El Niño related interannual variations in biological production in the North Pacific as evidenced by satellite and ship data     

Joaquim I. Goes  Helga do R. Gomes  Atsamon Limsakul  William M. Balch  Toshiro Saino   《Progress in Oceanography》2001,49(1-4)

A recently proposed method for estimating nitrate and new production from remotely sensed data (Goes and Goes) allowed us to observe significant deviations from the normal in the quantum of winter-time nitrate injected into the euphotic column and its consumption by phytoplankton in the North Pacific following the El Niño event of 1997. Results from this study allowed us to observe large differences in the ways in which the El Niño event affected the western and the eastern margins of the North Pacific basin. For the western North Pacific, a long-term (1972–1992) historical record of oceanographic data provided us with clear evidence supporting of our findings from satellite observations. In the eastern North Pacific Ocean also, our results compared well with those previously reported (Wong, Whitney, Matear, & Iseki, 1998). While it is clear from this study that El Niño/La Niña oscillations can have a major influence on interannual variations in biological processes in the North Pacific, these results also serve to highlight the value of remote sensing as a tool for studying large regional to basin-scale biological oceanographic events.  相似文献   

Mesoscale and Nutrient Conditions Associated with the Massive 2008 Cochlodinium polykrikoides Bloom in the Sea of Oman/Arabian Gulf     

Adnan R. Al-Azri  Sergey A. Piontkovski  Khalid A. Al-Hashmi  Joaquim I. Goes  Helga do R. Gomes  Patricia M. Glibert 《Estuaries and Coasts》2014,37(2):325-338

Cochlodinium polykrikoides formed large blooms in the coastal waters of Oman from October 2008 through mid-January 2009, and satellite images from Aqua-MODIS and region-wide reports suggest that this bloom was found throughout the Arabian Gulf and Sea of Oman for more than 10 months. The unusual occurrence of this species appears to have supplanted the more regularly occurring bloom species, Noctiluca scintillans, in 2008–2009. For the first 2 weeks of the coastal Omani bloom, C. polykrikoides abundance was near monospecific proportions, with cell densities ranging from 4.6?×?10³ to 9?×?10⁶ cells L^?1 and very high levels of chlorophyll a (78.0 μg L^?1) were also recorded. The regional progression of the bloom likely began with stronger than normal upwelling along the Iranian and northern Omani coasts during the southwest monsoon in late summer, followed by discharge of unusually warm coastal plume water along the coast of Oman with the reversal of monsoonal winds in late October. The occurrence and persistence of high densities of C. polykrikoides in Oman coastal water were also significantly influenced by an elevated nutrient load and warmer than normal temperatures. Concentrations of nutrients, especially NH₄ ⁺, urea, PO₄ ^3?, and organic nitrogen and phosphorus, were manyfold higher than observed in the year prior or since. These findings suggest that mesoscale features were important in bloom dynamics more regionally, but locally the bloom was sustained by nutrient enrichment supplemented by its mixotrophic capabilities.  相似文献   

Polyphase tectonics and late Variscan extension in Austria (Moldanubian Zone,Strudengau area)     

Helga Zeitlhofer  David Schneider  Bernhard Grasemann  Konstantin Petrakakis  Martin Thöni 《International Journal of Earth Sciences》2014,103(1):83-102

New data suggest syn-convergent extrusion and polyphase tectonics followed by late Variscan extension in the Strudengau area of the southern Moldanubian zone in Austria. The tectonic history can be summarized as follows: (1) The oldest ductile event is observed in HT/LP metamorphic pelitic gneisses, which preserve E-dipping foliation planes (D₁-fabric) with NW–SE-trending lineations. (2) The overlying gneisses record HT/HP conditions with decompression-induced anatexis in the central part of the domain. These gneisses exhibit N–S trending, horizontal lineations along steep-dipping foliation planes (D₂-fabric) crosscutting the D₁-fabric of the pelitic gneisses. Along the margin, these rocks have been strongly mylonitized under amphibolite facies conditions (D₂). D₂ is interpreted as a significant vertical shear zone, which juxtaposes the HT/LP rocks against the orogenic lower crust. (3) Lastly, the whole area is overprinted by localized shear zones (D₃-fabric) with top-to-the-NW kinematics. This newly discovered Strudengau shearing event is associated with isoclinal folding that possesses axial planes parallel to the mylonitic foliation and fold axes parallel to the stretching lineations. Initial mylonitization occurred under greenschist facies, representing the latest ductile event of the Strudengau area. The new geochronological data presented here indicate a narrow time frame (c. 323–318 Ma) for the D₃ deformation. Therefore, this event is contemporaneous with the intrusion of the granites of the South Bohemian Batholith (330–310 Ma). The nearby South Bohemian Batholith and generally steep dyke swarms in the Strudengau area and to the north trend in a NE–SW preferred orientation, interpreted to be D₃-synkinematic magmatism. In a regional context, the NW–SE stretching during D₃ together with the synkinematic intrusion of dykes is associated with late orogenic extension in the Austrian Moldanubian Zone. Kinematic data of brittle normal faults and tension gashes are consistent with NW–SE-oriented extension under cooler conditions.  相似文献   

Quo vadis neoliberalism? The remaking of global capitalist governance after the Washington Consensus     

Eric Sheppard  Helga Leitner 《Geoforum》2010,41(2):185-194

The Washington Consensus, through which neoliberal global capitalist governance gained hegemony over the third world, entered a crisis in the late 1990s. Triggered by the 1997 Asian financial crisis, and by contestations of neoliberal governance from global civil society, two remakings of global capitalist governance can be identified: A ‘post-Washington consensus’ whose relation to neoliberalism is complex; and a ‘new development economics’ that advocates Keynesian principles. Irrespective of the trajectory of this emergent phase of re-regulation, particularly after the 2008 global finance crisis, these remakings can be conceptualized as supplements reinforcing an imaginary of capitalism as the solution to, rather than progenitor of, uneven development. Through discourses of capitalist development as a sequential trajectory to be followed by all countries, as flattening the world to enable catch-up by backward countries, and as incorporating socio-spatial difference via its commodification, this socio-spatial imaginary functions to legitimate expertise located in the first world, and global capitalist governance, irrespective of serial policy failures.  相似文献   

Paleoindication of acidification in Kleiner Arbersee (Federal Republic of Germany,Bavarian Forest) by chydorids,chrysophytes, and diatoms     

Chrisitian Steinberg  Helga Hartmann  Klaus Arzet  Dieter Krause-Dellin 《Journal of Paleolimnology》1988,1(2):149-157

In a sediment core of Lake Kleiner Arbersee, located in the Bavarian Forest on gneiss bedrock and with spodosolic soils in the catchment, acidification was reconstructed using assemblages of chydorids, scaled chrysophytes, and diatoms as paleoindicators. All paleoindicators demonstrated acidification of Kleiner Arbersee. There were marked differences, however, in the extent of the indicated acidification: In lower layers, where scaled chrysophytes and chydorids clearly indicate beginning acidification, pH-decline inferred by diatoms lies within the standard deviation, and is statistically not significant until the 7 cm layer. We conclude that mallomonadaceans reflect the acidification of the water body and strongly respond to the lowest seasonal pH, as their indicated rate of acidification is higher than that of diatoms, which appear to more closely indicate the pH of the sediment/water interface, especially when the pH of the water column has dropped below ca. 5.5. Chydorids may additionally be influenced by proton release of dense Sphagnum-stands, which cover the littoral of Kleiner Arbersee completely.We dedicate this paper to Prof. Dipl.-Ing. L. Strobel, who encouraged new perspectives in limnological water management, on the occasion of his 65^th anniversary.  相似文献   

Vegetation geo-climatic zonation in the rocky mountains,Northern Utah,USA     

Antonin Kusbach  Helga Van Miegroet  Janis L. Boettinger  James N. Long 《山地科学学报》2014,11(3):656-673

We developed a vegetation geo-climatic zonation incorporating the zonal concept, gradient and discriminant analysis in Wasatch Range, northern Utah, USA. Mountainous forest ecosystems were sampled and described by vegetation, physiographic features and soil properties. The Snowpack Telemetry and National Weather Service Cooperative Observer Program weather station networks were used to approximate the climate of sample plots. We analysed vegetation and environmental data using clustering, ordination, classification, and ANOVA techniques to reveal environmental gradients affecting a broad vegetation pattern and discriminate these gradients. The specific objective was to assess and classify the response of the complex vegetation to those environmental factors operating at a coarse-scale climatic level. Ordination revealed the dominant role of regional, altitude-based climate in the area. Based on vegetation physiognomy, represented by five tree species, climatic data and taxonomic classification of zonal soils, we identified two vegetation geo-climatic zones： （1） a montane zone, with Rocky Mountain juniper and Douglas-fir; and （2） a subalpine zone, with Engelmann spruce and subalpine fir as climatic climax species. Aspen was excluded from the zonation due to its great ecological amplitude. We found significant differences between the zones in regional climate and landformgeomorphology/soils. Regional climate was represented by elevation, precipitation, and air and soil temperatures; and geomorphology by soil types. This coarsescale vegetation geo-climatic zonation provides a framework for a comprehensive ecosystem survey, which is missing in the central Rocky Mountains of the United States. The vegetationgeoclimatic zonation represents a conceptual improvement on earlier classifications. This framework explicitly accounts for the influence of the physical environment on the distribution of vegetation within a complex landscape typical of the central Rocky Mountains and in mountain ranges elsewhere.  相似文献   

Tropical cyclone hazard assessment using model-based track simulation   总被引：3，自引：1，他引：2  

Jonas Rumpf  Helga Weindl  Peter Höppe  Ernst Rauch  Volker Schmidt 《Natural Hazards》2009,48(3):383-398

A method is introduced for assessing the probabilities and intensities of tropical cyclones at landfall and applied to data from the North Atlantic. First, a recently developed model for the basin-wide Monte-Carlo simulation of tropical cyclone tracks is enhanced and transferred to the North Atlantic basin. Subsequently, a large number of synthetic tracks is generated by means of an implementation of this model. This synthetic data is far more comprehensive than the available historical data, while exhibiting the same basic characteristics. It, thus, creates a more sound basis for assessing landfall probabilities than previously available, especially in areas with a low historical landfall frequency.  相似文献   

Mineralogische Untersuchungen an fünf Bodenprofilen über Basalt,Muschelkalk und Buntsandstein     

Dr. Helga Huffmann 《Contributions to Mineralogy and Petrology》1954,4(1-2):67-88

Zusammenfassung Drei Bodenprofile caber Basalt, eins über Trochitenkalk und eins über Buntsandstein wurden mineralogisch untersucht. Die Schlämmanalyse brachte sehr ähnliche Ergebnisse in der Korngrößenverteilung der über Basalt liegenden Böden, während die beiden anderen Profile ihnen erst an der Erdoberfläche ähnlich wurden. Die mikroskopische Untersuchung zeigt, wie sich die Minerale im Boden verhalten und welche nicht aus dem anstehenden Gestein stammen. Die Tonfraktionen wurden mit Debye-Scherrer- und Texturaufnahmen röntgenograpbisch untersucht. Dabei wurde Halloysit als einziges Tonmineral in den Basaltprofilen und in mürbem Gestein festgestellt. Im Trochitenkalk wurden Illit und Montmorillonit, im Boden darüber gleichfalls Illit gefunden. Im Boden über Buntsandstein ist neben Kaolinit etwas Illit an Tonmineralen nachgewiesen wurden.Herrn Professor Dr.Carl W. Correns zum 60. Geburtstag gewidmet.  相似文献   

Detailed investigation of preserved maar structures by combined geophysical surveys     

Rüdiger Schulz  Hermann Buness  Gerald Gabriel  Rudolf Pucher  Christian Rolf  Helga Wiederhold  Thomas Wonik 《Bulletin of Volcanology》2005,68(2):95-106

The detection of completely preserved maar structures is important not only for underground mapping but also for paleoclimate research because laminated maar lake sediments may contain a very detailed archive of climate history. Objective evidence for the existence of such structures can only be provided by geophysics and boreholes. The combination of gravity and magnetic ground surveys appears to be an excellent tool to detect and identify buried maar structures. Their prominent properties are an almost circular gravity minimum corresponding to a crater filled with limnic sediments of low density, and a magnetic anomaly caused by a pyroclastic or basaltic body in the diatreme which indicates the volcanic character. Seismic measurements provide the most detailed information about the internal structure of the maar sediments. Zones of low seismic reflectivity and very low density represent sediments of the late maar-lake period. The early lake period is indicated by debris flow deposits and turbidites represented by seismic reflectors. The seismic sections clearly reveal the bowl-like structure of the maar. Outside this bowl-like structure, there are only a few reflections, which represent the basement. Taking into account the shape of the gravity anomaly, seismic information allows geometrical modelling of the maar structure. Optimal drilling sites can be selected based on the results of geophysical surveying. Comparing the results of combined geophysical surveys above two maar structures of different ages yields a marked similarity in their geophysical pattern.Editorial responsibility: J McPhie  相似文献   

Stochastic simulation model for tropical cyclone tracks,with special emphasis on landfall behavior     

Björn Kriesche  Helga Weindl  Anselm Smolka  Volker Schmidt 《Natural Hazards》2014,73(2):335-353

We consider a spatial stochastic model for the simulation of tropical cyclone tracks, which has recently been introduced. Cyclone tracks are represented as labeled polygonal lines, which are described by the movement directions, translational speeds, and wind speeds of the cyclones in regular 6-h intervals. In the present paper, we compare return levels for wind speeds of historically observed cyclone tracks with those generated by the simulator, where a mismatch is shown for most of the considered coastal regions. To adjust this discrepancy, we develop a stochastic algorithm for acceptance and rejection of simulated cyclone tracks with landfall. It is based on the fact that the locations, translational speeds, and wind speeds of cyclones at landfall constitute three-dimensional Poisson point processes, which are a basic model type in stochastic geometry. Due to that, a well-known thinning property of Poisson processes can be applied. This means that to each simulated cyclone, an acceptance probability is assigned, which is higher for cyclones with suitable landfall characteristics and lower for implausible ones. More intuitively, the algorithm comprises the simulation of a more comprehensive cyclone event set than needed and the random selection of those tracks that best match historical observations at landfall. A particular advantage of our algorithm is its applicability to multiple landfalls, i.e., to cyclones that successively make landfall at two geographically distinct coastlines, which is the most relevant case in applications. It turns out that the extended simulator provides a much better accordance between landfall characteristics of historical and simulated cyclone tracks.  相似文献