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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.

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NASA NTRS1984

Lightning activity and severe storm structure

Space-time mapping of VHF sources from four severe storms on June 19, 1980 reveals that lightning processes for cloud-to-ground (CG) and large intracloud (IC) flashes are confined to an altitude below about 10 km and closely associated with the central regions of high reflectivity. Another class of IC flashes produces a splattering of sources within the storms' main electrically active volumes and also within the large divergent wind canopy aloft. There is no apparent temporal association between the small high altitude IC flashes that occur almost continuously and the large IC and CG flashes that occur sporadically in the lower portions of storms.

Taylor, W. L.↗

NASA NTRS2002

MIMIC II: a massive temporal ICU patient database to support research in intelligent patient monitoring

Development and evaluation of Intensive Care Unit (ICU) decision-support systems would be greatly facilitated by the availability of a large-scale ICU patient database. Following our previous efforts with the MIMIC (Multi-parameter Intelligent Monitoring for Intensive Care) Database, we have leveraged advances in networking and storage technologies to develop a far more massive temporal database, MIMIC II. MIMIC II is an ongoing effort: data is continuously and prospectively archived from all ICU patients in our hospital. MIMIC II now consists of over 800 ICU patient records including over 120 gigabytes of data and is growing. A customized archiving system was used to store continuously up to four waveforms and 30 different parameters from ICU patient monitors. An integrated user-friendly relational database was developed for browsing of patients' clinical information (lab results, fluid balance, medications, nurses' progress notes). Based upon its unprecedented size and scope, MIMIC II will prove to be an important resource for intelligent patient monitoring research, and will support efforts in medical data mining and knowledge-discovery.

NASA Discipline Cardiopulmonary↗

NASA NTRS2011

Evaluating the Application of Multi-Satellite Observations in Hydrologic Modeling

When monitoring local or regional hydrosphere dynamics for applications such as agricultural productivity or drought and flooding events, it is necessary to have accurate, high-resolution estimates of terrestrial water and energy storages. Though in-situ observations provide reliable estimates of hydrologic states and fluxes, they are only capable of accurately capturing the dynamics at relatively discrete points in space and time, which makes them inadequate for characterizing the variability of the water budget across scales. In contrast, satellite-based remote sensing is ideal for providing observations of hydrological states and fluxes because it provides spatially-distributed observations at spatial and temporal scales required for regional land surface process modeling. Due to the continued progress in algorithm development and emerging satellite technology, we now have near-real time monitoring of several components of the water cycle including precipitation, soil moisture, lake and river height, terrestrial water storage, snow cover, and evapotranspiration. As these data become more readily available, their application to hydrologic modeling is becoming more common, however there remains little consensus on the most appropriate method for optimal integration and evaluation in regard to hydrological applications. Here we present two case studies operationally applying several remotely sensed products from AMSR-E, GRACE, and MODIS and discuss assimilation strategies, ease of integration and interpretation, and methods for quantifying the success of the application methodology.

Bolten, John↗

NASA NTRS2013

The Geospace Dynamics Observatory; A Paradigm Changing Geospace Mission

The Geospace Dynamics Observatory (GDO) mission observes the near-Earth region in space called Geospace with unprecedented resolution, scale and sensitivity. At a distance of 60 Earth Radii (Re) in a near-polar circular orbit and a approx. 27-day period, GDO images the earth's full disk with (1) a three-channel far ultraviolet imager, (2) an extreme ultraviolet imager of the plasmasphere, and (3) a spectrometer in the near to far ultraviolet range that probes any portion of the disk and simultaneously observes the limb. The exceptional capabilities of the GDO mission include (1) unprecedented improvement in signal to noise for globalscale imaging of Earth's space environment that enable changes in the Earth's space environment to be resolved with orders of magnitude higher in temporal and spatial resolution compared to existing data and other approaches, and (2) unrivaled capability for resolving the temporal evolution, over many days, in local time or latitude with a continuous view of Earth's global-scale evolution while simultaneously capturing the changes at scales smaller than are possible with other methods. This combination of new capabilities is a proven path to major scientific advances and discoveries. The GDO mission (1) has the first full disk imagery of the density and composition variability that exist during disturbed "storm" periods and the circulation systems of the upper atmosphere, (2) is able to image the ionosphere on a global and long time scale basis, (3) is able to probe the mechanisms that control the evolution of planetary atmospheres, and (4) is able to test our understanding of how the Earth is connected to the Sun. This paper explores the optical and technical aspects of the GDO mission and the implementation strategy. Additionally, the case will be made that GDO addresses a significant portion of the priority mission science articulated in the recent Solar and Space Physics Decadal Survey.

Spann, James↗

NASA NTRS2016

Study of the Effect of Temporal Sampling Frequency on DSCOVR Observations Using the GEOS-5 Nature Run Results: Cloud Coverage - Part II

This is the second part of a study on how temporal sampling frequency affects satellite retrievals in support of the Deep Space Climate Observatory (DSCOVR) mission. Continuing from Part 1, which looked at Earth's radiation budget, this paper presents the effect of sampling frequency on DSCOVR-derived cloud fraction. The output from NASA's Goddard Earth Observing System version 5 (GEOS-5) Nature Run is used as the "truth". The effect of temporal resolution on potential DSCOVR observations is assessed by subsampling the full Nature Run data. A set of metrics, including uncertainty and absolute error in the subsampled time series, correlation between the original and the subsamples, and Fourier analysis have been used for this study. Results show that, for a given sampling frequency, the uncertainties in the annual mean cloud fraction of the sunlit half of the Earth are larger over land than over ocean. Analysis of correlation coefficients between the subsamples and the original time series demonstrates that even though sampling at certain longer time intervals may not increase the uncertainty in the mean, the subsampled time series is further and further away from the "truth" as the sampling interval becomes larger and larger. Fourier analysis shows that the simulated DSCOVR cloud fraction has underlying periodical features at certain time intervals, such as 8, 12, and 24 h. If the data is subsampled at these frequencies, the uncertainties in the mean cloud fraction are higher. These results provide helpful insights for the DSCOVR temporal sampling strategy.

GEOS-5↗

NASA NTRS2000

The Formation Age of Comets: Predicted Physical and Chemical Trends

Dust grains in Herbig Ae/Be stars are continuously replenished by infalling comets. The IR spectra of these cometary grains appear to evolve temporally from initially amorphous astronomical silicates in young protostars to crystalline olivine in much older sources. Crystalline olivine can only be produced from amorphous silicates on a time scale of months-to-years via thermal annealing at temperatures near 1000 K. Since such sustained high temperatures only occur near the central star, dust annealed at 1000 K in inner nebular regions must be continuously transported beyond the nebular snowline to be incorporated into the next generation of cometesimals. The average formation age of a comet can therefore be measured as a ratio of the annealed crystalline olivine dust component to the total dust content of the comet. Comets formed from nearly pristine interstellar materials early in the protostellar nebula stage will contain very little crystalline dust whereas comets formed towards the end of the accretion period will incorporate a much higher percentage of annealed silicate. It is unlikely that only dust grains circulate from the inner to the outer nebula; the gas associated with such dust should also find its way beyond the snowline. Since this gas and dust will have equilibrated in the higher pressure-temperature regime of the inner nebula, it will contain a much higher proportion of hydrocarbons and ammonia than more pristine interstellar ices. Therefore, in addition to a higher fraction of crystalline dust, later forming comets should also contain higher ratios of hydrocarbons to CO and ammonia to N2 than do those formed early in the history of the nebula.

Nuth, Joseph A., III↗

NASA NTRS2011

Ground-Based Network and Supersite Observations to Complement and Enrich EOS Research

Since 1997 NASA has been successfully launching a series of satellites - the Earth Observing System (EOS) - to intensively study, and gain a better understanding of, the Earth as an integrated system. Space-borne remote sensing observations, however, are often plagued by contamination of surface signatures. Thus, ground-based in-situ and remote-sensing measurements, where signals come directly from atmospheric constituents, the sun, and/or the Earth-atmosphere interactions, provide additional information content for comparisons that confirm quantitatively the usefulness of the integrated surface, aircraft, and satellite datasets. Through numerous participations, particularly but not limited to the EOS remote-sensing/retrieval and validation projects over the years, NASA/GSFC has developed and continuously refined ground-based networks and mobile observatories that proved to be vital in providing high temporal measurements, which complement and enrich the satellite observations. These are: the AERO NET (AErosol RObotic NETwork) a federation of ground-based globally distributed network of spectral sun-sky photometers; the MPLNET (Micro-Pulse Lidar NETwork, a similarly organized network of micro-pulse lidar systems measuring aerosol and cloud vertical structure continuously; and the SMART-COMMIT (Surface-sensing Measurements for Atmospheric Radiative Transfer - Chemical, Optical & Microphysical Measurements of In-situ Troposphere, mobile observatories, a suite of spectral radiometers and in-situ probes acquiring supersite measurements. Most MPLNET sites are collocated with those of AERONET, and both networks always support the deployment of SMART-COMMIT worldwide. These data products follow the data structure of EOS conventions: Level-0, instrument archived raw data; Level-1 (or 1.5), real-time data with no (or limited) quality assurance; Level-2, not real high temporal and spectral resolutions. In this talk, we will present NASA/GSFC groundbased facilities, serving as network or supersite observations, which have been playing key roles in major international research projects over diverse aerosol regimes to complement and enrich the EOS scientific research.

Tsay, Si-Chee↗

NASA NTRS1980

A temporal-spectral analysis technique for vegetation applications of Landsat

This paper presents a method for describing the overall continuous pattern of crop spectral development from a set of discrete Landsat observations, using mathematical representations termed profiles. The agronomic basis for the approach is described along with model forms and techniques for estimation of the model parameters. In addition, several current or potential applications of the technology are described.

Crist, E. P.↗

NASA NTRS2021

Validation of Soil Moisture Data Products from the NASA SMAP Mission

The National Aeronautics and Space Administration (NASA)Soil Moisture Active Passive(SMAP) mission has been validatingits soil moisture (SM) products since the start of data production onMarch 31, 2015. Prior to launch, the mission defined a set of criteria for core validation sites (CVS) that enable the testing of the key mission SM accuracy requirement(unbiased root-mean-square error <0.04 m3/m3). Thevalidation approach also includes other (“sparse network”) in situSM measurements, satellite SM products, model-based SM products, and field experiments. Over the past six years, the SMAP SM products have been analyzed with respect to thesereference data,and the analysis approaches themselves have been scrutinizedin an effort to best understand the products’ performance. Validation of themost recent SMAP Level 2 and 3 SMretrievalproducts (R17000) shows that the L-band (1.4 GHz) radiometer-based SM record continues to meet mission requirements. The products aregenerallyconsistentwith SM retrievals from the European Space Agency (ESA)Soil Moisture Ocean Salinity mission, althoughthere aredifferencesin some regions. The high-resolution (3-km) SM retrieval product,generated by combining Copernicus Sentinel-1 data with SMAP observations,performswithin expectations. Currently, however,there is limited availability of3-kmCVSdatato support extensive validation at this spatial scale. The most recent (version 5)SMAP Level4 SMdata assimilation productprovidingsurface and root-zone SM with complete spatio-temporal coverageat 9-km resolution also meets performance requirements. The SMAP SM validation program will continue throughout the mission life; futureplans include expanding ittoforestedand high-latituderegions

SMAP↗

NASA NTRS2012

Drought Indicators Based on Model Assimilated GRACE Terrestrial Water Storage Observations

The Gravity Recovery and Climate Experiment (GRACE) twin satellites observe time variations in Earth's gravity field which yield valuable information about changes in terrestrial water storage (TWS). GRACE is characterized by low spatial (greater than 150,000 square kilometers) and temporal (greater than 10 day) resolution but has the unique ability to sense water stored at all levels (including groundwater) systematically and continuously. The GRACE Data Assimilation System (GRACE-DAS), based on the Catchment Land Surface Model (CLSM) enhances the value of the GRACE water storage data by enabling spatial and temporal downscaling and vertical decomposition into moisture 39 components (i.e. groundwater, soil moisture, snow), which individually are more useful for scientific applications. In this study, GRACE-DAS was applied to North America and GRACE-based drought indicators were developed as part of a larger effort that investigates the possibility of more comprehensive and objective identification of drought conditions by integrating spatially, temporally and vertically disaggregated GRACE data into the U.S. and North American Drought Monitors. Previously, the Drought Monitors lacked objective information on deep soil moisture and groundwater conditions, which are useful indicators of drought. Extensive datasets of groundwater storage from USGS monitoring wells and soil moisture from the Soil Climate Analysis Network (SCAN) were used to assess improvements in the hydrological modeling skill resulting from the assimilation of GRACE TWS data. The results point toward modest, but statistically significant, improvements in the hydrological modeling skill across major parts of the United States, highlighting the potential value of GRACE assimilated water storage field for improving drought detection.

Houborg, Rasmus↗

NASA NTRS2013

Geostationary Enhanced Temporal Interpolation for CERES Flux Products

The Clouds and the Earth's Radiant Energy System (CERES) instruments on board the Terra and Aqua spacecraft continue to provide an unprecedented global climate record of the earth's top-of-atmosphere (TOA) energy budget since March 2000. A critical step in determining accurate daily averaged flux involves estimating the flux between CERES Terra or Aqua overpass times. CERES employs the CERES-only (CO) and the CERES geostationary (CG) temporal interpolation methods. The CO method assumes that the cloud properties at the time of the CERES observation remain constant and that it only accounts for changes in albedo with solar zenith angle and diurnal land heating, by assuming a shape for unresolved changes in the diurnal cycle. The CG method enhances the CERES data by explicitly accounting for changes in cloud and radiation between CERES observation times using 3-hourly imager data from five geostationary (GEO) satellites. To maintain calibration traceability, GEO radiances are calibrated against Moderate Resolution Imaging Spectroradiometer (MODIS) and the derived GEO fluxes are normalized to the CERES measurements. While the regional (1 deg latitude x 1 deg longitude) monthly-mean difference between the CG and CO methods can exceed 25 W m(sub -2) over marine stratus and land convection, these regional biases nearly cancel in the global mean. The regional monthly CG shortwave (SW) and longwave (LW) flux uncertainty is reduced by 20%, whereas the daily uncertainty is reduced by 50% and 20%, respectively, over the CO method, based on comparisons with 15-min Geostationary Earth Radiation Budget (GERB) data.

Doelling, David R.↗

NASA NTRS2018

On-Board Battery Monitoring and Prognostics for Electric-Propulsion Aircraft

The reliability of the propulsion system of an aircraft is paramount for the aircraft safety and hence the aircraft health must be monitored continuously. In contrast to fuel- operated aircraft, electric battery-operated propulsion system poses specific problems, such as, the remaining battery power does not linearly decrease and cannot be measured directly. In this paper, we describe a combined monitoring and prognostics architecture that can continuously monitor all components of the electric propulsion system with respect to safety and performance properties as well as state of charge and rest of useful life for the battery. Our system combines a detailed electrochemical battery model for Li-ion batteries with a powerful prognostics engine based upon an Unscented Kalman Filter with the R2U2 monitoring device, which provides efficient observers for metric temporal logic and Bayesian reasoning. R2U2 is a real-time, realizable, responsive, unobtrusive unit, which continuously monitors sensor readings, outputs of the prognostics engine, as well as the ight software status for safety, performance, and security properties. We illustrate our architecture with two case studies, one reporting actual ight tests with an X8+ octocopter and the other a software-in-the-loop simulation with an unmanned Edge 540 electric aircraft model.

Kulkarni, Chetan↗

NASA NTRS1977

Observations of rapid X-ray flaring from Cygnus X-1

SAS-3 observations of Cyg X-1 in October 1976 show the source to be in a highly active state exhibiting rapid continual flaring on time scales of 1 to 10 s. The flares exhibit temporal structure and variable spectra, but their mean spectrum is similar to that of the source as a whole. The characteristic time scales of the source are 2 to 4 times longer than those previously observed. It is suggested that this active phase of Cyg X-1 signals a modified accretion-disk structure. The flares may result from correlated bunches of the same 'shots ' which are thought to explain the rest of the short-time-scale variability of the source. While the flares superficially resemble X-ray bursts, they are distinct in several respects.

Canizares, C. R.↗

NASA NTRS1985

Possible seasonal variability of mesospheric water vapor

Ground-based spectral line measurements of the 22.2 GHz water vapor line in atmospheric emission were made at the Jet Propulsion Laboratory, which have been used to deduce the mesospheric water vapor profile. The measurements were made nearly continuously in the spring and early summer of 1984. The results indicate a temporal increase in the water vapor mixing ratio in the upper mesosphere from April through June. At 75 km, this increase is nearly by a factor of 2. Comparison of the present results with the results of a similar series of measurements made at the Haystack (radio astronomy) Observatory indicate that this temporal increase is part of a seasonal variation.

Bevilacqua, R. M.↗

NASA NTRS1987

Measurements of surface energy budgets in the rocky mountains of Colorado

The surface energy balance of a mountain valley and a mountain peak were continuously monitored for periods of 126 and 34 days, respectively. The data yielded temporally resolved, high-quality measurements of the radiative, soil, and total atmospheric turbulent heat fluxes. Comparative data for the two sites reveal the effects of terrain setting and surface cover in modulating the heat balance. A procedure is suggested for accommodating local advective affects due to variable terrain and surface cover to allow partitioning of the total turbulent flux into values for sensible and latent heat. This procedure relies on a stability-dependent coefficient of turbulent transfer which is locally calibrated to systematically minimize advection-related errors. Scaling functions for the transfer coeffient are based on the effective blackbody temperature of the surface. Consequently, the procedure offers an opportunity for developing reliable bulk representations of heat transfer at the surface for use with remote sensing data and with models of the soil and surface cover in complex terrain.

Sheaffer, John D.↗

NASA NTRS1995

On-line estimation of error covariance parameters for atmospheric data assimilation

A simple scheme is presented for on-line estimation of covariance parameters in statistical data assimilation systems. The scheme is based on a maximum-likelihood approach in which estimates are produced on the basis of a single batch of simultaneous observations. Simple-sample covariance estimation is reasonable as long as the number of available observations exceeds the number of tunable parameters by two or three orders of magnitude. Not much is known at present about model error associated with actual forecast systems. Our scheme can be used to estimate some important statistical model error parameters such as regionally averaged variances or characteristic correlation length scales. The advantage of the single-sample approach is that it does not rely on any assumptions about the temporal behavior of the covariance parameters: time-dependent parameter estimates can be continuously adjusted on the basis of current observations. This is of practical importance since it is likely to be the case that both model error and observation error strongly depend on the actual state of the atmosphere. The single-sample estimation scheme can be incorporated into any four-dimensional statistical data assimilation system that involves explicit calculation of forecast error covariances, including optimal interpolation (OI) and the simplified Kalman filter (SKF). The computational cost of the scheme is high but not prohibitive; on-line estimation of one or two covariance parameters in each analysis box of an operational bozed-OI system is currently feasible. A number of numerical experiments performed with an adaptive SKF and an adaptive version of OI, using a linear two-dimensional shallow-water model and artificially generated model error are described. The performance of the nonadaptive versions of these methods turns out to depend rather strongly on correct specification of model error parameters. These parameters are estimated under a variety of conditions, including uniformly distributed model error and time-dependent model error statistics.

Dee, Dick P.↗

NASA NTRS1999

A Composite View of Lower Stratospheric Ozone Developed Using a Chemistry Transport Model and Observations from Airborne Lidar and Satellite

An ozone simulation from the Goddard three-dimensional chemistry and transport model for the 1995-96 northern hemisphere winter is compared with ozone observations from airborne Differential Absorption Lidar (DIAL), from the Polar Ozone and Aerosol Measurement (POAM), from the Microwave Limb Sounder (MLS), and from the Halogen Occultation Experiment (HALOE). The 3D model uses winds from the Goddard Data Assimilation System. The 3D model reproduces the latitude dependence of the horizontal and vertical ozone gradients of the subtropical DIAL observations. Comparisons with subtropical satellite observations, which lack the spatial resolution of DIAL but provide near continuous coverage throughout the subtropics, show that the model also reproduces longitude and temporal dependence in the tropical-midlatitude boundary. At polar latitudes, observations from DIAL flights on December 9 and January 30, and POAM and MLS between late December and late January are compared with the 3D model. Data from the three platforms consistently show that the observed ozone has a negative trend relative to the modeled ozone, and that the trend is uniform in time between early and mid winter, with no obvious dependence on proximity to the vortex edge.

Douglass, A. R.↗

NASA NTRS2017

Recent Developments in X-Ray Diagnostics for Cryogenic and Optically Dense Coaxial Rocket Sprays

The mixing and atomization of propellants is often characterized by optically dense flow fields and complex breakup dynamics. In the development of propulsion systems, the complexity of relevant physics and the range of spatio-temporal scales often makes computational simulation impractical for full scale injector elements; consequently, continued research into improved systems for experimental flow diagnostics is ongoing. One area of non-invasive flow diagnostics which has seen widespread growth is using synchrotron based x-ray diagostics. Over the past 3 years, a series of water and cryogenic based experiments were performed at the Advanced Photon Source, Argonne National Lab, on a NASA in-house designed swirl co-axial rocket injector, designed for operation using liquid oxygen and liquid methane in support of Project Morpheus. A range of techniques, such as x-ray fluorescence and time-averaged radiography were performed providing qualitative and quantitative mass and phase distributions, and were complemented by investigations using time-resolved radiography and white beam imaging, which provided information on breakup and mixing dynamics. Results of these investigations are presented, and conclusions regarding the viability of x-ray based diagnostics are discussed.

Radke, Christopher D.↗