Charakteristische Zirkulationstypen in mittleren Breiten der nördlichen Hemisphäre

Zusammenfassung In der vorliegenden Arbeit werden neue Klassifikationsprinzipien für Großwetterlagen entwickelt. Bisher wurde bei Wetterlagenklassifikationen das Druckfeld zugrunde gelegt, wobei quasistationären Druckzentren eine nicht berechtigte Vorrangstellung eingeräumt wurde. In der hier versuchten Klassifikation wird vom Strömungsfeld ausgegangen, das in elementare Formen zerlegt wird. Eine zu diesem Zweck durchgeführte statistische Untersuchung ergab, daß alle im Strömungsfeld auftretenden Zirkulationstypen auf drei Grundformen zurückgeführt werden können. Diese Grundformen sind:Driften, Wellen undWirbel.Die Untersuchung ergab im einzelnen, daß in mittleren Breiten der nördlichen Hemisphäre bei 49% aller untersuchten Fälle Driften, bei 23% Wellen und bei 28% Wirbel auftraten.In der hier durchgeführten Klassifikation wird das Druckfeld durch das Strömungsfeld und der Begriff Großwetterlage durch den umfassenderen Begriff des Zirkulationstyps ersetzt. Damit wird der unberechtigte Vorrang der Druckformen bei der Wetterlagenklassifikation aufgegeben. Die Klassifizierung der Zirkulationstypen ergibt sich schließlich durch Kombination der drei Zirkulationselemente: Drift, Welle und Wirbel.

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Summary New principles of classification for large-scale weather situations are outlined in this paper. Hitherto the pressure-field has been taken as a basis for such classifications by conceding a precedence of an unjustified position to semi-permanent centres of pressure. The new classification starts from the field of large-scale motions, which is dissected in elementary models. A statistical test yielded the possibility to reduce all types of atmospheric circulations in the following three elementary models:drifts, waves andeddies.In detail it was found out, that drifts occur in 49%, waves in 23% and eddies in 28% of all cases investigated.In the new classification the term pressure-field is substituted by field of motion and the expression large-scale weather situation by the more comprehensive conception type of circulation. By that the unjustified priority of pressure-centers in classifying weather situations is abolished. At last the classification of the types of circulation follows from a combination of the three elementary models: drift, wave and eddy.

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résumé La présente étude développe de nouveaux principes de classification des situations météorologiques. Alors que jusqu'ici on s'est fondé sur le champ de pression ce qui conduisait à attribuer aux centres d'action quasi stationnaires un rôle trop important, l'auteur part ici du champ de mouvement décomposé en formes élémentaires. Un examen statistique lui a montré que tous les types de circulation peuvent se ramener à trois formes fondamentales:courants, ondulations ettourbillons.Aux latitudes moyennes de l'hémisphère Nord les courants représentent le 49%, les ondulations le 23% et les tourbillons le 28%.Au champ de pression se substitue donc le champ de courant, et les situations météorologiques se groupent en types de circulation ce qui supprime le rôle prépondérant des formes isobariques. Le classement final des types de circulation résulte de la combinaison des trois types mentionnés:courants, ondulations ettourbillons.

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Mit 15 Textabbildungen     

The Pangean ice age: studies with a coupled climate-ice sheet model

 Application of an ice sheet model developed for the Pleistocene to the extensive Carboniferous glaciation on Gondwana yields an ice sheet which has several features consistent with observations. While complete deglaciation is not achieved without CO₂ changes, the Milankovich-induced fluctuations in ice sheet volume are comparable to Pleistocene glacial/ interglacial signals. This result is shown to hold for a large fraction of physically reasonable parameter space. The model also exhibits multiple equilibria and sharp bifurcations, as infinitesimal changes in the solar constant or precipitation can lead to a qualitatively different climate. The success of the model in predicting ice location in an environment quite different from the Pleistocene provides additional support for the robustness of the basic model physics and suggests that the model can be applied with some confidence to other pre-Pleistocene glaciations. Received: 30 June 1998 / Accepted: 5 January 1999     

Options to overcome the barriers to pricing European agricultural emissions

Although agriculture could contribute substantially to European emission reductions, its mitigation potential lies untapped and dormant. Market-based instruments could be pivotal in incentivizing cost-effective abatement. However, sector specificities in transaction costs, leakage risks and distributional impacts impede its implementation. The significance of such barriers critically hinges on the dimensions of policy design. This article synthesizes the work on emissions pricing in agriculture together with the literature on the design of market-based instruments. To structure the discussion, an options space is suggested to map policy options, focusing on three key dimensions of policy design. More specifically, it examines the role of policy coverage, instruments and transfers to farmers in overcoming the barriers. First, the results show that a significant proportion of agricultural emissions and mitigation potential could be covered by a policy targeting large farms and few emission sources, thereby reducing transaction costs. Second, whether an instrument is voluntary or mandatory influences distributional outcomes and leakage. Voluntary instruments can mitigate distributional concerns and leakage risks but can lead to subsidy lock-in and carbon price distortion. Third, the impact on transfers resulting from the interaction of the Common Agricultural Policy (CAP) with emissions pricing will play a key role in shaping political feasibility and has so far been underappreciated.

POLICY RELEVANCE

Following the 2015 Paris Agreement, European climate policy is at a crossroads. Achieving cost-effectively the 2030 and 2050 European targets requires all sectors to reduce their emissions. Yet, the cornerstone of European climate policy, the European Union Emissions Trading System (EU ETS), covers only about half of European emissions. Major sectors have been so far largely exempted from carbon pricing, in particular transport and agriculture. While transport has been increasingly under the spotlight as a possible candidate for an EU ETS sectoral expansion, policy discussions on pricing agricultural emissions have been virtually absent. This article attempts to fill this gap by investigating options for market-based instruments to reduce agricultural emissions while taking barriers to implementation into account.     

Measurement of DNA single-strand breaks in gill and hemolymph cells of mussels, Mytilus sp., collected on the French Atlantic Coast

DNA single-strand breaks were measured by the comet assay in both gill and hemolymph cells of mussels collected in 3 sampling areas of the French coast (Pointe du Castelli, Pen Bron and Saint-Nazaire Harbour). Whole mussel tissue samples were also collected for the chemical determination of PAH, PCB and heavy metal concentrations. In mussel, a higher level of DNA strand breaks was measured in gill than in hemolymph cells (p < 0.01). Despite a factor of contamination from 2 to 3 between sites, no difference in the extent of mussel DNA strand breaks was shown between sampling locations (p > 0.05), questioning the sensitivity of the assays used in biomonitoring studies.     

The next few years of the ICES Journal of Marine Science

This issue marks a change in the editorial team of the ICESJournal of Marine Science, in that we have bid farewell to ourformer Editor-in-Chief, Niels Daan, after six years of sterlingservice, and to our Elsevier Publishing Editor, Andrew Richford,after an even longer period of years. Both deserve credit fortheir energy and vision that has left us the legacy of a journalas widely read and cited as the ICES Journal now is, but theyleave a gap that will be a huge challenge for us to meet. However,in my new capacity as Editor-in-Chief and in Els Bosma's capacityas Elsevier's Publishing Editor, I     

Regime shifts and fishery management

Understanding regime shifts is important to management. Optimal allocation of fishery effort can be improved if it were known whether or not the regime was positive or negative. This determination is difficult because a high recruitment, when the stock is at a low level of abundance (or vice versa), may be the indication of the onset of a multidecadal regime shift, or just a chance occurrence. Accordingly, the determination of an increase or decrease in productivity from observations independent of those made directly on fish populations is important.     

Tectonic setting of the Azores Plateau deduced from a OBS survey

The studies of Azores seismicity generally show shocks with either normal faulting or right-lateral strike-slip along the ESE direction, compatible with a eastward relative motion of the Eurasian (EU) relative to the African (AF) plate. However, the 1 January 1980 earthquake was interpreted as a clear left-lateral strike-slip shock along the N150E direction. This pattern is difficult to explain in terms of the relative motion between the EU, AF and North American (NA) plates: all available models for the present day movement of this triple junction fail to explain the regional variability in the stress conditions of the area. Here we present data from a 34-day long Ocean Bottom Seismograph array deployment. We show that the seismicity is distributed along a band aligned with the island chain itself, and is concentrated along several faults with an approximate N150E strike, cutting the Azores plateau in all the area covered by the OBS network. The combination of these new results with other geophysical data permits us to conclude that the tectonic setting of the Azores plateau is characterised by the existence of two sets of faults, in the N120E and N150E directions, defining several crustal blocks, whose relative motion accommodates the interaction of the three megaplates. The deformation of these tectonic blocks is probably driven by the shear between the EU and AF plates. This model explains well the spatial variability of the stress conditions in the Azores domain, the combination of dextral and sinistral strike slip mechanisms and the observed seismotectonics of the Azores islands.