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991.
Alfons Zehnder Dr. J. Komárek Prof. Dr. S. Golubić Prof. Dr. R. Y. Stanier Dr. J. Komárek Dr. J. Ludvík Dr. L. Kováčik Dr. Asta Almestrand Prof. Dr. P. Compère Dr. D. Mollenhauer Dr. F. Hindák Dr. T. P. Chang Dr. Nagaraj Jeeji Bai C. V. Seshadri Dr. M. -E. Meffert Dr. R. Oberhäuser Dr. J. Overbeck Dr. F. Hindák Susan E. Campbell Dr. Jaroslava Komárková Dr. U. Uehlinger Dr. F. Schanz Dr. Alfons Zehnder 《Aquatic Sciences - Research Across Boundaries》1983,45(1):267-310
The 8th Symposium of the International Association for Cyanophyte Research IAC was attended by 29 specialists from 11 countries.
The 19 oral presentations and discussions centered on the following themes: The basic principles of cyanophyte taxonomy (3
lectures), systematic problems of certain taxonomic groups (5 lectures), morphology (6 lectures) and ecology (5 lectures).
The intensive discussions between representatives of the classical (european) taxonomic treatment of cyanophytes (based on
morphological and ecological characteristics) and those representing the bacteriological study of ‘cyanobacteria’ were especially
valuable. The central theme of the meeting was, however, the mutual microscopic study and discussion of problematic blue-greens
from natural habitats, that were mostly collected during the three field trips into different areas of central Switzerland
(Grimsel-Gotthard-Nufenen. Klewenalp. Gerzensee).
相似文献
992.
Timescales associated with climate change and their relevance in adaptation strategies 总被引:2,自引:1,他引:1
Anthropogenic greenhouse gas emissions that induce changes in the Earth’s climate affect particular variables and locations differently. A key part of this difference is the timescale at which this change takes place, which will eventually have important consequences for adaptation requirements. This idea of timescale associated with climate change has been used several times in the past to estimate the urgency of adaptation in particular regions. The definition of climate-change timescale is, however, not unique. For example, we can think of it in terms of an expected trend (e.g. in temperature) reaching a given threshold, or think of it in terms of the time it may take this trend to become statistically significant. We may also wonder about the validity of this speculation given that, due to natural variability, the expected trend may in fact not be realized. In this article we explore alternative ways of defining the timescale of climate-change, compare their properties, and illustrate them with an example for the case of projected surface temperature over North America. It is shown that these timescales are analytically related but may differ substantially in magnitude under certain conditions. In particular, it is shown that climate change impact on vulnerable systems may arrive before statistical detection of the variable’s trend takes place. This fact may have implications on how climate change impacts are seen by those with diverging interests. 相似文献
993.
Ocean feedback to tropical cyclones: climatology and processes 总被引:1,自引:0,他引:1
Swen Jullien Patrick Marchesiello Christophe E. Menkes Jérôme Lefèvre Nicolas C. Jourdain Guillaume Samson Matthieu Lengaigne 《Climate Dynamics》2014,43(9-10):2831-2854
This study presents the first multidecadal and coupled regional simulation of cyclonic activity in the South Pacific. The long-term integration of state-of the art models provides reliable statistics, missing in usual event studies, of air–sea coupling processes controlling tropical cyclone (TC) intensity. The coupling effect is analyzed through comparison of the coupled model with a companion forced experiment. Cyclogenesis patterns in the coupled model are closer to observations with reduced cyclogenesis in the Coral Sea. This provides novel evidence of air–sea coupling impacting not only intensity but also spatial cyclogenesis distribution. Storm-induced cooling and consequent negative feedback is stronger for regions of shallow mixed layers and thin or absent barrier layers as in the Coral Sea. The statistical effect of oceanic mesoscale eddies on TC intensity (crossing over them 20 % of the time) is also evidenced. Anticyclonic eddies provide an insulating effect against storm-induced upwelling and mixing and appear to reduce sea surface temperature (SST) cooling. Cyclonic eddies on the contrary tend to promote strong cooling, particularly through storm-induced upwelling. Air–sea coupling is shown to have a significant role on the intensification process but the sensitivity of TCs to SST cooling is nonlinear and generally lower than predicted by thermodynamic theories: about 15 rather than over 30 hPa °C?1 and only for strong cooling. The reason is that the cooling effect is not instantaneous but accumulated over time within the TC inner-core. These results thus contradict the classical evaporation-wind feedback process as being essential to intensification and rather emphasize the role of macro-scale dynamics. 相似文献
994.
Nicolas Kolodziejczyk Frédéric Marin Bernard Bourlès Yves Gouriou Henrick Berger 《Climate Dynamics》2014,43(11):3025-3046
The termination of the Equatorial Undercurrent (EUC) in the eastern equatorial Atlantic during boreal summer and fall, and the fate of the associated saline water masses, are analyzed from in situ hydrological and currents data collected during 19 hydrographic cruises between 2000 and 2007, complemented by observations from Argo profiling floats and PIRATA moorings, and from a numerical simulation of the Tropical Atlantic Ocean for the period 1993–2007. An intense variability of the circulation and hydrological properties is evidenced from observations in the upper thermocline (24.5–26.2 isopycnal layer) between June and November. During early boreal summer, saline water masses are transported eastward in the upper thermocline to the African coast within the EUC, and recirculate westward on both sides of the EUC. In mid-boreal summer, the EUC weakens in the upper thermocline and the equatorial salinity maximum disappears due to intense mixing with the surface waters during the upwelling season. The extra-equatorial salinity maxima are also partially eroded during the boreal summer, with a slight poleward migration of the southern hemisphere maximum until late boreal summer. The upper EUC reappears in September, feeding again the eastern equatorial Atlantic with saline waters until boreal spring. During December–January, numerical results suggest a second seasonal weakening of the EUC in the Gulf of Guinea, with a partial erosion of the associated equatorial salinity maximum. 相似文献
995.
Marta Fort J. Antoni Sellarès 《International journal of geographical information science》2014,28(9):1877-1903
Data analysis and knowledge discovery in trajectory databases is an emerging field with a growing number of applications such as managing traffic, planning tourism infrastructures or better understanding wildlife. In this paper, we study the problem of finding flock patterns in trajectory databases. A flock refers to a large enough subset of entities that move close to each other for, at least, a given time interval. We present parallel algorithms, to be run on a Graphics Processing Unit, for reporting three different variants of the flock pattern: (1) all maximal flocks, (2) the largest flock and (3) the longest flock. We also provide their complexity analysis together with experimental results showing the efficiency and scalability of our approach. 相似文献
996.
Lidia Pittarello Ludovic Ferrière Stepan M. Chernonozhkin Frank Vanhaecke Steven Goderis 《Meteoritics & planetary science》2023,58(11):1677-1690
Diogenites, which are part of the howardite–eucrite–diogenite (HED) group, are considered to represent rocks from the lower crust and mantle of a differentiated planetary body, likely the asteroid 4 Vesta. The Northwest Africa 12973 (NWA 12973) meteorite was classified as an anomalous diogenite due to the occurrence of a vesiculated layer. This work reports on the petrographic and geochemical study of two fragments of this meteorite, aiming to better constrain the origin of the vesiculated layer. Whereas the interior of NWA 12973 (here called host) presents the typical characteristics of an olivine diogenite, that is, coarse-grained pyroxene, olivine ribbons, chromite, and accessory phases, the vesiculated layer presents a fine-grained pyroxene groundmass with local rounded relics of olivine and interstitial chromite and metal, and is characterized by abundant large vesicles. The contact between the vesiculated layer and the host is sharply defined. The composition of individual minerals does not show any significant differences between the host and the vesiculated layer, suggesting in situ melting. Geothermobarometry indicates a slightly higher crystallization temperature at lower pressure for the vesiculated layer, consistent with melting and crystallization under lower crustal conditions upon exhumation. The trigger for the local melting was likely a large impact event, which was responsible for adiabatic decompression in the central area or deep faulting and frictional melting. 相似文献
997.
The green–blue swing: plasticity of plankton food‐webs in response to coastal oceanographic dynamics
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Domenico D'Alelio Maria Grazia Mazzocchi Marina Montresor Diana Sarno Adriana Zingone Iole Di Capua Gayantonia Franzè Francesca Margiotta Vincenzo Saggiomo Maurizio Ribera d'Alcalà 《Marine Ecology》2015,36(4):1155-1170
The internal organization of plankton communities plays a key role in biogeochemical cycles and in the functioning of aquatic ecosystems. In this study, the structure of a marine plankton community (including both unicellular and multicellular organisms) was inferred by applying an ecological network approach to species abundances observed weekly at the long‐term ecological research station MareChiara (LTER‐MC) in the Gulf of Naples (Tyrrhenian Sea, Mediterranean Sea) in the summers of 2002–2009. Two distinct conditions, characterized by different combination of salinity and chlorophyll values, alternated at the site: one influenced by coastal waters, herein named ‘green’, and the other reflecting more offshore conditions, named ‘blue’. The green and blue ‘phases’ showed different keystone biological elements: namely, large diatoms and small‐sized flagellates, respectively. Several correlations amongst species belonging to different trophic groups were found in both phases (connectance ~0.30). In the green phase, several links between phytoplankton and mesozooplankton and within the latter were detected, suggesting matter flow from microbes up to carnivorous zooplankton. A microbial‐loop‐like sub‐web, including mixo‐ and heterotrophic dinoflagellates and ciliates, was present in the green phase, but it was relatively more important in the blue phase. The latter observation suggests a more intense cycling of matter at the microbial trophic level in the blue phase. These results show that different modes of ecological organization can emerge from relatively small changes in the composition of aquatic communities coping with environmental variability. This highlights a significant plasticity in the internal structure of plankton webs, which should be taken into account in predictions of the potential effects of climatic oscillations on aquatic ecosystems and biogeochemical cycles therein. 相似文献
998.
999.
Emilio Lèbre La Rovere Carolina Burle Dubeux Amaro Olimpio Pereira Jr William Wills 《Climate Policy》2013,13(2):70-86
The main assumptions and findings are presented on a comparative analysis of three GHG long-term emissions scenarios for Brazil. Since 1990, land-use change has been the most important source of GHG emissions in the country. The voluntary goals to limit Brazilian GHG emissions pledged a reduction in between 36.1% and 38.9% of GHG emissions projected to 2020, to be 6–10% lower than in 2005. Brazil is in a good position to meet the voluntary mitigation goals pledged to the United Nations Framework Convention on Climate Change (UNFCCC) up to 2020: recent efforts to reduce deforestation have been successful and avoided deforestation will form the bulk of the emissions reduction commitment. In 2020, if governmental mitigation goals are met, then GHG emissions from the energy system would become the largest in the country. After 2020, if no additional mitigation actions are implemented, GHG emissions will increase again in the period 2020–2030, due to population and economic growth driving energy demand, supply and GHG emissions. However, Brazil is in a strong position to take a lead in low-carbon economic and social development due to its huge endowment of renewable energy resources allowing for additional mitigation actions to be adopted after 2020. Policy relevance The period beyond 2020 is now relevant in climate policy due to the Durban Platform agreeing a ‘protocol, legal instrument or agreed outcome with legal force’ that will have effect from 2020. After 2020, Brazil will be in a situation more similar to other industrialized countries, faced with a new challenge of economic development with low GHG energy-related emissions, requiring the adoption of mitigation policies and measures targeted at the energy system. Unlike the mitigation actions in the land-use change sector, where most of the funding will come from the national budgets due to sovereignty concerns, the huge financial resources needed to develop low-carbon transport and energy infrastructure could benefit from soft loans channelled to the country through nationally appropriate mitigation actions (NAMAs). 相似文献
1000.
Gisèle Schmid 《Climate Policy》2013,13(6):722-740
Technology transfer is not an explicit objective of the Clean Development Mechanism (CDM). However, it constitutes a potential co-benefit by helping to improve living conditions in developing countries. Understanding the drivers and barriers of technology transfer in CDM projects is therefore essential to direct investment flows in host countries and enhance the current CDM framework. In this respect, the contribution of this article is twofold. First, it identifies stepping stones and stumbling blocks to technology transfer in the CDM. Higher applied tariff rates on environmental goods and services as well as burdensome administrative procedures to start a new business are found to be negatively associated with the likelihood of a technology transfer. The results are robust to the exclusion of large host countries such as China and India from the sample. Second, as an extension, the article analyses the correspondence of these supporting factors and barriers with the likelihood of a transfer of the different types of technology (equipment, knowledge, or both). The article concludes with policy recommendations for non-Annex I governments, and suggestions for improvements to the CDM to better assess technology transfer in offsetting projects. 相似文献