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Starting from the occurrence of a zonal Walker circulation supplementing the meridional Hadley cell, the concept of ultralong waves with diagonal upper troughs extending far into the Tropics is stressed. The model of equatorial upwelling with air‐sea coupling is critically discussed and a modification proposed. An intensification of the subtropical jet at the peak of the 1972 El Niño (as suggested by Rowntree's model calculations) has been verified. Empirical studies deal with the large interannual and interdecadal variations of the energy fluxes at the air‐sea interface; time variations of the oceanic evaporation and sensible heat flux are greater than expected. Using spectrum analysis, the occurrence of a 5‐year periodicity in equatorial rainfall of the Pacific and Indonesia is demonstrated, together with a marked phase shift along the NE coast of New Guinea. 相似文献
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J. K. Cochran K. O. Buesseler M. P. Bacon H. W. Wang D. J. Hirschberg L. Ball J. Andrews G. Crossin A. Fleer 《Deep Sea Research Part II: Topical Studies in Oceanography》2000,47(15-16)
Repeated measurements of depth profiles of 234Th (dissolved, 1–70 and >70 μm particulate) at three stations (Orca, Minke, Sei) in the Ross Sea have been used to estimate the export of Th and particulate organic carbon (POC) from the euphotic zone. Sampling was carried out on three JGOFS cruises covering the period from October 1996 (austral early spring) to April 1997 (austral fall). Deficiencies of 234Th relative to its parent 238U in the upper 100 m are small during the early spring cruise, increase to maximum values during the summer, and decrease over the course of the fall. Application of a non-steady-state model to the 234Th data shows that the flux of Th from the euphotic zone occurs principally during the summer cruise and in the interval between summer and fall. Station Minke in the southwestern Ross Sea appears to sustain significant 234Th removal for a longer period than is evident at Orca or Sei. Particulate 234Th activities and POC are greater in the 1–70 μm size fraction, except late in the summer cruise, when the >70 μm POC fraction exceeds that of the 1–70 μm fraction. The POC/234Th ratio in the >70 μm fraction exceeds that in the 1–70 μm fraction, likely due in part to the greater availability of surface sites for Th adsorption in the latter. Particulate 234Th fluxes are converted to POC fluxes by multiplying by the POC/234Th ratio of the >70 μm fraction (assumed to be representative of sinking particles). POC fluxes calculated from a steady-state Th scavenging model range from 7 to 91 mmol C m−2 d−1 during late January–early February, with the greatest flux observed at station Minke late in the cruise. Fluxes estimated with a non-steady-state Th model are 85 mmol C m−2 d−1 at Minke (1/13–2/1/97) and 50 mmol C m−2 d−1 at Orca (1/19–2/1/97). The decline in POC inventories (0–100 m) is most rapid in the southern Ross Sea during the austral summer cruise (Smith et al., 2000. The seasonal cycle of phytoplankton biomass and primary productivity in the Ross Sea, Antarctica. Deep-Sea Research II 47, 3119–3140. Gardner et al., 2000. Seasonal patterns of water column particulate organic carbon and fluxes in the Ross Sea, Antarctica. Deep-Sea Research II 47, 3423–3449), and the 234Th-derived POC fluxes indicate that the sinking flux of POC is 30–50% of the POC decrease, depending on whether steady-state or non-steady-state Th fluxes are used. Rate constants for particle POC aggregation and disaggregation rates are calculated at station Orca by coupling particulate 234Th data with 228Th data on the same samples. Late in the early spring cruise, as well as during the summer cruise, POC aggregation rates are highest in near-surface waters and decrease with depth. POC disaggregation rates during the same time generally increase to a maximum and are low at depth (>200 m). Subsurface aggregation rates increase to high values late in the summer, while disaggregation rates decrease. This trend helps explain higher values of POC in the >70 m fraction relative to the 1–70 m fraction late in the summer cruise. Increases in disaggregation rate below 100 m transfer POC from the large to small size fraction and may attenuate the flux of POC sinking out of the euphotic zone. 相似文献
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Hani Sewilam Heribert Nacken Roman Breuer Christiane Pyka 《Environmental Earth Sciences》2017,76(3):131
Sustainable water management is one of humanity’s most important challenges—today and in the future. Germany does not face a significant water shortage problem, but it has three main challenges: protection of water quality, ensuring public water supply and public wastewater disposal, and protecting the public and infrastructure from floods. Capacity development is a key issue to overcome the challenges of water resources in any country including Germany. Engineers, technicians, and mechanics need to upgrade their knowledge on a regular basis to deal with the complex management and rapid technological developments. In order to create efficient training schemes, the Vocational Training Working Group of Global Water Partnership (GWP), part of the GWP Capacity Development Task Force, has worked on the definition of fundamental job profiles for the Water and Sanitation Sector (WASS). To cover all technical functions of the industrial water cycle, it was necessary to identify around thirty occupations. Then, a competence-based training approach was adopted. Additionally, an assessment approach was also developed based on comparing the level of competence of the workers to a standard level of competence for each job. The RWTH Aachen University with its partners have developed another game-based approach (SeCom2.0) based on serious gaming technology to enable water professionals dealing with flood risk management to be trained on different flood situations in a virtual environment. SeCom2.0 has three main components that are connected by a database layer. In addition to the serious games component, there is a collaboration component and a learning management system. For nearly 100 members from the flood competence centre (HochwasserKompetenzCentrum) in Cologne, Germany gave input to simulate the real flooding scenarios, and the learners will have to deal with a flood scenario by protecting the city in a given time and using a given resources and tools. This work concluded that both competence-based and game-based approaches could be significantly improved by blending both approaches. This will improve the process of training; for example, the competence-based approach can be enriched by using game-based simulation by introducing the trainees to a simulation of different technologies in water utilities. This can save resources and money and enrich the training. More importantly is modifying the game-based approach using the approach of competence-based to focus on specific competencies and to make use of the competence standards in its assessment component. The first section of this introduces and categorizes water challenges in Germany. In the second and third section, the two approaches are introduced in details. The competence-based approach is introduced to the WASS while the games-based to the flood risk management. Finally, a conclusion and recommendations are illustrated. 相似文献
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Christian Dumperth Joachim Rohn Alexander Fleer Jin-Ge Wang Wei Xiang Karsten Zimmermann 《山地科学学报》2016,13(10):1701-1710
Semi qualitative index based methods using rankings and ratings are commonly used in susceptibility estimations over a wide area. However, generalized ranking and ratings are not applicable for one single landslide. This paper gives an easy and transferable approach to a susceptibility assessment of Huangtupo landslide (P.R. China), using raster addition without taking account for ranking and ratings. Slope, aspect, curvature, location and drainage buffer distance raster data sets have been obtained out of open source digital elevation models using ESRI’s ArcGIS. These conditioning factor raster data sets have been translated into raster data sets including simple yes or no criteria, referring to triggering or not. Subsequently they have been added by raster math to acquire a simple raster overlay map. After that this map is compared to initial displacement measurements, obtained by using a ground based synthetic aperture radar device. Acquired data is recalculated to a raster data set using the same spatial extent, to provide the possibility of comparison of the two raster data sets. The results reveal, that 76.35% of all measured movements occur in areas where raster cells include three or more conditioning factors, indicating that easy raster math operations can lead to satisfying results in local scale. 相似文献
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Melanie Beck Jürgen Köster Bert Engelen Jan M. Holstein Antje Gittel Martin Könneke Thomas Riedel Kai Wirtz Heribert Cypionka Jürgen Rullkötter Hans-Jürgen Brumsack 《Ocean Dynamics》2009,59(2):371-383
Microbial activity in permeable tidal flat margin sediments is enhanced by two main processes. First, organic matter is supplied
by rapid sedimentation at prograding tidal flat margins. Second, surface and deep pore water advection lead to a replenishment
of the dissolved organic matter and sulfate pools. Increasing microbial activity towards the low water line is reflected in
sulfate and methane profiles as well as in total cell numbers, sulfate reduction rates, and remineralization products. The
impact of high sedimentation rates on pore water biogeochemistry is confirmed by inverse modeling reproducing the depth profiles
obtained by measurements. In central parts of the tidal flats, low sedimentation rates and pore water flow velocities limit
microbial activity despite the high availability of electron acceptors for microbial respiration such as sulfate. Therefore,
tidal flat margins with high microbial activity are of special importance for budgeting biogeochemical cycling in tidal flat
areas. 相似文献
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Subsurface sediments of tidal flats and the marine deep biosphere share several features. Although on different scales in
time and space, geochemical profiles and microbial successions follow the same trends. Microbial activities are governed by
the availability of electron acceptors and the quality of electron donors. Two deep-biosphere sites and a shallow site from
a German North Sea tidal flat were exemplarily chosen to compare geochemical settings and microbiological features. At all
sites, microbial abundance was elevated at sulfate–methane transition zones. The known discrepancy between cultivation-based
and molecular diversity assessments is observed, but similar microbial community compositions are found with each of the approaches
at deep and shallow sites. These findings lead to the conclusion that we are presently unable to draw a cutting line between
the shallow and the deep subsurface. Rather, there appears to exist only one “subsurface biosphere” with gradual differences.
Therefore, tidal flats serve as an excellent model to perform microbiological experiments and to test novel techniques before
applying them to much deeper and older samples.
Responsible editor: Meinhard Simon 相似文献
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Summary The interannual variations in sea surface temperature (SST) in the equatorial east Pacific, which are dominated by the El Niño phenomenon, are shown for the period 1870–1983. Since 1870 25 significant warm events have occurred. These events are classified as weak, moderate, strong and very strong, according to the normalized SST anomalies in the region 130° W–80° W, 0°–5° S.The spatial and temporal development of a composite El Niño/Southern Oscillation (ENSO) episode, based on 10 very strong or strong events, is presented in terms of SST, surface wind and divergence anomalies for the tropical Pacific (10° N–30° S). During its evolution the following phases are distinguished: Antecedent Conditions, Onset Phase, Peak Phase, Mature Phase and Dissipation Stage.Some aspects of ocean-atmosphere interaction associated with this evolution and, more specifically, the initiation of the composite event, are described. Seasonally varying feedback processes between SST, surface wind and convergence anomaly patterns in the western Pacific/Indonesian region suggest a possible mechanism for the initiation of typical ENSO events.
With 9 Figures 相似文献
Zusammenfassung Die interannuären Variationen der Meeresoberflächentemperatur (SST) im äquatorialen Ostpazifik, die von dem El Niño-Phänomen dominiert werden, werden für die Periode 1870–1983 aufgezeigt. Seit 1870 traten 25 signifikante Ereignisse auf. Diese Ereignisse werden entsprechend den normierten SST-Anomalien in der Region 130° W–80° W, 0°–5° S als schwach, mittel, stark und sehr stark klassifiziert.Die räumliche und zeitliche Entwicklung einer Komposit-El Niño/Southern Oscillation (ENSO)-Episode, die auf 10 sehr starken bzw. starken Ereignissen basiert, wird anhand von SST-, Bodenwind- und Divergenzanomalien für den tropischen Pazifik (10° N–30° S) dargestellt. Während ihrer Entwicklung werden die folgenden Phasen unterschieden: Vorausgehende Bedingungen, Einsetzphase, Spitzenphase, Reifestadium und Auflösungsstadium.Einige Aspekte der Wechselbeziehungen Ozean—Atmosphäre werden im Zusammenhang mit der Entwicklung und insbesondere der Auslösung des Komposit-Ereignisses beschrieben. Jahreszeitlich variierende Rückkopplungsprozesse zwischen SST-, Bodenwind- und Konvergenzanomalien in der westpazifischen/indonesischen Region stellen einen möglichen Mechanismus für die Auslösung typischer ENSO-Ereignisse dar.
With 9 Figures 相似文献