An RCM multi-physics ensemble over Europe: Multi-variable evaluation to avoid error compensation

ABSTRACT:Regional Climate Models (RCMs) are widely used tools to add detail to the coarse resolution of global simulations. However, these are known to be affected by biases. Usually, published model evaluations use a reduced number of variables, frequently precipitation and temperature. Due to the complexity of the models, this may not be enough to assess their physical realism (e.g. to enable a fair comparison when weighting ensemble members). Furthermore, looking at only a few variables makes difficult to trace model errors. Thus, in many previous studies, these biases are de- scribed but their underlying causes and mechanisms are often left unknown. In this work the ability of a multi-physics ensemble in reproducing the observed climatologies of any variables over Europe is analysed. These are temperature, precipitation, cloud cover, ra- diative fluxes and total soil moisture content. It is found that, during winter, the model suffers a significant cold bias over snow covered regions. This is shown to be re- lated with a poor representation of the snow-atmosphere interaction, and is amplified by an albedo feedback. It is shown how two members of the ensemble are able to alleviate this bias, but by generating a too large cloud cover. During summer, a large sensitivity to the cumulus parameterization is found, related to large differences in the cloud cover and short wave radiation flux. Results also show that small errors in one variable are sometimes a result of error compensation, so the high dimensionality of the model evaluation problem cannot be disregarded.This work was partially supported by Projects EXTREMBLES (CGL2010-21869) and CORWES (CGL2010-22158-C02), funded by the Spanish R&D Programme. WRF4G (CGL2011-28864) provided the framework to run the model; this Spanish R&D project is co-funded by the European Regional Development Fund (ERDF). Partial support from the 7th European Framework Programme (FP7) through Grant 308291 (EUPORIAS) is also acknowledged

EC-Review - Activities of the institutions of the European Union No. 588

Information hebdomadaire aux Delégotions de la Commission européenne sur ies travaux principaux des Institut1ons de l'Union européenne = Weekly information to the Delegations of the European Commission on the principle activities of the European Union

Les relations épistolaires de Nicolas Μavrocordatos avec Jean Le Clerc et William Wake

[Δεν διατίθεται περίληψη / no abstract available]No abstrac

Les relations épistolaires de Nicolas Μavrocordatos avec Jean Le Clerc et William Wake

[Δεν διατίθεται περίληψη / no abstract available]No abstrac

Change of existing circulating fluidized bed boilers to oxy-firing conditions for CO2 capture

This work investigates a circulating fluidized bed boiler, originally designed for air-firing, retrofitted to oxy-firing with the purpose of removing the CO2 emission from coal combustion. Previous studies have shown that the heat balance on the gas-particle side can be satisfied without changes in the boiler, but then the volume flow of gas is reduced. To retain the operation like that during air-firing, the volume flow, that is the fluidization velocity, in oxy-firing should be equal to that in air-firing. It is the main purpose of this work to determine the conditions for the transition from air to oxy-firing, while the heat transfer conditions are maintained at a constant fluidization velocity. Measures to achieve this, such as adjusting the supply of additional gas and the heat transfer surface, are analysed. The fulfilment of the furnace\u27s heat balance requires extra fuel or reduction of the heat-transfer surface in the furnace. These changes affect the performance of the back pass, which must be modified to accommodate the change in gas composition and the higher sensible heat content of the flue gas. Strategies to deal with these circumstances in CFB boilers are discussed

Arts Administration internship report : the New Museum of Contemporary Art : a report

Stephen Weil writes in his collection of essays, Rethinking the Museum and Other Meditations, .. we must never forget that ideas--and not just things alone--also lie at the heart of the museum enterprise. Reality is neither objects alone nor simply ideas about objects (2). Weil\u27s insight into the matter of museums prompted me to search out a particular type of organization in which to work for this internship. No doubt any number of respected and successful institutions in New York City could have offered me an extraordinary internship in arts administration, but I was drawn to The New Museum of Contemporary Art in SoHo for the way it sought to explore ideas about the nature of art, the way it defied standard institutional practice, and the way it brazenly undermined conventional expectations of the museum experience. The New Museum confronted the common assumptions about what art is and the way arts organizations relate to our culture. Here was a museum that took risks, that did not claim to know all the answers, but was willing to systematically open itself to criticism as part of its mission. The New Museum provided me the opportunity to explore the possibilities not described in the textbooks. I knew this organization would inevitably pose a new set of problems, but I was sure it was just as likely to set forth new solutions as well. As it turned out, my original semester-long internship became a year-long adventure that provided me the chance to work closely with the influential director of a major New York art museum, the responsibility of overseeing an installation in one of its smaller galleries, and, ultimately, the opportunity to assume the position of coordinator of an exhibition that encompassed the entire museum. Were it not for this museum\u27s willingness to take a chance on an unproven quantity, to trust, to try the untried, I would not have gained so soon the experience and confidence that this institution so freely granted

Arts Administration internship report : the New Museum of Contemporary Art : a report

Stephen Weil writes in his collection of essays, Rethinking the Museum and Other Meditations, .. we must never forget that ideas--and not just things alone--also lie at the heart of the museum enterprise. Reality is neither objects alone nor simply ideas about objects (2). Weil\u27s insight into the matter of museums prompted me to search out a particular type of organization in which to work for this internship. No doubt any number of respected and successful institutions in New York City could have offered me an extraordinary internship in arts administration, but I was drawn to The New Museum of Contemporary Art in SoHo for the way it sought to explore ideas about the nature of art, the way it defied standard institutional practice, and the way it brazenly undermined conventional expectations of the museum experience. The New Museum confronted the common assumptions about what art is and the way arts organizations relate to our culture. Here was a museum that took risks, that did not claim to know all the answers, but was willing to systematically open itself to criticism as part of its mission. The New Museum provided me the opportunity to explore the possibilities not described in the textbooks. I knew this organization would inevitably pose a new set of problems, but I was sure it was just as likely to set forth new solutions as well. As it turned out, my original semester-long internship became a year-long adventure that provided me the chance to work closely with the influential director of a major New York art museum, the responsibility of overseeing an installation in one of its smaller galleries, and, ultimately, the opportunity to assume the position of coordinator of an exhibition that encompassed the entire museum. Were it not for this museum\u27s willingness to take a chance on an unproven quantity, to trust, to try the untried, I would not have gained so soon the experience and confidence that this institution so freely granted

Oceanography, Climate and Vegetation development of tropical Africa during the last glacial: Palynology and geochemistry of marine sediments of ODP Site 1078 (off Angola)

In the last decades climate change research became more and more important due to the increasing impact of human activities on the Earth s climate system. The consideration of perspectives and results from paleoclimate observations has proven useful for climate change research, the verification of model outputs and thus future projections. The late Quaternary is characterised by large and abrupt climatic shifts on millennial and centennial time scales, the so-called Dansgaard-Oeschger (D-O) cycles and Heinrich Stadials (HS). Both, the D-O cycle and HS are thought to originate in the North Atlantic and are transmitted through the atmosphere and ocean circulation which results in a near-global footprint. It has been suggested that the abrupt climatic shifts associated with HS are the effect of a reduction in the strength of the Atlantic Meridional Overturning Circulation (AMOC). According to the hypothesis of the bipolar seesaw, a reduction in the AMOC leads to a build-up of heat in the South Atlantic. Although the tropics have the potential to alter the global atmosphere-ocean dynamics through changes in the heat and freshwater balance, little is known of their role in relation to abrupt climate perturbations. This thesis contains a compilation of high-resolution pollen records from South America and Africa covering the last glacial that documents the impact, timing and amplitude of abrupt climate change on the tropical vegetation. This thesis also focuses on the reconstruction of the vegetation, climate and oceanography of southern hemisphere Africa during the last glacial using marine sediments of Ocean Program Drilling Site 1078 (off Angola)