540 research outputs found
Statistical Analysis of Simulated Spaceborne Thermodynamics Lidar Measurements in the Planetary Boundary Layer
No full textThe performance of a spaceborne Raman lidar offering measurements of water vapor, temperature, aerosol backscatter and extinction is assessed statistically by use of a lidar simulator and a global model to provide inputs for simulation. The candidate thermodynamics lidar system is envisioned to make use of a sun-synchronous, dawn/dusk orbit. Cloud-free atmospheric profiles simulated by the NASA/GSFC GEOS model for the orbit of the CALIPSO satellite on 15 July 2009 were used as input to a previously validated lidar simulator where GEOS profiles that satisfy the solar zenith angle restrictions of the dawn/dusk orbit, and are located within the Planetary Boundary Layer as defined by the GEOS model, were selected for the statistical analysis. To assess the performance of the simulated thermodynamics lidar system, measurement goals were established by considering the WMO Observing Systems Capability Analysis and Review (OSCAR) requirements for Numerical Weather Prediction. The efforts of Di Girolamo et al., 2018 established the theoretical basis for the current work and discussed many of the technological considerations for a spaceborne thermodynamics lidar. The work presented here was performed during 2017–2018 under the auspices of the NASA/GSFC Planetary Boundary Layer Science Task Group and expanded on previous efforts by considerably increasing the statistical robustness of the performance simulations and extending the statistics to include those of aerosol backscatter and extinction measurements. Further work that is currently being conducted includes Observing Systems Simulation Experiments to assess the impact of a thermodynamics lidar on global forecast improvement
UV Raman Lidar measurements of atmospheric temperature/relative humidity during ihop: Measurements in presence of clouds
No full textRotational Raman Lidar measurements of atmospheric
temperature in the UV region have been recently
demonstrated by Di Girolamo et al. [1]. The
exploitation of the RR technique in the UV has the
potential to achieve high precision, even in daytime
conditions due to reduced sky background [1].
Additionally, this spectral region presents a limited
hazard for eye injury.
In this presentation we illustrate some of the RR lidar
measurements of atmospheric temperature performed
by the NASA Scanning Raman Lidar in the context of
the International H2O Project (May-June 2002), with
particular emphasis to the measurements in presence of
clouds. A specific case study (4 June 2002) is
considered to assess RR lidar measurement capability
in presence of mid-level/cirrus clouds. Examples are
provided of relative humidity measurements inferred
from simultaneous UV Raman lidar measurements of
water vapour and temperature. These probably
represent the first UV lidar based relative humidity
measurements ever
ANALYSIS OF SCATTERING PROPERTIES OF ECCENTRIC SPHERES IN APPLICATION TO LIDAR MEASUREMENTS
No full textA Mie backscattering model for spherical particles
with off-center inclusion has been developed and
tested. The program is capable to deal with size
parameter values up to ~1000, thus allowing to
simulate the optical behaviour of a large variety of
atmospheric aerosols, as well as cloud and precipitation
particles. Based on this model, we simulated the optical
properties of polydisperse composite atmospheric
particles observed both by ground-based and air-borne
lidar systems. Optical properties have been
characterized in terms of host and inclusion radii,
considering water particles with different composition
inclusions. The performed modelling provides some
insight into the so-called lidar bright and dark band
phenomenon
Starting with RefWorks
No full textPen to Paper image by mbgrigby shared under a CC BY-NC-ND 2.0 license.This document is an introduction to RefWorks - an online research management, writing and collaboration tool designed to help researchers easily gather, manage, store and share all types of information, as well as generate citations and bibliographies - for staff and students. The workbook contains copies of a PowerPoint presentation that is also available on this site. A workbook for an introductory workshop explaining and demonstrating how to set up a small database of references and use it in preparing a document using MS-Word
The Role of Narrative Fiction and Semi-Fiction in Organizational Studies
No full textIn this chapter, we discuss the use of narrative fiction and semi-fiction in organizational research and explore the strengths and weaknesses of these alternative approaches. We begin with an introduction reviewing the existing literature and clarifying what we mean by fiction and semi-fiction. We then present and discuss examples of fiction and semi-fiction focusing on how these approaches can be used in organizational research. We argue that fiction is more useful as a source of data and as a way of representing theory to an audience. Semi-fiction, on the other hand, provides a novel approach to the production and representation of theory. In both cases, researchers face a number of challenges, but also gain access to new and powerful techniques for developing insights into organizational topics.Organizational studies;Narrative fiction;Semi-fiction
The Case for Trend-Stationarity Is Stronger Than We Thought.
No full textIn DeJong and Whiteman (1991a), the authors concluded that 11 of the 14 macroeconomic time-series originally studied by Nelson and Plosser (1982) supported trend-stationarity. Phillips (1991) criticizes this inference, claiming that their procedure is biased against integration, and that their results are sensitive to model and prior specification. However, Phillips' alternative models and priors bias his results in favor of integration; despite these biases, Phillips' own findings indicate that the data provide the greatest relative support to trend-stationarity. This result is similar to their own (1989, 1990, 1991b) findings concerning the sensitivity of their results; the trend-stationarity inference is remarkably robust. Copyright 1991 by John Wiley & Sons, Ltd.
RETRIEVAL OF DUST PARTICLE PARAMETERS FROM MULTI-WAVELENGTH LIDAR MEASUREMENTS USING MODEL OF RANDOMLY ORIENTED SPHEROIDS
No full textThe algorithm based on a model of randomly oriented
spheroids for the inversion of multi-wavelength lidar
data is presented. The aerosols are modelled as a
mixture of two components: one composed only of
spherical and second composed of non-spherical
particles. The non-spherical component is an ensemble
of randomly oriented spheroids with size-independent
shape distribution. The accuracy of the retrieved
particle surface, volume concentration, and effective
radius for 10% measurement errors is estimated to be
below 30%. If the effect of particle non-sphericity is not
accounted for, the errors in the retrieved aerosol
parameters increase notably. The algorithm was tested
with experimental data from a Saharan dust outbreak
episode, measured with the BASIL multi-wavelength
lidar
Application of randomly oriented spheroids for retrieval of dust particle parameters from multi-wavelength lidar measurements
No full textMultiwavelength (MW) Raman lidars have demonstrated their potential to profile particle parameters; however, until now, the physical models used in retrieval algorithms for processing MW lidar data have been predominantly based on the Mie theory. This approach is applicable to the modeling of light scattering by spherically symmetric particles only and does not adequately reproduce the scattering by generally nonspherical desert dust particles. Here we present an algorithm based on a model of randomly oriented spheroids for the inversion of multiwavelength lidar data. The aerosols are modeled as a mixture of two aerosol components: one composed only of spherical and the second composed of nonspherical particles. The nonspherical component is an
ensemble of randomly oriented spheroids with size‐independent shape distribution. This approach has been integrated into an algorithm retrieving aerosol properties from the observations with a Raman lidar based on a tripled Nd:YAG laser. Such a lidar provides three backscattering coefficients, two extinction coefficients, and the particle
depolarization ratio at a single or multiple wavelengths. Simulations were performed for a bimodal particle size distribution typical of desert dust particles. The uncertainty of the retrieved particle surface, volume concentration, and effective radius for 10% measurement errors is estimated to be below 30%. We show that if the effect of particle
nonsphericity is not accounted for, the errors in the retrieved aerosol parameters increase notably. The algorithm was tested with experimental data from a Saharan dust
outbreak episode, measured with the BASIL multiwavelength Raman lidar in August 2007. The vertical profiles of particle parameters as well as the particle size distributions at different heights were retrieved. It was shown that the algorithm developed provided substantially reasonable results consistent with the available independent information about the observed aerosol event
The "Option for the Poor" and the Scottish Episcopal Church
No full textThis thesis looks at Blessed are the Poor?, a document presented to the General Synod of the Scottish Episcopal Church that sought to outline Liberation Theology to the Church. In response to this the Synod voted £1,000,000 of its resources to be used specifically in projects in the poorest parts of Scotland. The thesis outlines those projects and the way in which they sought to embody the "Option for the Poor". The thesis closes by looking at whether Blessed are the Poor? faithfully represented Liberation Theology and the "Option"; whether the projects represented that theology and concluding that they did not, recognises that it is the nature of both the "Option" and the institutional Church that such a task could never be achieved.
In order to understand the pastoral project this thesis outlines the historical development of Liberation Theology after the Second Vatican Council and in Latin America with particular emphasis on the "Option for the Poor". This thesis proceeds to look at the development of an "Option for the Poor" in the work of Gustavo Gutiérrez, the leading Liberation Theologian. The critiques of that work from the Vatican, Pablo Richard and Hugo Assmann are then considered. Gutiérrez’s works are used to develop a theological matrix that identifies the essential elements of the “Option for the Poor”. Having considered the notion of the "Option for the Poor" the thesis proceeds to look at how the "Option" was taken forward in the Churches in Britain before focussing on the specific response of the Scottish Episcopal Church. The matrix is used as a tool to assess whether the various parts of the response truly reflected the “Option for the Poor”
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