544 research outputs found

    Establishing and Preserving Section Corner Stones

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    Internal wave pressure, velocity, and energy flux from density perturbations

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    Determination of energy transport is crucial for understanding the energy budget and fluid circulation in density varying fluids such as the ocean and the atmosphere. However, it is rarely possible to determine the energy flux field J=pu\mathbf{J} = p \mathbf{u}, which requires simultaneous measurements of the pressure and velocity perturbation fields, pp and u\mathbf{u}. We present a method for obtaining the instantaneous J(x,z,t)\mathbf{J}(x,z,t) from density perturbations alone: a Green's function-based calculation yields pp, and u\mathbf{u} is obtained by integrating the continuity equation and the incompressibility condition. We validate our method with results from Navier-Stokes simulations: the Green's function method is applied to the density perturbation field from the simulations, and the result for J\mathbf{J} is found to agree typically to within 1%1\% with J\mathbf{J} computed directly using pp and u \mathbf{u} from the Navier-Stokes simulation. We also apply the Green's function method to density perturbation data from laboratory schlieren measurements of internal waves in a stratified fluid, and the result for J\mathbf{J} agrees to within 6%6\% with results from Navier-Stokes simulations. Our method for determining the instantaneous velocity, pressure, and energy flux fields applies to any system described by a linear approximation of the density perturbation field, e.g., to small amplitude lee waves and propagating vertical modes. The method can be applied using our Matlab graphical user interface EnergyFlux

    Connected Women: How Mobile Can Support Women's Economic and Social Empowerment

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    This report explores how mobile services provided by Vodafone and the Vodafone Foundation are enabling women to seize new opportunities and improve their lives. Accenture Sustainability Services were commissioned to conduct research on the services and to assess their potential social and economic impact if they were widely available across Vodafone's markets by 2020. It showcases the projects and the work of those involved and also poses the question -- what would the benefit to women and to society at large be if projects such as these were taken to scale and achieved an industrialscale of growth? This reflects the Foundation's commitment not solely to the development of pilots but rather the Trustees' ambition to see projects which lead to transformational change. In order to understand this more deeply, the Report looks at the benefits for women and society and providessome financial modelling for how the engagement of commercial players could achieve industrial, sustainable growth in these areas. Accenture has provided the modelling and, given the public benefit and understanding which the report seeks to generate, these are shared openly for all in the mobile industry to understand and share. It is the Trustees' hope that the collaboration with Oxford University and Accenture in the delivery of this Report will stimulate not only the expansion of existing charitable programmes but will also seed other philanthropic, social enterprise or commercial initiatives

    Validation of spaceborne and modelled surface soil moisture products with cosmic-ray neutron probes

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    The scale difference between point in situ soil moisture measurements and low resolution satellite products limits the quality of any validation efforts in heterogeneous regions. Cosmic Ray Neutron Probes (CRNP) could be an option to fill the scale gap between both systems, as they provide area-average soil moisture within a 150–250 m radius footprint. In this study, we evaluate differences and similarities between CRNP observations, and surface soil moisture products from the Advanced Microwave Scanning Radiometer 2 (AMSR2), the METOP-A/B Advanced Scatterometer (ASCAT), the Soil Moisture Active and Passive (SMAP), the Soil Moisture and Ocean Salinity (SMOS), as well as simulations from the Global Land Data Assimilation System Version 2 (GLDAS2). Six CRNPs located on five continents have been selected as test sites: the Rur catchment in Germany, the COSMOS sites in Arizona and California (USA), and Kenya, one CosmOz site in New South Wales (Australia), and a site in Karnataka (India). Standard validation scores as well as the Triple Collocation (TC) method identified SMAP to provide a high accuracy soil moisture product with low noise or uncertainties as compared to CRNPs. The potential of CRNPs for satellite soil moisture validation has been proven; however, biomass correction methods should be implemented to improve its application in regions with large vegetation dynamics
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