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| 2. |
- Döös, Kristofer, et al.
(författare)
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The Coupled Ocean-Atmosphere Hydrothermohaline Circulation
- 2017
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Ingår i: Journal of Climate. - 0894-8755 .- 1520-0442. ; 30:2, s. 631-647
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Tidskriftsartikel (refereegranskat)abstract
- The thermohaline circulation of the ocean is compared to the hydrothermal circulation of the atmosphere. The oceanic thermohaline circulation is expressed in potential temperature-absolute salinity space and comprises a tropical cell, a conveyor belt cell, and a polar cell, whereas the atmospheric hydrothermal circulation is expressed in potential temperature-specific humidity space and unifies the tropical Hadley and Walker cells as well as the midlatitude eddies into a single, global circulation. The oceanic thermohaline streamfunction makes it possible to analyze and quantify the entire World Ocean conversion rate between cold-warm and fresh-saline waters in one single representation. Its atmospheric analog, the hydrothermal streamfunction, instead captures the conversion rate between cold-warm and dry-humid air in one single representation. It is shown that the ocean thermohaline and the atmospheric hydrothermal cells are connected by the exchange of heat and freshwater through the sea surface. The two circulations are compared on the same diagramby scaling the axes such that the latent heat energy required to move an air parcel on the moisture axis is equivalent to that needed to move a water parcel on the salinity axis. Such a comparison leads the authors to propose that the Clausius-Clapeyron relationship guides both the moist branch of the atmospheric hydrothermal circulation and the warming branches of the tropical and conveyor belt cells of the oceanic thermohaline circulation.
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| 3. |
- Hemphälä, Jens, 1973-
(författare)
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Exploring Sustainable Work Systems : An Interactional Perspective on Learning and Organizing
- 2005
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Licentiatavhandling (övrigt vetenskapligt/konstnärligt)abstract
- Working conditions are increasingly unpredictable, complex, and ungovernable creating severe health risks for employees and negative economic consequences for both corporations and society. Considering the growth in understanding human psychology and sociology, and the progression in measuring working conditions and health, this phenomenon is most perplexing. The enigma has yielded interest in a field known as sustainable work systems, where the challenge is to organize work in a manner that is both beneficial for the business and for its employees. In an attempt to shed light on the growing issue, this dissertation outlines the features of a model intended to capture conditions of organization where learning is of paramount importance, and where organization is conceptualised using interaction as the foundation. One central question concerns which forms of interactions and co-operations replace traditional structures in organizations. Another relevant question, linked to the former, concerns the way in which these structures shape conditions of organization, learning, efficiency, and effectiveness. A combination of research methods has been employed to provide an enhanced picture of this inquiry. Four corporate sub-units have been subject to a cross-sectional study. These sub-units were chosen by middle managers of a corporation because they excelled in an organizational reform that was initiated two years prior. During 2004, a survey was constructed and distributed to all employees in these four sub-units. Data regarding the sub-units’ efficiency and effectiveness has been collected; and, interviews with managers leading the organizational change have been conducted. The two papers included in this thesis disclose four distinctly different approaches to organizational design. All four sub-units have separate conceptions of function and organization, although the guiding principles prescribed by top-management were identical for each of the four first-line managers who were leading the change. Three of the four sub-units have made more pervasive change efforts, and have a higher degree of learning and development, efficiency and effectiveness. The results of this thesis suggest that interaction serves as a vehicle for shaping organizational conditions and outcomes. As a consequence of the chosen design, interaction varied between sub-units, thus influencing conditions of organization, learning, efficiency and effectiveness.
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| 4. |
- Kjellsson, Joakim, 1986-, et al.
(författare)
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The Atmospheric General Circulation in Thermodynamical Coordinates
- 2014
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Ingår i: Journal of the Atmospheric Sciences. - 0022-4928 .- 1520-0469. ; 71:3, s. 916-928
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Tidskriftsartikel (refereegranskat)abstract
- The zonal and meridional components of the atmospheric general circulation are used to define a global thermodynamic stream function in dry static energy versus latent heat coordinates. Diabatic motions in the tropical circulations and fluxes driven by midlatitude eddies are found to form a single, global thermodynamic cycle. Calculations based on the ERA-Interim reanalysis dataset indicate that the cycle has a peak transport of 428 Sv (Sv = 109 kg s−1). The thermodynamic cycle encapsulates a globally interconnected heat and water cycle comprising ascent of moist air where latent heat is converted into dry static energy, radiative cooling where dry air loses dry static energy, and a moistening branch where air is warmed and moistened. It approximately follows a tropical moist adiabat and is bounded by the Clausius-Clapeyron relationship for near-surface air. The variability of the atmospheric general circulation is related to ENSO events using reanalysis data from recent years (1979-2009) and historical simulations from the EC-Earth coupled climate model (1850-2005). The thermodynamic cycle in both EC-Earth and ERA-Interim widens and weakens with positive ENSO phases and narrows and strengthens during negative ENSO phases with a high correlation coefficient. Weakening in amplitude suggests a reduction in moist convection in the tropics, while widening suggests an increase in mean tropical near-surface moist static energy.
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| 5. |
- van Sebille, Erik, et al.
(författare)
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Lagrangian ocean analysis : Fundamentals and practices
- 2018
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Ingår i: Ocean Modelling. - : Elsevier BV. - 1463-5003 .- 1463-5011. ; 121, s. 49-75
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Forskningsöversikt (refereegranskat)abstract
- Lagrangian analysis is a powerful way to analyse the output of ocean circulation models and other ocean velocity data such as from altimetry. In the Lagrangian approach, large sets of virtual particles are integrated within the three-dimensional, time-evolving velocity fields. Over several decades, a variety of tools and methods for this purpose have emerged. Here, we review the state of the art in the field of Lagrangian analysis of ocean velocity data, starting from a fundamental kinematic framework and with a focus on large-scale open ocean applications. Beyond the use of explicit velocity fields, we consider the influence of unresolved physics and dynamics on particle trajectories. We comprehensively list and discuss the tools currently available for tracking virtual particles. We then showcase some of the innovative applications of trajectory data, and conclude with some open questions and an outlook. The overall goal of this review paper is to reconcile some of the different techniques and methods in Lagrangian ocean analysis, while recognising the rich diversity of codes that have and continue to emerge, and the challenges of the coming age of petascale computing.
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