Resolving the Aerosol Seagull Problem in SAGE III/ISS 6.0.0 Data Products with Updated Ozone Absorption Cross Sections
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Relativistic Three-Dimensional Lippmann-Schwinger Cross Sections for Space Radiation Applications
Radiation transport codes require accurate nuclear cross sections to compute particle fluences inside shielding materials. The Tripathi semi-empirical reaction cross section, which includes over 60 parameters tuned to nucleon-nucleus (NA) and nucleus-nucleus (AA) data, has been used in many of the world’s best-known transport codes. Although this parameterization fits well to reaction cross section data, the predictive capability of any parameterization is questionable when it is used beyond the range of the data to which it was tuned. Using uncertainty analysis, it is shown that a relativistic Three- Dimensional Lippmann-Schwinger (LS3D) equation model based on Multiple Scatter- ing Theory (MST) that uses 5 parameterizations—3 fundamental parameterizations to nucleon-nucleon (NN) data and 2 nuclear charge density parameterizations—predicts NA and AA reaction cross sections as well as the Tripathi cross section parameterization for reactions in which the kinetic energy of the projectile in the laboratory frame (TLab) is greater than 220 MeV/n. The relativistic LS3D model has the additional advantage of being able to predict highly accurate total and elastic cross sections. Consequently, it is recommended that the relativistic LS3D model be used for space radiation applications in which TLab > 220 MeV/n.
C M Werneth↗
Analysis of selected nitric oxide observations in the lower thermosphere by HALOE on UARS
Measurements of nitric oxide mixing ratios have been made by the Halogen Occultation Experiment on the Upper Atmosphere Research Satellite over an altitude range extending from 15 to 130 km on every spacecraft sunrise and sunset event with the exception of about 8 percent downtime. Selected NO profiles from the first few months of observations were examined with emphasis on the relation between geomagnetic disturbances and enhanced NO in the lower thermosphere. During a large geomagnetic storm on November 8-9, 1991, HALOE obtained 15 NO sunrise profiles along about the 50 deg N latitude circle. A factor of three increase in NO mixing ratio above about 115 km at this latitude and a one to two day decay time were observed. The measured NO longitude/altitude cross section on this day shows a longitudinal asymmetry in the NO distribution with a maximum near the geomagnetic pole. From approximately one month's data, a latitude/altitude cross section of zonal mean NO mixing ratio was calculated. An example of such cross sections demonstrates a strong positive correlation between geomagnetic activity and thermospheric NO globally. This auroral forcing has a larger effect on increasing NO at high latitude than at low latitude.
Luo, Mingzhao↗
The POPOP4 library and codes for preparing secondary gamma-ray production cross sections
The POPOP4 code for converting secondary gamma ray yield data to multigroup secondary gamma ray production cross sections and the POPOP4 library of secondary gamma ray yield data are described. Recent results of the testing of uranium and iron data sets from the POPOP4 library are given. The data sets were tested by comparing calculated secondary gamma ray pulse height spectra measured at the ORNL TSR-II reactor.
Ford, W. E., III↗
Aerosol Measurements by the Globally Distributed Micro Pulse Lidar Network
Full time measurements of the vertical distribution of aerosol are now being acquired at a number of globally distributed MP (micro pulse) lidar sites. The MP lidar systems provide full time profiling of all significant cloud and aerosol to the limit of signal attenuation from compact, eye safe instruments. There are currently eight sites in operation and over a dozen planned. At all sited there are also passive aerosol and radiation measurements supporting the lidar data. Four of the installations are at Atmospheric Radiation Measurement program sites. The network operation includes instrument operation and calibration and the processing of aerosol measurements with standard retrievals and data products from the network sites. Data products include optical thickness and extinction cross section profiles. Application of data is to supplement satellite aerosol measurements and to provide a climatology of the height distribution of aerosol. The height distribution of aerosol is important for aerosol transport and the direct scattering and absorption of shortwave radiation in the atmosphere. Current satellite and other data already provide a great amount of information on aerosol distribution, but no passive technique can adequately resolve the height profile of aerosol. The Geoscience Laser Altimeter System (GLAS) is an orbital lidar to be launched in early 2002. GLAS will provide global measurements of the height distribution of aerosol. The MP lidar network will provide ground truth and analysis support for GLAS and other NASA Earth Observing System data. The instruments, sites, calibration procedures and standard data product algorithms for the MPL network will be described.
Spinhirne, James↗
Data Needs for Stellar Atmosphere and Spectrum Modeling
The main data need for stellar atmosphere and spectrum modeling remains atomic and molecular transition data, particularly energy levels and transition cross-sections. We emphasize that data is needed for bound-free (b - f) as well as bound-bound (b - b), and collisional as well as radiative transitions. Data is now needed for polyatomic molecules as well as atoms, ions, and diatomic molecules. In addition, data for the formation of, and extinction due to, liquid and solid phase dust grains is needed. A prioritization of species and data types is presented, and gives emphasis to Fe group elements, and elements important for the investigation of nucleosynthesis and Galactic chemical evolution, such as the -elements and n-capture elements. Special data needs for topical problems in the modeling of cool stars and brown dwarfs are described.
Short, C. I.↗
Characteristics of satellite breakups from radar cross section and plane change angle
A problem of considerable interest in orbital debris research is the determination of the cause of the fragmentation of a satellite from the observed radar cross section and orbital element data. In this paper, analytic representations of the observed distribution functions of the radar cross section and the orbital plane change angle are derived. This then allows for the extraction of a small number of features that describe the observed data. Based on the known cause of fragmentation of a subset of satellites, a linear classifier is trained on these derived features. The discriminant function derived from this training is used to determine the previously unknown cause of the satellite breakup. the technique developed is objective and has been applied to the study of the cause of a number of unknown satellite breakup events.
Badhwar, Gautam D.↗
Target correlation effects on neutron-nucleus total, absorption, and abrasion cross sections
Second order optical model solutions to the elastic scattering amplitude were used to evaluate total, absorption, and abrasion cross sections for neutron nucleus scattering. Improved agreement with experimental data for total and absorption cross sections is found when compared with first order (coherent approximation) solutions, especially below several hundred MeV. At higher energies, the first and second order solutions are similar. There are also large differences in abrasion cross section calculations; these differences indicate a crucial role for cluster knockout in the abrasion step.
Cucinotta, Francis A.↗
Application of 'steady' state finite element and transient finite difference theory to sound propagation in a variable duct - A comparison with experiment
Experimental data are presented for sound propagation in a simulated infinite hard wall duct with a large change in duct cross sectional area. The data are conveniently tabulated for further use. The 'steady' state finite element theory of Astley and Eversman (1981) and the transient finite difference theory of White (1981) are in good agreement with the data for both the axial and transverse pressure profiles and the axial phase angle. Therefore, numerical finite difference and finite element theories appear to be ideally suited for handling duct propagation problems which encounter large axial gradients in acoustic parameters. The measured energy reflection coefficient agrees with the values from the Astley-Eversman modal coupling model.
Baumeister, K. J.↗
Mojave remote sensing field experiment
The Mojave Remote Sensing Field Experiment (MFE), conducted in June 1988, involved acquisition of Thermal Infrared Multispectral Scanner (TIMS); C, L, and P-band polarimetric radar (AIRSAR) data; and simultaneous field observations at the Pisgah and Cima volcanic fields, and Lavic and Silver Lake Playas, Mojave Desert, California. A LANDSAT Thematic Mapper (TM) scene is also included in the MFE archive. TM-based reflectance and TIMS-based emissivity surface spectra were extracted for selected surfaces. Radiative transfer procedures were used to model the atmosphere and surface simultaneously, with the constraint that the spectra must be consistent with field-based spectral observations. AIRSAR data were calibrated to backscatter cross sections using corner reflectors deployed at target sites. Analyses of MFE data focus on extraction of reflectance, emissivity, and cross section for lava flows of various ages and degradation states. Results have relevance for the evolution of volcanic plains on Venus and Mars.
Arvidson, Raymond E.↗
Pion and Kaon Lab Frame Differential Cross Sections for Intermediate Energy Nucleus-Nucleus Collisions
Space radiation transport codes require accurate models for hadron production in intermediate energy nucleus-nucleus collisions. Codes require cross sections to be written in terms of lab frame variables and it is important to be able to verify models against experimental data in the lab frame. Several models are compared to lab frame data. It is found that models based on algebraic parameterizations are unable to describe intermediate energy differential cross section data. However, simple thermal model parameterizations, when appropriately transformed from the center of momentum to the lab frame, are able to account for the data.
Norbury, John W.↗
Radar cross-section measurements and simulation of a tethered satellite. The small expendable deployer system end-mass payload
The first Small Expendable Deployer System (SEDS-1), a tethered satellite system, was developed by NASA and launched March 29, 1993 as a secondary payload on a United State Air Force (USAF) Delta-2 launch vehicle. The SEDS-1 successfully deployed an instrumented end-mass payload (EMP) on a 20-km nonconducting tether from the second stage of the Delta 2. This paper describes the effort of NASA Langley Research Center's Antenna and Microwave Research Branch to provide assistance to the SEDS Investigators Working Group (IWG) in determining EMP dynamics by analyzing the mission radar skin track data. The radar cross section measurements taken and simulations done for this study are described and comparisons of the measured data with the simulated data for the EMP at 6 GHz are presented.
Cravey, Robin L.↗
Dependence of the microwave radar cross section on ocean surface variables - Comparison of measurements and theory using data from the Frontal Air-Sea Interaction Experiment
The purpose of this investigation was to study the ability of theoretical radar cross section (RCS) models to predict the absolute magnitude of the ocean radar cross section under a wide variety of sea and atmospheric conditions. The dependence of the RCS on wind stress (as opposed to wind speed) was also studied. An extensive amount of experimental data was acquired during the Frontal Air-Sea Interaction Experiment. Measurements across an ocean front demonstrated that the vertical polarization and horizontal polarization radar cross section were more strongly dependent on wind stress than on wind magnitude. Current theoretical models for the RCS, based on stress, were tested with this data. In situations where the Bragg scattering theory does not agree with the measured radar cross section (magnitude and angle dependence), revisions are hypothesized and evaluated.
Weissman, David E.↗
Information Retrieval from SAGE II and MFRSR Multi-Spectral Extinction Measurements
Direct beam spectral extinction measurements of solar radiation contain important information on atmospheric composition in a form that is essentially free from multiple scattering contributions that otherwise tend to complicate the data analysis and information retrieval. Such direct beam extinction measurements are available from the solar occultation satellite-based measurements made by the Stratospheric and Aerosol Gas Experiment (SAGE II) instrument and by ground-based Multi-Filter Shadowband Radiometers (MFRSRs). The SAGE II data provide cross-sectional slices of the atmosphere twice per orbit at seven wavelengths between 385 and 1020 nm with approximately 1 km vertical resolution, while the MFRSR data provide atmospheric column measurements at six wavelengths between 415 and 940 nm but at one minute time intervals. We apply the same retrieval technique of simultaneous least-squares fit to the observed spectral extinctions to retrieve aerosol optical depth, effective radius and variance, and ozone, nitrogen dioxide, and water vapor amounts from the SAGE II and MFRSR measurements. The retrieval technique utilizes a physical model approach based on laboratory measurements of ozone and nitrogen dioxide extinction, line-by-line and numerical k-distribution calculations for water vapor absorption, and Mie scattering constraints on aerosol spectral extinction properties. The SAGE II measurements have the advantage of being self-calibrating in that deep space provides an effective zero point for the relative spectral extinctions. The MFRSR measurements require periodic clear-day Langley regression calibration events to maintain accurate knowledge of instrument calibration.
Lacis, Andrew A.↗
Full Aerothermal Characterization of the NASA Glenn Research Center 9- by 15-Foot Low-Speed Wind Tunnel (2019 Test)
Following completion of the 9- by 15-Foot Low Speed Wind Tunnel acoustic improvement modification project, a characterization of the flow field throughout the 9- by 15-foot test section was conducted in 2019. The acoustic improvement modifications project included several large-scale tunnel loop modifications and reconstruction of the 9- by 15-Foot Low Speed Wind Tunnel test section and diffuser to decrease the noise floor in the test section. Data were collected at three cross-sectional planes in the 9- by 15-ft test section using a 15-foot traversing calibration rake and a set of eight boundary layer rakes. The data from the characterization test were used to generate calibration relationships for facility operation and understand the flow quality in the new test section, including uniformity, flow angularity, turbulence intensity, and boundary layer characteristics. Additionally, the subsonic quick check rake was used to baseline the check calibration data set for the new test section.
Wind↗
Test Section Characterization of the 9- by 15-Foot Low Speed Wind Tunnel
Following completion of the 9- by 15-Foot Low Speed Wind Tunnel acoustic improvement modification project, a characterization of the flow field throughout the 9- by 15-foot test section was conducted in 2019. The acoustic improvement modifications project included several large-scale tunnel loop modifications and reconstruction of the 9- by 15-Foot Low Speed Wind Tunnel test section and diffuser to decrease the noise floor in the test section. Data were collected at three cross-sectional planes in the 9- by 15-ft test section using a 15-foot traversing calibration rake and a set of eight boundary layer rakes. The data from the characterization test were used to generate calibration relationships for facility operation and understand the flow quality in the new test section, including uniformity, flow angularity, turbulence intensity, and boundary layer characteristics. Additionally, the subsonic quick check rake was used to baseline the check calibration data set for the new test section.
Calibration↗
Revised Production Rates for Na-22 and Mn-54 in Meteorites Using Cross Sections Measured for Neutron-induced Reactions
The interactions of galactic cosmic rays (GCR) with extraterrestrial bodies produce small amounts of radionuclides and stable isotopes. The production rates of many relatively short-lived radionuclides, including 2.6-year Na-22 and 312-day Mn-54, have been measured in several meteorites collected very soon after they fell. Theoretical models used to calculate production rates for comparison with the measured values rely on input data containing good cross section measurements for all relevant reactions. Most GCR particles are protons, but secondary neutrons make most cosmogenic nuclides. Calculated production rates using only cross sections for proton-induced reactions do not agree well with measurements. One possible explanation is that the contribution to the production rate from reactions initiated by secondary neutrons produced in primary GCR interactions should be included explicitly. This, however, is difficult to do because so few of the relevant cross sections for neutron-induced reactions have been measured.
Sisterson, J. M.↗
The Limb Infrared Monitor of the Stratosphere - Experiment description, performance, and results
An experiment and results, using a six-channel infrared radiometer aboard the Nimbus 7 spacecraft to sound the composition and structure of the middle atmosphere, are described. The measurement requirements are discussed, and critical instrument parameters are identified. Next, the instrument and its laboratory calibration are described. Temperature accuracy and precision are estimated to be 2 K and about 0.4 K respectively. Accuracy of the trace gas measurements is about 25 percent, comparable to the estimated accuracy of the in situ comparison data; their precision is about 0.25 ppmv for ozone and water vapor and 0.2 ppbv for nitric acid and nitrogen dioxide. Examples of the vertical profiles, maps, and cross sections of the data show previously unobserved variations with latitude, altitude, and time. The results demonstrate that infrared limb scanning is an extremely powerful method for sounding the middle atmosphere.
Gille, J. C.↗