Accumulation, velocities, fluxes and mass balance of glacial tributaries to the Lambert Glacier-Amery Ice Shelf system, Antarctica

By incorporating recently available remote sensing data, we investigated the mass balance for all individual tributary glacial basins of the Lambert Glacier-Amery Ice Shelf system, East Antarctica. On the basis of the ice flow information derived from SAR interferometry and ICESat laser altimetry, we have determined the spatial configuration of eight tributary drainage basins of the Lambert-Amery glacial system. By combining the coherence information from SAR interferometry and the texture information from SAR and MODIS images, we have interpreted and refined the grounding line position. We calculated ice volume flux of each tributary glacial basin based on the ice velocity field derived from Radarsat three-pass interferometry together with ice thickness data interpolated from Australian and Russian airborne radio echo sounding (RES) surveys and inferred from ICESat laser altimetry data. Our analysis reveals that three tributary basins have a significant net positive imbalance, while five other subbasins are slightly positive or close to zero balance. Overall, in contrast to previous studies, we find that the grounded ice in Lambert Glacier-Amery Ice Shelf system has a positive mass imbalance of 22.9 ± 4.4 Gt/a. The net basal melting for the entire Amery Ice Shelf is estimated to be 27.0 ± 7.0 Gt/a. The melting rate decreases rapidly from the grounding zone to the ice shelf front. Significant basal refreezing is detected in the downstream section of the ice shelf. The mass balance estimates for both the grounded ice sheet and the ice shelf mass differ substantially from other recent estimates.

Phytoplankton fluxes and biomass in the White Sea in 2007 and 2008

Vertical fluxes of phytoplankton (VF_phyto) and particulate organic carbon (VF_POC) in the White Sea were determined using seven long-term (292 to 296 days) sediment traps moored at five stations at depths 67 to 255 m. Annual VF_phyto and VF_POC ranged from 0.55 to 24.64 g C/m**2 and from 3.7 to 93.9 g C/m**2, respectively. The highest VF_phyto was observed in the Basin region located close to the Gorlo along the Tersk coast. Algal biomass accounted for 15-43% of VF_pOC. Diatoms comprised the most important group accounting for 83-100% in sinking biomass. Thalassiosira nordenskioeldii dominated in VF_phyto at all trap stations except for one in the Basin close to the Onega Bay, where Ditylum brightwellii was the most abundant.

Fluxes and meteorological observations on Spitsbergen

Arctic permafrost may be adversely affected by climate change in a number of ways, so that establishing a world-wide monitoring program seems imperative. This thesis evaluates possibilities for permafrost monitoring at the example of a permafrost site on Svalbard, Norway. An energy balance model for permafrost temperatures is developed that evaluates the different components of the surface energy budget in analogy to climate models. The surface energy budget, consisting of radiation components, sensible and latent heat fluxes as well as the ground heat flux, is measured over the course of one year, which has not been accomplished for arctic land areas so far. A considerable small-scale heterogeneity of the summer surface temperature is observed in long-term measurements with a thermal imaging system, which can be reproduced in the energy balance model. The model can also simulate the impact of different snow depths on the soil temperature, that has been documented in field measurements. Furthermore, time series of terrestrial surface temperature measurements are compared to satellite-borne measurements, for which a significant cold-bias is observed during winter. Finally, different possibilities for a world-wide monitoring scheme are assessed. Energy budget models can incorporate different satellite data sets as training data sets for parameter estimation, so that they may constitute an alternative to purely satellite-based schemes.

Particulate matter fluxes determined in the area of the NS Komsomolets wreck in different years

The sedimentation system of the bottom contour current over the continental slope of the Bear Island in the Norwegian Sea is considered. The nepheloid layer that provides high horizontal flux of sedimentary material represents the main source of matter for bottom sediments. Vertical particulate matter flux is largely formed in the nepheloid layer; flux from higher layers of the water column is insignificant. Horizontal and vertical fluxes of sedimentary matter show positive correlation. Matter flux from bottom sediment into the nepheloid layer and residence time of particles in the latter are estimated.