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NASA NTRS2017

Cryogenic Refractive Index of Heraeus Homosil Glass

This paper reports measurements of the refractive index of Homosil (Heraeus) over the wavelength range of 0.343.16 m and temperature range of 120335 K. These measurements were performed by using the Cryogenic High Accuracy Refraction Measuring System (CHARMS) facility at the NASAs Goddard Space Flight Center. These measurements were in support of an integrated Structural-Thermal-Optical-Performance (STOP) model that was developed for a field-widened Michelson interferometer that is being built and tested for the High Spectral Resolution Lidar (HSRL) project at the NASA Langley Research Center (LaRC). The cryogenic refractive index measurements were required in order to account for the highly sensitivity performance of the HSRL instrument to changes in refractive index with temperature, temperature gradients, thermal expansion, and deformation due to mounting stresses. A dense coverage of the absolute refractive index over the aforementioned wavelength and temperature ranges was used to determine the thermo-optic coefficient (dndT) and dispersion relation (dnd) as a function of wavelength and temperature. Our measurements of Homosil will be compared with measurements of other glasses from the fused silica family studied in CHARMS as well as measurements reported elsewhere in literature.

Homosil↗
NASA NTRS2018

Remote Sensing of the Ocean Surface Refractive Index via Short-Wave Infrared Polarimetry

The linear polarization of sunlight reflected by ocean surfaces in the shortwave infrared (SWIR), at geometries where specular reflection dominates the signal, is a direct function of the refractive index of the surface microlayer(SML). This simple physical concept is at the base of a novel technique presented in this study. We invert observations obtained by the airborne Research Scanning Polarimeter (RSP) in the sun glint region, where each pixel's radiance is dominated by the signal originating from the wave slopes oriented precisely to cause specular reflection. The SWIR wavelength ensures minimization of aerosol interference when radiance travels through the atmosphere; strong absorption by the water body then limits the penetration depth to the first micrometer or so, effectively probing the SML. The resulting Degree of Linear Polarization (DoLP) is then governed by the refractive index via the Fresnel law for the specfic pixel geometry, independently of the wind speed. The selected dataset concerns several field deployments from both low- and high-altitude aircraft, including total reflectance measurements with the sole purpose of accounting for the residual aerosol effect.Stable retrievals from transects above pure seawater yielded values of refractive index that match the values published in the literature within an accuracy of 5 x 10 [superscript 4]. Flying over the oil spill caused by the explosion of the Deepwater Horizon platform, detected variations were found compatible with the presence of an oil slick. The robustness of the results, guaranteedby the high RSP polarimetric accuracy (less than or equal to 0:2%), opens the possibility for remote-sensing detection of other entities that similarly affect the refractive index including whitecaps, microplastics, biological gels, seaweed and grass mats.

Surface Microlayer↗
NASA NTRS2018

Multi-Sensor Integration of Vegetation Index Products for Long-Term Monitoring of Vegetation Dynamics: A Case Study from MODIS to VIIRS

Spectral vegetation index (VI) time series data from moderate resolution sensors, such as Earth Observing System (EOS) Moderate Resolution Imaging Spectroradiometer (MODIS), have widely been used to identify "hot spot" areas of vegetation changes and to characterize long-term trends of vegetation changes. The Visible Infrared Imaging Radiometer Suite (VIIRS) sensor series of the Joint Polar Satellite System (JPSS) program is slated to continue the highly calibrated data stream initiated with MODIS. The first VIIRS sensor has operationally been acquiring Earth-reflected radiation since March 2012. The second VIIRS sensor (NOAA-20) was launched in November 2017, which is to continue the measurements made by the first VIIRS sensor. In this study, we examined an integrated use of MODIS and VIIRS VI time series data on capturing vegetation dynamics in the Asia-Pacific region using their overlapped period of observations (2013-2017). Three VIs, the "top-of-canopy (TOC)" normalized difference vegetation index (NDVI), TOC enhanced vegetation index (EVI), and TOC two-band enhanced vegetation index (EVI2), were investigated. For all the three VIs, VIIRS VIs were systematically higher than the MODIS counterparts due mainly to their spectral bandpass differences. However, both VIIRS and MODIS VIs showed the comparable spatial patterns in their temporal variations. Empirical spectral corrections allowed to merge the two data streams, which slightly improved the temporal resolution of the VI temporal profiles. These results suggest the suitability of VIIRS data to extend and merge into the MODIS VI record for long-term vegetation dynamics studies.

MODIS↗
NASA NTRS2019

Refractive Index of Polyaryletherketone (PEEK) at X- and W-Band

This report details refractive index measurements of polyaryletherketone (PEEK) thermoplastic between X-band (8 to 12 GHz) and W-band (75 to 110 GHz) frequencies. Scattering-parameter data are collected using both traditional waveguide and modified free-space techniques. The complex-valued refractive index is calculated using the standard Nicolson-Ross-Weir method. Results indicate that PEEK’s refractive index is n = 1.783 – 0.001i across X-band and n = 1.792 – 0.007i across W-band. Therefore, PEEK exhibits a moderate real refractive index component and low transmission loss. Coupled with its favorable mechanical and thermal properties, this makes PEEK an ideal material to inspect using NASA’s submillimeter radiofrequency-based technology.

Polyaryletherketone↗
NASA NTRS1970

Apollo 12 photography 70 mm, 16 mm, and 35 mm frame index

For each 70-mm frame, the index presents information on: (1) the focal length of the camera, (2) the photo scale at the principal point of the frame, (3) the selenographic coordinates at the principal point of the frame, (4) the percentage of forward overlap of the frame, (5) the sun angle (medium, low, high), (6) the quality of the photography, (7) the approximate tilt (minimum and maximum) of the camera, and (8) the direction of tilt. A brief description of each frame is also included. The index to the 16-mm sequence photography includes information concerning the approximate surface coverage of the photographic sequence and a brief description of the principal features shown. A column of remarks is included to indicate: (1) if the sequence is plotted on the photographic index map and (2) the quality of the photography. The pictures taken using the lunar surface closeup stereoscopic camera (35 mm) are also described in this same index format.

Source record↗
NASA NTRS1976

NASA patent abstracts bibliography: A continuing bibliography. Section 2: Indexes (supplement 08)

This bibliography is issued in two sections: Section 1 - Abstracts, and Section 2 - Indexes. This issue of the Abstract Section cites 180 patents and applications for patents introduced into the NASA scientific and technical information system during the period July 1975 through December 1975. Each entry in the Abstract Section consists of a citation, an abstract, and, in most cases, a key illustration selected from the patent or application for patent. This issue of the Index Section contains entries for 2,905 patents and applications for patent citations covering the period May 1969 through December 1975. The Index Section contains five indexes -- subject, inventor, source, number, and accession number.

Source record↗
NASA NTRS1976

Magnetic pulsations as a probe of the interplanetary magnetic field - A test of the Borok B index

A magnetic pulsation index based on the periods of Pc 2-4 pulsations as recorded in earth current measurements at the Borok Geophysical Observatory has been claimed to be a measure of the interplanetary field. Tests of this index for the period 1972 to June 1974 show only a 27% success rate. However, a simple recalibration of the index improves the success rate to 51%. The success of the index indicates that the source of many terrestrial magnetic pulsations is external to the magnetosphere.

Russell, C. T.↗
NASA NTRS1978

Radial and solar cycle variations in the solar wind phase fluctuation spectral index as determined from Voyager 1978 solar conjunction data

Columnar spectral index information that has been extracted from a sizable volume of Voyager 1978 solar conjunction Doppler phase fluctuation data is presented. The Voyager 1978 results, when compared to similar information derived from the 1976 Helios and Viking Solar Conjunctions, lead to the following inferences: (1) there has been a significant change in the spectral index from 1976 to 1978; (2) there is continuing evidence that favors a slight (positive) correlation between the spectral index and the solar cycle; and (3) there is little or no evidence in support of a radial variation of the spectral index.

Berman, A. L.↗
NASA NTRS1983

KSC Construction Cost Index

Kennedy Space Center cost Index aids in conceptual design cost estimates. Report discusses development of KSC Cost Index since January 1974. Index since January 1974. Index provides management, design engineers, and estimators an up-to-data reference for local labor and material process. Also provides mount and rate of change in these costs used to predict future construction costs.

Brown, J. A.↗
NASA NTRS1983

Development of an operational specific CAT risk (SCATR) index

The original formulations of Roach (1970) and Oard (1974) for the calculation of clear air turbulence (CAT) potential from synoptic scale data were extended. An index which gives a measure of the specific risk of encountering CAT - the specific clear air turbulence risk (SCATR) index - was defined. This index takes into account both the locally and advected contributions to the energy necessary for CAT. The advected contribution is associated with the role of atmospheric gravity waves. The SCATR index was calculated for a number of cases where documented encounters with CAT occurred. Of particular interest were those made for cases involving severe CAT. The results for the two severe CAT cases run were quite impressive and elicited considerable interest from operational aviation meteorologists.

Keller, J. L.↗
NASA NTRS1984

Spatial variation of stratospheric aerosol acidity and model refractive index - Implications of recent results

Recent experimental results indicate that little or no solid ammonium sulfate is present in background stratospheric aerosols. Other results allow straightforward calculation of sulfuric acid/water droplet properties (acidity, specific gravity, refractive index) as functions of stratospheric temperature and humidity. These results are combined with a variety of latitudinal and seasonal temperature and humidity profiles to obtain corresponding profiles of droplet properties. These profiles are used to update a previous model of stratospheric aerosol refractive index. The new model retains the simplifying approximation of vertically constant refractive index in the inner stratosphere, but has sulfuric acid/water refractive index values that significantly exceed the previously used room temperature values. Mean conversion ratios (e.g., extinction-to-number, backscatter-to-volume) obtained using Mie scattering calculations with the new refractive indices are very similar to those obtained for the old indices, because the effects of deleting ammonium sulfate and increasing acid indices tend to cancel each other.

Russell, P. B.↗
NASA NTRS1987

Computer aided indexing at NASA

The application of computer technology to the construction of the NASA Thesaurus and in NASA Lexical Dictionary development is discussed in a brief overview. Consideration is given to the printed and online versions of the Thesaurus, retrospective indexing, the NASA RECON frequency command, demand indexing, lists of terms by category, and the STAR and IAA annual subject indexes. The evolution of computer methods in the Lexical Dictionary program is traced, from DOD and DOE subject switching to LCSH machine-aided indexing and current techniques for handling natural language (e.g., the elimination of verbs to facilitate breakdown of sentences into words and phrases).

Buchan, Ronald L.↗
NASA NTRS1987

Machine-aided indexing for NASA STI

One of the major components of the NASA/STI processing system is machine-aided indexing (MAI). MAI is a computer process that generates a set of indexing terms selected from NASA's thesaurus, is used for indexing technical reports, is based on text, and is reviewed by indexers. This paper summarizes the MAI objectives and discusses the NASA Lexical Dictionary, subject switching, and phrase matching or natural languages. The benefits of using MAI are mentioned, and MAI production improvement and the future of MAI are briefly addressed.

Wilson, John↗
NASA NTRS1989

A mesoscale numerical simulation of an index for use in the forecasting of the potential severity of wet microbursts

This paper demonstrates the feasibility of using the wet microburst potential intensity index developed by Proctor (1989) for predicting the onset of a wet microburst. After describing the index and the principles involved in its derivation, the version 4.0 of the Mesoscale Atmospheric Simulation System (MASS) model described by Karyampudi et al. (1988) was used to illustrate how the index would perform as a forecast product. An analysis is presented of the use of the microburst potential intensity index in the numerical simulation of the DFR aircraft accident on August 2, 1985 in a downburst environment.

Zack, John W.↗
NASA NTRS1991

Potential vorticity index

Based on the European Center For Medium Range Weather Forecasting (ECMWF) First Global Atmospheric Research Program Global Experiment (FGGE) IIIb data set in the 1978 to 1979 winter, a potential vorticity (PV) index was defined as a measure of the zonally averaged, mid-latitude PV gradient on the 300 K isentropic surface in the Northern Hemisphere. The evolution of that index and its relation to teleconnection patterns of 500 mb geopotential height anomaly are studied. The results of the temporal and spatial variation of blocking and cyclogenesis in the 1978 to 1979 winter and its relation to global and local PV gradients were obtained. Complex empirical orthogonal function (EOF) analyses were performed, using the same FGGE data set for the 1978 to 1979 winter, for a representative high latitude band and mid latitude band geopotential height anomalies at 500 mb, phi sub h, phi sub m, and PV gradient at 300 K, delta(Q), at each longitude for the three month period. The focus of current research is the following: (1) to perform Fourier analyses for the first three EOF's of phi sub h, phi sub m, and delta(Q) at given latitude bands, and to find the dominant wavenumbers and frequencies which are responsible for these EOF's; (2) to compare the results from EOF and Fourier analyses which will be used to explore the relations of blocking and cyclogensis with local and global PV gradients; and (3) to study the time dependence of the local PV gradients and relate it to the PV index vacillation cycles observed in the PV index cycle.

Barcilon, Albert↗
NASA NTRS1993

Variable Refractive Index Effects on Radiation in Semitransparent Scattering Multilayered Regions

A simple set of equations is derived for predicting the temperature distribution and radiative energy flow in a semitransparent layer consisting of an arbitrary number of laminated sublayers that absorb, emit, and scatter radiation. Each sublayer can have a different refractive index and optical thickness. The plane composite region is heated on each exterior side by a different amount of incident radiation. The results are for the limiting case where heat conduction within the layers is very small relative to radiative transfer, and is neglected. The interfaces are assumed diffuse, and all interface reflections are included in the analysis. The thermal behavior is readily calculated from the analytical expressions that are obtained. By using many sublayers, expressions provide the temperature distribution and heat flow for a diffusing medium with a continually varying refractive index, including internal reflection effects caused by refractive index gradients. Temperature and heat flux results are given to show the effect of variations in refractive index and optical thickness through the multilayer laminate.

Siegel, R.↗
NASA NTRS1993

The use of a vegetation index for assessment of the urban heat island effect

A vegetation index and radiative surface temperature were derived from NOAA-11 Advanced Very High Resolution Radiometer (AVHRR) data for the Seattle, WA region from 28 June through 4 July 1991. The vegetation index and surface temperature values were computed for locations of weather observation stations within the region and compared to observed minimum air temperatures. These comparisons were used to evaluate the use of AVHRR data to assess the influence of the urban environment on observed minimum air temperatures (the urban heat island effect). AVHRR derived normalized difference vegetation index (NDVI) and radiant surface temperature data from a one week composite product were both related significantly to observed minimum temperatures, however, the vegetation index accounted for a greater amount of the spatial variation observed in mean minimum temperatures. The difference in the NDVI between urban and rural regions appears to be an indicator of the difference in surface properties (i.e., evaporation and heat storage capacity) between the two environments that are responsible for differences in urban and rural minimum temperatures.

Gallo, K. P.↗
NASA NTRS1993

NASA directives master list and index

This Handbook sets forth in two parts the following information for the guidance of users of the NASA Management Directives System. Part A is a master list of management directives in force as of March 31, 1993. Chapter 1 contains introductory informative material on how to use this Handbook. Chapter 2 is a complete master list of Agencywide management directives, describing each directive by type, number, effective date, expiration date, title, and organization code of the office responsible for the directive. Chapter 3 includes a consolidated numerical list of all delegations of authority and a breakdown of such delegation by the office or installation to which special authority is assigned. Chapter 4 sets forth a consolidated list of all NASA Handbooks (NHB's) and important footnotes covering the control and ordering of such documents. Chapter 5 is a consolidated list of NASA management directives applicable to the Jet Propulsion Laboratory. Chapter 6 is a consolidated list of NASA management directives published in the Code of Federal Regulations. Complementary manuals to the NASA Management Directives System are described in Chapter 7. Part B is the index to NASA management directives in force as of March 31, 1993. This part contains an in-depth alphabetical index to all NASA management directives other than Handbooks. NHB's 1610.6, 'NASA Personnel Security Handbook,' 1620.3, 'NASA Physical Security Handbook,' 1640.4, 'NASA Information Security Program,' 1900.1, 'Standards of Conduct for NASA Employees,' 5103.6, 'Source Evaluation Board Handbook,' and 7400.1, 'Budget Administration Manual,' are indexed in-depth. All other NHB's are indexed by titles only.

Source record↗