Climatic bisection of the last interglacial warm period in the Polar North Atlantic

New multiproxy marine data of the Eemian interglacial (MIS5e) from the Norwegian Sea manifest a cold event with near-glacial surface ocean summer temperatures (3–4 °C). This mid-Eemian cooling divided the otherwise relatively warm interglacial climate and was associated with widespread expansions of winter sea-ice and polar water masses due to changes in atmospheric circulation and ocean stability. While the data also verify a late rather than early last interglacial warm peak, which is in general disharmony with northern hemisphere insolation maximum and the regional climatic progression of the early Holocene, the cold event itself was likely instrumental for delaying the last interglacial climate development in the Polar North when compared with regions farther south. Such a ‘climatic decoupling’ of the Polar region may bear profound implications for the employment of Eemian conditions to help evaluate the present and future state of the Arctic cryosphere during a warming interglacial.     

Late Cenozoic depositional history of the western Svalbard continental shelf, controlled by subsidence and climate

Based on a grid of high resolution, single channel seismic lines, this paper addresses the Late Cenozoic evolution of the western Svalbard continental shelf. The seismic structure of the shelf includes at least 16 erosional unconformities, each representing a glacial advance. The evolution during the last approximately one million years has been divided into six main erosional and depositional phases. Differential margin subsidence around a hinge zone is an important controlling mechanism for the accumulation of the sedimentary wedge at the outer shelf. The most significant depositional change appears to be related to a general climatic shift, globally recorded to be centred around 1 Ma. At this level, corresponding to the Upper Regional Unconformity (URU) on the shelf, the depositional regime changed from net erosion to net deposition and shelf aggradation. Of major significance is probably a shift from thick, eroding glaciers with steep ice profiles, to low profile fast flowing ice streams maintained by an increased amount of interglacial and interstadial sediments. The relationship between climatic fluctuations, glacial dynamics and depositional regime is discussed.     

HAXTEL: A Laue lens telescope development project for a deep exploration of the hard X-ray sky (> 60 keV)

A review of the HAXTEL project devoted to the development of a Laue lens telescope for hard X-/gamma-ray observation of the continuum spectra of celestial sources is presented. Main design properties, open issues, the status of the project and an example of multi-lens configuration with sensitivity expectations are discussed.     

High‐resolution reconstruction of a coastal barrier system: impact of Holocene sea‐level change

This study presents a detailed reconstruction of the sedimentary effects of Holocene sea‐level rise on a modern coastal barrier system. Increasing concern over the evolution of coastal barrier systems due to future accelerated rates of sea‐level rise calls for a better understanding of coastal barrier response to sea‐level changes. The complex evolution and sequence stratigraphic framework of the investigated coastal barrier system is reconstructed using facies analysis, high‐resolution optically stimulated luminescence and radiocarbon dating. During the formation of the coastal barrier system starting 8 to 7 ka rapid relative sea‐level rise outpaced sediment accumulation. Not before rates of relative sea‐level rise had decreased to ca 2 mm yr^?1 did sediment accumulation outpace sea‐level rise. From ca 5·5 ka, rates of regionally averaged sediment accumulation increased to 4·3 mm yr^?1 and the back‐barrier basin was filled in. This increase in sediment accumulation resulted from retreat of the barrier island and probably also due to formation of a tidal inlet close to the study area. Continued transgression and shoreface retreat created a distinct hiatus and wave ravinement surface in the seaward part of the coastal barrier system before the barrier shoreline stabilized between 5·0 ka and 4·5 ka. Back‐barrier shoreline erosion due to sediment starvation in the back‐barrier basin was pronounced from 4·5 to 2·5 ka but, in the last 2·5 kyr, barrier sedimentation has kept up with and outpaced sea‐level. In the last 0·4 kyr the coastal barrier system has been prograding episodically. Sediment accumulation shows considerable variation, with periods of rapid sediment deposition and periods of non‐deposition or erosion resulting in a highly punctuated sediment record. The study demonstrates how core‐based facies interpretations supported by a high‐resolution chronology and a well‐documented sea‐level history allow identification of depositional environments, erosion surfaces and hiatuses within a very homogeneous stratigraphy, and allow a detailed temporal reconstruction of a coastal barrier system in relation to sea‐level rise and sediment supply.     

A precise multipass method for satellite Doppler positioning

A precise and efficient algorithm is developed for determining the locations of radio beacons (e.g. of the ARGOS or COSPAS/SARSAT type) based on Doppler shift measurements in overflying satellites. The method distinguishes itself through: (1) the use of a very compact analytic orbital theory valid for all eccentricities, (2) autonomous orbit improvement based on Doppler data for one or more local reference beacons accessible at a single LUT, (3) simultaneous orbit improvement and calculation of beacon coordinates for an arbitrary number of satellites, satellite passes, and beacons, and (4) very efficient semi-analytic matrix inversion by partitioning into global, semi-global, and local parameters.The algorithm has been implemented in a FORTRAN program which can be run on a PC. Error statistics are presented from applications of the program to a large number of actual Doppler curves obtained with the ARGOS and COSPAS/SARSAT systems.