2007 – 2008 US ITASE Field Report
Paul Andrew Mayewski, Gordon Hamilton (University of Maine)
Brian Welch (St. Olaf College)
Introduction: US ITASE is foremost a scientific endeavor that seeks to collect the highest quality scientific data under the safest and most efficient conditions possible. It has been operating successfully as a traverse platform since 1999 for a total of six field seasons and over this period has traversed >8000km.
US ITASE is a multi-disciplinary project that as of the 2007-2008 field season includes six separately funded science projects:
Surface radar (PI Steve Arcone, CRREL)
Surface glaciology and remote sensing (PI Gordon Hamilton, UMaine)
Deep radar (PIs Bob Jacobel and Brian Welch, St. Olaf College)
Ice core chemistry (PIs Paul Mayewski and Kirk Maasch)
Ice core stratigraphy (PI Deb Meese, UMaine)
Ice core stable isotopes (PI Eric Steig, UWashington).
These science activities are coordinated logistically under the umbrella of a science management office (PIs Paul Mayewski and Gordon Hamilton, UMaine)
This report includes a brief introduction to ITASE, US ITASE Phase 1 (1999-2003) and details of the second portion (2007-2008) of Phase 2 US ITASE. Previous US ITASE Annual Field Reports (1999-2000, 2000-2001, 2001-2002, 2002-2003, 2006-2007) describing logistics and science are available at (Field Reports).
Introduction to ITASE: ITASE is a multi-national (21 nations), multi-disciplinary field research program with the broad aim of understanding the recent environmental history of Antarctica and the Southern Ocean. Primary emphasis is placed on collecting records covering the last ~200 to 1000 years of past climate over Antarctica to allow examination of the modern anthropogenic era plus at least the previous 100 years of naturally forced climate. We conduct our research at selected sites to include the two most recent analogs for cold and warm climates, the Little Ice Age and the Medieval Warm Period, respectively.
ITASE evolved from discussions between representatives from several national ice coring programs during a meeting hosted by the European Science Foundation in Grenoble, France in 1990. Twelve nations formulated the original concept (Australia, Canada, China, France, Italy, Germany, Japan, Russia, Sweden, Switzerland, the United Kingdom and the United States) at the suggestion of the US representative to that meeting (P. Mayewski). Scientists from Belgium, Brazil, Chile, Canada, India, Korea, New Zealand, Norway and Poland have since joined the program.
ITASE was formally accepted in 1991 by the overarching international committee for Antarctic research, the Scientific Committee on Antarctic Research (SCAR), as one of its primary initiatives. ITASE is officially recognized as a Scientific Program Group. It was adopted as an IGBP (International Geosphere-Biosphere Program) Project in 1993. The SCAR ITASE Project Office is located at the University of Maine along with the US ITASE Scientific Management Office. Phase 2 of US ITASE (2006-2008) is one of the US contributions to IPY (International Polar Year).
Since the initiation of ITASE, several international workshops have been held for purposes of organization and data interpretation. One of these workshops led to the development of an international Science and Implementation Plan for ITASE (Mayewski and Goodwin, 1997, (see Science Plan). Other international workshops have taken place in Durham, New Hampshire (1999), Potsdam, Germany (2002), Milan, Italy (2003), Bremen, Germany (2005), and Hobart, Tasmania (2006). The next SCAR sponsored ITASE meeting will be held in St. Petersburg, Russia. These workshops have provided important venues for data sharing, concept development, preparation of joint publications, and coordinated logistics planning.
Introduction to US ITASE: US ITASE is effectively a polar research vessel. It offers the ground-based opportunities of traditional style traverse travel coupled with the modern technology of GPS navigation, crevasse detecting radar, remote sensing, satellite communications and multi-disciplinary research. By operating as a ground-based transport system US ITASE offers scientists the opportunity to experience the dynamic environment they are studying. US ITASE also offers an important interactive venue for research through multi-disciplinary interactions similar to that afforded by oceanographic research vessels and large polar field camps, without the cost of the former or the lack of mobility of the latter. More importantly the combination of disciplines represented by US ITASE provides a unique, multi-dimensional (space and time) view of the atmosphere, the ice sheet and their histories (Fig. 1). When US ITASE Phase 1 reached South Pole at the end of the 2002-2003 field season, it had sampled the physical and chemical environment of West Antarctica over spatial scales in excess of 5500 km and 3500 m in depth, and over time periods ranging from several hundred years (at sub-annual scale) from ice cores to thousands of years from geophysical techniques.
Figure 1 � US ITASE multi-disciplinary view of ice and climate over Antarctica. Figure prepared by B. Welch.
A list of scientific products (abstracts, papers, reports) produced by research teams involved in US ITASE is available in: �Toward a High Resolution Southern Hemisphere Climate Reconstruction: Mapping the Antarctic ice sheet in space and time� produced by members of US ITASE available at (Publications/hirespaper).
Among the scientific accomplishments of US ITASE thus far are:
- high resolution detailing of surface and deep radar reflectors as continuous stratigraphic time horizons across the thousands of km of traverse route,
- ice core calibration of radar reflectors in the upper 100 meters of the ice sheet to determine the source of these reflectors,
- mapping of spatial and temporal variability in accumulation rates over large distances using ground penetrating radar, and investigating the causes of these variations,
- examination of physical causes of radar backscatter variations in RADARSAT imagery and other remote sensing validation work,
- examination of spatial variability in chemistry over West Antarctica and relationship to changes in source regions and source strengths,
- ice core reconstructions of seasonal, inter-annual and decadal scale variability in accumulation rate, temperature, atmospheric circulation, volcanic activity, and sea ice extent with climate model validation,
- identification of ENSO (El N�no Southern Oscillation), ACW (Antarctic Circumpolar Wave), PDO (Pacific Decadal Oscillation), EAH (East Antarctic High), and ASL (Amundsen Sea Low) atmospheric circulation structure in glaciochemical time-series with implications for understanding climate over the Antarctic and Southern Ocean,
- assessment of modern global climate change (short-term variability in snowfall, temperature, and atmospheric circulation, pollution) in the context of decadal to centennial-scale climate and sea level change
- deconvolution of local-scale variability in ice core-derived accumulation rate compared to regional scale variability,
- glaciological reconnaissance for deep drilling in West and East Antarctica (inland WAIS deep drilling, Hercules Dome, Titan Dome),
- high resolution mapping of subglacial topography, and subglacial lakes in previously unexplored region and as validation for previous surveys such as SPRI and BEDMAP,
- characterization of ice flow dynamics based on deformation of internal stratigraphy, basal and ice surface topography,
- characterization of basal reflectivity based on changes in basal temperature and/or geology
- identification of zones of basal melting in the interior of West Antarctica and ice stream shear along the coast utilizing satellite-derived (GPS) ice flow measurements,
- air sampling in the interior of West Antarctica,
- snow and firn permeability and microstructure measurements at locations with greatly differing accumulation rates and average temperatures,
- physical property measurements of annual layer stratigraphy, depth/density profiles and crystal growth profiles as a function of age and in situ temperature in snowpits and ice cores, and
- causes of variability in firn stratigraphy including the effects of ice speed, wind and topography.
The results of many of these projects are contained in peer-reviewed papers in a dedicated special volume of Annals of Glaciology (volume 41) plus in several other journals (Publications).
In addition to the foregoing US ITASE and ITASE have been instrumental in producing a document entitled: “State of the Antarctic and Southern Ocean Climate System (SASOCS)” prepared for the Antarctica and the Global Climate System committee of SCAR. This document provides a basis for assessing and understanding future climate change over Antarctica and the Southern Ocean and will be released over the next few months. SASOCS also serves as a building block for an even larger SCAR initiated document entitled: “Antarctic Climate Change and the Environment (ACCE)” that will be finalized by 2009.
The 2007-2008 FIELD SEASON
Field Party Members and brief list of qualifications:
- Dan Breton (Graduate Student, GPS, surface radar, Maine Automated Density Gauge Experiment, high resolution borehole logging measurements, 2nd Antarctic season, UMaine)
- Dan Dixon (Graduate Student, ice core processing oversight and surface snow sampling, 5th Antarctic season, UMaine)
- Gordon Hamilton (PI, GPS, surface radar, accumulation rate, 12th Antarctic season, Associate Professor, University of Maine)
- Elena Korotkikh (Graduate Student, ice core processing and field assistant, 1st Antarctic season, UMaine)
- Paul Mayewski (PI, Field Leader, ice coring, 21st Antarctic season, Director/Professor, UMaine)
- Luci Pandolfi (Cook, oversight for food and water supply, weather obs, WFR, 5th Antarctic season, UMaine)
- Sharon Sneed (Geochemist, ice core processing, 1st Antarctic season, UMaine)
- Nicky Spaulding (Graduate Student, ice core processing and field assistant, 1st Antarctic season, UMaine)
- Joshua Swanson (Lead mechanic (mechanical oversight for Challengers and Pisten Bulley, traverse platform organization, WFR, 7th Antarctic season, 5 winter-overs, UMaine)
- Luke Wagner (Camp organization (weather obs, field communications, aircraft operations, light mechanical equipment maintenance), WFR, 5th Antarctic season, UMaine)
- Mike Waszkiewicz, Driller (oversight for ice core drilling, 5th Antarctic season, Data Logging North and UMaine)
- Brian Welch (PI, deep radar, 5th Antarctic season, AssistantProfessor, St. Olaf College)
Figure 2 � Change in elevation, temperature, wind speed and wind chill during the season.
Note increased wind speeds 8-11 Dec (days 40-43) and 20 Dec (day 52) resulting in two and
one days lost for research, respectively due to poor travel and drilling conditions.
Surface conditions over the traverse route varied from hard packed firn (first half of the route) to soft snow (second half of the route) with alternating regions of variable height (cm to >1m) sastrugi.
Shift Schedule During Travel: During travel the team was divided up into two groups that operated as separate shifts. Each shift required two Challenger 55 drivers, one Pisten Bulley driver, one crevasse detector operator, one shallow radar operator). The deep radar was operated by one person throughout the traverse (B. Welch). After some experimentation with number of shifts per day it was decided that a maximum of 3 shifts would operate per day, Shifts lasted nominally 3 waypoints (10km/waypoint) that averaged out to 4.5-5.5 hours per shift. Following the day’s shifts the team stopped travel, rested for 8 hours, had a hot meal and then returned to travel.
Monitoring Team Member Fatigue: Pulse and oxygen saturation were measured every morning for every member of the team to assess acclimatization to field conditions. Unfortunately the O²/pulse meter was not made available to US ITASE until several days into the field season so only one individual (who arrived later in the season) could be monitored from their season’s start to end.
Team average O² shows a decline with elevation within expected limits. Team average pulse shows considerable variability over time. This variability can be ascribed to a combination of changing work and environmental conditions.
O²/pulse meters are inexpensive and easy to use. They should be standard issue to field teams working at elevation. Previous use by P. Mayewski in high altitude (>20,000’ ) environments has been invaluable in identifying individuals under stress and those likely to suffer from altitude effects.
Route reconnaissance: US ITASE has had considerable success in finding safe crevasse routes utilizing RADARSAT, Landsat and MODIS imagery (G. Hamilton and L. Stearns). During the 2006-2007 season crevasse-like features were encountered several km from site 06-4. Landsat imagery examined following this season revealed the location of these features. Unfortunately Landsat imagery only extends to 82°S and this season’s traverse went from 80 to 90°S. The entire route south of 82°S was crevasse free except for one series of several en echelon crevasses (average width 50-100’) revealed during a Basler reconnaissance flight of the region from site 1 to site 3. This fortunate finding allowed us to correct our route by a few km, sufficient to avoid the crevasses. While satellite imagery is an excellent tool for investigating traverse routes it should always be followed by aircraft reconnaissance.
Environmental Spills: One incident occurred. A Challenger 55 radiator broke at winter–over site (06–4, long 144.6988309, lat 80.30768631) during season start–up resulting in one gallon of glycol spilled onto the snow surface. All of the glycol was recovered with a spill kit and returned to McMurdo prior to departure of the traverse from the site.
Challenger 55s and Traverse Platform Configuration: One forklift–equipped, one plow–equipped; the same units used on previous US ITASE traverses. The plow unit pulled in a single line: one Lehman, one Polar Haven Berco, 3 Siglin sleds, and the Polar Pooper. The fork unit pulled in a single line: one Lehman, one Kitchen module mounted on a Berco, Blue Room (sleeping and science) mounted on a Berco, and the deep radar sled. Both 55s operated well this season although they are beginning to show wear. The plow 55 has been in the field since 2000 and the fork since 2001. Throughout phase one, the Challengers were almost new, but since their introduction to the field they have traveled ~8000 km with US ITASE and >1500km with LGT RPSC oversnow traverse. See “Mechanic’s Repair” section later on this report for details of repairs and the mechanic’s (Josh Swanson) recommendations.
Spreader Bars: Spreader bars were introduced to the traverse platform at the onset of the 2006–2007 season by the RPSC camp manager at that time. Spreader bar construction and related complications resulted in US ITASE losing several weeks of work. The spreader bars were introduced to reduce sled drag by spreading out sled loads and by reducing re–use of sled tracks. This system has apparently worked well for the SPIT traverse. However, the SPIT traverse has operated largely over the Ross Ice Shelf and apparently does not use spreader bars on the plateau due to issues related to sastrugi (G. Blaisdell, pers. comm. 2007 US ITASE out brief). As it turns out spreader bars enhance sled torque in sastrugi regions and as demonstrated by US ITASE in 2006–2007 create unsafe conditions for individuals riding in modules towed on the ends of spreader bars in sastrugi fields. For the first half of the 2007–2008 season we configured one train in line and one utilizing a spreader bar primarily because the Siglin sleds were not equipped (as requested) with rear towbars. Once we encountered softer snow (midway on the traverse) the in–line train performed well and the spreader bar train was repeatedly stuck requiring extrication by double–teaming the two Challengers. In addition following storms the spreader bars posed additional digging challenges because they are wider than the rest of the train. Further the spreader bar skiis were poorly constructed and they dug into the snow acting as anchors. In summation, the spreader bars wasted time at the onset of 2006–2007 and have served as little more than additional weight plus something extra to have to drag and deal with on traverse. It is unfortunate that so much US ITASE time and effort was wasted on the spreader bars.
Pisten Bully (PB): As of 2006 the PB has served as lead vehicle for the traverse since it houses the crevasse radar. The PB is highly maneuverable and has proven to be an excellent vehicle for the task. It was also excellent for conducting deep radar traverses around ice core sites. The mechanic’s report (later in this section) suggests that the PB be returned to McMurdo for overhaul this season.
Generators: Qty 2 diesel 12kw (primary camp energy supply, second unit for back-up) for heating of the kitchen and Blue Room plus powering the snow melter and the Eclipse drill plus other lesser uses (e.g. recharging batteries). Qty 1 gasoline 5kw (back–up power – never used). Qty 2 gasoline 2kw (primary use deep radar). Qty 1 gasoline 1kw (radar back up).
Use of the 12kw generators during the 2007-08 season reduced dependence on less safe systems such as propane and increased available power. A make–shift chimney was built in the field to divert generator fumes from shelters. This system requires upgrade.
Fuel Consumption: AN8 usage for two Challenger 55s, one Pisten Bully, two 12kw generators.
Aircraft support: US ITASE was supported this season primarily by Basler and by Twin Otter for delivery of small items. The Basler provided support for all put-in requirements, fuel caching, and pick up of expended fuel drums. The Basler is a perfect aircraft for traverse support.
Food: Food quality was excellent this season. Luci Pandolfi prepared hot dishes for all three daily meals.
Shelters (Blue Room, Kitchen, Polar Haven): The same Berco mounted shelters available during previous US ITASE traverses were available this season. As reported in previous field reports the Kitchen and Blue Room while adequate for their purpose are far heavier than necessary and both shelters are extremely top heavy.
The Blue Room and Kitchen shelters are attached to Berco sleds by a small number of bolts that have regularly sheared or fallen out. More substantial attachments were requested following the 2006-2007 season, but no repairs were made during the put–in phase of 2007–2008.
Lehman Sleds: Qty two Lehman sleds were provided for the 2006 traverse. As in the past they were used for the heaviest loads (e.g., fuel drums) and served well.
Berco Sleds: Qty three Berco sleds were available for the 2007 traverse. As in the past the Berco sleds did well. The state of the rear hitches turned out to be a major issue in 2006–2007 and we had one failure this season. The rear hitches are designed to fail under excessive stress to save the Berco frames. One Berco rear hitch failed in 2006–2007 after having traveled >8000km. Rear hitches for each Berco were replaced, by US ITASE team members at the start of the 2007–2008 season.
Plastic sleds: Qty three Siglin designed plastic sleds were specially ordered for the 2006–07 traverse. Their intended purpose was to be for light–weight transport (e.g., empty fuel drums and air drop materials). The Siglins turned out to be excellent even for heavier loads (up to 12,000 lbs) once equipped with pallets and draw bar chains attached to the pallets. Although two pallets failed and one Siglin was slightly damaged the concept of plastic sleds proved to be very promising and four heavy–duty plastic sleds equipped with heavy–duty tow bars and rear hitching capability were requested for the 2007 season. The three 2006–07 sleds were upgraded. These sleds are relatively inexpensive compared to Bercos and Lehmans and can be shipped in pieces (although the bolt holes for assembling the sleds in the field should not be pre–drilled since the pieces have different rates of thermal expansion). For this season the Siglins were reinforced structurally. Unfortunately, lightweight carriage bolts were employed and several bolts failed necessitating stops to rip away the structural segments damaged after bolt failure. The design for the structural reinforcement seems to be successful but the quality of materials and repair were inadequate.
Mechanic’s Repairs (prepared by Josh Swanson):
- Eberspacher heater unit 12 volt. Both Fork and Dozer Cat units failed and were replaced in 2007.
- Old unit from Fork Cat needs a glow plug. It is reboxed and good for spare parts.
- Grid heater failed on the PB 11–2007 and was replaced. If a PB is used with this train again that part should be re–inventoried.
- One 25 volt coolant heater failed on the PB and was replaced.
- PB front axle has a crack on the top left gusset on the left side of vehicle. Needs a new front axle or repair by cutting a V and welding shut.
- Voltage regulator sent out for Onan generator when installed to fix an over charge on the DC side of 15.5 volts. After installed DC charger was back in range to 13.2 volts. But the AC volt range was 136–145 volts when adjusting by the dial.
- The Boom for the Ground Penetrating Radar on the front of the PB had a few failures. First one Rune tower was bent due to using the winch and the new front sled being far too heavy to be lifted. It broke apart en route and was replaced with a new extension at drill site 1. Then the front bracket broke due to the extra stress from the added leverage and weight that the new GPR sled added. This was fixed by strapping the boom directly to the plastic sheet. It appears to have been a solid fix.
- Siglin upgrade failed in route to site 2. The under plate appears to have caught a strong piece of ice shearing the carriage bolts on the right side and wrapping the metal under the sled. The upgrade was removed and the sled was used as a light haul only sled. Two rear plates were ruined later in the season with the same result. One had no weight on the rear so possible sled flex caused the weak carriage bolts to break. Recommend if this upgrade is wanted for future traverses with Siglins to use grade bolts and more of them.
- Another Siglin sled split at the welded seam in the middle. This happened last year as well on a different Siglin, same left side. Repaired by drilling end of crack and bolting in rubber strips to hold the split ends together. This sled was hauling a light load of food boxes. Last year it was a heavy load of fuel barrels.
- Magneto failed on a Herman burner. It was replaced. The spark plug insulation to the burner failed as well causing spark in wrong location or not at all and was replaced.
- Rear wiper arm replaced on Dozer Cat.
- Starter relay replaced on Dozer Cat.
- Coolant radiator and fan replaced on Dozer Cat.
- Throttle cable on fork Cat was not moving up or down. Removed and warmed up cable which freed it to move again. Water found a way in and froze it unmovable. Added alcohol in sleeve to help remove any left over moisture and to help keep from happening again.
PB should go back to MCM to be torn apart and inspected for cracks. Have a complete full pm done including calibrations of hydraulic pressures and synchronizing of moog units. Inspection for frame cracks and cracks in axles. Bogie wheels removed and bearings inspected, replaced or repacked.
The Challenger 55s need a thorough go through. Leak down test of engine, undercarriage measurements. Track replacement and full fluids change. Batteries are old and working fine but replacement would add reliability if used on traverse again.
Fork Cat has an exhaust leak on the manifold. It has been leaking since I started with ITASE last year. Parts are here and ready to be installed. Didn’t install in field due to fear of studs breaking and not being able to get them out with tools here. Decided it best to be done in a warm shop with easy outs and other tools to remove broken studs from head.
Dozer Cat needs a hydraulic cable installed from lever to valve body. It is on hand. Wasn’t a priority in field since I changed hoses to a different lever control valve. Due to time restraints it may or may not be done in the field.
Communications: Primary communications this season were made using Iridium phones. HF base stations were used between vehicles and VHF for close heavy equipment use.
Deep Radar: (prepared by B. Welch, St. Olaf College): The radar system was essentially the same as previous years. Some requests for improvements to the radar sled and shelter were made this year:
Figure 3: ICDS ice core box converted for
use as an insulated generator box. Exhaust
vent is shown with metal duct tape to protect
box. Air intake vent is hidden behind strap.”
- Solution to generator problems of 2006
- Surging and stalling of generator motor. Two new Honda 2 kW generators were purchased. These did not solve the problem alone and continued stalls meant the loss of 15 km of radar data along the traverse route and delays. Josh Swanson diagnosed the problem as icing in the carburetor, so an insulated box was made from a spare ICDS ice core box (Fig. 3). Small holes for exhaust and air intake allowed for ventilation and could be covered when not in use. The generator was stored in the heated Blue Room at night. This solution: keeping the generator warm when not in use and running in the insulated box, seemed to resolve the problem of stalling in temperatures below −30°C.
- The original request was for a diesel generator to reduce electrical noise that interferes with the radar signal reception. The hope was that the Honda generators with the RF �chip� would solve the problem. This year�s data proves that the RF chip does NOT reduce RF noise even to the level of the old Honda 1.8 kW alternator–type generator. While it�s possible that the newer inverter–type generator might work for relatively shallow surveys (<1,500 m ice thickness), they reduce the signal/noise too much for use in deeper ice surveys. Alternator–type gasoline generators or solar–powered systems should be used for deep surveys.
- Solar power for receiver computer was still inhibited by the lack of new reliable 100 amp–hr batteries (all were tasked to the power systems in the shelters). The solar panels and charge controller were used to assist in charging the smaller 35 amp–hr batteries for the transmitter. At least one of the new (�Vessel 2007�) 35 amp–hr batteries never held a charge. It might be necessary to look into solar charge controllers that are compatible with the new AGM batteries since they have a different voltage range than the older gel–cells.
- A suspension system for the radar shelter was requested last year in order to protect the radar equipment from the large sastrugi found on the plateau. A request for pneumatic air pillows (e.g. Firestone or Goodyear) was turned down based on concerns about temperature. Three ATV tires with inflated inner tubes were sent out to the winter–over site. These were sent back because there was no way to install them under the shelter in a manner that would distribute the weight properly. Josh Swanson (ASE–certified in suspension systems) believes that the pneumatic air suspensions should be just as reliable as tire inner tubes at cold temperatures. The addition of stabilizer bars would help keep the shelter in place.
Suggestions for US ITASE Platform as of 2007 season end:
As recommended by J. Swanson (mechanic) we suggest that the PB be returned to McMurdo for inspection and overhaul. The PB worked well for two seasons, but it is a fairly delicate vehicle and prone to fractures that are best inspected and repaired in a warm shop.
Swanson also recommended a complete inspection and overhaul of the two Challenger 55s. To return these vehicles to McMurdo will require considerable effort since the 55 cabs must b e partially deconstructed. If these vehicles are to be used away from stations on future traverses they must be carefully inspected and given significant overhauls. This is well worth the time and cost since the vehicles served their purpose. Ideally mechanics should be deployed to South Pole to conduct inspection/overhaul there allowing these vehicles and their accompanying traverse sleds to remain as complete platforms. To reassemble these platforms requires considerable time, experience and care.
The traverse trains (Lehmans, Bercos with modules) should be left at South Pole intact. They are not the perfect traverse platform, but they are highly functional for certain activities.
US ITASE Phase Two traveled from Taylor Dome to South Pole (Fig. 4). During the 2007-2008 season US ITASE traveled 1200 km from the 2006-2007 winter-over site (06-4) to South Pole. For details of the traverse route coordinates see ITASEWaypointsScience.xls attached to this report.
Figure 4 � US ITASE route in red and work sites (yellow triangles). Note also location of crevasses discovered on aerial reconnaissance. Original traverse route was changed slightly to avoid these crevasses. Click on figure for larger version.
Fig. 5 is a summary of science products resulting from this season. Details are provided in the following text.
Figure 5 � Science products as a function of traverse distance.
Crevasse radar: Conducted in parallel with all travel.
Shallow radar: Firn stratigraphy in the upper ~100 m of the ice sheet was imaged using a 200 MHz Ground Penetrating Radar (GPR) system. The system operated continuously along the entire traverse route, and several local profiles were collected at each ice core site.
Deep radar: The 3 MHz (deep) radar collected data along all but 15 km of the traverse route, plus local profiles at each of the ice core sites for a total of more than 1300 km of data. Ice thickness ranged from 1500 to 3100 m and internal stratigraphy was detected to depths up to 2750 m. At least one subglacial lake was found along the traverse route just north of Titan Dome.
Ice coring: Ice coring was conducted using both the 2” Rongbuk and the 3” Eclipse drill. The Rongbuk drill was used for recovery of shallow cores (<25m) dedicated to studies described below under surface glaciology. The Eclipse drill was used to recover cores up to 100m depth at four sites (Fig. 4). At all sites the cores represent at least 200 years and more probably several hundred to >1000 years of record at some sites. Stratigraphy was conducted on all ice cores recovered this season.
Surface snow sampling: Surface snow sampling was conducted at 30 km intervals along the 2007–2008 traverse route and every 10k between site 07–4 and South Pole (Fig. 6). This sampling consists of IC/isotope and ICPMS sample collection at the surface, 0–5cm and 0–15m. This data is part of a continent wide ITASE surface sampling scheme that has already demonstrated the spatial distribution of major ions and stable isotopes over Antarctica.
Figure 6 � Surface snow sampling coverage for Phase 2 US ITASE (Taylor Dome to South Pole).
Surface Glaciology: Geodetic–quality kinematic GPS data were recorded continuously along the traverse route for the purpose of characterizing ice sheet surface elevations and for geolocating radar data. Three mass balance measurement sites (“coffee cans”) were installed at ice core sites (each site consists of 4–5 markers at depths from 4–25 m). Novel geophysical techniques were used to investigate properties of the surface firn. MADGE (Maine Automated Density Gauging Experiment) uses a high–energy nuclear source to make fine resolution (~3 mm) measurements of density along cores collected with the 2” drill. A second instrument, deployed down the boreholes, makes in situ measurements of borehole wall strength (an indicator of possible locations of missing core, reflectivity (an indicator of grain size), and temperature.
US ITASE 1999-2008 Summary
Since 1999 US ITASE has traversed >8000 km throughout West and East Antarctica (Fig. 7) and collected a total of 3945m of ice core. Together with six shallow cores collected as part of LGT, US ITASE has conducted scientific investigations (ice coring, surface glaciology, radar) at 45 sites and radar (crevasse, shallow, and deep) along almost all of the US ITASE routes. US ITASE has therefore sampled the ice climate record surrounding the Ross Ice Shelf and hundreds of km inland. US ITASE has now completed six field seasons of multi–disciplinary research setting a new benchmark for Antarctic climate multi–disciplinary research