Ice coring 2008-2009 (Law Dome W10k, Mill Island PICO, Totten PICOs)

Full description

Metadata record for data from AAS (ASAC) project 3025.

Public
An ice core drilling expedition is proposed for Aurora Basin, between Law Dome and Dome C. This will provide a climate record in excess of 2000 years and will be used to compare coastal and inland Antarctic records. This will improve interpretation of ice core climate records and increase our knowledge of the role of Antarctica in the global climate system.

Project objectives:
The overall goal for this project is to recover a 2000 year plus climate record from a site ('GC41') in Aurora Basin, inland East Antarctica.

The project aims to achieve a number of objectives:
1 To provide a new, high resolution accurately dated, ice core climate record (greater than 2000 years) from the sparsely explored Aurora Basin region in the East Antarctic sector;

2 To gain an improved synthesis of the regional climate signals through better connection between the Law Dome (coastal) and EDC (inland) climate records in the pre-industrial late Holocene and into the period of anthropogenic climate change;

3 To provide better interpretation of ice core records through comparison of deposition and preservation mechanisms from the high accumulation coastal zone through to the low accumulation interior;

4 To contribute towards locating a site for drilling a very old record, in excess of 1 million years;

5 Finally, although not an objective with immediate scientific return, this project is designed to demonstrate and develop remote ice coring logistical capabilities using Australia's new combined inter-/intra-continental air transport system.

Taken from the 2008-2009 Progress Report:
Progress against objectives:
Ice core drilling at Aurora Basin (site GC41) was not achieved, however ice cores were recovered from Law Dome (site W10k, 127m; site DSS 10m), Mill Island (site MI 17m) and Totten Glacier (site TOT1 17m; TOT2 15m).

(a) Planning changes prior to getting into the field The shortened flying season due to a medical incident at Davis initially led to a clash for limited C212 resources on Casey station between the proposed ABN project and other C212 operational requirements. A modified ABN project was proposed and accepted with the following changes:
- No mid-season changeover of personnel (this essentially ended the participation of the international field personnel)
- Lighter camp requiring less C212 deployment flights (we removed all field-based ice core processing tasks and consolidated our living arrangements, reducing power requirements and therefore fuel, generators and tents)
- Shortened our field season requiring less fuel/food (again removing ice core processing allowed for a faster drilling rate)

This proposed modified project would achieve the primary goal of retrieving an ice core, however it lost two very important components:
- International field participation (4 persons, Denmark and USA)
- Field based ice core processing

(b) Planning changes on getting into the field All 8 ABN field personnel arrived at Casey station on 1st December 2008. At Casey a number of reconnaissance flights and a skidrag were undertaken to Aurora Basin, however, we could not access our original GC41 drilling site. The topography at the site was considered too rough to land an aircraft. The surface was very different than that from reconnaissance in 2006/2007 and may have been due to un-seasonal storm activity in the area. Further reconnaissance in the area failed to find a suitable landing site. These operational reasons led to withdrawing of the ABN project for 2008/2009.

Taken from the 2009-2010 Progress Report:
This year was spent processing and analysing the ice cores collected in the 2008/2009 field season. As stated in last years progress report (AAS 3025), this analysis was reported on in AAS 757, and will also be reported on here. This will result in duplication between this report and progress reported on in AAS 757.

Approximately 80% of the core processing and analysis has been achieved, including the handling of just over 19,000 samples.

Lineage

Progress Code: completed

Statement: The values provided in temporal and spatial coverage are approximate only. Taken from the 2008-2009 Progress Report: Variations to work plan or objectives: Project AAS 3025 was varied from the original plan to drill an ice core at Aurora Basin. For operational reasons, we could not access our original GC41 drilling site on Aurora Basin. The topography at the site was considered too rough to land an aircraft. Further reconnaissance in the area failed to find a suitable landing site. Consequently, a modification to the project (AAS 3025) was submitted and approved to retrieve an ice core from Law Dome, Totten Glacier and/or Mill Island. Our revised aims were: (i) To collect an intermediate depth ice core at W10k to at least 110m (~200 years). (ii) To collect shallow cores (10-15m) at either or both Totten Glacier and Mill Island. (iii) If possible, to collect ice samples for AAS project 3064 at DSS on Law Dome. Law Dome was accessed by traverse from Casey and three ice cores were collected (127m Hans Tausen ice core at W10k; a 10m PICO ice core at DSS and W10k sites). Totten Glacier and Mill Island were accessed using C212 aircraft and three ice cores were collected (17m PICO ice core at Mill Island; 17m and 15m PICO ice cores at Totten Glacier). Samples were also taken for AAS project 3064. Summary of achievements against revised aims: (i) Our aim was to drill at least 110m on Law Dome at a site 10 km (W10k) to the west of our deep ice core site (Dome Summit South DSS). We drilled to 127m (in 5 drilling days) and we had no major problems with the drill and the core quality was excellent. This will provide a 250 year record from a site with intermediate accumulation on Law Dome. This will compliment our records from DSS and W19k. At a minimum we needed to drill to around 200 years before present to a volcanic layer from the Tambora eruption (1815). This will give us accurate dating and accurate mean snow accumulation rate to compare with DSS and WS19k. We intend to send this ice to Joe McConnell's lab for analysis (consistent with existing project 3025) and compliment with our in-house analysis of trace chemistry and stable isotopes. This project also provided a unique opportunity to test, and train with, the Danish Hans Tausen (HT) ice core drill and training our staff with ice core drilling and looking at succession. As a stepping stone for Aurora Basin ice core drilling, we achieved a lot including, staff training, camp experience, grooming a skiway, flight landing operations, weather observations and air ground support. (ii) A great effort from the Casey logistics coordinators, station leader and expeditioners, and in particular Skytraders ensured success achieving more than we originally aimed. Two ice cores were recovered from the Totten Glacier - upper (15m) and lower (17m) Totten (Table 1). These will be used to look at accumulation changes over the past decade to investigate why the Totten is thinning. These results will feed into models, and will provide valuable information to the ICECAP project on why the Totten is thinning. A shallow ice core (17m) was also collected from Mill Island which will be a valuable pilot study towards drilling a deeper record at this site in 2009/10 (AAS project 1236). At all sites, deeper cores were recovered than we hoped for, which gives us a longer and therefore better record to work with. All assistance for this work was greatly appreciated. (iii) An opportunity to collect ice cores and snow pit samples for AAS project 3064 was taken. All samples required for this project were collected at the required site (DSS) and according to the work plan listed in AAS 3064. Field work: Table 1 Details of ice cores drilled in season 2008/2009 in the Casey region: Site Drill date Depth (m) ~age elevation (m) lat long AAS DSS 0809 W10k 18/12/2008 127.00 250 1242 66o 46'10.56"S 112o 34'47.76"E 3025/757 DSS 0809 pW10k 14/12/2008 1.83 3 1242 66o 46'10.56"S 112o 34'47.76"E 3025/757 DSS 0809 p2W10k 16/12/2008 9.75 13 1242 66o 46'10.56"S 112o 34'47.76"E 3025/757 DSS 0809 29/12/2008 10.43 6 1263 66o 49'60.00"S 112o 49'60.00"E 3025/757 DSS 0809 P1 29/12/2008 5.67 4 1263 66o 49'60.00"S 112o 49'60.00"E 3064 DSS 0809 P2 29/12/2008 5.79 4 1263 66o 49'60.00"S 112o 49'60.00"E 3064 DSS 0809 P3 29/12/2008 5.90 4 1263 66o 49'60.00"S 112o 49'60.00"E 3064 DSS 0809 pit 29/12/2008 0.75 0.4 1309 66o 43'46.56"S 112o 50'5.28"E 3064 DSS 0809 pit pico 29/12/2008 1.02 0.5 1309 66o 43'46.56"S 112o 50'5.28"E 3064 Totten Glacier 1 1/01/2009 17.45 10 89 66o 59'49.90"S 116o 0'11.50"E 3025/757 Totten Glacier 2 30/01/2009 15.33 9 528 67o 26'31.62"S 113o 32'27.66"E 3025/757 Mill Island 22/01/2009 16.69 15 338 65o 33'25.02"S 100o 33'26.46"E 3025/757 Laboratory activity/analysis: The core collected this season will be analysed and reported against AAS 757 Difficulties affecting project: Ice core drilling at Aurora Basin (site GC41) was not achieved, however ice cores were recovered from Law Dome (site W10k, 127m; site DSS 10m), Mill Island (site MI 17m) and Totten Glacier (site TOT1 17m; TOT2 15m). Details given in Table 1.

Notes

Purpose
To obtain and analyse ice cores from Law Dome (site W10k, 127m; site DSS 10m) Mill Island (site MI 17m) Totten Glacier (site TOT1 17m; TOT2 15m). These work contribute to the Polar Ice Coring Office (PICO).