New Zealand staff
Communication with Antarctica New Zealand staff was professional, timely, and effective.
Provision of maps and aerial photographs
N.A.
Preseason information
In late May 2005 we were informed that our planned work at Cape Hallett (GPR and drilling of 200m ice core) could not be supported due to Antarctica New Zealand logistics constraints. For this reason our programme was condensed to our long-term mass balance monitoring at Victoria Lower Glacier and the maintenance work on the automatic weather station at Evans Piedmont Glacier. Furthermore, Antarctica New Zealand accommodated an additional visit to Mt Erebus Saddle to deploy snow stakes for mass balance measurements.
Medicals, documentation and flights to Antarctica
The information received was timely and valuable
Environmental Advice
The information received was timely and valuable
Other comments
In our experience over the last years, Antarctica New Zealand excelled through practical, innovative approaches and reasonable flexibility to evolving situations and opportunities. In contrast, we feel that last season, communication and discussions on the practical execution of fieldwork preparations were noticeable bureaucratic and lacked some of the flexibility that has made the New Zealand programme so successful. While growing demands and challenges may necessitate the organisation to streamline, we would hope that the practical and innovative spirit of the New Zealand programme will be retained and not exchanged for a bureaucratic and removed administration.
Reception and planning for your event
The reception was well organised, friendly and efficient. The main issues of the event were promptly discussed and organised.
Availability and condition of equipment received
The equipment requested from Scott Base was supplied in good condition.
Field training
The re-fresher AFT for Pyne and Bertler was helpful and appreciated. The frequency of full AFT requirements for experienced people should be reviewed to take account of personal experience and regular Antarctic activity that includes fieldwork. The current 3-year frequency is too short and has changed from the 5-year frequency implemented by Rex Hendry.
Field party equipment 'shakedown' journey
N.A.
Delays at Scott Base, whatever the cause
Unsuitable weather conditions at the start of our schedule delayed the deployment of mass balance snow stakes at Mt Erebus Saddle until the end of our field deployment. Good weather conditions and a smooth flight plan permitted all other moves to be carried out according to schedule.
Safety and Risk Management processes
Safety and risk management is a difficult task and benefited from the personal experience of the Antarctica New Zealand coordinator. However, the established process does not take into account local knowledge and/or experience of the field party. To allow a realistic evaluation we
General comments about Scott Base
Scott Base staff created a friendly, professional, and supportive environment. We are grateful for the enthusiastic and helpful support we received. The new HFC is an excellent facility to test field and science equipment, to pack helicopter loads and to prepare cargo shipment. The use of the elevator in the HFC should be open to science groups moving polar tents and other field equipment between floors. It is difficult to understand why it requires currently a Scott Base operator to do this for the field groups.
Other comments
Overall, we experienced a significant increase in paper work. The requirement for each field party member to fill out a Scott Base Clearance Form seems excessive and impractical.
Vehicles
N.A.
Aircraft Operations
All aircraft operations were performed professionally. We are also particular grateful for the reliable and experienced support of HNO.
Ship Operations
N.A.
N.A.
Quality, suitability and performance of field clothing
The issued field clothing was of suitable for the warm, calm weather conditions we encountered. However, we would like to reinforce our recommendation from last year that Antarctica NZ should investigate active field clothing that is warmer than the standard ECW's,
Performance and design of field equipment such as tents, technical climbing equipment, kitchen gear, primus boxes, sleep kits and sledges
The new macpac tents represent a good, light-weight alternative to polar tents in warm, calm conditions for short field deployments. The tent is easy and fast to pitch and is spacious for two people. However, the tent is like the Olympus model very temperature sensitive. As seen in Fig.2 during our field deployment, the temperature in the Olympus tent changed by as much as 12°C within a couple of hours, while air temperature only showed moderate changes and remained below 0°C. These fluctuations, caused by solar heating or cooling during cloudy periods impact on the sleep quality as a sleeping person will be either too cold or too warm over the course of the night. Moreover, the outer cover of the tent is of light quality and only suitable for calm conditions to moderate winds (<30knots). In addition, the lack of snow flaps prevented secure pitching.
We used skis and a manhaul pulk to move equipment (~100lb) between sites at both Evans and Victoria Lower Glacier. As in previous years, the pulk performed very well and can be used on snowy and icy surfaces alike (Fig.3). The Mukluk-Skis showed signs of fatigue, especially the bindings, which broke or fell apart. Furthermore, there was a lack of skins. The use of cord tight around the skis is less efficient and makes pulling a heavy sledge uphill very difficult. We recommend that Antarctica New Zealand invests in new skies and skins to be pre-allocated to field parties undertaking glaciological traverses.
20 person day ration box system
The new food boxes (or bags) were well packed in terms of quantity and nutrition and were favourably received by all members. The addition of savoury snack food and new innovative extras, such as bagged tuna and couscous was very much appreciated.
Suitability and effectiveness of the radio equipment
A high gain aerial was required at EPG and MES locations. We noted the radio batteries were more difficult to charge than in previous years. While all batteries were charged in the comfort of HFC before heading into the field, even unused batteries discharged within 24hours in moderate temperatures.
Moreover, the solar panel charger for the radio batteries has two disadvantages: The batteries are cold during the charging process and in moderate winds the solar panel cannot be securely anchored to e.g. a tent. We suggest providing a black plastic box with clear lid to store the batteries and charger during charging. In sunny conditions solar heating will significantly rise battery temperature and hence charging capacity. A simple and inexpensive thermistor mechanism could be used prevent overheating through regulating air circulation within the box. A couple karabiners glued to the solar panel will assist greatly in charging batteries in windy locations.
Reception/transmission conditions and suitability of radio schedule timing
As last year, we noted that communications at EPG on channel 3 and 5 were poorer than the previous season at a very similar location when a hand held without high gain aerial was reliable.
Scott Base's general efficiency during radio schedule
Radio communication was efficient, professional, and appreciated. The timing of the radio schedule convenient.
Assistance the science technicians gave with computer / IT issues
N.A.
Issues concerning public computer facilities in the Hatherton Laboratory
The computer network met our needs satisfactorily. A possibility to connect laptops to the Scott Base external net connection would be highly appreciated, especially during prolonged delays at Scott Base.
Other comments
*Differences from original Preliminary Environmental Evaluation (PEE)
We completed the mass balance measurement at VLG II. The submergence velocity device (77° 20.81846S; 162° 29.5371 E, Fig. 5) was completely removed.
Note that all event leaders who hold permits for entry to an ASPA need to complete a Visit Report for each ASPA entered. Please contact Rebecca Roper-Gee, the Environmental Advisor for report forms.
New ASPA or ASMA designation to be considered:
N.A.
Seven key locations were identified for the NZ ITASE (International Transantarctic Scientific Expedition) programme. The analyses on the ice core from the first site, Victoria Lower Glacier in the McMurdo Dry Valleys, have been completed. During the 2003/04 field season we carried out a detailed reconnaissance of sites 2 and 3: Evans Piedmont Glacier (EPG) and Mt Erebus Saddle (MES) and determined the most suitable locations for the ice core recovery. During the 2004/05 field season we recovered to intermediate length ice cores (180m and 200m, respectively) from these locations and conduct further in-situ measurements, such as borehole temperature and light penetration characteristics, snow density and stratigraphy and its geographical variability. Furthermore, we installed a weather station and mass balance devices at EPG and cased the borehole at MES for future measurements. For the 2005/06 field season proposed to identify a drilling location and recover an intermediate length ice core from Whitehall Glacier in the vicinity of Cape Hallett. Due to logistical constraints of Antarctica New Zealand this was part of our programme was postponed and our field programme condensed accordingly. During the 2005/06 field season we re-visited VLG and EPG to conduct GPS measurements of the submerge velocity devices and to sample shallow snow pits. Furthermore, we retrieved the meteorological data and carried out maintenance work on the automatic weather station at EPG. Lastly we deployed 6m snow stakes at the high accumulation site at MES.
Unprecedented changes are occurring in the Earth's climate. The 1990's were the warmest decade in the last 2000 years and average global temperature is projected to rise between 1.4°C and 5.8°C by 2100 [IPCC 2001]. Although the scientific evidence of global warming is now widely regarded as incontrovertible, predicting regional impacts is proving more problematic. Especially, conclusions of the Southern Hemisphere record are limited by the sparseness of available proxy data at present [Mann and Jones 2003].
While meteorological records from instrumental and remote sensing data display the large intercontinental climate variability, they series are insufficient to infer trends or to understand the forcing, which renders prediction difficult [Jones et al. 1999; Mann and Jones 2003]. The long ice core records from the Antarctic interior and Greenland revolutionised our understanding of global climate and showed for the first time the occurrence of RCE (Rapid Climate Change Events) (for review e.g. Mayweski and White [2002]). To understand the drivers and consequences of climate change on timescales important to humans, a new focus of ice core work is now moving towards the acquisition of 'local' ice cores that overlap with and extend the instrumental records of the last 40 years back over the last several thousand years.
This has been a key motivation behind the US-led International Transantarctic Scientific Expedition (ITASE) of which New Zealand is a member. The NZ ITASE objective is to recover a series of ice cores from glaciers along a 14 degree latitudinal transect of the climatically sensitive Victoria Land coastline to establish the drivers and feedback mechanism of the Ross Sea climate variability [Bertler and 54 others 2005; Bertler et al. 2004a; Bertler et al. 2005a; Bertler et al. 2004b; Bertler et al. 2005b; Patterson et al. 2005]. Furthermore, the ice core records will provide a baseline for climate change in the region that will contribute to the NZ-led multinational Latitudinal Gradient Project as well as providing a reference record for the NZ-led ANDRILL objective to obtain a high-resolution sedimentary archive of Ross Ice Shelf stability.
Our 2005/60 field season comprises 4 objectives.
In 2004/05 we deployed an automatic weather station on Evans Piedmont Glacier. We anticipate to collect data from the site for at least two years. The data permit the calculation of transfer functions between ice core proxies and meteorological parameters, such as temperature, precipitation, meso-scale atmospheric circulation pattern, katabatic winds, and seasonality of snow accumulation. In addition a new snow accumulation sensor and high precision snow temperature probes allow us to monitor snow accumulation rates, the potential influence of snow loss through sublimation, wind erosion or melt, and the quality of preservation of the meteorological signal in the snow. Furthermore, the data allow us to estimate the uncertainty of re-analysis data (NCEP/NCAR and ERA-40 data) in the region.
The response time of a glacier to changes in accumulation or ablation is dependent on the size and thickness of the ice mass. In general, the response time of cold-based glaciers is positively correlated with the size of its ice mass, leading to long response times in Antarctica. For glaciers in the McMurdo Dry Valleys, with lengths on average of 5-10km and flow rates of 1 to 3 m/a, the response times are thought to range from 1,500a to 15,000a [Chinn 1987; Chinn 1998]. Consequently, annual variations in surface elevation may only reflect changes in loss rates. As a result surface measurements of mass balance are difficult to interpret in terms of long-term mass balance [Hamilton and Whillans 2000]. This is especially the case in places like the McMurdo Dry Valleys where mass loss is thought to be predominately due to sublimation at ice cliffs and glacier surface caused by wind and solar radiation [Chinn 1987; Chinn 1998]. For Victoria Lower Glacier, two mass balance measurements are available in the literature for 1983 and 1991 based on ice cliff characteristics and the motion of the glacier snout [Chinn 1998]. The measurements indicate that VLG was advancing 1.24m/a into Victoria Valley during this time period. However, the small number of observations (2) and the cliff's sensitivity to sublimation (contemporary surface ablation) result in a high uncertainty of longer term mass balance. To determine the longer-term mass balance of the glaciers, unaffected by annual surface variations, three 'coffee-can' or 'submergence velocity' devices [Hamilton and Whillans 2000; Hamilton et al. 1998] were deployed at Victoria Lower Glacier in 1999/2000 and two at Evans Piedmont Glacier in 2004/05.
Intermediate length cores were recovered from Victoria Lower Glacier and Evans Piedmont Glacier in 2001/02 and 2004/05, respectively. High resolution samples from shallow snow pits are used to update the records and to investigate post-depositional changes in the snow signal, such as isotopic diffusion or nitrate loss. Furthermore, meteorological data recorded at Evans Piedmont Glacier and re-analysis data are used to calculate transfer functions and establish seasonality in the ice core record. In order to estimate the influence of small-scale local
We have recovered a 200m deep ice core from the slopes of Mt Erebus Saddle during the 2004/05 Antarctic field season. The site topography promotes strong winds leading to significant compaction of the surface snow (~0.45 gcm−3). Furthermore, average snow accumulation lies in the range of 72 – 150 cm yr−1 water equivalent. This is more than one order of magnitude higher than the regional average [Bertler et al. 2004a; Bertler et al. 2004b; Bromwich 1988; Bromwich et al. 1998] and provides ideal characteristics for a high resolution ice core gas record. To measure the accumulation rate at the drill site we deployed three snow stakes, which we hope will endure the high wind velocities and snow accumulation.
An automatic weather station has been established near the 2004/2005 ice coring site that records several parameters to help characterise the meteorology and snow accumulation regime of the area (Fig.2).
Parameters measured as of 15 November 2004 are:
To these were added as of 01 December 2005
During the 1999/2000 season three submergence velocity devices [Hamilton and Whillans 2000] for mass balance measurements in the McMurdo Dry Valleys were installed (Fig.3). During the 2004/2005 season two submergence velocity devices have also been installed at EPG (Fig.3). This method is used to determine mass balance by comparing vertical velocity of a marker in firn or ice with long-term, average snow accumulation rates. The movement of the marker is the result of three motions: firn compaction, gravitational glacial flow, and changes in mass balance.
High precision GPS measurements are used to determine absolute position of the tracking point during subsequent years. Trimble 5700 base station and rover unit were used to measure the absolute position of the tracking point of the mass balance devices. At Victoria Lower Glacier, the base station was deployed on a rocky platform at Staeffler Ridge <3km away from all mass
The rate of thickness change H, can then be calculated using [Hamilton et al. 1998]:
where:
H−1)m−2yr−1)−3)−1)−1 with azimuth)
At EPG and VLG I, 1m deep snow sequences were sampled with 1cm resolution for analysis on snow chemistry (Na, Ca, K, Mg, Cl, NO3, SO4, MS, Al, Fe, Si, Sr, Tr, Zn), isotopic composition
To accommodate high accumulation rates of about 2m snow/year, 6m snow stakes that are anchored 2m into the ground were deployed. The three snow stakes, made of epoxy/carbon fibre, have been chosen for their flexibility to withstand high wind velocities in excess of 100knts.
The weather station has only recorded data from 15th Nov 2004 to 1st Jun 2005, when it stopped due to storage limitations but remained operating throughout the winter. The storage limitations have been addressed for future measurements. The recorded data for solar irradiation, air temperature, snow temperature, dew point, and snow accumulation are shown in below (Fig.7).
The time scale is in decimal years; months are indicated on top.
As shown in Fig.7 the decrease in solar irradiance from January to mid April is accompanied by cooling temperatures. Interestingly the temperature increases again from mid April until mid May before cooling once again. A higher frequency temperature variability is superimposed on this trend from mid February onwards with positive temperature deviations on a 4-6 day periodicity with an amplitude of up to 20K. The cause of these warm events could be katabatic outflow from the McKay Glacier portal. Due to the lack of barometric and wind data caused by hardware failure, we will use data from existing weather stations (e.g. Scott Base, Lake Vida, Terra Nova) and satellite imagery to investigate this pattern further. Temperatures in the snow pack measured concurrently at 16 depth horizons from 0.135m to 2.085m show the decreasing influence of air temperature variability with depth. While the temperature in the upper most horizon (starting at 13.5cm arriving in June at 43.5cm) ranges from −2°C to −30°C, at the deepest sensor (starting at 197.5cm arriving in June at 227.5cm) ranges from −17°C to −27°C. The snow temperatures have yet to be corrected for their change in depth, which increased by 30cm as shown in the snow accumulation graph below. The snow accumulation record shows that most of the precipitation occurred during three event of 5 to 15cm snow accumulation. The data show also that are no prolonged time periods of snow loss, except in the first 2-5 days after the snow precipitation event which is partly due to snow compaction. After this time period the snow surface remains stable. Overall, the data confirm EPG as an excellent ice core site. The snow pit data and submergence velocity measurements from EPG and VLG have yet to be processed.
Our preceding research – Holocene Climate History from Coastal Ice – has identified the value of the specific characteristics of ice core records from coastal, low altitude sites [Bertler and 54 others 2005; Bertler et al. 2004a; Bertler et al. 2005a; Bertler et al. 2004b; Bertler et al. 2005b; Mayewski et al. 2005; Patterson et al. 2005] and showed how tropical phenomena, such as ENSO have a significant influence on the Ross Sea Region. In contrast to Antarctica's interior, which is influenced by temperature inversion and climatic cooling of the stratosphere, the coastal sites are dominated by cyclonic activity, and hence by the climate of the lower troposphere [King and Turner 1997]. As a result, coastal sites are especially climate sensitive and show potential to archive local, rapid climate change events that are subdued or lost in the 'global' inland ice core records, such as Vostok. It is those rapid climate change events that are of greatest concern to human civilisation in the near future. The NZ ITASE programme contains five objectives that are scientifically inter-linked to the following programmes.
The main objective of ITASE is to determine the spatial climate variability across Antarctica over the last 200 years, and where possible further back in time. The focus of the New Zealand ITASE group (this proposal) is to provide information from the climate sensitive, low altitude, coastal sites (Fig.8). This will capture the climate signature of the troposphere, which represents a regional account on the Ross Sea climate. Our preceding research showed that while the direct ENSO influence warms the eastern Ross Sea (oceanic forcing), the indirect ENSO influence dominated in the western Ross Sea, leading to the observed cooling in McMurdo Sound Region (atmospheric forcing) [Bertler et al. 2004a; Bertler et al. 2005b]. The comparison with data from other ITASE-nations will allow us to date relative phasing and signal migration velocities of these climate drivers across Antarctica.
Furthermore, the gas record will allow us to determine the role of CO2 and in rapid climate change events and the CO2 and methane source/sink fluxes of the Ross Sea. The isotopic fractionation of biogenic (terrestrial) material is –with the exception of C4 plants – enriched in the lighter 13C isotopes and carries therefore a different signature than ocean derived carbon, which shows no such enrichment [Indermühle et al. 1999; Sigman and Boyle 2000]. For this reason the change of isotopic ratio in CO2 and CH4 can be used to determine the change in sources of GHG concentration through time. This is particular important to determine the role of the oceans versus the atmosphere in rapid climate change [Broecker 2000; Broecker 2003; Ferretti et al. 2005; Schrag 2000; Stocker 1998; Stocker 2002; White 1993] and has the potential to detect influences of early human activities in the late Holocene [Ruddimann 2003].
In conjunction with the US-ITASE traverse of our collaboration partners altitude and continentality gradients across the Trans Antarctic Mountains (TAM) can be established. Temperature and humidity gradients across the TAM are amongst the most extreme on the continent and exceed the latitudinal gradients by more than one order of magnitude. The correlation between the US-ITASE polar plateau traverse (Fig.8) and our data will allow determining the climatic influence of the mountain range and also the position of the Antarctic Vortex, the geographical boundary of tropospheric and stratospheric influence.
Our project is expected to contribute an important data set to the Latitudinal Gradient Project, as it provides a history of temperature, humidity, sea ice cover, precipitation source, atmospheric circulation, and ocean productivity along the Victoria Coast for the last 1000 to 10,000 years depending on the site. This will help to determine whether the current ecological system found has evolved under prevailing climate, or how much time the ecological system had to adjust to potential climate change in the recent past. Furthermore, the timing and velocity of the Ross Ice Shelf retreat some 9 to 5ka years ago is still discussed controversially [Hall and Denton 2000;
Proposed ice core locations no. 2 and 3 (Evans Piedmont and Mt. Erebus) are in the immediate vicinity of planned ANDRILL coring locations (Granite Harbour and Windless Bight). The ice core records will provide a high-resolution climate dataset, which serves as a reference for the younger part of marine record recovered through ANDRILL. This will provide the unique opportunity to compare contemporary on- and off-shore records.
During the 1999/2000 season mass balance measurement devices (submerge velocity method [Hamilton and Whillans 2000; Hamilton et al. 1998]) have been deployed at Victoria Lower Glacier and at Evans Piedmont Glacier during 2004/05. The measurements at Victoria Lower Glacier show that the glacier has a slightly negative mass balance, losing around 12cm thickness per year. A continuation of the measurements will allow monitoring changes in the ablation intensity of the McMurdo Sound Region.
New Zealand's future economic and social development, environmental sustainability, and infrastructural planning relies critically upon the accurate assessment of the impact of "global warming" in our sector of the planet. A joint programme between IGNS, University of Maine, and Victoria University is investigating ice core records from New Zealand (Tasman Glacier and Mt. Ruapehu ice field). The comparison between our NZ and Antarctic ice core records will provide much needed data for the development of realistic regional climate models to predict NZ climate in the 21th Century [Mullan et al. 2001].
Publications since the 2004/05 Antarctic field season include:
2006, Opposing oceanic and atmospheric ENSO influences on the Ross Sea Region, Antarctica:
We would like to thank Antarctica New Zealand staff based in Christchurch and Scott Base for their enthusiastic and innovative support with our project. We are indebt to Helicopter NZ staff, in particular Rob McPhearson. This project is funded by Victoria University of Wellington, Geological and Nuclear Sciences, FRST, and Marsden.