NCAR Technical Notes

The NCAR Technical Notes Collection comprises over 500 scientific and technical reports, issued by NCAR divisions and programs, and consists of data compilations, theoretical and numerical investigations, and experimental results.


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A Generalized Theoretical Analysis of Cross-correlation and Cross-spectra for Spaced-antenna Wind Profilers
A Generalized Theoretical Analysis of Cross-correlation and Cross-spectra for Spaced-antenna Wind Profilers
In the analysis of data obtained from SA systems, the most common approach is to assume models of the diffraction pattern without relating it to the statistical properties of the scattering'media (e.g. Briggs and Vincent, 1992). To better understand the fundamental principles and limitations of spacedantenna theory, we develop a formulation which relates the properties of the refractive index field (e.g., its spatial spectrum) and its advecting flow (e.g., uniform or turbulent) to the cross-correlation of the diffraction pattern of the scattered field and, consequently, the cross-correlation and cross-spectra of echoes in spaced receivers.
A Global Monthly Sea Surface Temperature Climatology
A Global Monthly Sea Surface Temperature Climatology
This document presents a new global 2? x 2? monthly sea surface temperature (SST) climatology, which was primarily derived from a 1950 to 1979 based SST climatology from the Climate Analysis Center(CAC). Its purpose is to provide a well documented and improved global SST climatology which can be used as a reference for defining SST anomalies, as a specified oceanic lower boundary condition in atmospheric general circulation models, and to validate ocean and coupled climate model simulations.
A Global Ocean Wind Stress Climatology Based on ECMWF Analyses
A Global Ocean Wind Stress Climatology Based on ECMWF Analyses
This report discusses the computations of the surface wind stress over the global oceans using surface winds from the European Centre for Medium Range Weather Forecasts (ECMWF) for seven years, as well as month-by-month mean fields. It is anticipated that these fields will be useful for driving ocean general circulation models. All the results, including long term and individual monthly means, are archived and available at NCAR.
A Glossary on the Environmental Impact of a Nuclear War
A Glossary on the Environmental Impact of a Nuclear War
This glossary defines a number or words, expressions and acronyms used in the description of the impact of nuclear war on the environment, and associated issues. Selected additional words related to the problems of armaments, disarmament, and nuclear war in general have also been added for convenience, although terms and expressions specifically related to the medical aspects of the problem have not been included. This glossary is an enlarged and updated version of the glossary that was published as part of the SCOPE-Enuwar study on the same subject, and published by Wiley (Pittock et al., 1986). It is based on the references listed at the end. Some acronym definitions are taken verbatim (with permission) from the U.S. National Academy of Sciences report on Nuclear Arms Control. These are clearly indicated by a &#8225. The environmental impacts of a nuclear war are so vast and complex that their study is naturally and necessary of an interdisciplinary nature. Indeed, the SCOPE-Enuwar study mentioned above was the result of consultations between hundreds of scientists from all continents working in many different disciplines. For various reasons, different authors tend to use different-although equivalent-sets of units; but the reader of the literature on this subject may often have to perform conversions between different systems of units. For this reason, the precise definitions of a number of units of measurement, both within and outside of the Systeme International d'Unites (SI) have been included in an appendix, together with the appropriate conversion factors. The symbol adopted for each is indicated in brackets after the name of the unit. There are extensive cross-references within the glossary: Any word printed in italics, whether in the text or in the 'See also' sections, refers to a concept defined elsewhere in the glossary. When such a cross-reference is indicated in the text, it is not repeated in the 'See also' section.
A Guide to Transform Software for Nonlinear Normal-mode Initialization of the NCAR Community Forecast Model
A Guide to Transform Software for Nonlinear Normal-mode Initialization of the NCAR Community Forecast Model
This report represents the culmination of efforts by Ronald Errico and James Vickroy of the Large-Scale Dynamics Section of NCAR's Atmospheric Analysis and Prediction Division with the purpose to provide both NCAR and the university community with software for both initializing and examining atmospheric data. This software has been designed for use with both the NCAR Community Climate Model (CCM) and Community Forecast Model (CFM). It enlarges the range of studies that can be performed with those two models. It was designed especially for those investigators who want software computationally efficient, simple to use, and easy to modify.
A Guide to the Data Systems of the High Altitude Observatory's Coronal Dynamics Project
A Guide to the Data Systems of the High Altitude Observatory's Coronal Dynamics Project
This report describes the structure and operation of the Coronal Dynamics (C/D) Project's data system. The instrument system, based on the island of Hawaii, has been fully described by Fisher et al. (1981), and the text given here is a logical and natural extension of that work, aimed at C/D data users. The intent of this document is two-fold: First, there is the task of accurately specifying the software system at the end of the development phase. Secondly, this is also a user's manual for the C/D systems, and as such is the most important of the C/D experiment system's documents from the viewpoint of the scientific user.
A Kalman Filter to Improve Measurements of Wind from NSF/NCAR Research Aircraft
A Kalman Filter to Improve Measurements of Wind from NSF/NCAR Research Aircraft
To improve the measurements of wind made from NSF/NCAR aircraft, a Kalman filter is developed and applied to archived data files from research projects. The filter is an error-state Kalman filter, and the emphasis is on improving the measurements of pitch and heading because they are usually the dominating source of uncertainty in measured wind. The NSF/NCAR Gulfstream V research aircraft is emphasized in the development, but the filter as developed can be applied to data from other present and past NCAR aircraft as well. So that the resulting filter can be applied in cases where the primary measurements from the inertial reference system were not recorded in the data file, a method is developed for retrieving those measurements by differentiating the recorded variables representing attitude angles and aircraft-velocity components. In addition, some new algorithms are introduced for estimating the rate of climb of the aircraft from the measured accelerations and for estimating the angle of attack from pressures measured at ports on the radome. In addition, simplified methods for estimating the errors in pitch and heading without the full complexity and processing requirements of the Kalman filter are documented. The result is that standard uncertainties in pitch and heading are reduced to about 0.01, so that they no longer dominate the uncertainty in the wind measurements. Some examples illustrate the effects of the Kalman filter on measured wind and on variance spectra. The processing technique is incorporated into an R script that can add the improved variables to a standard netCDF data archive so that they can be made available for community use. Documents that are accessible via links in this technical document provide information on the workflow that generated the document, the details of the processing algorithms, and instructions for use and modification of the processing script.
A Land Surface Model (LSM Version 1.0) for Ecological, Hydrological, and Atmospheric Studies: Technical Description and User's Guide
A Land Surface Model (LSM Version 1.0) for Ecological, Hydrological, and Atmospheric Studies: Technical Description and User's Guide
This technical note describes version 1 of this LSM land surface model. In this model, land surface processes are described in terms of biophysical fluxes (latent heat, sensible heat, momentum, reflected solar radiation, emitted longwave radiation) and biogeochemical fluxes (CO?) that depend on the ecological and hydrologic state of the land. Consequently, ecological and hydrologic sub-models are needed to simulate temporal changes in terrestrial biomass and water. Component processes and their interactions are illustrated in Figure 1. Scientific justification for many of the parameterizations used in this model can be found in Bonan (1994), Bonan (1995a) [CO ? fluxes], Bonan (1995b) [lakes], and Bonan (1996) [infiltration].
A Method for the Calculation of Invariant Manifolds in Hydrodynamics Stability Problems
A Method for the Calculation of Invariant Manifolds in Hydrodynamics Stability Problems
The method developed by the authors referred to in the Preface has been improved in a number of minor respects, to make possible calculations at Taylor numbers up to about 106, for invariant manifolds up to dimension 14, and to suppress axial flow. The method was programmed for the Cray-1 computer and applied to two series of calculations, one for a narrow gap between the cylinders and one for a wide gap. The calculations exhibited the first few bifurcations and the corresponding modes of motion and determined the stability of those modes. No aperiodic motions were found. There is evidence for an additional subcritical bifurcation from the wavy vortex mode at a Taylor number �� 1,148 x 106 in the wide gap problem. Orbit calculations at 1.15 x 106 failed to find further attractors and indicated an explosive transition to regions of the configuration space beyond the applicability of the present method.
A Microfilm Atlas of Magnetic Fields in the Solar Corona
A Microfilm Atlas of Magnetic Fields in the Solar Corona
This is a Microfilm atlas of magnetic fields in the solar corona. The original item included a text of 26 pages and 11,000 maps on 11 reels of microfilm. This Atlas contains 11,000 maps of the calculated potential (or current-free) magnetic fields of the solar corona between August 1959 and June 1970. For each solar rotation in this interval, there are two sets of maps. The first set of maps shows the geometry of the coronal magnetic field but includes field lines originating from both strong or weak fields at the photosphere. (However, no field lines are drawn from a photospheric region if the calculated field strength there is less than 0.08 Gauss.) The second set of maps shows field lines which emanate from the regions of strongest photospheric magnetic field. Each set provides one map for every 100 interval of solar longitude or 36 maps for each rotation.

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