The contribution to IHY from the COST296 Action MIERS: Mitigation of Ionospheric Effects on Radio Systems     

Giorgiana De Franceschi  Lucilla Alfonsi  David Altadill  Pal Bencze  Alain Bourdillon  Dalia Buresova  Ljiljana R. Cander  Benito de la Morena  Lefteris Economou  Miguel Herraiz  Kirsti Kauristie  Jan Lastovicka  Silvia Pau  Gracia Rodriguez  Richard Stamper  Iwona Stanislawska 《Earth, Moon, and Planets》2009,104(1-4):63-67

The objective of the COST296 Action MIERS (Mitigation of Ionospheric Effects on Radio Systems) is to develop an increased knowledge of the effects imposed by the ionosphere on practical radio systems, and for the development and implementation of techniques to mitigate the deleterious effects of the ionosphere on such systems (http://www.cost296.rl.ac.uk). The COST296 Community contributes to the international efforts of IHY with scientific and outreach activities as well. After the realization of a web site hosted by Istituto Nazionale di Geofisica e Vulcanologia (INGV), developed also to promote the ionospheric physics to the open public, the COST296 Community supported an initiative addressed to the pupils of the primary school of several European Countries: the realization of a school-calendar dedicated to the Sun and to the Sun-Earth connections.  相似文献   

Climate-change effects on extreme precipitation in central Europe: uncertainties of scenarios based on regional climate models   总被引：1，自引：0，他引：1  

Jan Kyselý  Romana Beranová 《Theoretical and Applied Climatology》2009,95(3-4):361-374

Observations as well as most climate model simulations are generally in accord with the hypothesis that the hydrologic cycle should intensify and become highly volatile with the greenhouse-gas-induced climate change, although uncertainties of these projections as well as the spatial and seasonal variability of the changes are much larger than for temperature extremes. In this study, we examine scenarios of changes in extreme precipitation events in 24 future climate runs of ten regional climate models, focusing on a specific area of the Czech Republic (central Europe) where complex orography and an interaction of other factors governing the occurrence of heavy precipitation events result in patterns that cannot be captured by global models. The peaks-over-threshold analysis with increasing threshold censoring is applied to estimate multi-year return levels of daily rainfall amounts. Uncertainties in scenarios of changes for the late 21st century related to the inter-model and within-ensemble variability and the use of the SRES-A2 and SRES-B2 greenhouse gas emission scenarios are evaluated. The results show that heavy precipitation events are likely to increase in severity in winter and (with less agreement among models) also in summer. The inter-model and intra-model variability and related uncertainties in the pattern and magnitude of the change is large, but the scenarios tend to agree with precipitation trends recently observed in the area, which may strengthen their credibility. In most scenario runs, the projected change in extreme precipitation in summer is of the opposite sign than a change in mean seasonal totals, the latter pointing towards generally drier conditions in summer. A combination of enhanced heavy precipitation amounts and reduced water infiltration capabilities of a dry soil may severely increase peak river discharges and flood-related risks in this region.  相似文献   

Temporal instability of temperature singularities in a long-term series at Prague-Klementinum     

Michaela Radová  Jan Kyselý 《Theoretical and Applied Climatology》2009,95(3-4):235-243

The recent study of meteorological singularities in the Czech Republic—?ezní?ková et al. (Theor Appl Climatol 88:179–192, 2007)—is supplemented with respect to findings concerning temporal stability of air temperature singularities. A long-term daily series at Prague-Klementinum is examined over 1881–2000, adopting the same statistical background for the detection of singularities. A procedure that reduces the dependence of results on the choice of a reference period is proposed. It is shown that nearly all temperature singularities found over the period since 1961 and/or the whole period of 1881–2000 are temporally unstable, and a lot of them should be treated as statistical properties of particular data samples (time periods) reflecting sampling variability rather than stable and recurrent anomalies related to distinct circulation patterns. The most important singularities are identified, occurring on 4 days in year only (around St. Médard’s Day, 8 June), and they are linked to intraseasonal variations in the occurrence of circulation patterns conducive to warm and cold temperature anomalies. A sharp increase (decrease) in the frequency of north (south) circulation types after 8 June leads to the most robust irregularity in the mean annual cycle of temperature.  相似文献   

Should carbon-exporting countries strive for consumption-based accounting in a global cap-and-trade regime?     

Jan Christoph Steckel  Matthias Kalkuhl  Robert Marschinski 《Climatic change》2010,100(3-4):779-786

In the context of the post-Kyoto policy debate, the question was raised whether the current practice of production-based emissions accounting should be replaced by a consumption-based approach. In this paper, we qualify the conditions under which the way of carbon accounting makes a difference, and show how this affects the incentive of countries to opt for one or the other alternative. Two main insights are presented: First, it is emphasized—and formally shown with a general equilibrium trade model—that the way of accounting has neither efficiency nor distributive effects in the presence of a global cap-and-trade regime with full coverage and given national emission caps. Second, the accounting scheme does matter whenever the initial allocation rule for emission rights is related to past emissions. However, for a net exporter of carbon such as China, the preference for one or the other turns out to be ambiguous, since the current production-based accounting would be favored under grandfathering, whereas consumed carbon would be the preferred measure whenever higher current or historic emissions imply a lower initial allowance, as e.g. under the principle of historical responsibility.  相似文献   

Atmospheric properties of ENSO: models versus observations     

Sjoukje Yvette Philip  Geert Jan van Oldenborgh 《Climate Dynamics》2010,34(7-8):1073-1091

Two important atmospheric features affecting El Niño-Southern Oscillation (ENSO) are atmospheric noise and a nonlinear atmospheric response to SST. In this article, we investigate the roles of these atmospheric features in ENSO in observations and coupled Global Climate Models (GCMs). We first quantify the most important linear couplings between the ocean and atmosphere. We then characterize atmospheric noise by its patterns of standard deviation and skewness and by spatial and temporal correlations. GCMs tend to simulate lower noise amplitudes than observations. Additionally, we investigate the strength of a nonlinear response of wind stress to SST. Some GCMs are able to simulate a nonlinear response of wind stress to SST, although weaker than in observations. These models simulate the most realistic SST skewness. The influence of the couplings and noise terms on ENSO are studied with an Intermediate Climate Model (ICM). With couplings and noise terms fitted to either observations or GCM output, the simulated climates of the ICM versions show differences in ENSO characteristics similar to differences in ENSO characteristics in the original data. In these model versions the skewness of noise is of minor influence on ENSO than the standard deviation of noise. Both the nonlinear response of wind stress to SST anomalies and the relation of noise to the background SST contribute to SST skewness. The ICM is not yet fully evolved, the results rather show that this is a promising route. Overall, atmospheric noise with realistic standard deviation pattern and spatial correlations seems to be important for simulating an irregular ENSO. Both a nonlinear atmospheric response to SST and the dependence of noise on the background SST influence the El Niño/La Niña asymmetry.  相似文献   

Introducing population-adjusted historical contributions to global warming     

Nathan Rive  Jan S. Fuglestvedt 《Global Environmental Change》2008,18(1):142-152

The 1997 Brazilian Proposal suggested that differentiated emissions reduction targets for Annex I parties of the UNFCCC should be based on the impact of their historic greenhouse gas emissions on global temperature rise. In this paper, we develop methodologies for (and undertake) population-adjusted historical responsibility calculations. These adjust national-level historical responsibility calculations for historical population trends. We find a weak correlation between current per capita emissions levels and population-adjusted historical responsibility. Our calculations may contribute to burden sharing schemes in future climate agreements.  相似文献   

利用多时相Landsat影像生成白洋淀湖底DEM的研究   总被引：5，自引：2，他引：3  

沈欣  欧阳志云  Jan de LEEUW 《地理与地理信息科学》2005,21(2):16-19

该文使用多时相Landsat影像,以白洋淀地区为例,阐述基于中等分辨率的可见光—近红外遥感影像生成具有较高精度数字高程模型的非常规方法。对覆盖同一研究区的不同时相影像分别进行淹没区与非淹没区的分类,提取不同水位高度时的水域边界,并以此为相应水位高度的等高线,对获得的等高线进行插值生成数字高程模型(DEM)。这种由一系列遥感影像提取的水域图生成数字高程模型的方法适用于人为干预较少、地形相对简单的湿地或季节性湖泊,可以弥补该类地区数字高程信息不足或精度不够的缺陷。  相似文献   

Potential of space-borne GNSS reflectometry to constrain simulations of the ocean circulation     

Jan Saynisch  Maximilian Semmling  Jens Wickert  Maik Thomas 《Ocean Dynamics》2015,65(11):1441-1460

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Research in hydrographic technology at the Norwegian continental shelf institute (IKU)     

Jan Chr. Blankenburgh  John O. Klepsvik 《Marine Geodesy》2013,36(3-4):195-217

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Species-specific responses of late Miocene Discoaster spp. to enhanced biosilica productivity conditions in the equatorial Pacific and the Mediterranean     

Jan Backman  Isabella Raffi  Marina Ciummelli  Jack Baldauf 《Geo-Marine Letters》2013,33(4):285-298

Census data of a major Cenozoic calcareous nannofossil genus (Discoaster) have been acquired from Site U1338, located near the Equator in the eastern Pacific Ocean and drilled in 2009 during Integrated Ocean Drilling Program (IODP) Expedition 321. The investigated 147.53 m thick upper Miocene sediment sequence is primarily composed of biogenic carbonate and biogenic silica. Diatom biostratigraphic data were used to develop a revised biomagnetostratigraphic age model, resulting in more variable late Miocene sedimentation rates. Carbonate content variations mainly reflect dilution by biogenic silica production, although intense carbonate dissolution affects a few shorter intervals. Abundance variations of discoasters show no distinct correlation with either carbonate or biosilica contents. The two dominant Discoaster taxa are D. brouweri and D. variabilis, except for a 12 m thick interval where D. bellus outnumbers the sum of all other discoasters by a factor of 4.6. Data presented indicate that first D. hamatus and then D. berggrenii both evolved from D. bellus. Three unusual morphotypes, here referred to as Discoaster A, B and C, increase in relative abundance during episodes of enhanced biosilica production in the upper half of the investigated sequence (Messinian). Strikingly similar morphotypes have been observed previously in Messinian age sediments from the Mediterranean, characterized by alternating deposition of biogenic carbonate and biosilica. This suggests a species-specific response among some of the late Miocene discoasters to broader oceanographic and climatic forcing that promoted episodes of enhanced deposition of biogenic silica.  相似文献