ALBERT

Beschreibung: This study has investigated serial (temporal) clustering of extra-tropical cyclones simulated by 17 climate models that participated in CMIP5. Clustering was estimated by calculating the dispersion (ratio of variance to mean) of 30 December-February counts of Atlantic storm tracks passing nearby each grid point. Results from single historical simulations of 1975-2005 were compared to those from historical ERA40 reanalyses from 1958-2001 ERA40 and single future model projections of 2069-2099 under the RCP4.5 climate change scenario. Models were generally able to capture the broad features in reanalyses reported previously: underdispersion/regularity (i.e. variance less than mean) in the western core of the Atlantic storm track surrounded by overdispersion/clustering (i.e. variance greater than mean) to the north and south and over western Europe. Regression of counts onto North Atlantic Oscillation (NAO) indices revealed that much of the overdispersion in the historical reanalyses and model simulations can be accounted for by NAO variability. Future changes in dispersion were generally found to be small and not consistent across models. The overdispersion statistic, for any 30 year sample, is prone to large amounts of sampling uncertainty that obscures the climate change signal. For example, the projected increase in dispersion for storm counts near London in the CNRMCM5 model is 0.1 compared to a standard deviation of 0.25. Projected changes in the mean and variance of NAO are insufficient to create changes in overdispersion that are discernible above natural sampling variations.

Beschreibung: The Journal of Organic Chemistry DOI: 10.1021/acs.joc.5b01373

Beschreibung: The Journal of Organic Chemistry DOI: 10.1021/acs.joc.6b00983

Beschreibung: This study investigates whether or not predictability always decreases for more extreme events. Predictability is measured by the Mean Squared Error (MSE), estimated here from the difference of pairs of ensemble forecasts, conditioned on one of the forecast variables (the “pseudo-observation”) exceeding a threshold. Using an exchangeable linear regression model for pairs of forecast variables, we show that the MSE can be decomposed into the sum of three terms: a threshold-independent constant, a mean term that always increases with threshold, and a variance term that can either increase, decrease, or stay constant with threshold. Using the Generalised Pareto Distribution to model wind speed excesses over a threshold, we show that MSE always increases with threshold at sufficiently high threshold. However, MSE can be a decreasing function of threshold at lower thresholds but only if the forecasts have finite upper bounds. The methods are illustrated by application to daily wind speed forecasts for London made using the 24 member Met Office Global and Regional Ensemble Prediction System from 1 Jan 2009 to 31 May 2011. For this example, the mean term increases faster than the variance term decreases with increasing threshold, and so predictability decreases for more extreme events.

Beschreibung: The Carboniferous Bowland Shale of northern England has drawn considerable attention because it has been estimated to have 1329 trillion cubic feet hydrocarbons in-place (gas and liquids) resource potential (Andrews 2013). Here we report on the oil and gas generation characteristics of three selected Bowland Shale whole-rock samples taken from cores and their respective kerogen concentrates. Compositional kinetics and phase properties of the primary and secondary fluids were calculated through the PhaseKinetics and GOR-Fit approaches and PVT modelling software. The three Bowland Shale samples contain immature, marine type II kerogen. Pyrolysate compositions imply primary generation of paraffinic–naphthenic–aromatic (PNA) oil with low contents of wax and sulphur. Bulk kinetic parameters have many similarities to those of productive American Palaeozoic marine shale plays. The secondary gas generation potential of Bowland Shale is greater than the primary gas potential although it requires a 10 kcal mol –1 higher activation energy to achieve peak production. Primary oil, primary gas and secondary gas reach their maximum generation at 137, 150 and 200°C respectively for a 3°C Ma –1 heating rate. Different driving forces of expulsion including the generation of hydrocarbon and overpressure caused by phase separation during sequential periods of subsidence and uplift could be inferred.

Beschreibung: The Greater Caucasus and southern Crimean Mountains form part of a fold–thrust belt located on the northern margin of the Black Sea, south of the Precambrian craton of eastern Europe. Its southern limit is approximated by the Main Caucasus Thrust, which runs to the west from onshore Russia and Georgia along the whole of the northern margin of the Black Sea. The Main Caucasus Thrust is related to a zone of present-day seismicity along the southern Crimea–Caucasus coast of the Black Sea called the Crimea–Caucasus Seismic Zone. Thick continental crust north of the Main Caucasus Thrust lies adjacent to the thin ‘suboceanic' or transitional crust of the Black Sea Basin. A local seismic tomography study of this area in the vicinity of the Kerch and Taman peninsulas, which lie between the Azov Sea and the Black Sea, has been carried out based on 195 weak (m b ≤3) earthquakes occurring from 1975 to 2010 and recorded at four permanent and three temporary seismological stations on the Kerch and Taman peninsulas. The results, for a volume of about 200 x 100 km (east–west and north–south, respectively) and a depth of about 40 km, provide evidence for significant heterogeneity in the P-wave and S-wave velocities. Velocities inferred in the northern part of the model suggest that the continental crust underlying the Crimea–Azov region north of the Main Caucasus Thrust is of different tectonic affinity (cratonic) than that underlying the northeastern part of the Black Sea, south of the Main Caucasus Thrust (Neoproterozoic–Palaeozoic accretionary domain). In the southern part of the model, at depths of 25–40 km, the uppermost mantle below the thin quasi-oceanic crust of the Black Sea has anomalous low P-wave velocities with high P- to S-wave velocity ratios. This is tentatively interpreted as representing serpentinized upper mantle of continental lithosphere exhumed during Cretaceous rifting and lithospheric hyperextension of the eastern Black Sea. The transition between the continental domains and the crust underlain by anomalous upper mantle is closely related to the Crimea–Caucasus Seismic Zone, where earthquake foci deepen northwards, suggesting that the latter is being thrust under the former in this intra-plate setting.

Beschreibung: Extreme wave events in coastal zones are principal drivers of geomorphic change. Evidence of boulder entrainment and erosional impact during storms is increasing. However, there is currently poor time coupling between pre- and post-storm measurements of coastal boulder deposits. Importantly there are no data reporting shore platform erosion, boulder entrainment and/or boulder transport during storm events – rock coast dynamics during storm events are currently unexplored. Here, we use high-resolution (daily) field data to measure and characterise coastal boulder transport before, during and after the extreme Northeast Atlantic extra-tropical cyclone Johanna in March 2008. Forty-eight limestone fine-medium boulders (n = 46) and coarse cobbles (n = 2) were tracked daily over a 0.1 km 2 intertidal area during this multi-day storm. Boulders were repeatedly entrained, transported and deposited, and in some cases broken down (n = 1) or quarried (n = 3), during the most intense days of the storm. Eighty-one percent (n = 39) of boulders were located at both the start and end of the storm. Of these, 92% were entrained where entrainment patterns were closely aligned to wave parameters. These data firmly demonstrate rock coasts are dynamic and vulnerable under storm conditions. No statistically significant relationship was found between boulder size (mass) and net transport distance. Graphical analyses suggest that boulder size limits the maximum longshore transport distance but that for the majority of boulders lying under this threshold, other factors influence transport distance. Paired analysis of 20 similar sized and shaped boulders in different morphogenic zones demonstrates that geomorphological control affects entrainment and transport distance – where net transport distances were up to 39 times less where geomorphological control was greatest. These results have important implications for understanding and for accurately measuring and modelling boulder entrainment and transport. Coastal managers require these data for assessing erosion risk.

Beschreibung: The DOBRE-2 wide-angle reflection and refraction profile was acquired in June 2007 as a direct, southwestwards prolongation of the 1999 DOBREfraction'99 that crossed the Donbas Foldbelt in eastern Ukraine. It crosses the Azov Massif of the East European Craton, the Azov Sea, the Kerch Peninsula (the easternmost part of Crimea) and the northern East Black Sea Basin, thus traversing the entire Crimea–Caucasus compressional zone centred on the Kerch Peninsula. The DOBRE-2 profile recorded a mix of onshore explosive sources as well as airguns at sea. A variety of single-component recorders were used on land and ocean bottom instruments were deployed offshore and recovered by ship. The DOBRE-2 datasets were degraded by a lack of shot-point reversal at the southwestern terminus and by some poor signal registration elsewhere, in particular in the Black Sea. Nevertheless, they allowed a robust velocity model of the upper crust to be constructed along the entire profile as well as through the entire crust beneath the Azov Massif. A less well constrained model was constructed for much of the crust beneath the Azov Sea and the Kerch Peninsula. The results showed that there is a significant change in the upper crustal lithology in the northern Azov Sea, expressed in the near surface as the Main Azov Fault; this boundary can be taken as the boundary between the East European Craton and the Scythian Platform. The upper crustal rocks of the Scythian Platform in this area probably consist of metasedimentary rocks. A narrow unit as shallow as about 5 km and characterized by velocities typical of the crystalline basement bounds the metasedimentary succession on its southern margin and also marks the northern margin of the northern foredeep and the underlying successions of the Crimea–Caucasus compressional zone in the southern part of the Azov Sea. A broader and somewhat deeper basement unit (about 11 km) with an antiformal shape lies beneath the northern East Black Sea Basin and forms the southern margin of the Crimea–Caucasus compressional zone. The depth of the underlying Moho discontinuity increases from 40 km beneath the Azov Massif to 47 km beneath the Crimea–Caucasus compressional zone.

Beschreibung: The origin and age of topography along the west Greenland margin is a matter of continued debate. Evidence for tectonically driven Neogene uplift has been argued from interpretations of offshore seismic surveys, onshore fission-track data and inferred episodes of cooling. Here, analysis of seismic reflection profiles and 1D modelling of exploration wells along the Greenland margin of Davis Strait demonstrate that the data are consistent with a model of ancient continental topography affected by late Cretaceous–early Palaeocene rifting followed by thermal subsidence where offshore Neogene tectonic uplift is not required. This interpretation for the offshore evolution of the west Greenland margin has implications for the adjacent onshore evolution and for other continental margins developed throughout the Atlantic–Arctic rift system.

Beschreibung: The Journal of Organic Chemistry DOI: 10.1021/jo300162c