ALBERT

Description: A total of 125 aerosol samples were analysed for their lithium concentrations and deposition flux. Daily aerosol samples were collected from the Pacific Ocean during CLIVAR-CO2 Repeat Hydrography Sections P16 and P2. The P16 section follows 150°-152°W and was divided into two legs, a southern leg from 17°S to 71°S in January-February 2005, and a northern leg from 16°S to 56°N in February-March 2006. CLIVAR-CO2 section P2 from Japan to San Diego, along 30°N, was visited in June-August 2004. The aerosol data from both CLIVAR-CO2 sections include aerosol lithium concentration measured following digestion in HF:HNO3:HCl mixture and corrected for sea-salt contributions (Li xs total), the P16 data also includes aerosol lithium extracted with ultrapure deionised water (≥18 MΩ) by pulling 100 mL of deionised water within ten seconds through the filter (Li xs MQ). Aerosol lithium deposition flux was calculated based on the local rain rate.

Description: The properties of background aerosols and their dependence on meteorological, geographical and human influence are examined using measured spectral aerosol optical depth (AOD), total mass concentration (Mt) and derived number size distribution (NSD) over two distinct coastal locations of Antarctica; Maitri (70°S, 12°E, 123 m m.s.l.) and Larsemann Hills (LH; 69°S, 77°E, 48 m m.s.l.) during southern hemispheric summer of 2007-2008 as a part of the 27th Indian Scientific Expedition to Antarctica (ISEA) during International Polar Year (IPY). Our investigations showed comparable values for the mean columnar AOD at 500 nm over Maitri (0.034±0.005) and LH (0.032±0.006) indicating good spatial homogeneity in the columnar aerosol properties over the coastal Antarctica. Estimation of Angstrom exponent a showed accumulation mode dominance at Maitri (alpha ~1.2±0.3) and coarse mode dominance at LH (0.7±0.2). On the other hand, mass concentration (M(T)) of ambient aerosols showed relatively high values (~8.25±2.87 µg/m**3) at Maitri in comparison to LH (6.03±1.33 µg/m**3).

Description: A total of 603 seawater samples and 125 aerosol samples were analysed for their lithium concentrations. The seawater samples were collected during eight research expeditions. All seawater lithium concentrations were normalised to TEOS-10 absolute salinity of 35 g/kg. Most seawater samples were collected using Niskin bottles and filtered using 0.22 µm filters. Exceptions are samples UW1-UW26 that were collected from the underway water system of RV Kilo Moana during cruise CDisK-IV, and surface water samples from the Red Sea that were collected using a bucket lowered from the deck of a container ship. Samples from cruises SOE09, RS2015 and RS2018 were not filtered. The seawater samples were collected during the following cruises: CDisK-IV from Hawaii to Alaska in 01-30 August 2017; SN105 from Goa to Mauritius, samples collected during 7-16 December 2015; RS2015 from the Bay of Bengal to the Mediterranean Sea, samples collected during 27 December 2015 to 3 January 2016; RS2018 from the Bay of Bengal to the Mediterranean Sea, samples collected during 23-31 March 2018; SOE09 in the Indian sector of the Southern Ocean in 12 January - 21 February 2017; JR274 in the Atlantic sector of the Southern Ocean between 9 January and 12 February 2013; D357 and JC068 sailed from South Africa to South America, mostly along 40°S, cruise D357 in 18 October – 22 November 2010, and cruise JC068 in 24 December 2011 – 27 January 2011. Daily aerosol samples were collected from the Pacific Ocean during CLIVAR-CO2 Repeat Hydrography Sections P16 and P2. The P16 section follows 150°-152°W and was divided into two legs, a southern leg from 17°S to 71°S in January-February 2005, and a northern leg from 16°S to 56°N in February-March 2006. CLIVAR-CO2 section P2 from Japan to San Diego, along 30°N was visited in June-August 2004. The aerosol data from both CLIVAR-CO2 sections include aerosol lithium concentration measured following digestion in HF:HNO3:HCl mixture and corrected for sea-salt contributions (Li xs total), the P16 data also includes aerosol lithium extracted with ultrapure deionised water (≥18 MΩ) by pulling 100 mL of deionised water within ten seconds through the filter (Li xs MQ). The aerosol dataset also includes calculation of lithium deposition flux based on the local rain rate.

Description: A total of 603 seawater samples were analysed for their lithium concentrations. The seawater samples were collected during eight research expeditions. All seawater lithium concentrations were normalised to TEOS-10 absolute salinity of 35 g/kg. Most seawater samples were collected using Niskin bottles and filtered using 0.22 µm filters. Exceptions are samples UW1-UW26 that were collected from the underway water system of RV Kilo Moana during cruise CDisK-IV, and surface water samples from the Red Sea that were collected using a bucket lowered from the deck of a container ship. Samples from cruises SOE09, RS2015 and RS2018 were not filtered. The seawater samples were collected during the following cruises: CDisK-IV from Hawaii to Alaska in 01-30 August 2017; SN105 from Goa to Mauritius, samples collected during 7-16 December 2015; RS2015 from the Bay of Bengal to the Mediterranean Sea, samples collected during 27 December 2015 to 3 January 2016; RS2018 from the Bay of Bengal to the Mediterranean Sea, samples collected during 23-31 March 2018; SOE09 in the Indian sector of the Southern Ocean in 12 January - 21 February 2017; JR274 in the Atlantic sector of the Southern Ocean between 9 January and 12 February 2013; D357 and JC068 sailed from South Africa to South America, mostly along 40°S, cruise D357 in 18 October – 22 November 2010, and cruise JC068 in 24 December 2011 – 27 January 2011.

Description: The Pliocene and Early Pleistocene, between 5.3 and 0.8 million years ago, span a transition from a global climate state that was 2-3 °C warmer than present with limited ice sheets in the Northern Hemisphere to one that was characterized by continental-scale glaciations at both poles. Growth and decay of these ice sheets was paced by variations in the Earth's orbit around the Sun. However, the nature of the influence of orbital forcing on the ice sheets is unclear, particularly in light of the absence of a strong 20,000-year precession signal in geologic records of global ice volume and sea level. Here we present a record of the rate of accumulation of iceberg-rafted debris offshore from the East Antarctic ice sheet, adjacent to the Wilkes Subglacial Basin, between 4.3 and 2.2 million years ago. We infer that maximum iceberg debris accumulation is associated with the enhanced calving of icebergs during ice-sheet margin retreat. In the warmer part of the record, between 4.3 and 3.5 million years ago, spectral analyses show a dominant periodicity of about 40,000 years. Subsequently, the powers of the 100,000-year and 20,000-year signals strengthen. We suggest that, as the Southern Ocean cooled between 3.5 and 2.5 million years ago, the development of a perennial sea-ice field limited the oceanic forcing of the ice sheet. After this threshold was crossed, substantial retreat of the East Antarctic ice sheet occurred only during austral summer insolation maxima, as controlled by the precession cycle.

Description: Warm intervals within the Pliocene epoch (5.33-2.58 million years ago) were characterized by global temperatures comparable to those predicted for the end of this century (Haywood and Valdes, doi:10.1016/S0012-821X(03)00685-X) and atmospheric CO2 concentrations similar to today (Seki et al., 2010, doi:10.1016/j.epsl.2010.01.037; Bartoli et al., 2011, doi:10.1029/2010PA002055; Pagani et al., 2010, doi:10.1038/ngeo724). Estimates for global sea level highstands during these times (Miller et al., 2012, doi:10.1130/G32869.1) imply possible retreat of the East Antarctic ice sheet, but ice-proximal evidence from the Antarctic margin is scarce. Here we present new data from Pliocene marine sediments recovered offshore of Adélie Land, East Antarctica, that reveal dynamic behaviour of the East Antarctic ice sheet in the vicinity of the low-lying Wilkes Subglacial Basin during times of past climatic warmth. Sedimentary sequences deposited between 5.3 and 3.3 million years ago indicate increases in Southern Ocean surface water productivity, associated with elevated circum-Antarctic temperatures. The geochemical provenance of detrital material deposited during these warm intervals suggests active erosion of continental bedrock from within the Wilkes Subglacial Basin, an area today buried beneath the East Antarctic ice sheet. We interpret this erosion to be associated with retreat of the ice sheet margin several hundreds of kilometres inland and conclude that the East Antarctic ice sheet was sensitive to climatic warmth during the Pliocene.