SEARCH · Engineering Papers

Results for “terrestrial models”

Search indexed NASA NTRS and DOE OSTI research on propulsion, heat transfer, battery materials and energy systems. Follow report and document links to the original sources.

SourceResearch connectionFrom yearThrough year

Quote a phrase for an exact phrase match. Source license links do not imply unrestricted reuse.

At least 847 records · Page 47

All sources NASA NTRS DOE OSTI

NASA NTRS2015

Evaluation of a Model-Based Groundwater Drought Indicator in the Conterminous U.S.

Monitoring groundwater drought using land surface models is a valuable alternative given the current lack of systematic in situ measurements at continental and global scales and the low resolution of current remote sensing based groundwater data. However, uncertainties inherent to land surface models may impede drought detection, and thus should be assessed using independent data sources. In this study, we evaluated a groundwater drought index (GWI) derived from monthly groundwater storage output from the Catchment Land Surface Model (CLSM) using a GWI similarly derived from in situ groundwater observations. Groundwater observations were obtained from unconfined or semi-confined aquifers in eight regions of the central and northeastern U.S. Regional average GWI derived from CLSM exhibited strong correlation with that from observation wells, with correlation coefficients between 0.43 and 0.92. GWI from both in situ data and CLSM was generally better correlated with the Standard Precipitation Index (SPI) at 12 and 24 month timescales than at shorter timescales, but it varied depending on climate conditions. The correlation between CLSM derived GWI and SPI generally decreases with increasing depth to the water table, which in turn depends on both bedrock depth (a CLSM parameter) and mean annual precipitation. The persistence of CLSM derived GWI is spatially varied and again shows a strong influence of depth to groundwater. CLSM derived GWI generally persists longer than GWI derived from in situ data, due at least in part to the inability of coarse model inputs to capture high frequency meteorological variability at local scales. The study also showed that groundwater can have a significant impact on soil moisture persistence where the water table is shallow. Soil moisture persistence was estimated to be longer in the eastern U.S. than in the west, in contrast to previous findings that were based on models that did not represent groundwater. Assimilation of terrestrial water storage data from the Gravity Recovery and Climate Experiment (GRACE) satellite mission improved the correlation between CLSM based regional average GWI and that based on in situ data in six of the eight regions. Practical issues regarding the application of GRACE assimilated groundwater storage for drought detection are discussed. An important conclusion of this study is that model parameters that control the depth to the water table, including bedrock depth, strongly influence the evolution and persistence of simulated groundwater and require careful configuration for drought monitoring.

Evaluation↗

NASA NTRS2014

Evaluation of a Model-Based Groundwater Drought Indicator in the Conterminous U.S.

hydrology↗

NASA NTRS1977

Analysis of the depletion of a stored aerosol in low gravity

The depletion of an aerosol stored in a container has been studied in l-g and in low gravity. Models were developed for sedimentation, coagulation and diffusional losses to the walls. The overall depletion caused by these three mechanisms is predicted to be of order 5 to 8 percent per hour in terrestrial conditions, which agrees with laboratory experience. Applying the models to a low gravity situation indicates that there only coagulation will be significant. (Gravity influences diffusional losses because of convection currents caused by random temperature gradients). For the types of aerosol studied, the rate of depletion of particles should be somewhat less than 0.001 N percent per hour, where N is the concentration per cu cm.

Squires, P.↗

NASA NTRS2016

Horizontal and Vertical Velocities Derived from the IDS Contribution to ITRF2014, and Comparisons with Geophysical Models

In the context of the 2014 realization of the International Terrestrial Reference Frame (ITRF2014), the International DORIS Service (IDS) has delivered to the IERS a set of 1140 weekly SINEX files including station coordinates and Earth orientation parameters, covering the time period from 1993.0 to 2015.0. From this set of weekly SINEX files, the IDS Combination Center estimated a cumulative DORIS position and velocity solution to obtain mean horizontal and vertical motion of 160 stations at 71 DORIS sites. The main objective of this study is to validate the velocities of the DORIS sites by comparison with external models or time series. Horizontal velocities are compared with two recent global plate models (GEODVEL 2010 and NNR-MORVEL56). Prior to the comparisons, DORIS horizontal velocities were corrected for Global Isostatic Adjustment (GIA) from the ICE-6G (VM5a) model. For more than half of the sites, the DORIS horizontal velocities differ from the global plate models by less than 2-3 mm/yr. For five of the sites (Arequipa, Dionysos/Gavdos, Manila, Santiago) with horizontal velocity differences wrt these models larger than 10 mm/yr, comparisons with GNSS estimates show the veracity of the DORIS motions. Vertical motions from the DORIS cumulative solution are compared with the vertical velocities derived from the latest GPS cumulative solution over the time span 1995.0-2014.0 from the University of La Rochelle (ULR6) solution at 31 co-located DORIS-GPS sites. These two sets of vertical velocities show a correlation coefficient of 0.83. Vertical differences are larger than 2 mm/yr at 23 percent of the sites. At Thule the disagreement is explained by fine-tuned DORIS discontinuities in line with the mass variations of outlet glaciers. Furthermore, the time evolution of the vertical time series from the DORIS station in Thule show similar trends to the GRACE equivalent water height.

DORIS↗

DOE OSTI2023

Synergy between cosmological and laboratory searches in neutrino physics

The intersection of the cosmic and neutrino frontiers is a rich field where much discovery space still remains. Neutrinos play a pivotal role in the hot big bang cosmology, influencing the dynamics of the universe over numerous decades in cosmological history. Recent studies have made tremendous progress in understanding some properties of cosmological neutrinos, primarily their energy density. Upcoming cosmological probes will measure the energy density of relativistic particles with higher precision, but could also start probing other properties of the neutrino spectra. When convolved with results from terrestrial experiments, cosmology can become even more acute at probing new physics related to neutrinos or even Beyond the Standard Model (BSM). Any discordance between laboratory and cosmological data sets may reveal new BSM physics and/or suggest alternative models of cosmology. Here we give examples of the intersection between terrestrial and cosmological probes in the neutrino sector, and briefly discuss the possibilities of what different laboratory experiments may see in conjunction with cosmological observatories.

72 PHYSICS OF ELEMENTARY PARTICLES AND FIELDS↗

DOE OSTI2023

Data, scripts, and figures associated with a manuscript studying impact of climate and topography on post-fire vegetation recovery.

This data package is associated with the publication “Impact of Topography and Climate on Post-fire Vegetation Recovery Across Different Burn Severity and Land Cover Types through Machine Learning” submitted to Remote Sensing of Environment (Zahura et al. 2023). In this research, a machine learning algorithm, random forest (RF), was utilized to examine the impact of climate and topography on post-fire vegetation recovery. We used enhanced vegetation index (EVI) to examine varying burn severity and land cover types. The data package includes the input files for RF model training, outputs from model predictions and analysis, and python scripts to run the model, analyze the results to understand model performance and interpretability, and plot manuscript figures. This data package contains three folders (Data, Scripts, and Figures), a file-level metadata (FLMD) csv, and a data dictionary (dd) csv. Please see Postfire_recovery_flmd.csv for a list of all files contained in this data package and descriptions for each. The data dictionary (Postfire_recovery_dd.csv) describes the csv column headers. The “Data” folder provides all the inputs and outputs to train the RF model, evaluate performance, and interpret predictions. The “Scripts” folder contains python scripts and jupyter notebooks for model training and result analysis. The “Figures” folder includes the figures used in the manuscript in “.png” and “.jpg” format.

54 ENVIRONMENTAL SCIENCES↗

NASA NTRS2021

A multi-model CMIP6-PMIP4 study of Arctic sea ice at 127 ka: sea ice data compilation and model differences

The Last Interglacial period (LIG) is a period with increased summer insolation at high northern latitudes, which results in strong changes in the terrestrial and marine cryosphere. Understanding the mechanisms for this response via climate modelling and comparing the models' representation of climate reconstructions is one of the objectives set up by the Paleoclimate Modelling Intercomparison Project for its contribution to the sixth phase of the Coupled Model Intercomparison Project. Here we analyse the results from 16 climate models in terms of Arctic sea ice. The multi-model mean reduction in minimum sea ice area from the pre industrial period (PI) to the LIG reaches 50 % (multi-model mean LIG area is 3.20×10^6 sq.km, compared to 6.46×10^6 sq.km for the PI). On the other hand, there is little change for the maximum sea ice area (which is 15–16×10^6 sq.km for both the PI and the LIG. To evaluate the model results we synthesise LIG sea ice data from marine cores collected in the Arctic Ocean, Nordic Seas and northern North Atlantic. The reconstructions for the northern North Atlantic show year-round ice-free conditions, and most models yield results in agreement with these reconstructions. Model–data disagreement appear for the sites in the Nordic Seas close to Greenland and at the edge of the Arctic Ocean. The northernmost site with good chronology, for which a sea ice concentration larger than 75 % is reconstructed even in summer, discriminates those models which simulate too little sea ice. However, the remaining models appear to simulate too much sea ice over the two sites south of the northernmost one, for which the reconstructed sea ice cover is seasonal. Hence models either underestimate or overestimate sea ice cover for the LIG, and their bias does not appear to be related to their bias for the pre-industrial period. Drivers for the inter-model differences are different phasing of the up and down short-wave anomalies over the Arctic Ocean, which are associated with differences in model albedo; possible cloud property differences, in terms of optical depth; and LIG ocean circulation changes which occur for some, but not all, LIG simulations. Finally, we note that inter-comparisons between the LIG simulations and simulations for future climate with moderate (1 %/yr) CO2 increase show a relationship between LIG sea ice and sea ice simulated under CO2 increase around the years of doubling CO2. The LIG may therefore yield insight into likely 21st century Arctic sea ice changes using these LIG simulations.

Arctic sea ice↗

DOE OSTI2024

Spectroscopic Measurements and Models of Energy Deposition in the Substrate of Quantum Circuits by Natural Ionizing Radiation

Naturally occurring background radiation is a potential source of correlated decoherence events in superconducting qubits that will challenge error-correction schemes. In order to characterize the radiation environment in an unshielded laboratory representative of superconducting qubits’ environments, we performed broadband, spectroscopic measurements of background radiation events inside a millikelvin refrigerator. The spectrometer was designed to mimic the size and composition of a quantum circuit. Specifically, we measured the background radiation spectra in silicon substrates of two thicknesses, 500 and 1500 µm, and one area, 25 mm 2 . The observed spectra span energies from a few kilo-electron-volts up to nearly 10 MeV, are nearly featureless, and decrease in intensity by a factor of 40 000 between 100 keV and 3 MeV for the 500-µm substrate. We integrate the spectra to obtain the average event rates and deposited power levels. These quantities correspond to a rate of 0.023 events per second and a power of 4.9 keV s -1 , when counting events that deposit at least 40 keV for the 500-µm-thick substrate. We find that the cryogenic measurements are in good agreement with predictions based on simple measurements of the terrestrial gamma-ray flux outside the refrigerator, published models of cosmic-ray fluxes, a crude model of the cryostat, and radiation-transport simulations. This model requires no free parameters to predict the background radiation spectra in the silicon substrates. The agreement between measurements and predictions demonstrates that the model we present can be used to assess the relative contributions of terrestrial and cosmic-ray sources to background radiation interactions in silicon substrates of varying thickness. These spectroscopic measurements are performed with a novel combination of superconducting microresonators located on micromachined silicon islands that define the interaction volume with background radiation. The resonators transduce deposited energy to a readily detectable electrical signal. Microresonator readout closely resembles dispersive superconducting qubit readout, so similar devices—with or without micromachined islands—are suitable for integration with superconducting quantum circuits as detectors for background radiation events. For our specific laboratory conditions, we find that gamma-ray emissions from radioisotopes are responsible for the majority of events that deposit E < 1 ⁢Me⁢V. We present results demonstrating that the background radiation spectrum contains relevant contributions from cosmic-ray particles other than muons, particularly a tail of multi-mega-electron-volt events due to protons and neutrons. These observations suggest several paths to reducing the impact of background radiation on quantum circuits, supported by an empirically validated model for generating reliable predictions of radiation interactions with silicon substrates.

71 CLASSICAL AND QUANTUM MECHANICS, GENERAL PHYSIC↗

NASA NTRS1996

Importance of the Natural Terrestrial Environment with Regard to Advanced Launch Vehicle Design and Development

The terrestrial environment is an important forcing function in the design and development of the launch vehicle. The scope of the terrestrial environment includes the following phenomena: Winds; Atmospheric Thermodynamic Models and Properties; Thermal Radiation; U.S. and World Surface Environment Extremes; Humidity; Precipitation, Fog, and Icing; Cloud Characteristics and Cloud Cover Models; Atmospheric Electricity; Atmospheric Constituents; Vehicle Engine Exhaust and Toxic Chemical Release; Occurrences of Tornadoes and Hurricanes; Geological Hazards, and Sea States. One must remember that the flight profile of any launch vehicle is in the terrestrial environment. Terrestrial environment definitions are usually limited to information below 90 km. Thus, a launch vehicle's operations will always be influenced to some degree by the terrestrial environment with which it interacts. As a result, the definition of the terrestrial environment and its interpretation is one of the key launch vehicle design and development inputs. This definition is a significant role, for example, in the areas of structures, control systems, trajectory shaping (performance), aerodynamic heating and take off/landing capabilities. The launch vehicle's capabilities which result from the design, in turn, determines the constraints and flight opportunities for tests and operations.

Pearson, S. D.↗

NASA NTRS2004

Structural modeling and analysis

Explore the source record for details and available documents.

coronagraph↗

NASA NTRS1989

Report from ionospheric science

The general strategy to advance knowledge of the ionospheric component of the solar terrestrial system should consist of a three pronged attack on the problem. Ionospheric models should be refined by utilization of existing and new data bases. The data generated in the future should emphasize spatial and temporal gradients and their relation to other events in the solar terrestrial system. In parallel with the improvement in modeling, it will be necessary to initiate a program of advanced instrument development. In particular, emphasis should be placed on the area of improved imaging techniques. The third general activity to be supported should be active experiments related to a better understanding of the basic physics of interactions occurring in the ionospheric environment. These strategies are briefly discussed.

Raitt, W. J.↗

NASA NTRS1974

Impact cratering models and their application to lunar studies - A geologist's view

Impact cratering models are discussed which were derived from: (1) laboratory hypervelocity experiments in cohesive materials; (2) laboratory impact experiments in noncohesive materials such as sand; and (3) terrestrial meteorite impact craters (specifically the Ries Crater, the largest well-preserved terrestrial meteorite crater). Salient features of these three categories of models are compared in order to point out unresolved controversies and inconsistencies. Arguments and evidence are presented to support the conclusions that (1) penetrations of secondary impacts are insignificant and are not likely to stir up much local material, (2) the laboratory hypervelocity experiments are perhaps the best model for lunar glass-lined microcraters, (3) laboratory impact experiments in noncohesive materials such as sand are the best model for impacts in lunar regolith, and (4) the Ries is considered the best model for large lunar impact craters. From analogy with the Ries, it appears that lateral and low-angle transport of ejecta and accelerated lateral growth are important in formation of large impact craters.

Chao, E. C. T.↗

NASA NTRS2006

Towards a Framework for Modeling Space Systems Architectures

Topics covered include: 1) Statement of the problem: a) Space system architecture is complex; b) Existing terrestrial approaches must be adapted for space; c) Need a common architecture methodology and information model; d) Need appropriate set of viewpoints. 2) Requirements on a space systems model. 3) Model Based Engineering and Design (MBED) project: a) Evaluated different methods; b) Adapted and utilized RASDS & RM-ODP; c) Identified useful set of viewpoints; d) Did actual model exchanges among selected subset of tools. 4) Lessons learned & future vision.

cost savings↗

DOE OSTI2026

Model Data Archive for Manuscript Titled "Evaluation of a Coupled Surface–Subsurface Hydrologic Model Using Dense Water‑Level Sensors in a Mixed Urban–Rural Watershed"

This archive provides scripts, input files, and datasets used for the implementation and evaluation of a fully coupled surface–subsurface hydrologic model in the Neches River Basin, southeast Texas. The study uses the Advanced Terrestrial Simulator (ATS) to simulate coupled surface–subsurface hydrologic processes over a mixed urban–rural watershed and evaluates model performance using a dense network of 136 in situ water-level sensors, nine U.S. Geological Survey (USGS) stream gauges, and SSEBop-derived evapotranspiration estimates during the period October 2014–June 2024. The workflow is implemented primarily in Python 3 using the Watershed Workflow package. The Jupyter notebooks can be executed using open-source software such as Anaconda JupyterLab or Visual Studio Code. Other data files include TXT, CSV, XML, SHP, TIF, NetCDF, HDF5, and ExodusII files, which can be processed using the provided Python scripts. ATS input files are provided in XML format and can be edited using any commonly used text editor. This archive contains: *Scripts and input files used to generate the ATS model setup, including watershed discretization, mesh generation, parameter mapping, and model configuration. *Jupyter notebooks used for preprocessing observational data, evaluating streamflow, water levels, and evapotranspiration, computing performance metrics, and generating the figures presented in the manuscript. *ATS simulation outputs and processed observational datasets, including OneRain and DD6 water-level sensors, USGS streamflow observations, GIS data, and supporting spatial datasets used throughout the study.

Dense water-level sensor network↗

NASA NTRS1989

Atmospheric occultation of a solar flare in hard x rays

The objective of this study is two-fold: to investigate the absorption of hard x rays along a tangential path through the terrestrial atmosphere, and to locate, other than the use of imaging devices, the flare source of x ray emission in the sun. Observational data were taken with the Hard X Ray Burst Spectrometer (HXRBS) on board the Solar Maximum Mission satellite (SMM). The occultation event chosen for investigation is the flare on 14 October 1981. Night fell on SMM during the decaying phase of the flare. In about fifteen seconds, the x ray flux decreased to zero. The model for computing synthetic light curve, which is directly comparable to the observed curve, consists of two computing programs. One is a modified version of an existing code, which compute the coordinates of the tangent points of the SMM-sun lines. The other program computed the atmospheric densities along the angles (N to S and E to W) measured from the center of the sun. The various model also depends on the destination of the terrestrial atmosphere at geocentric positions of SMM and the sun, the mean atmospheric densities at different heights and latitudes, and the x ray absorption cross of nitrogen, oxygen, and argon. The optical length, at a given time and for a x ray energy, is computed with the two angular parameters. The fit of a particular synthetic light, curve, i.e., the exponentials of the optical lengths, to the observed eclipse curve, yields the desired angular parameters.

Chen, Kwan-Yu↗

NASA NTRS2019

Lunar Seismometer and Burial System

Beginning in 1969, Apollo successfully deployed a long-lived network of seismometers on the Moon. Seismic studies provide definitive knowledge of internal planetary structure, and analysis of the Apollo seismic data has contributed to the magma ocean hypothesis for initial terrestrial planetary differentiation [Wieczoreket al., 2006]. While the general model is widely accepted, details such as mantle composition, stratification and possible overturn, lateral structure, and thermal inhomogeneities remain unresolved. The Moon experiences moonquakes at varying depths [Nakamura, 1983]. Shallow quakes are relatively large but rare, similar to terrestrial intra-plate earthquakes. Deeper quakes are comparatively smaller but more frequent, occurring periodically according to the tidal cycle. On the Moon, the lack of an atmosphere enables seismic experiments to potentially constrain meteorite impact flux, which informs cratering rates assumed throughout the solar system. The large diurnal temperature variation between day and night also induces thermal moonquakes, which may contribute to regolith production [Duennebier& Sutton, 1974; Weber et al., 2017]. Still, many questions remain regarding the frequency and distribution of natural moonquakes. This translates into an incomplete understanding of the Moon’s hemispherical dichotomies in crustal thickness, mare volcanism, seismicity, and the distribution of heat-producing elements. The Planetary Decadal Survey (National Research Council, 2013) identifies a New Frontiers Lunar Geophysical Network (LGN) mission to answer such questions.

Bailey, S. H.↗

NASA NTRS2024

Magma-Sediment Hydrothermal Systems on Mars Explored Through Thermochemical Modeling and Analogue Studies

High temperature impact-generated and magmatic hydrothermal systems on Noachian Mars may have produced habitable environments by providing heat, energy, and volatiles necessary to support microbial life. Magmatic hydrothermal systems formed when mafic magma intruded into sedimentary rocks are of primary interest when investigating the habitability of high-temperature aqueous environments on Mars because contact metamorphism favors the alteration of the country rocks and the release of bound fluids in minerals and fluids in ice and pore spaces, and mobilization of bio-essential elements. Magma-sediment hydrothermal systems on Mars are difficult to identify from orbit and only limited in-situ investigations have been performed. Thus, terrestrial analogues need to be investigated. Recent studies focused on a magmatic hydrothermal system characterized by near-neutral Cl-S-CO 2 -rich fluids produced by a mafic dike intruding the Jurassic Entrada sandstone (Colorado Plateau, UT). Chemical and mineralogical changes identified in the dike and in the sediments were attributed to high-temperature metamorphism (> 700 °C), and low-temperature regimes (< 200 °C) when the system cooled down, and became potentially habitable [6]. However, compositional differences exist between the terrestrial dike and basaltic rocks on Mars, making difficult a comparison between secondary minerals and fluid chemistries of terrestrial and Martian systems. Here, we use thermochemical modelling to explore how differences in bulk dike composition will affect reaction pathways, secondary mineralogy, fluid chemistry, and bio-essential element availability.

S Cogliati↗

NASA NTRS2004

A Model for Variable Levee Formation Rates in an Active Lava Flow

Channelized lava flows on Mars and the Earth often feature levees and collateral margins that change in volume along the path of the flow. Consistent with field observations of terrestrial flows, this suggests that the rate of levee formation varies with distance and other factors. Previous models have assumed a constant rate of levee growth, specified by a single parameter, lambda. The rate of levee formation for lava flows is a good indicator of the mass eruption rate and rheology of the flow. Insight into levee formation will help us better understand whether or not the effusion rate was constant during an eruption, and once local topography is considered, allows us to look at cooling and/or rheology changes downslope. Here we present a more realistic extension of the levee formation model that treats the rate of levee growth as a function of distance along the flow path. We show how this model can be used with a terrestrial flow and a long lava flow on Mars. The key statement of the new formulation is the rate of transfer from the active component to the levees (or other passive components) through an element dx along the path of the flow. This volumetric transfer equation is presented.

Glaze, L. S.↗