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Sillmann J.,University of Victoria | Sillmann J.,Max Planck Institute for Meteorology | Mischa M.C.,Federal Office of Meteorology and Climatology | Kallache M.,French Climate and Environment Sciences Laboratory | And 2 more authors.
Journal of Climate | Year: 2011

North Atlantic atmospheric blocking conditions explain part of the winter climate variability in Europe, being associated with anomalous cold winter temperatures. In this study, the generalized extreme value (GEV) distribution is fitted to monthly minima of European winter 6-hourly minimum temperatures from the ECHAM5/MPI-OM global climate model simulations and the ECMWF reanalysis product known as ERA- 40, with an indicator for atmospheric blocking conditions being used as covariate. It is demonstrated that relating the location and scale parameter of the GEV distribution to atmospheric blocking improves the fit to extreme minimum temperatures in large areas of Europe. The climate model simulations agree reasonably with ERA-40 in the present climate (1961-2000). Under the influence of atmospheric blocking, a decrease in the 0.95th quantiles of extreme minimum temperatures can be distinguished. This cooling effect of atmospheric blocking is, however, diminished in future climate simulations because of a shift in blocking location, and thus reduces the chances of very cold winters in northeastern parts of Europe. © 2011 American Meteorological Society.


Kallache M.,Climpact | Kallache M.,CEA Saclay Nuclear Research Center | Vrac M.,CEA Saclay Nuclear Research Center | Naveau P.,CEA Saclay Nuclear Research Center | Michelangeli P.-A.,Climpact
Journal of Geophysical Research: Atmospheres | Year: 2011

Reanalysis data and general circulation model outputs typically provide information at a coarse spatial resolution, which cannot directly be used for local impact studies. Downscaling methods have been developed to overcome this problem, and to obtain local-scale information from large-scale atmospheric variables. The deduction of local-scale extremes still is a challenge. Here a probabilistic downscaling approach is presented where the cumulative distribution functions (CDFs) of large- and local-scale extremes are linked by means of a transfer function. In this way, the CDF of the local-scale extremes is obtained for a projection period, and statistical characteristics, like return levels, are inferred. The input series are assumed to be distributed according to an extreme value distribution, the Generalized Pareto distribution (GPD). The GPD parameters are linked to further explanatory variables, hence defining a nonstationary model. The methodology (XCDF-t) results in a parametric CDF, which is as well a GPD. Realizations generated from this CDF provide confidence bands. The approach is applied to downscale National Centers for Environmental Prediction reanalysis precipitation in winter. Daily local precipitation at five stations in southern France is obtained. The calibration period 1951-1985 is used to infer precipitation over the validation period 1986-1999. The applicability of the approach is verified by using observations, quantile-quantile plots, and the continuous ranked probability score. The stationary XCDF-t approach shows good results and outperforms the nonparametric CDF-t approach or quantile mapping for some stations. The inclusion of covariate information improves results only sometimes; therefore, covariates have to be chosen with care. Copyright 2011 by the American Geophysical Union.


Kallache M.,Climpact | Maksimovich E.,LOCEAN IPSL | Michelangeli P.-A.,Climpact | Naveau P.,LSCE IPSL
Journal of Climate | Year: 2010

The performance of general circulation models (GCMs) varies across regions and periods. When projecting into the future, it is therefore not obvious whether to reject or to prefer a certain GCM. Combining the outputs of several GCMs may enhance results. This paper presents a method to combine multimodel GCM projections by means of a Bayesian model combination (BMC). Here the influence of each GCM is weighted according to its performance in a training period, with regard to observations, as outcome BMC predictive distributions for yet unobserved observations are obtained. Technically, GCM outputs and observations are assumed to vary randomly around common means, which are interpreted as the actual target values under consideration. Posterior parameter distributions of the authors' Bayesian hierarchical model are obtained by a Markov chain Monte Carlo (MCMC) method. Advantageously, all parameters-such as bias and precision of the GCM models-are estimated together. Potential time dependence is accounted for by integrating a Kalman filter. The significance of trend slopes of the common means is evaluated by analyzing the posterior distribution of the parameters. The method is applied to assess the evolution of ice accumulation over the oceanic Arctic region in cold seasons. The observed ice index is created out of NCEP reanalysis data. Outputs of seven GCMs are combined by using the training period 1962-99 and prediction periods 2046-65 and 2082-99 with Special Report on Emissions Scenarios (SRES) A2 and B1. A continuing decrease of ice accumulation is visible for the A2 scenario, whereas the index stabilizes for the B1 scenario in the second prediction period. © 2010 American Meteorological Society.


Beugnet F.,Merial | Kolasinski M.,Climpact | Michelangeli P.-A.,Climpact | Vienne J.,Climpact | Loukos H.,Climpact
Geospatial Health | Year: 2011

Rhipicephalus sanguineus, the brown dog tick, has a worldwide distribution in areas with a relatively warm climate, including mild winters. This tick plays an important role as vector for various animal and human pathogens, including bacteria and protozoa. Based on precise daily meteorological data from the past 40 years, combined with mathematical modelling designed to predict tick activity, two modelling approaches were developed. The first examined the evolution of the number of weeks with favourable biological conditions for ticks in four French cities located at various latitudes of the country: Nîmes in the south, Paris in the north, Lyon in the east and Nantes in the west. The second analysed the extension of the geographical surface area in km2 where the biological conditions favour tick activity for at least 12 weeks per year. Both analyses revealed clear evidence of increased temperatures coupled with an augmented tick activity index in three of the four cities. However, the change was not significant in Nîmes, where the climate is Mediterranean and the tick is already endemic. For Paris, Lyon and Nantes, the activity index values have increased significantly, i.e. by 4.4%, 4.0% and 3.4%, respectively. The distribution of the activity index values is evolving strongly with significantly fewer values below 50% since the 1960s and a clear decrease of values between 20% and 50% during the latest decade. Between 1960 and 2000, the theoretical extension of the surface area where the climatic index is suitable for R. sanguineus has increased by 66%. Even though several other important factors, such as changes in biotopes or human activity, are not included in this study, the resulting patterns and trends are noticeable. Our models constitute the first demonstration of the impact of climate change on the activity and distribution of ticks and confirm the observed northward migration trend for this Mediterranean domestic tick.


Grant
Agency: Cordis | Branch: FP7 | Program: CPCSA | Phase: INFRA-2007-1.2-01 | Award Amount: 2.85M | Year: 2008

Climate science plays an increasingly important role for European policy-makers and private sector companies. Basic research and development of effective strategies to mitigate climate change and deal with its impact on society are required, involving a wide range of experts from multiple disciplines. These expert need to access climate data, in particular data from model projections for the next decades and centuries, and to assess the suitability of that data for their purposes. Currently, even if large repositories of climate data are accessible, these repositories are poorly connected and described. The data is therefore difficult to understand, compare and exploit because there is no common information paradigm.\n\nThe main objective of METAFOR is to define a Common Information Model (CIM) that describes in a standard way climate data and the models that produce the data. METAFOR will build on existing metadata (data describing data) currently used in existing data repositories and address issues like metadata fragmentation, gaps, or duplication. In close interaction with related initiatives at the international level, METAFOR will propose solutions to identify, access and use the climate data in these repositories. To support the adoption of the CIM, METAFOR will build CIM-based tools and services, allowing specific data and models to be found and compared between holdings at partner sites. METAFOR will therefore optimise the way climate data infrastructures are used to store knowledge, thereby adding value to primary research data for an increasingly wide range of stakeholders.\n\nMETAFOR will take the first step in doing for climate data what search engines have done for the Internet: it will put users of climate data in touch with the information they need. Simply unlocking existing climate data repositories for new communities will provide new exciting opportunities for scientific research, policy making, and private sector competitiveness.


Trademark
Climpact | Date: 2011-08-02

Computer software programs for use in database management in the field of weather services. Conducting marketing studies, business organisation consultancy, organisation of exhibitions for commercial purposes, computerised file management, all these services relating to issues associated with meteorology, climatology and the environment. Provision of access to data or documents stored electronically in central files for remote consultation in the fields of economic, financial or environmental data. Conducting feasibility studies of technical projects relating to meteorological and climatic constraints; computer programming; services of engineers, namely, engineering; conducting technical project studies; design and development of computer software, all these services relating to consultancy in meteorology, climatology and the environment; scientific research and computer modeling, namely, computer simulation from computer programs of others of the weather and climate and their impact on economic activity; professional consultancy on the issues of the weather, climate and the environment, namely, providing scientific information in the fields of climate change and global warming; evaluations and research in the scientific and technological fields provided by engineers, namely engineering consultancy in meteorology, climatology and the environment; information agency for issues relating to the weather, climate and the environment, namely, providing meteorological information and scientific information and environmental information in the fields of climate change.


Trademark
Climpact | Date: 2011-08-02

Computer software programs for use in database management in the field of weather services. Conducting marketing studies, business organization consultancy, organization of exhibitions for commercial purposes, computerized file management, all these services relating to issues associated with meteorology, climatology and the environment. Provision of access to data or documents stored electronically in central files for remote consultation in the fields of economic, financial or environmental data. Conducting feasibility studies of technical projects relating to meteorological and climatic constraints; computer programming; services of engineers, namely, engineering; conducting technical project studies; design and development of computer software, all these services relating to consultancy in meteorology, climatology and the environment; scientific research and computer modeling, namely, computer simulation from computer programs of others of the weather and climate and their impact on economic activity; professional consultancy on the issues of the weather, climate and the environment, namely, providing scientific information in the fields of climate change and global warming; evaluations and research in the scientific and technological fields provided by engineers, namely, engineering consultancy in meteorology, climatology and the environment; information agency for issues relating to the weather, climate and the environment, namely, providing meteorological information and scientific information and environmental information in the fields of climate change.


Trademark
Climpact | Date: 2011-06-21

computer software for use in database management in the field of weather and climate services. Market research, business organization consultancy, organization of exhibitions for commercial purposes, computerized file management, all of these services being dedicated to the impact of climate and weather on the economy. Providing access to a computer database in the field of finances, economics, weather and climate. Technical project studies in relation to climate and environment constrains, namely, research in the field of climate change; software development and design; scientific research and environmental and climate modeling, namely, computer modeling services, namely, computer simulation from computer programs for others; professional consultancy in the area of climate and the environment, namely, providing scientific information in the fields of climate change and global warming; evaluations, estimates and scientific and technological research provided by engineers, namely, engineering consultancy in meteorology, oceanography, climatology and the environment; information agencies relating to climate and the environment, namely, providing scientific information on the weather and the environment.


Trademark
Climpact | Date: 2011-03-29

Computer software for use in database management in the field of weather and climate services. Providing access to a computer database in the field of finances, economics, weather and climate. Technical project studies in relation to climate and environment constrains, namely, research in the field of climate change; software development and design; scientific research and environmental and climate modeling, namely, computer modeling services, namely, computer simulation from computer programs for others; professional consultancy in the area of climate and the environment, namely, providing scientific information in the fields of climate change and global warming; evaluations, estimates and scientific and technological research provided by engineers, namely, engineering consultancy in meteorology, oceanography, climatology and the environment; information agencies relating to climate and the environment, namely, providing scientific information on the weather and the environment.


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