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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 37 records · Page 2
All sourcesNASA NTRSDOE OSTI
NASA NTRS1986

Strontium and neodymium isotopic variations in early Archean gneisses affected by middle to late Archean high-grade metamorphic processes: West Greenland and Labrador

Relicts of continental crust formed more than 3400 Ma ago are preserved fortuitously in most cratons. The cratons provide the most direct information about crust and mantle evolutionary processes during the first billion years of Earth history. In view of their polymetamorphic character, these terrains are commonly affected by subsequent tectonothermal events. Hence, their isotope systematics may be severely disturbed as a result of bulk chemical change or local isotopic homogenization. This leads to equivocal age and source information for different components within these terrains. The Sr and Nd isotopic data are presented for early Archean gneisses from the North Atlantic Craton in west Greenland and northern Labrador which were affected by younger metamorphic events.

Collerson, K. D.↗
NASA NTRS1990

Distribution of tropospheric ozone determined from satellite data

An analysis of more than 22,000 ozone profiles from Stratospheric Aerosol and Gas Experiment I (SAGE I) (1979-1981) and SAGE II (1984-1987) between 50 deg N and 50 deg S is used in conjunction with 9 years (1979-1987) of daily global depictions of total ozone from the TOMS instrument aboard Nimbus 7 to investigate the spatial distribution and seasonal cycle of the integrated amount of ozone in the troposphere. In the tropics, highest concentrations are found in the eastern Atlantic Ocean downwind (west) of Africa and maximize during the time when biomass burning is most prevalent, between July and October. A different seasonal cycle in the tropics is also observed over Indonesia, where a relative maximum is present in the March-April time frame, likewise consistent with when biomass burning is most prevalent. At mid-latitudes, highest concentrations are found downwind of Asia and maximize in the summer. Relatively higher amounts of tropospheric ozone are similarly observed downwind of North America and Europe. At mid-latitudes, the ratio between the amount of tropospheric ozone in the Northern Hemisphere and the amount in the Southern Hemisphere is 1.4, in good agreement with in situ measurements.

Fishman, Jack↗
NASA NTRS2012

Propagation of Convective Complexes Observed by TRMM in the Eastern Tropical Atlantic

Precipitation maxima during the West African summer monsoon propagate generally westward in tandem with African easterly waves. A heretofore unreported, repeating pattern of northward drift of precipitation maxima is detected on Tropical Rainfall Measurement Mission (TRMM satellite) time-latitude distributions of daily accumulations over the eastern tropical Atlantic. Corresponding 3-hourly TRMM accumulations show that the northward drifting envelopes of precipitation during August 2006 are often comprised of individual swaths propagating towards the southwest, presumably as mesoscale squall lines. The implied northward drift on the time-latitude distribution is a component of a resultant northwestward movement. The study examines the entire available record of TRMM precipitation observations, 1998-2010, to summarize TRMM maxima propagation over the eastern tropical Atlantic. Meridional displacements of precipitation maxima are most prevalent in June-September 2006, occurring less frequently during other summers. An investigation of geopotential and circulation fields, limited to two case studies, suggests mechanisms to explain some of the observed propagation of TRMM maxima. In one event, northward drift of the precipitation envelope is consistent with the corresponding displacement of the intertropical convergence zone trough, although the southwest propagation of individual mesoscale convection maxima does not correspond to any synoptic feature on reanalysis circulation or reanalysis downscaled by a regional model. One speculation is that southwestward propagation of precipitation maxima could be caused by regeneration of convection at outflow boundaries of mature thunderstorms.

Druyan, Leonard M.↗
DOE OSTI2022

Episodes of Early Pleistocene West Antarctic Ice Sheet Retreat Recorded by Iceberg Alley Sediments

Abstract Ice loss in the Southern Hemisphere has been greatest over the past 30 years in West Antarctica. The high sensitivity of this region to climate change has motivated geologists to examine marine sedimentary records for evidence of past episodes of West Antarctic Ice Sheet (WAIS) instability. Sediments accumulating in the Scotia Sea are useful to examine for this purpose because they receive iceberg‐rafted debris (IBRD) sourced from the Pacific‐ and Atlantic‐facing sectors of West Antarctica. Here we report on the sedimentology and provenance of the oldest of three cm‐scale coarse‐grained layers recovered from this sea at International Ocean Discovery Program Site U1538. These layers are preserved in opal‐rich sediments deposited ∼1.2 Ma during a relatively warm regional climate. Our microCT‐based analysis of the layer's in‐situ fabric confirms its ice‐rafted origin. We further infer that it is the product of an intense but short‐lived episode of IBRD deposition. Based on the petrography of its sand fraction and the Phanerozoic 40 Ar/ 39 Ar ages of hornblende and mica it contains, we conclude that the IBRD it contains was likely sourced from the Weddell Sea and/or Amundsen Sea embayment(s) of West Antarctica. We attribute the high concentrations of IBRD in these layers to “dirty” icebergs calved from the WAIS following its retreat inland from its modern grounding line. These layers also sit at the top of a ∼366‐m thick Pliocene and early Pleistocene sequence that is much more dropstone‐rich than its overlying sediments. We speculate this fact may reflect that WAIS mass‐balance was highly dynamic during the ∼41‐kyr (inter)glacial world.

Bailey, Ian↗
NASA NTRS1998

Validation of Saharan Dust Layer Characteristics with Lidar Observations

Lidar backscattering profiles available from the LITE data set have been used to estimate the optical depths of the Saharan dust layer over West Africa and E. Atlantic regions, in the context of validating the 3-D conceptual model of the Saharan dust plume proposed by Karyampudi and Carlson. The aerosol extinction profiles and optical depths were retrieved from LITE using the Fernald et al. (1972) method. An extinction-to-backscattering ratio, S(sub a), of 25 was selected for optical depth calculations. The spatial analysis of total column and Saharan dust layer optical depths show higher optical depths over W. Africa that decrease westward over E. Atlantic. The higher optical depths over W. Africa, in general, are associated with heavy dust being raised from the surface in dust source regions. Rapid depletion of these heavy dust particles, perhaps due to sedimentation, appear to decrease the dust loading within the dust layer as the plume leaves the west African continent. Higher optical depths are generally confined to the southern edge of the dust layer, where the middle level jet appears to transport the heavy dust concentrations that tend to mix downward from vertical mixing associated with the strong vertical shears underneath the middle jet. Thus, LITE measurements although, in general, validate the Saharan dust plume conceptual model, show maximum values of optical depths near the southern edge of the dust plume over the E. Atlantic region instead of near the center of the dust plume as described in the conceptual model.

Karyampudi, V. Mohan↗
NASA NTRS1999

Biomass Burning Influences on the Composition of the Remote South Pacific Troposphere: Analysis Based on Observations from PEM Tropics-A

Airborne, in-situ measurements from PEM-Tropics-A (September/October 1996) are analyzed to show the presence of distinct pollution plumes in the middle-tropical troposphere of the remote South Pacific (10-30degS). These elevated plumes cause a relative maximum at about 5-7km attitude in the vertical distribution of primary and secondary species characteristic of fuel combustion and biomass burning (CO, C2H2, C2H6, CH3Cl, PAN, O3). Similar plumes were also observed at mid-latitudes in the middle troposphere during three flights east of New Zealand (40-45degS). In all, pollution plumes with CO larger than 100 ppb were observed 24 times on 7 separate flight days south of the equator. The observed plumes were generally embedded in very dry air. Ten-day back trajectory analysis supports the view that these originated from the biomass burning regions of South Africa (and South America) and were transported to the South Pacific along long-distance subsiding trajectories. The chemical composition of the southern Pacific troposphere analyzed from the PEM-Tropics-A data is compared with data from the tropical regions of the northern Pacific (PEM-West-A) and southern Atlantic (TRACE-A) during the same Sept/Oct time period. Sizable perturbations in the abundance of ozone and its key precursors, resulting from the transport of pollution originating from biomass burning sources, are observed in much of the Southern Hemispheric troposphere.

Singh, H. B.↗
NASA NTRS1999

A New Frontier Beckons: Space Exploration in the 21st Century

Throughout recorded history, small groups of explorers have Pushed back the edge of the frontier and opened up new territories for others to follow. As the 20th Century closes, history will record that in the 1960's humankind opened the vast frontier beyond Earth's atmosphere. Although the Apollo program blazed a trail of exploration to the Moon, the development of space has only reached into low Earth orbit. The Space Shuttle and International Space Station programs, and the communication and scientific satellite networks established in orbit around the Earth, are all stepping stones that will enable explorers to venture once again beyond our home planet. Exploration is difficult. It is difficult for the people and machines that travel in extreme environments and endure harsh conditions, and it is difficult for the national leaders who must champion and fund the programs that lead to discovery and reward. Christopher Columbus spent many years meeting with the Kings of Portugal, England, and France only to see his dream of sailing west into the vast Atlantic with ships and crew. discredited. Queen Isabella of Spain was willing to look beyond the many problems plaguing her own shores and see the potential reward for her investment in the future. The voyages of Columbus set the stage for more Spanish explorers, who turned Spain into a great world power. The Apollo program and the unpiloted Lunar Orbiter, Surveyor, Mariner and Viking spacecraft that NASA launched in the 1966's &1970's were our country's first investment, in the exploration of the solar system. These human and robotic missions rewarded us with the first close views of the lunar and martian surfaces, and laid before our eyes territories as vast as all the continents of Earth combined. The Lunar Prospector, Near Earth Asteroid Rendezvous, and Mars Pathfinder and Global Surveyor missions are continuing our scientific conquest of the inner solar system, leading the way for humans to follow.

Mendell, Wendell W.↗
NASA NTRS2002

STS-111 Flight Day 10 Highlights Replay

The most important highlight of flight day 10 of STS-111 was the undocking of the Leonardo Multi Purpose Logistical Module (MPLM) from the Unity module of the International Space Station (ISS). The undocking is shown, as is Leonardo resting in Endeavour's payload bay. The video also includes an interview, and footage of the West Africa and the Atlantic Ocean, Gibraltar and the Mediterranean Sea, Italy, Mexico and the Pacific Ocean, Hispanola, an unknown land mass, and unknown mountains.

Source record↗
NASA NTRS1992

Rain rate statistics and fade distributions at 20 and 30 GHz derived from a network of rain gauges in the Mid-Atlantic coast over a five year period

A network of ten tipping bucket rain gauges located within a grid 70 km north-south and 47 km east-west in the Mid-Atlantic coast of the United States was used to analyze rain rate and modeled slant path attenuation distributions at 20 and 30 GHz. It was shown that, for realistic fade margins at 20 GHz and above, the variable integration times results are adequate to estimate slant path attenuations using models which require 1 min averages. Crane's Global Model was used to derive fade distributions at 20 and 30 GHz.

Goldhirsh, Julius↗
NASA NTRS2002

Convective Systems Over the South China Sea: Cloud-Resolving Model Simulations

The South China Sea Monsoon Experiment (SCSMEX) was conducted in May-June 1998. One of its major objectives is to better understand the key physical processes for the onset and evolution of the summer monsoon over Southeast Asia and southern China. Multiple observation platforms (e.g., upper-air soundings, Doppler radar, ships, wind profilers, radiometers, etc.) during SCSMEX provided a first attempt at investigating the detailed characteristics of convective storms and air pattern changes associated with monsoons over the South China Sea region. SCSMEX also provided rainfall estimates which allows for comparisons with those obtained from the Tropical Rainfall Measuring Mission (TRMM), a low earth orbit satellite designed to measure rainfall from space. The Goddard Cumulus Ensemble (GCE) model (with 1-km grid size) is used to understand and quantify the precipitation processes associated with the summer monsoon over the South China Sea. This is the first (loud-resolving model used to simulate precipitation processes in this particular region. The GCE-model results captured many of the observed precipitation characteristics because it used a fine grid size. For example, the temporal variation of the simulated rainfall compares quite well to the sounding-estimated rainfall variation. The time and domain-averaged temperature (heating/cooling) and water vapor (drying/ moistening) budgets are in good agreement with observations. The GCE-model-simulated rainfall amount also agrees well with TRMM rainfall data. The results show there is more evaporation from the ocean surface prior to the onset of the monsoon than after the on-~et of monsoon when rainfall increases. Forcing due to net radiation (solar heating minus longwave cooling) is responsible for about 25% of the precipitation in SCSMEX The transfer of heat from the ocean into the atmosphere does not contribute significantly to the rainfall in SCSMEX. Model sensitivity tests indicated that total rain production is reduced 17-18% in runs neglecting the ice phase. The SCSMEX results are compared to other GCE-model-simulated weather systems that developed during other field campaigns (i.e., west Pacific warm pool region, eastern Atlantic region and central USA). Large-scale forcing vie temperature and water vapor tendency, is the major energy source for net condensation in the tropical cases. The effects of large-scale cooling exceed that of large-scale moistening in the west pacific warm pool region and eastern Atlantic region. For SCSMEX, however, the effects of large-scale moistening predominate. Net radiation and sensible and latent hc,it fluxes play a much more important role in the central USA.

Tao, Wei-Kuo↗
NASA NTRS2011

Sulfate Aerosol Control of Tropical Atlantic Climate over the Twentieth Century

The tropical Atlantic interhemispheric gradient in sea surface temperature significantly influences the rainfall climate of the tropical Atlantic sector, including droughts over West Africa and Northeast Brazil. This gradient exhibits a secular trend from the beginning of the twentieth century until the 1980s, with stronger warming in the south relative to the north. This trend behavior is on top of a multi-decadal variation associated with the Atlantic multi-decadal oscillation. A similar long-term forced trend is found in a multimodel ensemble of forced twentieth-century climate simulations. Through examining the distribution of the trend slopes in the multimodel twentieth-century and preindustrial models, the authors conclude that the observed trend in the gradient is unlikely to arise purely from natural variations; this study suggests that at least half the observed trend is a forced response to twentieth-century climate forcings. Further analysis using twentieth-century single-forcing runs indicates that sulfate aerosol forcing is the predominant cause of the multimodel trend. The authors conclude that anthropogenic sulfate aerosol emissions, originating predominantly from the Northern Hemisphere, may have significantly altered the tropical Atlantic rainfall climate over the twentieth century

Chang, C.-Y.↗
DOE OSTI2020

Three new symbiotic crabs of the genus Glassella Campos & Wicksten, 1997 from Atlantic and Gulf of Mexico coasts of Florida, USA (Decapoda: Brachyura: Pinnotheridae)

Abstract New species of the pinnotherid crab genus GlassellaCampos & Wicksten, 1997 are described from western Atlantic waters along the east and west coasts of Florida, with the generic assignment of one being provisional. Glassella chaneyin. sp., Glassella martinin. sp., and Glassella taylorin. sp., all morphologically resemble the long-known species G. floridana (Rathbun, 1918) and overlap part of its distributional range, there occupying similar habitats and at least sometimes found with similar hosts. While genomic DNA sequencing has previously established the generic assignment of G. floridana, small sizes and suboptimal preservation histories of specimens representing the three new species have rendered all sequencing attempts unsuccessful, and thus not allowed their inclusion in molecular phylogenetic analyses. To facilitate present morphological comparisons, a rediagnosis of G. floridana was undertaken, and previously published illustrations were augmented, the latter now including figures of its previously undescribed male first gonopod and gonopodal plate. Comparisons of G. floridana to the three new species reveal striking diagnostic differences between all four species in their male first gonopods and varied configurations in the gonopodal plate or its probable homologs. These characters support the otherwise established separation of G. floridana from its congeners on the basis of its more strongly armed flexor margins of the fourth and fifth pereopods. In G. taylorin. sp., representing the smallest known member of Glassella, development of the third maxilliped and male first gonopod is so exceptional as to suggest the species may warrant eventual assignment to a separate genus.

Marine & Freshwater Biology↗
DOE OSTI2022

Crustal and uppermost mantle structure of Cape Verde from ambient noise tomography

SUMMARY We present a seismic ambient noise tomography of the Cape Verde archipelago, located in the Atlantic Ocean, approximately 600 km west of Senegal. We used 38 seismic broad-band stations that continuously recorded for 10 months, in order to construct the first 3-D model of Sv-wave velocities for the crust and uppermost mantle beneath the Cape Verde region. We started by computing phase cross-correlations for vertical component recordings using all possible inter-island station pairs. Next, a time–frequency phase-weighted stack was applied to obtain robust Rayleigh-wave group-velocity dispersion curves in the period band between 10 and 24 s. Group-velocity maps at different periods are obtained by inverting the dispersion curves. We then inverted the group-velocity maps to obtain the 3-D shear wave velocity structure of the crust and uppermost mantle beneath Cape Verde. The final 3-D model extends from 8 km down to 23 km and has a lateral resolution of about 50 km. The crust in the southwestern sector, encompassing Fogo, presents lower S-wave velocities that may be caused by the presence of melt pockets and/or hydrothermal fluids circulation. The uppermost mantle beneath the northwestern sector is characterized by higher S-wave velocities in agreement with previous results obtained from Ps and Sp receiver functions. Those high-velocity anomalies can reflect non-altered crust or remnants of magma chambers or solidified basaltic intrusions, which fed the volcanism in these islands. Our maps revealed the presence of crustal underplating across the entire archipelago, yet stronger beneath the groups Santo Antão—São Vicente—São Nicolau and Fogo—Santiago—Maio.

Carvalho, J. (ORCID:0000000310778994)↗
DOE OSTI2024

Atmospheric Radiation Measurement (ARM) airborne field campaign data products between 2013 and 2018

Airborne measurements are pivotal for providing detailed, spatiotemporally resolved information about atmospheric parameters and aerosol and cloud properties, thereby enhancing our understanding of dynamic atmospheric processes. For 30 years, the US Department of Energy (DOE) Office of Science supported an instrumented Gulfstream 1 (G-1) aircraft for atmospheric field campaigns. Data from the final decade of G-1 operations were archived by the Atmospheric Radiation Measurement (ARM) Data Center and made publicly available at no cost to all registered users. To ensure a consistent data format and to improve the accessibility of the ARM airborne data, an integrated dataset was recently developed covering the final 6 years of G-1 operations (2013 to 2018, https://doi.org/10.5439/1999133; Mei and Gaustad, 2024). The integrated dataset includes data collected from 236 flights (766.4 h), which covered the Arctic, the US Southern Great Plains (SGP), the US West Coast, the eastern North Atlantic (ENA), the Amazon Basin in Brazil, and the Sierras de Córdoba range in Argentina. These comprehensive data streams provide much-needed insight into spatiotemporal variability in the thermodynamic quantities and aerosol and cloud properties for addressing essential science questions in Earth system process studies. This paper describes the DOE ARM merged G-1 datasets, including information on the acquisition, data collection challenges and future potentials, and quality control processes. It further illustrates the usage of this merged dataset to evaluate the Energy Exascale Earth System Model (E3SM) with the Earth System Model Aerosol–Cloud Diagnostics (ESMAC Diags) package.

54 ENVIRONMENTAL SCIENCES↗
NASA NTRS1973

Compendium of marine luminescence signatures, part 2 (appendix C)

Chlorophyll and Gelbstoff excitation and emission spectra of sea water samples are assembled according to geographic sites from the Atlantic and Gulf coasts, the west coast, and a location north of Hawaii. Data were taken by fluorescent spectrophotometer and include also laboratory algal cultures for comparison with the sea water samples.

Hornig, A. W.↗
NASA NTRS1981

SAGE measurements of the stratospheric aerosol dispersion and loading from the Soufriere Volcano

Explosions of the Soufriere volcano on the Caribbean Island of St. Vincent reduced two major stratospheric plumes which the stratospheric aerosol and gas experiment (SAGE) satellite tracked to West Africa and the North Atlantic Ocean. The total mass of the stratospheric ejecta measured is less than 0.5% of the global stratospheric aerosol burden. No significant temperature or climate perturbation is expected. It is found that the movement and dispersion of the plumes agree with those deduced from high altitude meteorological data and dispersion theory. The stratospheric aerosol dispersion and loading from the Soufrier volcano was measured.

Mccormick, M. P.↗
NASA NTRS1982

Stratospheric aerosol effects from Soufriere Volcano as measured by the SAGE satellite system

During its April 1979 eruption series, Soufriere Volcano produced two major stratospheric plumes that the SAGE (Stratospheric Aerosol and Gas Experiment) satellite system tracked to West Africa and the North Atlantic Ocean. The total mass of these plumes, whose movement and dispersion are in agreement with those deduced from meteorological data and dispersion theory, was less than 0.5 percent of the global stratospheric aerosol burden; no significant temperature or climate perturbation is therefore expected.

Mccormick, M. P.↗
NASA NTRS1985

On the Global Distribution of Three-Dimensional Eliassen-Palm Fluxes by Stationary Waves

The global distribution of three dimensional EP fluxes is investigated by using statistics for Dec. 1980 to Feb. 1981 and June to August 1981 calculated from operational analyses. Results at 1000 and 150 mb are given. During the Northern Hemisphere (NH) winter strong upward fluxes can be seen at 1000 mb in the lee of the Himalayas and Rockies, windward of the Canadian Rockies in the east Pacific, to the north of the Atlantic stormtrack and over the west Pacific in a region of strong land sea thermal contrast. Upward fluxes also appear near the west coasts of the Southern Hemisphere (SH) subtropical continents regions of strong land sea thermal contrast. At 150 mb (Fig. 1b) the strongest upward flux now occurs south of Alaska. The horizontal fluxes imply poleward propagation from the convection over Indonesia to 20 N, a region where the assumptions underlying EP fluxes are not well met. Equatorward propagation dominates the NH midlatitude except over the Pacific. The fluxes given offer hints of the sources of stationary waves, but also show several puzzling features and a rather cavalier disregard of regions of easterly wind. The physical meaning and interpretation of three dimensional EP fluxes is not yet clear.

White, G. H.↗