ALBERT

Description: The destructive power of extreme natural events is causing more and more material damages and losses of life. With the number of natural disasters globally increasing, coordinated disaster management is getting more important. During the past years, several research centers within the Helmholtz Association established extensive expertise in the field of disaster management. Via the Natural Disaster Networking Platform (NaDiNe), this expertise will be provided a larger number of users beyond the realm of scientific facilities.

Description: An innovative technique has been developed to assess moisture sources contributing to precipitation. It represents an advance with respect to previously developed methodologies because it allows to discriminate more effectively between terrestrial versus oceanic sources, and also to detect with greater precision the relative importance of remote versus local sources together with the sequence of evaporation associated with a rainfall event. It is based upon the use of a mesoscale model to simulate a selected precipitation episode and a Lagrangian trajectory model to evaluate three-dimensional back-trajectories in order to track the vapor parcels transporting the target precipitation to their surface evaporative sources. An extreme sequence of rainfall events occurred over central Europe between August 11th and 13th is chosen to put the methodology into test. A domain centered in the region and spanning 6372 km in the W-E direction and 5940 km in the N-S direction is chosen to assess moisture sources. Results show the evolving role of various sources throughout the duration of the event, indicating that they shift from the southern to northern and eastern source regions, while a simultaneous decrease of marine sources with respect to terrestrial sources occurs from the onset of the event to its ending phase. The capability of discriminating moisture sources with precision is an important requirement to better understand the mechanisms of extreme rainfalls.

Description: This article investigates an extreme rainfall event occurred over wide areas of central Europe on August 11-13, 2002. By using a synergistic approach that includes regional modeling, air mass tracking, and observational data sets, the importance of moisture accumulation processes in the Western Mediterranean basin (WMB) is acknowledged as an important mechanism responsible for the magnitude of this event. The RAMS-HYPACT modeling system is used to track air masses from potential marine sources of evaporation. MODIS water vapor products, wind profilers and surface rain gauge measurements are used to substantiate our simulations. Results show that most of the precipitation occurring in central Europe during the initiation of the rainfall episode (August 11) came from vapor accumulated over 4 days (August 6-9) within the WMB: the vapor was transported, after the irruption of the Vb cyclone Ilse, through the Italian Peninsula and the Adriatic Sea, into the target area, causing the precipitation episode. On August 12 and 13 the marine sources of evaporation changed to include the north-Atlantic region. The north-African convergence region, the eastern Mediterranean and the Black Sea are revealed to be sources more related to the intense rainfall experienced in eastern Europe. The subsidence-related processes through which pollutants and water vapor can accumulate for several days in the WMB are shown to be very relevant for this event. The quantification of the evaporative sources, responsible for the extreme rainfall events in central Europe, and the relative importance of marine and terrestrial sources within a chosen regional domain are discussed in the companion following article.

Description: Fish stocks have made surprising comebacks in the North and Baltic seas. But much remains to be done. Beginning in January, new EU laws will impose more sustainable practices with stricter quotas and by-catch rules.

Description: Micro-Raman spectroscopy has been used on adult bivalve shells to investigate organic and inorganic shell components but has not yet been applied to bivalve larvae. It is known that the organic matrix of larval shells contains pigments, but less is known about the presence or source of these molecules in larvae. We investigated Raman spectra of seven species of bivalve larvae to assess the types of pigments present in shells of each species and how the ratio of inorganic : organic material changes in a dorso-ventral direction. In laboratory experiments, we reared larvae of three clam species in waters containing different organic signatures to determine if larvae incorporated compounds from source waters into their shells. We found differences in spectra and pigments between most species but found less intraspecific differences. A neural network classifier for Raman spectra classified five out of seven species with greater than 85% accuracy. There were slight differences between the amount and type of pigment present along the shell, with the prodissoconch I and shell margin areas being the most variable. Raman spectra of 1-day-old larvae were found to be differentiable when larvae were reared in waters with different organic signatures. With micro-Raman spectroscopy, it may be possible to identify some unknown species in the wild and trace their natal origins, which could enhance identification accuracy of bivalve larvae and ultimately aid management and restoration efforts.

Description: On the Earth, the atmosphere, ocean, and land interact with each other. For example, an atmospheric pressure system directly influences the Sea Surface Heights (SSHs) in a barometric sense; the associated wind transfers momentum from the atmosphere into the ocean, which alters the ocean currents affecting again the SSHs. The integrated effects of all motion components directly influence the angular momentum of the Earth, while the integrated effect of all mass variations alters the Earth’s inertia. Both can excite the Earth Orientation Parameters (EOPs). In this study, we use the Community Earth System Model (CESM) to simulate mass and motion variations within a coupled climate system. The modeled mass and motion variations of all subcomponents are used to compute the total excitation functions, which then are compared to very precise global EOP observations, provided by the International Earth Rotation and Reference Systems Service (IERS). For further reference, the modeled excitation functions of the subcomponents are compared to operational excitations, provided by the German Research Centre for Geosciences (GFZ). This allows an evaluation of the global model behavior and of the subcomponents. Further, regions of particularly high influence on the excitations as well as regions of especially strong dynamical coupling are identified. Four CESM experiments were performed, one reference experiment featuring solely natural variations, while the others separate the influence of (I) a coupled ocean component; (II) the quasi-biennial oscillation (QBO) and (III) anthropogenic forcings, e.g. greenhouse gas (GHG) emissions and ozone depleting substances (ODS). The modeled EOPs are in good agreement with the reference data sets, but reveal an slight overestimation of the modeled atmospheric mass component in the North Pacific for annual to interannual timescales, leading to deviations in the X1 component. Analyzing variations among the CESM experiments reveal (I) the complete absence of interannual subtropical tropospheric jet variability when using a climatological ocean; (II) a significantly increased atmospheric mass variation in the arctic region in the absence of a QBO; and (III) hardly any modeled effect of the global dynamics with respect to anthropogenic forcings. Finally, the North Pacific - a region with particularly strong atmosphere-ocean coupling - is investigated, highlighting wind driven ocean mass variations within the model and GRACE observations. The identified significant wind patterns explain the modeled ocean mass variations and can be directly projected onto ERA-Interim data in order to estimate the independent GRACE observations. The here presented relation between the ERA-Interim winds and the GRACE gravity field observations supporting the following two conclusions: (I) ERA-Interim winds can be used to further refine GRACE observations; (II) GRACE observations contain assimilation worthy information for atmospheric models.

Description: The stratigraphic successions exposed in Wadi El Mizeira have been dated through the analysis of the calcareous nannofossil assemblages. The results of this study indicate that the successions comprise the Santonian-Late Maastrichtian (Sudr Formation), the Paleocene (Esna Formation) and the Early Eocene (Thebes Formation). The following biozones were recognized: Late Santonian, CC16 Zone; Late Santonian/Early Campanian, CC17 Zone; Early Campanian, Aspidolithus parcus Zone (CC18) Zone; Late Maastrichtian, CC25c Zone; Early Paleocene (Late Danian), NP3 Zone and NP4 Zone; Late Paleocene (Thanethian-Selandian), NP5 Zone; Early Eocene, NP9b Zone, NP10a Zone, NP11 Zone, NP12 Zone and NP14 Zone. Several stratigraphic hiatus were recorded in the studied interval including the absence of Cretaceous nannofossil Zones CC19 to CC25b and CC26 as well as the early Paleocene Zones NP1 and NP2 and probably the basal part of Zone NP3, in addition to the absence of the Zones NP6 and NP7/8. These hiatus may be attributed to environmental conditions, structural activity and/or post depositional processes. This work represents the first attempt to evaluate the nannofossil taxa of the Wadi El Mizeira, Northeastern Sinai.

Description: Hemigrapsus sanguineus (Asian Shore Crab) has shown a remarkable ability to colonize rocky intertidal communities along the east coast of the United States since its introduction in the late 1980s and is an important predator of juvenile Mytilus edulis (Blue Mussel) in invaded habitats. In this study, we used two field-caging experiments and the Kaplan-Meier model to assess the impact of predation by Asian Shore Crab on the survival of juvenile Blue Mussels in an intertidal habitat of western Long Island Sound along the Connecticut coastline. Five treatment levels (high-density enclosure, low-density enclosure, exclosure, partial cage, and open plot) were used in the 2007 experiment. The high-density enclosure treatment was omitted in the 2010 experiment since there was no statistically significant difference in the proportion of mussels surviving between low- and high-density crab treatments in 2007. In 2007, we measured a statistically significant difference in mussel mortality between exclosure and crab-enclosure cages, with crabs lowering the median survival time for mussels from 15.4 to 7.6 days. In 2010, we again measured a statistically significant difference in mussel mortality between exclosure and crab-enclosure cages, suggesting a crab effect on mussel survival. In the 2010 experiment, approximately 25% of the mussel mortality was attributable to crab predation, which reduced median survival time for mussels from 12.8 to 5.6 days. The median survival time for mussels exposed to the full complement of factors affecting survival (open plots and partial cages) was only 2–3 days. Our study shows that predation by Asian crabs may account for up to 25% of the Blue Mussel mortality in the intertidal zone at Black Rock Harbor. Further studies focusing on the importance of other biotic and abiotic factors are needed to understand the apparent declines in Blue Mussel populations and the interannual variability in recruitment success in this area.