Radiocarbon age, and sedimentation and accumulation rate of core JM05-G001 obtained during Jan Mayen cruise JM050704 to the Barents Sea

Instrumental monitoring of the climate at high northern latitudes has documented the ongoing warming of the last few decades. Climate modelling has also demonstrated that the global warming signal will be amplified in the polar region. Such temperature increases would have important implications on the ecosystem and biota of the Barents Sea. This study therefore aims to reconstruct the climatic changes of the Barents Sea based on benthic foraminifera over approximately the last 1400 years at the decadal to sub-decadal scale. Oxygen and carbon isotope analysis and benthic foraminiferal species counts indicate an overall warming trend of approximately 2.6°C through the 1400-year record. In addition, the well-documented cooling period equating to the 'Little Ice Age' is evident between c. 1650 and 1850. Most notably, a series of highly fluctuating temperatures are observed over the last century. An increase of 1.5°C is shown across this period. Thus for the first time we are able to demonstrate that the recent Arctic warming is also reflected in the oceanic micro-fauna.

Multi-temporal mapping of seagrass cover, species and biomass of the Eastern Banks, Moreton Bay, Australia, with links to shapefiles

The spatial and temporal dynamics of seagrasses have been studied from the leaf to patch (100 m**2) scales. However, landscape scale (> 100 km**2) seagrass population dynamics are unresolved in seagrass ecology. Previous remote sensing approaches have lacked the temporal or spatial resolution, or ecologically appropriate mapping, to fully address this issue. This paper presents a robust, semi-automated object-based image analysis approach for mapping dominant seagrass species, percentage cover and above ground biomass using a time series of field data and coincident high spatial resolution satellite imagery. The study area was a 142 km**2 shallow, clear water seagrass habitat (the Eastern Banks, Moreton Bay, Australia). Nine data sets acquired between 2004 and 2013 were used to create seagrass species and percentage cover maps through the integration of seagrass photo transect field data, and atmospherically and geometrically corrected high spatial resolution satellite image data (WorldView-2, IKONOS and Quickbird-2) using an object based image analysis approach. Biomass maps were derived using empirical models trained with in-situ above ground biomass data per seagrass species. Maps and summary plots identified inter- and intra-annual variation of seagrass species composition, percentage cover level and above ground biomass. The methods provide a rigorous approach for field and image data collection and pre-processing, a semi-automated approach to extract seagrass species and cover maps and assess accuracy, and the subsequent empirical modelling of seagrass biomass. The resultant maps provide a fundamental data set for understanding landscape scale seagrass dynamics in a shallow water environment. Our findings provide proof of concept for the use of time-series analysis of remotely sensed seagrass products for use in seagrass ecology and management.

Mapping the Antarctic Polar Front: Weekly realizations from 2002 to 2014, links to NetCDF file and MPEG4 movie

We map the weekly position of the Antarctic Polar Front (PF) in the Southern Ocean over a 12-year period (2002-2014) using satellite sea surface temperature (SST) estimated from cloud-penetrating microwave radiometers. Our study advances previous efforts to map the PF using hydrographic and satellite data and provides a unique realization of the PF at weekly resolution across all longitudes. The mean path of the PF is asymmetric; its latitudinal position spans from 44 to 64° S along its circumpolar path. SST at the PF ranges from 0.6 to 6.9 °C, reflecting the large spread in latitudinal position. The average intensity of the front is 1.7 °C per 100 km, with intensity ranging from 1.4 to 2.3 °C per 100 km. Front intensity is significantly correlated with the depth of bottom topography, suggesting that the front intensifies over shallow bathymetry. Realizations of the PF are consistent with the corresponding surface expressions of the PF estimated using expendable bathythermograph data in the Drake Passage and Australian and African sectors. The climatological mean position of the PF is similar, though not identical, to previously published estimates. As the PF is a key indicator of physical circulation, surface nutrient concentration, and biogeography in the Southern Ocean, future studies of physical and biogeochemical oceanography in this region will benefit from the provided data set.