The effects of sampling frequency on the climate statistics of the European Center for Medium-Range Weather Forecast General Circulation Model

The effects of sampling frequency on the first- and second-moment statistics of selected European Centre for Medium-Range Weather Forecasts (ECMWF) model variables are investigated in a simulation of ''perpetual July'' with a diurnal cycle included and with surface and atmospheric fields saved at hourly intervals. The shortest characteristic time scales (as determined by the e-folding time of lagged autocorrelation functions) are those of ground heat fluxes and temperatures, precipitation and runoff, convective processes, cloud properties, and atmospheric vertical motion, while the longest time scales are exhibited by soil temperature and moisture, surface pressure, and atmospheric specific humidity, temperature, and wind. The time scales of surface heat and momentum fluxes and of convective processes are substantially shorter over land than over oceans. An appropriate sampling frequency for each model variable is obtained by comparing the estimates of first- and second-moment statistics determined at intervals ranging from 2 to 24 hours with the ''best'' estimates obtained from hourly sampling. Relatively accurate estimation of first- and second-moment climate statistics (10% errors in means, 20% errors in variances) can be achieved by sampling a model variable at intervals that usually are longer than the bandwidth of its time series but that often are shorter than its characteristic time scale. For the surface variables, sampling at intervals that are nonintegral divisors of a 24-hour day yields relatively more accurate time-mean statistics because of a reduction in errors associated with aliasing of the diurnal cycle and higher-frequency harmonics. The superior estimates of first-moment statistics are accompanied by inferior estimates of the variance of the daily means due to the presence of systematic biases, but these probably can be avoided by defining a different measure of low-frequency variability. Estimates of the intradiurnal variance of accumulated precipitation and surface runoff also are strongly impacted by the length of the storage interval. In light of these results, several alternative strategies for storage of the EMWF model variables are recommended

SMP: A solid modeling program

A prototype solid modeling program, SMP, developed by CSC for Langley Research Center (LaRC) is documented in this paper. The SMP software is employed by the System and Experiments Branch (SEB) of the Space Systems Division (SSD) for preliminary space station design, but is intended as a general purpose tool. The SMP document provides details concerning: the basic geometric modeling primitives and associated operators, the data representation scheme utilized to structure the geometric model, the available commands for both editing and displaying the solid model, the interactive user interface and the input/output interfaces to external software, and the utility of the package in the LaRC computing environment. The document is sufficiently detailed to serve both as a user's guide and reference manual

Computer generated animation and movie production at LARC: A case study

The process of producing computer generated 16mm movies using the MOVIE.BYU software package developed by Brigham Young University and the currently available hardware technology at the Langley Research Center is described. A general overview relates the procedures to a specific application. Details are provided which describe the data used, preparation of a storyboard, key frame generation, the actual animation, title generation, filming, and processing/developing the final product. Problems encountered in each of these areas are identified. Both hardware and software problems are discussed along with proposed solutions and recommendations

SMP: A solid modeling program version 2.0

The Solid Modeling Program (SMP) provides the capability to model complex solid objects through the composition of primitive geometric entities. In addition to the construction of solid models, SMP has extensive facilities for model editing, display, and analysis. The geometric model produced by the software system can be output in a format compatible with existing analysis programs such as PATRAN-G. The present version of the SMP software supports six primitives: boxes, cones, spheres, paraboloids, tori, and trusses. The details for creating each of the major primitive types is presented. The analysis capabilities of SMP, including interfaces to existing analysis programs, are discussed

Toward optimal water management in Colorado's Lower Arkansas River Valley: monitoring and modeling to enhance agriculture and environment

Edition 1.0 June 2006.Includes bibliographical references (pages 42-44).For several years, Colorado State University has been documenting flow and water quality conditions in Colorado's Lower Arkansas River Valley with the goal of providing data and models that water users and managers can use to enhance both agriculture and the environment in the Valley. Extensive measurements are being made in the field, and some previously gathered data are still undergoing analysis. Models of the irrigated stream-aquifer system are under development, calibration, and refinement. Potential strategies for improving conditions in the river valley are being formulated and investigated. Small-scale pilot testing of solutions are scheduled to begin during the summer of 2006. The results presented in this technical report are published as a benchmark to document completion of the first phase of this work. They also provide broad information in support of current decision making in the river valley and hopefully will stimulate feedback and discussion. Some of the information presented here is provisional since it is still undergoing refinement and expansion.This research was partially funded by the U.S. Department of the Interior Geological Survey and Colorado Water Resources Research Institute Project on Grant Number 01HQGR0077, Project 2002CO6B and the Colorado Agricultural Experiment Station project COL00694 entitled 'Multidisciplinary Research on Salinity Issues in the Arkansas River Valley.

Lorentz Violating Supersymmetric Quantum Electrodynamics

Theory of Supersymmetric Quantum Electrodynamics is extended by interactions with external vector and tensor backgrounds, that are assumed to be generated by some Lorentz-violating (LV) dynamics at an ultraviolet scale perhaps related to the Planck scale. Exact supersymmetry requires that such interactions correspond to LV operators of dimension five or higher, providing a solution to the naturalness problem in the LV sector. We classify all dimension five and six LV operators, analyze their properties at the quantum level and describe observational consequences of LV in this theory. We show that LV operators do not induce destabilizing D-terms, gauge anomaly and the Chern-Simons term for photons. We calculate the renormalization group evolution of dimension five LV operators and their mixing with dimension three LV operators, controlled by the scale of the soft-breaking masses. Dimension five LV operators are constrained by the low-energy precision measurements at 10^{-10}-10^{-5} level in units of the inverse Planck scale, while the Planck-scale suppressed dimension six LV operators are allowed by observational data.Comment: 37 pages LaTeX, minor revisions, and typos correcte

Variant Supercurrents and Linearized Supergravity

In this paper the variant supercurrents based on consistency and completion in off-shell N=1 supergravity are studied. We formulate the embedding relations for supersymmetric current and energy tensor into supercurrent multiplet. Corresponding linearized supergravity is obtained with appropriate choice of Wess-Zumino gauge in each gravity supermultiplet.Comment: v1: 9 pp; v2: minor changes; v3: 10 pp, published versio

Effective Symmetries of the Minimal Supermultiplet of N = 8 Extended Worldline Supersymmetry

A minimal representation of the N = 8 extended worldline supersymmetry, known as the `ultra-multiplet', is closely related to a family of supermultiplets with the same, E(8) chromotopology. We catalogue their effective symmetries and find a Spin(4) x Z(2) subgroup common to them all, which explains the particular basis used in the original construction. We specify a constrained superfield representation of the supermultiplets in the ultra-multiplet family, and show that such a superfield representation in fact exists for all adinkraic supermultiplets. We also exhibit the correspondences between these supermultiplets, their Adinkras and the E(8) root lattice bases. Finally, we construct quadratic Lagrangians that provide the standard kinetic terms and afford a mixing of an even number of such supermultiplets controlled by a coupling to an external 2-form of fluxes.Comment: 13 Figure

Generalized BF Theory in Superspace as Underlying Theory of 11D Supergravity

We construct a generalized BF theory in superspace that can embed eleven-dimensional supergravity theory. Our topological BF theory can accommodate all the necessary Bianchi identities for teleparallel superspace supergravity in eleven-dimensions, as the simplest but nontrivial solutions to superfield equations for our superspace action. This indicates that our theory may have solutions other than eleven-dimensional supergravity, accommodating generalized theories of eleven-dimensional supergravity. Therefore our topological theory can be a good candidate for the low energy limit of M-theory, as an underlying fundamental theory providing a `missing link' between eleven-dimensional supergravity and M-theory.Comment: 16 pages, latex, two new paragraphs in section 4 and in Concluding Remarks with two new reference

Variant supercurrents and Noether procedure

Consistent supercurrent multiplets are naturally associated with linearized off-shell supergravity models. In arXiv:1002.4932 we presented the hierarchy of such supercurrents which correspond to all the models for linearized 4D N = 1 supergravity classified a few years ago. Here we analyze the correspondence between the most general supercurrent given in arXiv:1002.4932 and the one obtained eight years ago in hep-th/0110131 using the superfield Noether procedure. We apply the Noether procedure to the general N = 1 supersymmetric nonlinear sigma-model and show that it naturally leads to the so-called S-multiplet, revitalized in arXiv:1002.2228.Comment: 6 page