Abstract. Small changes in the radiation budget at the earth's surface can lead to large climatological responses when persistent over time. With the increasing debate on anthropogenic influences on climatic processes during the 1980s the need for accurate radiometric measurements with higher temporal resolution was identified, and it was determined that the existing measurement networks did not have the resolution or accuracy required to meet this need. In 1988 the WMO therefore proposed the establishment of a new international Baseline Surface Radiation Network (BSRN), which should collect and centrally archive high-quality ground-based radiation measurements in 1 min resolution. BSRN began its work in 1992 with 9 stations; currently (status 2018-01-01), the network comprises 59 stations (delivering data to the archive) and 9 candidates (stations recently accepted into the network with data forthcoming to the archive) distributed over all continents and oceanic environments. The BSRN database is the World Radiation Monitoring Center (WRMC). It is hosted at the Alfred Wegener Institute (AWI) in Bremerhaven, Germany, and now offers more than 10 300 months of data from the years 1992 to 2017. All data are available at https://doi.org/10.1594/PANGAEA.880000 free of charge.

[1] On the basis of the quantitative study of diatom, radiolarian, and planktic foraminiferal assemblages, we estimated summer sea surface temperature (SSST) and sea-ice extent at 50 sediment core localities in the Atlantic and western Indian sector of the Southern Ocean to reconstruct the last glacial environment at the GLAMAP (18 to 15 ka, equal to 21,500 to 18,000 calendar (cal) years BP) and EPILOG (19.5 to 16.0 ka, equal to 23,000 to 19,000 cal years BP) time slices. Stratigraphic identification of the time slices was accomplished by a combination of AMS 14 C measurements, benthic isotope, and siliceous microfossil abundance records. While the SSST estimates reveal greater surface water cooling than reconstructed by CLIMAP [1981], reaching a maximum in the area of the present Subantarctic Zone, the sea-ice reconstruction indicates that CLIMAP overestimated the expansion of the Antarctic sea-ice field, especially for austral summer. During winter the seaice field was expanded by 60-70% compared to the present. Last glacial summer sea surface isotherms indicate a northward shift of the zonal bands of the Antarctic Circumpolar Current and a relative expansion of the cold water realm south of the Subantarctic Front by $5°in latitude. This coincides with a northward displacement of the zone of enhanced biogenic silica deposition and iceberg occurrence. As a result of northward expansion of Antarctic cold waters and a relatively small displacement of the Subtropical Front, thermal gradients were steepened during the last glacial in the area of the present Subtropical Front. The northward displacement of Antarctic cold waters and the related deflection of Southern Ocean waters along the eastern boundary of South America may have resulted in a weakened ''cold water route'' across the Drake Passage. In contrast, the transport of warm and salty surface water from the Indian into the Atlantic Ocean via the ''warm water route'' was not blocked allowing continuous but reduced import of heat into the South Atlantic.

The marine sedimentary record in Kejser Franz Joseph Fjord and on the East Greenland continental margin contains a history of Late Quaternary glaciation and sedimentation. Evidence suggests that a middle-shelf moraine represents the maximum shelfward extent of the Greenland Ice Sheet during the last glacial maximum. On the upper slope, coarse-grained sediments are derived from the release of significant quantities of iceberg-rafted debris (IRD) and subsequent remobilization by subaqueous mass-flows. The middle-lower slope is characterized by hemipelagic sedimentation with lower quantities of IRD (dropstone mud and sandy mud), punctuated episodically by deposition of diamicton and graded sand/gravel facies by subaqueous debris flows and turbidity currents derived from the mass failure of upper slope sediments. The downslope decrease of IRD reflects either the action of the East Greenland Current (EGC) confining icebergs to the upper slope, or to the more ice-proximal setting of the upper slope relative to the LGM ice margin. Sediment gravity flows on the slope are likely to have fed into the East Greenland channel system, contributing to its formation in conjunction with the cascade of dense brines down the slope following sea-ice formation across the shelf.Deglaciation commenced after 15 300 14C years BP, as indicated by meltwater-derived light oxygen isotope ratios. An abrupt decrease in both IRD deposition and delivery of coarse-grained debris to the slope at this time supports ice recession, with icebergs confined to the shelf by the EGC. Glacier ice had abandoned the middle shelf before 13 000 14C years Bp with ice loss through iceberg calving and deposition of diamicton. Continued retreat of glacier-ice from the inner shelf and through the fjord is marked by a transition from subglacial till/bedrock in acoustic records, to ice-proximal meltwaterderived laminated mud to ice-distal bioturbated mud. Ice abandoned the inner shelf before 9100 14C years BP and probably stabilized in Fosters Bugt at 10 000 14C years BP. Distinct oxygen isotope minima on the inner shelf indicate meltwater production during ice retreat. The outer fjord was free of ice before 744014C years BP. Glacier retreat through the mid-outer fjord was punctuated by topographically-controlled stillstands where iceproximal sediment was fed into fjord basins. The dominance of fine-grained, commonly laminated facies during deglaciation supports ablation-controlled, ice-mass loss.Glacimarine sedimentation within the Holocene middle-outer fjord system is dominated by sediment gravity flow and suspension settling from meltwater plumes. Suspension sediments comprise mainly mud facies indicating significant meltwater-deposition that overwhelms debris release from icebergs in this East Greenland fjord system. The relatively widespread occurrence of fine-grained lithofacies in East Greenland fjords suggests that meltwater sedimentation can be significant in polar glacimarine environments. The icedistal continental margin is characterized by meltwater sedim...

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Ehrmann, W.U., Melles, M., Kuhn, G. and Grobe, H., 1992. Significance of clay mineral assemblages in the Antarctic Ocean.Mar. Geol., 107: 249-273. 249Typical examples from different morphological and geological settings in the Antarctic Ocean are reviewed in order to discuss the value of clay mineral assemblages for reconstructing the glacial history of Antarctica, the paleoceanographic history of the Antarctic Ocean and the sedimentary processes at the Antarctic continental margin. The significance of clay minerals for paleoenvironmental reconstructions strongly varies with both the position of the sites under investigation and the age of the sediments.In late Mesozoic to Paleogene sediments clay mineral assemblages are sensitive tools for reconstructing climatic conditions. For example, the shift from smectite-dominated assemblages to illite-and chlorite-dominated assemblages in the earliest Oligocene clearly documents the transition from chemical weathering conditions under a warm and humid climate to physical weathering under cooler conditions. Submarine elevations such as Maud Rise and Kerguelen Plateau give the best record for direct paleoclimatic and paleoceanographic studies. At the proximal sites of the continental slope and shelf, as well as in the deep sea, the paleoclimatic information normally is masked by a variety of processes resulting in sediment redistribution. At those sites, in contrast, the clay mineral assemblages bear a wealth of information on different sedimentary processes.After the establishment of a continental East Antarctic ice sheet, physical weathering prevailed. Variations in the clay mineral records predominantly reflect the influence of different sediment sources resulting from different glacial, hydrographic or gravitational transport processes. Because these sedimentation processes are generally linked to climatic variations, the clay mineral assemblages in most of the Neogene and Quaternary sediments provide indirect paleoclimatic information. The processes are best documented in the clay mineral composition in those areas where changes in source regions with distinct petrographic differences are expected and where distances from the source region are low.