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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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At least 181 records · Page 10
All sourcesNASA NTRSDOE OSTI
NASA NTRS1988

Intercomparison of NO column measurements during MAP/GLOBUS 1985

Simultaneous NO column measurements made in France in September, 1985, using several techniques, are compared with one another. The observed NO distributions vary significantly from day to day. It is shown that NO measurements using IR or UV absorption are self-consistent and show good agreement with predictions from a one-dimensional photochemical model. In situ chemiluminescent measurements produced NO columns which were systematically higher than those predicted.

Mckenzie, R. L.↗
NASA NTRS1991

Remote sensing of atmospheric chemistry; Proceedings of the Meeting, Orlando, FL, Apr. 1-3, 1991

The present volume on remote sensing of atmospheric chemistry discusses special remote sensing space observations and field experiments to study chemical change in the atmosphere, network monitoring for detection of stratospheric chemical change, stratospheric chemistry studies, and the combining of model, in situ, and remote sensing in atmospheric chemistry. Attention is given to the measurement of tropospheric carbon monoxide using gas filter radiometers, long-path differential absorption measurements of tropospheric molecules, air quality monitoring with the differential optical absorption spectrometer, and a characterization of tropospheric methane through space-based remote sensing. Topics addressed include microwave limb sounder experiments for UARS and EOS, an overview of the spectroscopy of the atmosphere using an FIR emission experiment, the detection of stratospheric ozone trends by ground-based microwave observations, and a FIR Fabry-Perot spectrometer for OH measurements.

Mcelroy, James L.↗
NASA NTRS2006

Is the Linear Mode Conversion Theory Viable for Generating Kilometric Continuum?

Kilometric Continuum (KC) usually exhibits a complicated banded radiation pattern observed in frequency time spectrograms. Can the number of bands, the frequency range over which the bands are observed, and their time variation be explained with Linear Mode Conversion Theory (LMCT) using realistic plasmapause models and Extreme Ultraviolet (EUV) plasmaspheric observations? In this paper we compare KC observations with simulated frequency emission bands based on LMCT for a number of cases. In LMCT the allowed frequency range across the equatorial plasmapause is restricted to frequencies much greater than the electron cyclotron frequency (fce) and less than the maximum plasma frequency in this region. Fce also determines the number of allowed bands in this range. Is the observed frequency range and number of bands consistent with the predications of LMCT? Can irregularities in the shape of plasmaspheric structures like notches be observed in the time variations of KC emissions? We will investigate these and other questions. Simulated radiation patterns will be generated by ray tracing calculations in the L-O mode from the radio window at the near equatorial plasmapause. The KC observations used in this study are from the Plasma Wave Instrument on the Geotail spacecraft and from the Radio Plasma Imager on the IMAGE spacecraft. The plasmasphere and plasmapause will be derived either from plasmasphere simulations, from images by the EUV imager on the IMAGE spacecraft, and by using empirical models. In situ plasma density measurements from a number of spacecraft will also be used in order to reconstruct the plasmasphere for these case studies.

Boardsen, Scott A.↗
NASA NTRS2009

Satellite Contributions to Global Change Studies

By providing a global view with a level playing field (no region missed because of unfavorable surface conditions or political boundaries), satellites have made major contributions to improved monitoring and understanding of our constantly changing planet. The global view has allowed surprising realizations like the relative sparsity of lightning strikes over oceans and the large-scale undulations on the massive Antarctic ice sheet. It has allowed the tracking of all sorts of phenomena, including aerosols, both natural and anthropogenic, as they move with the atmospheric circulation and impact weather and human health. But probably nothing that the global view allows is more important in the long term than its provision. of unbiased data sets to address the issue of global change, considered by many to be among the most important issues facing humankind today. With satellites we can monitor atmospheric temperatures at all latitudes and longitudes, and obtain a global average that lessens the likelihood of becoming endlessly mired in the confusions brought about by the certainty of regional differences. With satellites we can monitor greenhouse gases such as CO2 not just above individual research stations but around the globe. With satellites we can monitor the polar sea ice covers, as we have done since the late 1970s, determining and quantifying the significant reduction in Arctic sea ice and the slight growth in Antarctic sea ice over that period, With satellites we can map the full extent and changes in the Antarctic stratospheric ozone depletions that were first identified from using a single ground station; and through satellite data we have witnessed from afar land surface changes brought about by humans both intentionally, as with wide-scale deforestation, and unintentionally, as with the decay of the Aral Sea. The satellite data are far from sufficient for all that we need in order to understand the global system and forecast its changes, as we also need sophisticated climate models, in situ process studies, and data sets that extend back well before the introduction of satellite technology. Nonetheless, the repetitive, global view provided by satellites is contributing in a major way to our improved recognition of how the Earth im changing, a recognition that is none too soon in view of the magnitude of the impacts that humans can now have.

Parkinson, Claire L.↗
NASA NTRS2010

Applied Meteorology Unit (AMU) Quarterly Report

By providing a global view with a level playing field (no region missed because of unfavorable surface conditions or political boundaries), satellites have made major contributions to improved monitoring and understanding of our constantly changing planet. The global view has allowed surprising realizations like the relative sparsity of lightning strikes over oceans and the large-scale undulations on the massive Antarctic ice sheet. It has allowed the tracking of all sorts of phenomena, including aerosols, both natural and anthropogenic,as they move with the atmospheric circulation and impact weather and human health. But probably nothing that the global view allows is more important in the long term than its provision of unbiased data sets to address the issue of global change, considered by many to be among the most important issues facing humankind today. With satellites we can monitor atmospheric temperatures at all latitudes and longitudes, and obtain a global average that lessens the likelihood of becoming endlessly mired in the confusions brought about by the certainty of regional differences. With satellites we can monitor greenhouse gases such as CO2 not just above individual research stations but around the globe. With satellites we can monitor the polar sea ice covers, as we have done since the late 1970s, determining and quantifying the significant reduction in Arctic sea ice and the slight growth in Antarctic sea ice over that period. With satellites we can map the full extent and changes in the Antarctic stratospheric ozone depletions that were first identified from a single ground station; and through satellite data we have witnessed from afar land surface changes brought about by humans both intentionally, as with wide-scale deforestation, and unintentionally, as with the decay of the Aral Sea. The satellite data are far from sufficient for all that we need in order to understand the global system and forecast its changes, as we also need sophisticated climate models, in situ process studies, and data sets that extend back well before the introduction of satellite technology. Nuomthc)cmm, the repetitive, global view provided by satellites is contributing in a major way to our improved recognition of how the Earth is changing, a recognition that is none too soon in view of the magnitude of the impacts that humans can now have.

Bauman, William↗
NASA NTRSDate not supplied

Characterizing Martian X-ray Amorphous Materials through Terrestrial Analogs

X-ray amorphous materials (i.e., lacking long-range crystallographic order) have been identified on the martian surface from orbit and in-situ. Initial models of orbital IR spectral data identified volcanic glasses [e.g., 1], but subsequent interpretations suggested that amorphous silicates are dominantly secondary in nature and formed from water-rock interactions [e.g., 2-4]. ThermalIR spectra from the Mini-Thermal Emission Spectrometer on the Spirit rover show evidence for the amorphous secondary product opaline silica[e.g., 5].X-ray diffraction (XRD) measurements by the CheMin instrument on the Mars Science Laboratory rover have identified 20-70 wt.% amorphous materials in every sample analyzed in Gale crater to date [e.g., 6]. Mass balance calculations using CheMin results and bulk elemental measurements by the Alpha Particle X-ray Spectrometer suggest the amorphous component in Gale crater is variably enriched in Si, Fe, and S[e.g., 7,8].The compositions are not consistent with pure volcanic glass, indicating water must have been involved in the formation of amorphous materials in Gale crater. We seek to better constrain the conditions under which amorphous materials on Mars formed by studying the composition and short-range atomic order of amorphous materials in terrestrial analog environments via XRD and transmission electron microscopy (TEM).

E. B. Rampe↗
NASA NTRSDate not supplied

Characterizing Martian X-Ray Amorphous Materials Through Terrestrial Analogs

X-ray amorphous materials (i.e., lacking long-range crystallographic order) have been identified on the martian surface from orbit and in-situ. Initial models of orbital IR spectral data identified volcanic glasses [e.g., 1], but subsequent interpretations suggested that amorphous silicates are dominantly secondary in nature and formed from water-rock interactions [e.g., 2-4]. Thermal IR spectra from the Mini-Thermal Emission Spectrometer on the Spirit rover show evidence for the amorphous secondary product opaline silica [e.g., 5]. X-ray diffraction (XRD) measurements by the CheMin instrument on the Mars Science Laboratory rover have identified 20-70 wt.% amorphous materials in every sample analyzed in Gale crater to date [e.g., 6]. Mass balance calculations using CheMin results and bulk elemental measurements by the Alpha Particle X-ray Spectrometer suggest the amorphous component in Gale crater is variably enriched in Si, Fe, and S [e.g., 7,8]. The compositions are not consistent with pure volcanic glass, indicating water must have been involved in the formation of amorphous materials in Gale crater. We seek to better constrain the conditions under which amorphous materials on Mars formed by studying the composition and short-range atomic order of amorphous materials in terrestrial analog environments via XRD and transmission electron microscopy (TEM).

E B Rampe↗
NASA NTRSDate not supplied

Merging Analytic Collaborative Frameworks with New Observing Strategies Toward a Digital Twin: Earth – Episodic Pulse Event Impacts on Ocean Carbon Cycle as an Example

Virtual representations of the Earth will allow us to address some of the most critical environmental issues of our time. Here, we show the first steps toward representation of riverine, estuarine, and coastal carbon processes to enable scenario driven “what-if” analyses of the carbon system and human footprint. Excess sediment and nutrient runoff from land-based human activities impact water quality and can pose serious threats to coastal and marine ecosystems. Episodic pulse events, such as extreme precipitation events, can increase the amount of nutrients entering estuaries and coastal regions, potentially leading to large phytoplankton blooms followed by anoxic conditions. Consequences of coastal runoff are predicted to increase with the higher intensity and frequency of extreme events. Beyond the threat to coastal ecosystems, recent findings suggest these episodic pulses might play a significant role for biological production influencing regional and global carbon fluxes and budgets. An improved understanding of these events through optimal, dynamic observing strategies will increase our knowledge of the land-ocean continuum and how regional events and nutrient fluxes affect the carbon cycle and ocean ecosystem. This conceptual framework enables focused science investigations by pairing data analytics and artificial intelligence tools (otherwise termed an Analytic Center Framework, ACF) with targeted measurement acquisition through distributed sensing and intelligent asset tasking (or New Observing Strategies, NOS). This NOS and ACF iterative approach acquires and integrates complementary and coincident satellite, in-situ and model data to build a more complete and in-depth picture of science phenomena. Specifically, Apache Science Data Analytic Platform (SDAP) is extended to incorporate relevant datasets for data access, harmonized analysis, and anomaly detection. When conditions are met for a likely pulse event, NASA’s D-SHIELD (Distributed Spacecraft with Heuristic Intelligence to Enable Logistical Decisions) tool is triggered to optimize asset overpass frequency and schedule observations for persistent monitoring. Targeted data is ingested by SDAP for enhanced investigation via iterative analysis until the trigger criteria is no longer met - steps toward a digital twin.

Laura Rogers↗
NASA NTRSDate not supplied

The Complex Refractive Indices of Mineral Aerosols and Why They Matter

Aerosol refractive indices are fundamental parameters that are generally measured by spec-troscopists with specialized knowledge. We in the Earth science community frequently utilizethese refractive indices because they are essential for computing aerosol radiative effects andretrieving aerosol composition. Unfortunately, there are a wide variety of refractive indiceswith significant differences for some aerosol species (e.g., hematite) and a lack of refractiveindex choices for other aerosols (e.g., clay minerals, goethite), and this hinders our ability toaccurately compute the radiative effect of mineral dust. Additionally, the mineral refractiveindices used in atmospheric science are not necessarily linked to the mineral reflectancesused to identify surface mineralogy; this creates a disconnect between the atmosphere andthe surface that frustrates closure analyses.In this talk, we will present an overview of some refractive indices of radiative importancein aeolian dust (illite, kaolinite, montmorillonite, hematite, goethite). We will discuss howmineral refractive indices are used in aerosol retrievals, and how we can use remote sensingretrievals to narrow the range of viable choices. We will also discuss how we can use pub-lished spectroscopic measurements to extrapolate the refractive indices that are inferred ata handful of visible and near-infrared wavelengths to the longwave regime. Finally, we willdiscuss how working groups like MIRA (Models, In situ, and Remote sensing of Aerosols;https://science.larc.nasa.gov/mira-wg/) and community repositories like TAO (Tables ofAerosol Optics) can improve radiative closure by enhancing interactions between the threedisciplines.1

aerosols↗
NASA NTRS2024

Deciphering the Spectra of Flowers to Map Landscape-scale Blooming Dynamics

Like leaves, floral coloration is driven by inherent optical properties, which are determined by pigments, scattering structure, and thickness. However, establishing the relative contribution of these factors to canopy spectral signals is usually limited to in-situ observations. Modeling flowering dynamics (e.g., blooming duration, spatial distribution) at the landscape scale may reveal insights into ecological processes and phenological adaptations to environmental changes. Multitemporal visible to shortwave infrared (VSWIR) imaging spectroscopy observations are especially suited for such efforts. Reflectance in this spectral range is sensitive to major flower pigments, flowering phenology traces, and biophysical differences between flowers and other plant parts. We explored how flowers contribute to spectral signals using a time series of imagery from the Airborne Visible InfraRed Imaging Spectrometer - Next Generation (AVIRIS-NG) collected as part of the SBG High-Frequency Time Series (SHIFT) campaign as a case study. Airborne data were collected weekly during the spring of 2022 across two natural reserves in California. Field spectra were gathered from blooming plots at leaf, flower, and canopy levels at two time points during the campaign. The processed data was used to investigate flowering species' spectro-temporal variation and spatial distribution using Spectral Mixture Residual, Gaussian clustering techniques, and a proposed narrow-band flowering index. Linear spectral unmixing allowed the computation of the weighted contribution of four major high-variance endmembers (leaves, flowers, soil, dark) and low-variance residual signal that comprises subtle spectral features used to track biophysical processes. The reflectance residual was projected on a low principal component basis to characterize flowering clusters' variation and spatial distribution based on the Gaussian mixture model, providing an uncertainty metric to assess the results. Mapping flowering events from modeling spectro-temporal dynamics throughout the season, from pre-blooming to post-flowering stages, allowed us to identify gradient variations in spectral features within the VSWIR spectral range linked to flowering pigments. Time series of the Mixture Residual Blooming Index and the Red-Edge Normalized Difference Vegetation Index revealed specific flowering and greenness phenophases across the two main species (Coreopsis gigantea, Artemisia californica) in the flowering areas. Overall, our approach opens opportunities for future satellite monitoring of floral cycles at broader scales.

Yoseline Angel↗
NASA NTRS2018

Satellite and In Situ Observations for Advancing Global Earth Surface Modelling: A Review

In this paper we review the use of satellite-based remote sensing in combination with in situ data to inform Earth surface modelling. This involves verification and optimization methods that can handle both random and systematic errors and result in effective model improvement for both surface monitoring and prediction applications. The reasons for diverse remote sensing data and products include (i) their complementary areal and temporal coverage, (ii) their diverse and covariant information content, and (iii) their ability to complement in situ observations, which are often sparse and only locally representative. To improve our understanding of the complex behavior of the Earth system at the surface and sub-surface, we need large volumes of data from high-resolution modelling and remote sensing, since the Earth surface exhibits a high degree of heterogeneity and discontinuities in space and time. The spatial and temporal variability of the biosphere, hydrosphere, cryosphere and anthroposphere calls for an increased use of Earth observation (EO) data attaining volumes previously considered prohibitive. We review data availability and discuss recent examples where satellite remote sensing is used to infer observable surface quantities directly or indirectly, with particular emphasis on key parameters necessary for weather and climate prediction. Coordinated high-resolution remote-sensing and modelling/assimilation capabilities for the Earth surface are required to support an international application-focused effort.

Earth observations↗