Law Dome Summit Snow-Climate Observatory

This project has successfully continued to extend and update the time-series of ice core chemical and physical measurements at Law Dome, Dome Summit South (DSS) ice core site. This has been completed through repeat visits to Law Dome to drill and collect shallow overlapping ice cores and subsequent completion of chemical and physical measurements to extend and update the DSS ice core record that now spans the time-period 1990 to 2022.

The new and extended measured high resolution ice core records at DSS in conjunction with meteorological records has further enabled improved calibration of ice core data and interpretations used in ice core studies; enabled validation and comparison of ice core records with climate reanalysis data; enabled the DSS ice core records and other East Antarctic ice core records to contribute to reconstruction of regional, continental and hemispheric climate (e.g. temperature, snow accumulation); and has also enabled the use of high resolution ice core records to explore, quantify and determine the natural variability of climate processes and climate modes (e.g. rainfall and streamflow reconstructions for Eastern Australia, El Nino-Southern Oscillation (ENSO) and Interdecadal Pacific Oscillation (IPO)).

During the 2022/23 Australian Antarctic Program (AAP) season the following scientific advancements were achieved:

- The analysis, interpretation and synthesis of the calibrated DSS time-series proxy data continued during 2022/23 through other linked Australian Antarctic Science projects.

- The completed analytical measurements on the Law Dome, Dome Summit South (DSS) ice core collected during the 2021/22 AAP season were shown to:

i. Extend the time-series of ice core chemical and physical core measurements and covers the time-period 2012 to 2022; and to

ii. Overlap with the DSS ice core collected in 2016/17 AAP season that covers the time-period 1990 to 2017.

- The updated and extended DSS ice core record has been used to:

i. Compare and correlate sea salt concentrations with eastern Australian rainfall to show there is a clear alignment with dry and wet periods over eastern Australian.

ii. Present 2000 years of annual ice core data from Law Dome, DSS, East Antarctica. Ice core chemical and physical measurement have been used to update and extend previously published DSS ice core results with improved and extended annual dating.

- The project was included in the 2022/23 AAP season even though project was to conclude in 2021/22. The proposed field work to Law Dome DSS ice core site during the 2022/23 AAP season did not proceed. The decision not to participate in the AAP season was requested to relieve pressure on logistical and station support as discussed with different AAD sections.

During the 2021/22 Australian Antarctic Program season the following scientific advancements were achieved:

- The project team travelled to Law Dome – Dome Summit South (DSS) and recovered a 12-metre ice core.
- The updated Law Dome DSS ice core record from the 2016/17 season extends the time-series of ice core chemical and physical core measurements and covers the time period 1990 to 2017.
- The updated and extended DSS ice core record has been used to compare sea salt concentrations with the recently drilled Mount Brown South ice core to further explore the signal of the El Niño–Southern Oscillation; to extend the snow accumulation record and derive a 2000 year rainfall reconstruction for South West Western Australia; and to enable a comparison of 150 years of observations of the Interdecadal Pacific Oscillation (IPO), and to reconstruct a 2000 year IPO index from Antarctic ice core records.

During the 2016/17 Australian Antarctic Program season the following scientific advancements were achieved:

- Project investigators travelled to Law Dome – Dome Summit South (DSS) and recovered a 31-metre firn core. The firn core updates and extends the valuable DSS ice core record to 2017 and provides a means to extend the calibration of ice core chemical and physical measurements against meteorological records.

- Different shallow ice core drilling systems were tested and ice core drilling training was completed.

- The updated Law Dome DSS record from the 2015/16 season has extended the time-series of ice core chemical and physical core measurements. This 7-metre firn core covers the time period 2012 to 2016.

- DSS firn core and surface snow samples have been used to validate a new proxy record for the reconstruction sea-ice extent.

During the 2015/16 Australian Antarctic Program season project investigators travelled to Law Dome – Dome Summit South (DSS) and recovered a 7-metre firn core. The firn core updates and extends the valuable DSS ice core record to 2016 and provides means to extend the calibration of ice core chemical and physical measurements against meteorological records.

The updated Law Dome DSS record from the 2012/13 season has extended the time-series of ice core chemical and physical core measurements. The extension of the ice core proxy records has enabled the further calibration studies of ice core proxies against meteorological records. The extended ice core record has been used to reconstruct 1013 years of rainfall (1000-2012 CE) in eastern Australia (Tozer et al., 2016), and provides an updated direct estimate of recent snow accumulation at the DSS site, where we have a high fidelity record that extends back 2000 years (Roberts et al, 2015).

During the 2012/13 Australian Antarctic season project investigators travelled to Law Dome – Dome Summit South (DSS) and successfully drilled a 30-metre ice core in East Antarctica, bringing home a single continuous climate record from the Law Dome site.

This ice core will be used to extend the calibration of ice core chemical and physical measurements against meteorological records. This will further enhance the value of ice core proxy records used for exploring climate processes and forcing for the Law Dome Summit Snow-Climate Observatory monitoring project. The information from the ice cores is gained by sampling ice from the different sections of the core and measuring chemical and physical properties. The 30-metre ice core holds information going back about ~30 years.