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All sourcesNASA NTRSDOE OSTI
NASA NTRS1979

Observations of solar oscillations with periods of 160 minutes

Severny et al. (1976) have reported oscillations of the sun with a period near 160 min. A description is presented of observations made at the Stanford Solar Observatory during the time from 1975 to the present which seem to support the reports by Severny et al. At Stanford the relative velocity between a central circular area of radius 0.5 solar radius on the solar disk and most of the remaining area of the solar disk is measured. A superposed epoch analysis of the observations using a period of 160 min is discussed. An apparent agreement in phase between the obtained observational data and those reported by Severny et al. tends to support the interpretation that solar oscillations are being observed.

Scherrer, P. H.↗
NASA NTRS1979

Spectrophotometry of Michigan-Tololo quasars

The Michigan-Tololo sample of quasars is discussed using observational data for 48% of this sample. Emission-line quasar characteristics are confirmed for 80% of the objects observed, including at least four new quasars with spectral features indicative of 'supernova-like' outflow. Approximately 73% of the redshifts predicted from the discovery plates are found to be accurate, with a mean error in z of 0.03; a large range of z (from about 0.1 to 3.16) is represented in the sample. The interpretation of the observed redshift distribution for quasars is strongly dependent upon the significance ascribed to wavelength-dependent selection effects. It appears that the behavior of the comoving quasar density above z = 2.0 may be represented by a constant or an exponential increase.

Lewis, D. W.↗
NASA NTRS1985

Ionization equilibrium in isolated H II regions

Theoretical ionization equilibrium models are combined with Copernicus ultraviolet observations to study a particular H II region absorption-line component in the spectra of Lambda Sco and Upsilon Sco. The Lambda Sco observations imply that the region is characterized by a hydrogen density of approximately 0.2/cu cm and an extent along the line of sight of approximately 16 pc. Three choices for the relative placement of Lambda Sco and Upsilon Sco are considered. Conclusions are that Lambda Sco is the primary source of ionization and that there is a separation of approximately 5 pc between the H II region and Lambda Sco. Observational data support an enhanced dielectronic recombination rate for S III. Comparison of the Upsilon Sco and Lambda Sco observations suggests that spatial variations of density may be present.

Eder, D. C.↗
NASA NTRS1986

Spectral energetics of the observed and simulated Northern Hemisphere general circulation during blocking episodes

The spectral energetics of the Northern Hemisphere circulation during blocking episodes of the FGGE year is investigated with gridded analyses of observational data and parallel simulation experiments. The purpose of this study is to describe the energetics distinctions of the observed and simulated blockings in the context of the general circulation and to assess the capability of the model to simulate blockings. In the observed circulation a pronounced winter blocking is developed and maintained by the nonlinear wave-wave interaction L(1) from the kinetic energy source for n = 3-10, where L(n) is the transfer of eddy kinetic energy from all other wavenumbers to wavenumber n. In the case of the double blocking in the winter, both L(1) and L(2) support the blocking. The kinetic energy source of n = 10 for upscale input at n = 1 and 2 is supported by the baroclinic conversion at n = 3-10. The simulated winter circulation shows strong baroclinic conversion at all wavenumbers, including ultralong waves. However, the simulation fails to produce pronounced blocking for the absence of L(1), and the converted energy cascades down to shorter waves. The wave-mean transfer of kinetic energy from the large-scale disturbances to the zonal mean component further prevents the accumulation of the kinetic energy at the ultralong waves. In contrast to the winter situation, the summer blocking seems to be directly supported by both L(4) and baroclinic conversion at other planetary-scale waves. Consequently, the summer circulation is better simulated than the winter circulation.

Kung, Ernest C.↗
NASA NTRS1989

Antiprotons in cosmic rays and their implications

A brief description of the experiments carried out so far to measure the energy spectrum of antiprotons is made and the reason for the excitement in this field of research is elucidated. The observed spectrum appears to be different form the other components of cosmic rays. Various physical processes by which antiprotons could be created are summarized. The equilibrium spectrum of antiprotons in the Galaxy, arising from each of these processes, is derived for different propagation models. It is shown that no single model can predict correctly the observed data over the entire energy region. However, the recent data at low energies suggest that the conventional models with large amount of matter traversal by cosmic rays, either in the source region or during propagation, can reproduce the data closely. The implications of these propagation models for other components are discussed and the need for more observations is emphasized.

Stephens, S. A.↗
NASA NTRS1990

X-ray emission from normal stars

The paper addresses the potential for future X-ray missions to determine the fundamental cause of stellar X-ray emissions based on available results and existing analyses. The determinants of stellar X-ray emission are listed, and the relation of stellar X-ray emissions to the 'universal' activity-rotation connection is discussed. The specific rotation-activity connection for evolved stars is mentioned, and the 'decay' of stellar activity at the low-mass end of the main sequence is related to observational data. The data from Einstein and EXOSAT missions that correspond to these issues are found to be sparse, and more observational work is found to be necessary. Also, it is concluded that some issues need to be addressed, such as the X-ray dividing line in evolved stars and the absence of X-ray emission from dA stars. The related observational requirements and instrumental capabilities are given for each significant research focus.

Rosner, Robert↗
NASA NTRS2007

A Contrast in Use of Metrics in Earth Science Data Systems

In recent years there has been a surge in the number of systems for processing, archiving and distributing remotely sensed data. Such systems, working independently as well as in collaboration, have been contributing greatly to the advances in the scientific understanding of the Earth system, as well as utilization of the data for nationally and internationally important applications. Among such systems, we consider those that are developed by or under the sponsorship of NASA to fulfill one of its strategic objectives: "Study Earth from space to advance scientific understanding and meet societal needs." NASA's Earth science data systems are of varying size and complexity depending on the requirements they are intended to meet. Some data systems are regarded as NASA's "Core Capabilities" that provide the basic infrastructure for processing, archiving and distributing a set of data products to a large and diverse user community in a robust and reliable manner. Other data systems constitute "Community Capabilities". These provide specialized and innovative services to data users and/or research products offering new scientific insight. Such data systems are generally supported by NASA through peer reviewed competition. Examples of Core Capabilities are 1. Earth Observing Data and Information System (EOSDIS) with its Distributed Active Archive Centers (DAACs), Science Investigator-led Processing Systems (SIPSs), and the EOS Clearing House (ECHO); 2. Tropical Rainfall Measurement Mission (TRMM) Science Data and Information System (TSDIS); 3. Ocean Data Processing System (ODPS); and 4. CloudSat Data Processing Center. Examples of Community Capabilities are projects under the Research, Education and Applications Solutions Network (REASON), and Advancing Collaborative Connections for Earth System Science (ACCESS) Programs. In managing these data system capabilities, it is necessary to have well-established goals and to measure progress relative to them. Progress is measured through "metrics", which can be a combination of quantitative as well as qualitative assessments. The specific metrics of interest depend on the user of the metrics as well as the type of data system. The users of metrics can be data system managers, program managers, funding agency or the public. Data system managers need metrics for assessing and improving the performance of the system and for future planning. Program managers need metrics to assess progress and the value of the data systems sponsored by them. Also, there is a difference in the metrics needed for core capabilities that tend to be more complex, larger and longer-term compared to community capabilities and the community capabilities that tend to be simpler, smaller and shorter-term. Even among community capabilities there are differences; hence the same set of metrics does not apply to all. Some provide data products to users, some provide services that enable better utilization of data or interoperability among other systems, and some are a part of a larger project where provision of data or services is only a minor activity. There is also a contrast between metrics used for internal and external purposes. Examples of internal purposes are: ensuring that the system meets its requirements, and planning for evolution and growth. Examples of external purposes are: providing to sponsors indicators of success of the systems, demonstrating the contributions of the system to overall program success, etc. This paper will consider EOSDIS, REASON and ACCESS programs to show the various types of metrics needed and how they need to be tailored to the types of data systems while maintaining the overall management goals of measuring progress and contributions made by the data systems.

Ramapriyan, Hampapuram↗
NASA NTRS2010

Maintaining a Local Data Integration System in Support of Weather Forecast Operations

Since 2000, both the National Weather Service in Melbourne, FL (NWS MLB) and the Spaceflight Meteorology Group (SMG) at Johnson Space Center in Houston, TX have used a local data integration system (LDIS) as part of their forecast and warning operations. The original LDIS was developed by NASA's Applied Meteorology Unit (AMU; Bauman et ai, 2004) in 1998 (Manobianco and Case 1998) and has undergone subsequent improvements. Each has benefited from three-dimensional (3-D) analyses that are delivered to forecasters every 15 minutes across the peninsula of Florida. The intent is to generate products that enhance short-range weather forecasts issued in support of NWS MLB and SMG operational requirements within East Central Florida. The current LDIS uses the Advanced Regional Prediction System (ARPS) Data Analysis System (ADAS) package as its core, which integrates a wide variety of national, regional, and local observational data sets. It assimilates all available real-time data within its domain and is run at a finer spatial and temporal resolution than current national- or regional-scale analysis packages. As such, it provides local forecasters with a more comprehensive understanding of evolving fine-scale weather features

Watson, Leela R.↗
NASA NTRS2017

NASA Wrangler: Automated Cloud-Based Data Assembly in the RECOVER Wildfire Decision Support System

NASA Wrangler is a loosely-coupled, event driven, highly parallel data aggregation service designed to take advantageof the elastic resource capabilities of cloud computing. Wrangler automatically collects Earth observational data, climate model outputs, derived remote sensing data products, and historic biophysical data for pre-, active-, and post-wildfire decision making. It is a core service of the RECOVER decision support system, which is providing rapid-response GIS analytic capabilities to state and local government agencies. Wrangler reduces to minutes the time needed to assemble and deliver crucial wildfire-related data.

decision support↗
NASA NTRSDate not supplied

Employing NASA Earth Observations and Socioeconomic Data to Conduct Site Suitability Analyses on Residential Tree Planting Initiatives in Phoenix, Arizona

Phoenix, Arizona is the hottest large city in the United States with an average summer daytime temperature of 106°F. Temperatures in Phoenix continue to climb due to increasing global greenhouse gas concentrations and regional urbanization. The impacts of high temperatures, including heat-related illnesses and deaths, are disproportionately concentrated in low-income neighborhoods often characterized by little tree canopy, lack of green space, and insufficient access to shade. The City of Phoenix’s Office of Heat Response and Mitigation and Arizona State University’s Urban Climate Research Center, partnered with NASA DEVELOP to identify residential neighborhoods and parcels within qualified census tracts (QCTs) to be prioritized for tree planting initiatives using funding from the American Rescue Plan Act (ARPA). This project conducted analyses using NASA Earth observations, socioeconomic data from the 2019 American Community Survey, and local tree canopy and mobility data. For Earth observations, daytime land surface temperature, vegetation, and land cover were obtained from the Landsat 8 Thermal Infrared Sensor (TIRS) and Operational Land Imager (OLI). The project team incorporated these data into a heat vulnerability index (HVI) with an emphasis on tree canopy and social vulnerability to rank block groups within QCTs and focused on the resulting top 25 block group HVI scores. These top 25 most vulnerable block groups were then processed through a parcel analysis to determine the feasibility of residential tree planting based on building footprints on each parcel. Within the top 25 block groups, 2,411 parcels were analyzed, and 3,133 existing trees were identified averaging 1.3 trees per parcel with 90% of parcels having 3 trees or less. Homes with 2 trees or fewer were considered high priority for future planting efforts. Based on the City’s goals for increased tree canopy the project team determined that <10,000 additional trees would need to be planted within the most vulnerable 25 block groups. The project findings have helped initiate community engagement efforts and have contributed to the approval of tree planting funds in Phoenix.

Ryan Hammock↗
NASA NTRS1986

FEDS - An experiment with a microprocessor-based orbit determination system using TDRS data

An experiment in microprocessor-based onboard orbit determination has been conducted at NASA's Goddard Space Flight Center. The experiment collected forward-link observation data in real time from a prototype transponder and performed orbit estimation on a typical low-earth scientific satellite. This paper discusses the hardware and organizational configurations of the experiment, the structure of the onboard software, the mathematical models, and the experiment results.

Shank, D.↗
DOE OSTI2025

In-orbit performance of the soft X-ray imaging telescope Xtend aboard XRISM

Here, we present a summary of the in-orbit performance of the soft X-ray imaging telescope Xtend onboard the X-Ray Imaging and Spectroscopy Mission (XRISM), based on in-flight observation data, including first-light celestial objects, calibration sources, and results from the cross-calibration campaign with other currently operating X-ray observatories. XRISM/Xtend has a large field of view of ${38{^{\prime }_{.}}5}$ $\times$ ${38{^{\prime }_{.}}5}$, covering an energy range of 0.4–13 keV, as demonstrated by the first-light observation of the galaxy cluster Abell 2319. It also features an energy resolution of 170–180 eV at 6 keV, which meets the mission requirement and enables us to resolve He-like and H-like Fe K$\alpha$ lines. Throughout the observation during the performance verification phase, we confirm that two issues identified in the Soft X-ray Imager (SXI) onboard the previous Hitomi mission—light leakage and crosstalk events—are addressed and suppressed in the case of Xtend. A joint cross-calibration observation of the bright quasar 3C 273 results in an effective area measured to be $\sim$420 cm$^{2}$ at1.5 keV and $\sim$310 cm$^{2}$ at 6.0 keV, which matches values obtained in ground tests. We also continuously monitor the health of Xtend by analyzing overclocking data, calibration source spectra, and day-Earth observations; the readout noise is stable and low, and contamination is negligible even one year after launch. A low background level compared with other major X-ray instruments onboard satellites, combined with the largest grasp ($\Omega _{\rm eff}\sim 60$ cm$^2$ deg$^2$) of Xtend, will not only support Resolve analysis, but also enable significant scientific results on its own. This includes near-future follow-up observations and transient searches in the context of time-domain and multi-messenger astrophysics.

instrumentation: detectors: Xtend↗
NASA NTRS1984

The v = 0 - 0 spectrum of H2

Ground-state rotational parameters for molecular hydrogen are evaluated using a combination of laboratory and observational data. High-accuracy v = 0 - 0 S(0)-S(5) frequencies from infrared laboratory measurements are analyzed simultaneously with available observed frequencies for the S(8), S(9), S(12), S(13), S(14), and S(15) Orion emission lines. The laboratory and Orion measurements are consistent with each other within their measurement errors. The combined data set yields a determination of five v = 0 rotational parameters and an improvement in the high-J calculated line positions. The analysis produces the parameters (in per cm): B(0) = 59.334627(30), D(0) = 0.0456912(30), H(0) = 4.8974(90) x 10 to the -5th, L(0) = -6.320(110) x 10 to the -8th, M(0) = 7.19(30) x 10 to the -11th, where a correction is made for the estimated contribution of sixth and higher orders.

Jennings, D. E.↗
NASA NTRS2016

A Global Capacity Building Vision for Societal Applications of Earth Observing Systems and Data: Key Questions and Recommendations

Capacity building using Earth observing (EO) systems and data (i.e., from orbital and nonorbital platforms) to enable societal applications includes the network of human, nonhuman, technical, nontechnical, hardware, and software dimensions that are necessary to successfully cross the valley [of death; see NRC (2001)] between science and research (port of departure) and societal application (port of arrival). In many parts of the world (especially where ground-based measurements are scarce or insufficient), applications of EO data still struggle for longevity or continuity for a variety of reasons, foremost among them being the lack of resilient capacity. An organization is said to have resilient capacity when it can retain and continue to build capacity in the face of unexpected shocks or stresses. Stresses can include intermittent power and limited Internet bandwidth, constant need for education on ever-increasing complexity of EO systems and data, communication challenges between the ports of departure and arrival (especially across time zones), and financial limitations and instability. Shocks may also include extreme events such as disasters and losing key staff with technical and institutional knowledge.

shocks↗
NASA NTRS1975

A determination of the sea level muon spectrum using accelerator data and some implications

The differential sea-level muon spectrum is calculated from first principle for a pure beam of cosmic-ray protons cascading in the atmosphere by using a representation of the invariant cross section that describes the observed data from 6 GeV to 1500 GeV. This spectrum is compared with the observed muon spectrum to deduce information on the interaction characteristics of nuclei-nuclei collisions.

Badhwar, G. D.↗
NASA NTRS2002

Decadal Changes in Global Ocean Annual Primary Production

The Sea-viewing Wide Field-of-View Sensor (SeaWiFS) has produced the first multi-year time series of global ocean chlorophyll observations since the demise of the Coastal Zone Color Scanner (CZCS) in 1986. Global observations from 1997-present from SeaWiFS combined with observations from 1979-1986 from the CZCS should in principle provide an opportunity to observe decadal changes in global ocean annual primary production, since chlorophyll is the primary driver for estimates of primary production. However, incompatibilities between algorithms have so far precluded quantitative analysis. We have developed and applied compatible processing methods for the CZCS, using modern advances in atmospheric correction and consistent bio-optical algorithms to advance the CZCS archive to comparable quality with SeaWiFS. We applied blending methodologies, where in situ data observations are incorporated into the CZCS and SeaWiFS data records, to provide improvement of the residuals. These re-analyzed, blended data records provide maximum compatibility and permit, for the first time, a quantitative analysis of the changes in global ocean primary production in the early-to-mid 1980's and the present, using synoptic satellite observations. An intercomparison of the global and regional primary production from these blended satellite observations is important to understand global climate change and the effects on ocean biota. Photosynthesis by chlorophyll-containing phytoplankton is responsible for biotic uptake of carbon in the oceans and potentially ultimately from the atmosphere. Global ocean annual primary decreased from the CZCS record to SeaWiFS, by nearly 6% from the early 1980s to the present. Annual primary production in the high latitudes was responsible for most of the decadal change. Conversely, primary production in the low latitudes generally increased, with the exception of the tropical Pacific. The differences and similarities of the two data records provide evidence of how the Earth's climate may be changing and how ocean biota respond. Furthermore, the results have implications for the ocean carbon cycle.

Gregg, Watson↗
DOE OSTI2025

Identifying Nuclear Data Correlated Through Predicting Bias in Integral Experiments via Applying Principal Component Analysis to Random Forest

ABSTRACT Nuclear data (ND) are the input data for neutron‐transport simulations to answer questions related to nuclear technologies. Subsets of ND, here > 20,000 data points, are validated with respect to thousands of criticality experiments that represent various applications on a small scale. The aim of validation with these experiments is to find errors in ND or methods. The key challenge here is that several hundreds of ND are used to simulate one integral value. Hence, one cannot clearly identify what ND are leading to bias in criticality measurements. In fact, a mistake in one nuclear‐data observable can be compensated with an error in another, and the predicted criticality value would still be predicted in agreement with experimental data. Random forest (RF) was previously employed to predict bias in criticality measurements using sensitivities of simulated criticality experiments to ND. The SHapley Additive exPlanations (SHAP) metric was then applied to attribute the importance of each ND experiment and observable to bias prediction. This, however, did not highlight what ND were jointly related to predicting bias. This is important as it could inform us about where compensating errors in ND could hide. We tackle this shortcoming here by first decomposing the ND sensitivities to integral‐experiment simulations into principal components. Then we use principal component projections to predict bias via the RF and SHAP. The SHAP values and principal components are employed to reconstruct detailed SHAP values for each ND observable. We demonstrate that these extended SHAP bias predictions are more robust, less noisy, and more efficient. In addition, we show that this approach accounts for covariance in ND sensitivities and automates the identification of where compensating errors could hide in ND.

73 NUCLEAR PHYSICS AND RADIATION PHYSICS↗
DOE OSTI2020

An Efficient Numerical Algorithm for Solving Data Driven Feedback Control Problems

The goal of this paper is to solve a class of stochastic optimal control problems numerically, in which the state process is governed by an Itô type stochastic differential equation with control process entering both in the drift and the diffusion, and is observed partially. The optimal control of feedback form is determined based on the available observational data. In this work, we call this type of control problems the data driven feedback control. The computational framework that we introduce to solve such type of problems aims to find the best estimate for the optimal control as a conditional expectation given the observational information. To make our method feasible in providing timely feedback to the controlled system from data, we develop an efficient stochastic optimization algorithm to implement our computational framework.

97 MATHEMATICS AND COMPUTING↗