Engineering Papers⌕ Search

SEARCH · Engineering Papers

Results for “PaN”

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.

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

At least 847 records · Page 47
All sourcesNASA NTRSDOE OSTI
NASA NTRS1994

Feasibility study of transmission of OTV camera control information in the video vertical blanking interval

The Operational Television system at Kennedy Space Center operates hundreds of video cameras, many remotely controllable, in support of the operations at the center. This study was undertaken to determine if commercial NABTS (North American Basic Teletext System) teletext transmission in the vertical blanking interval of the genlock signals distributed to the cameras could be used to send remote control commands to the cameras and the associated pan and tilt platforms. Wavelength division multiplexed fiberoptic links are being installed in the OTV system to obtain RS-250 short-haul quality. It was demonstrated that the NABTS transmission could be sent over the fiberoptic cable plant without excessive video quality degradation and that video cameras could be controlled using NABTS transmissions over multimode fiberoptic paths as long as 1.2 km.

White, Preston A., III↗
NASA NTRS1995

Next generation fire suppressants

Spectrex, Inc., located in Cedar Grove, NJ is a manufacturer of fire detection and suppression equipment. Spectrex is one of the original pioneers in high speed fire detection and suppression systems for combat vehicles. Spectrex has installed fire suppressions systems in thousands of combat vehicles and ships throughout the world. Additionally, they manufacture flame explosion detectors, ship damage control systems, and optical gas and vapor detectors. The culmination of several years of research and development has recently produced an innovative electro-optical continuous monitoring systems called SharpEye 20/20I IR(sup 3) and SAFEYE that provide fast and reliable gas, vapor, aerosol, flame, and explosion detection. SharpEye 20/20I IR(sup 3) is a self-contained triple spectrum flame detector which scans for oscillating IR radiation (1 to 10 Hz) in the spectral bands ranging from 4.0 to 5.0 microns and uses programmed algorithms to check the ratio and correlation of data received by the three sensors to make the system highly immune to false alarms. It is extremely sensitive as it can detect a 1 x 1 square foot gasoline pan fire at 200 feet in less than 3 seconds. The sensitivity is user programmable, offering 4 ranges of detection. SAFEYE is comprised of a selected number of multispectral ban microprocessors controlled detectors which are in communication with one or more radiation sources that is projected along a 600 feet optical path. The signals from the selected narrow bands are processed and analyzed by highly sophisticated algorithms. It is ideal for high risk, remote, large areas such as petroleum and chemical manufacturing sites, waste dumps, aircraft cargo bays, and ship compartments. The SAFEYE will perform direct readings of the presence or rate of rise of concentrations of gases, vapors, or aerosols at the range of parts per million and provide alarms at various set points at different levels of concentrations.

Brown, Jerry A.↗
NASA NTRS1994

Acetone in the atmosphere: Distribution, sources, and sinks

Acetone (CH3COCH3) was found to be the dominant nonmethane organic species present in the atmosphere sampled primarily over eastern Canada (0-6 km, 35 deg-65 deg N) during ABLE3B (July to August 1990). A concentration range of 357 to 2310 ppt (= 10(exp -12) v/v) with a mean value of 1140 +/- 413 ppt was measured. Under extremely clean conditions, generally involving Arctic flows, lowest (background) mixing ratios of 550 +/- 100 ppt were present in much of the troposphere studied. Correlations between atmospheric mixing ratios of acetone and select species such as C2H2, CO, C3H8, C2Cl4 and isoprene provided important clues to its possible sources and to the causes of its atmospheric variability. Biomass burning as a source of acetone has been identified for the first time. By using atmospheric data and three-dimensional photochemical models, a global acetone source of 40-60 Tg (= 10(exp 12) g)/yr is estimated to be present. Secondary formation from the atmospheric oxidation of precursor hydrocarbons (principally propane, isobutane, and isobutene) provides the single largest source (51%). The remainder is attributable to biomass burning (26%), direct biogenic emissions (21%), and primary anthropogenic emissions (3%). Atmospheric removal of acetone is estimated to be due to photolysis (64%), reaction with OH radicals (24%), and deposition (12%). Model calculations also suggest that acetone photolysis contributed significantly to PAN formation (100-200 ppt) in the middle and upper troposphere of the sampled region and may be important globally. While the source-sink equation appears to be roughly balanced, much more atmospheric and source data, especially from the southern hemisphere, are needed to reliably quantify the atmospheric budget of acetone.

Singh, H. B.↗
NASA NTRS1994

Reactive nitrogen oxides and ozone above a taiga woodland

Measurements of reactive nitrogen oxides (NO(x) and NO(y)) and ozone (O3) were made in the planetary boundary layer (PBL) above a taiga woodland in northern Quebec, Canada, during June-August, 1990, as part of NASA Artic Boundary Layer Expedition (ABLE) 3B. Levels of nitrogen oxides and O3 were strongly modulated by the synoptic scale meteorology that brought air from various source regions to the site. Industrial pollution from the Great Lakes region of the U.S. and Canada appears to be a major source for periodic elevation of NO(x), and NO(y) and O3. We find that NO/NO2 ratios at this site at midday were approximately 50% those expected from a simple photochemical steady state between NO(x) and O3, in contrast to our earlier results from the ABLE 3A tundra site. The difference between the taiga and tundra sites is likely due to much larger emissions of biogenic hydrocarbons (particularly isoprene) from the taiga vegetation. Hydrocarbon photooxidation leads to relatively rapid production of peroxy radicals, which convert NO to NO2, at the taiga site. Ratios of NO(x) to NO(y) were typically 2-3 times higher in the PBL during ABLE 3B than during ABLE 3A. This is probably the result of high PAN levels and suppressed formation of HNO3 from NO2 due to high levels of biogenic hydrocarbons at the ABLE 3B site.

Bakwin, Peter S.↗
NASA NTRS1995

Influence of fiber architecture on the elastic an d inelastic response of metal matrix composites

This three part paper focuses on the effect of fiber architecture (i.e., shape and distribution) on the elastic and inelastic response of metal matrix composites. The first part provides an annotative survey of the literature, presented as a historical perspective, dealing with the effects of fiber shape and distribution on the response of advanced polymeric matrix and metal matrix composites. Previous investigations dealing with both continuously and discontinuously reinforced composites are included. A summary of the state-of-the-art will assist in defining new directions in this quickly reviving area of research. The second part outlines a recently developed analytical micromechanics model that is particularly well suited for studying the influence of these effects on the response of metal matrix composites. This micromechanics model, referred to as the generalized method of cells (GMC), is capable of predicting the overall, inelastic behavior of unidirectional, multi-phased composites given the properties of the constituents. In particular, the model is sufficiently general to predict the response of unidirectional composites reinforced by either continuous or discontinuous fibers with different inclusion shapes and spatial arrangements in the presence of either perfect or imperfect interfaces and/or interfacial layers. Recent developments regarding this promising model, as well as directions for future enhancements of the model's predictive capability, are included. Finally, the third pan provides qualitative results generated using GMC for a representative titanium matix composite system, SCS-6/TlMETAL 21S. Results are presented that correctly demonstrate the relative effects of fiber arrangement and shape on the longitudinal and transverse stress-strain and creep response, with both strong and weak fiber/matrix interfacial bonds. The fiber arrangements include square, square diagonal, hexagonal and rectangular periodic arrays, as well as a random array. The fiber shapes include circular, square and cross-shaped cross sections. The effect of fiber volume fraction on the observed stress-strain response is also discussed, as the thus-far poorly documented strain rate sensitivity effect. In addition to the well documented features of architecture dependent response of continuously reinforced two-phase MMC's, new results involving continuous multi-phase internal architectures are presented. Specifically, stress strain and creep response of composites with different size fibers having different internal arrangements and bond strengths are investigated with the aim of determining the feasibility of using this approach to enhance the transverse toughness and creep resistance of TMC's.

Arnold, Steven M.↗
NASA NTRS1995

Nearly sonic and transsonic convective motions in the solar atmosphere related to the solar wind origin

MHD equations are considered for the solar atmosphere. 15 different simplest MHD regimes are indicated for the momentum transport equation depending on the mutual binary interplay between 6 possible and locally dominant terms: non-stationarity and inhomogeneity of the flow, gas pressure, magnetic tensions, viscous and gravity forces. These regimes are delimited by five physically independent dimensionless parameters, for example, Strouhal, sonic Mach, alfvenic Mach, Reynolds and Froude numbers or their combinations. Another partially overlapping classification of the simplest regimes may be introduced based on the energy conservation equation. There are also 15 independent binary combinations between nonstationary and inhomogeneous convective terms, dissipative energy sinks and sources (viscous, heat-conductive, Joule and radiative ones) in the energy equation. More complicated regimes are considered with multiple dominated terms. All these MHD regimes play their important role somewhere in the solar atmosphere complicated by the tensor transport coefficients in the magnetically dominated regions of the upper atmosphere. Nearly sonic and transsonic nonstationary convective motions with ascending and descending flows are observed in the solar chromosphere. the transition region and the lower pans of the solar corona together with related horizontal velocity components. This convection represents a kind of the 'cocoonery' manufacturing nonstationary vortices generated here and partially connected to the photosphere and to the solar wind. The solar wind originates from this powerful transsonic muddle in the solar atmosphere as a tiny fraction of the streamlines which are temporarily getting detached from the 'cocoons; and going to the infinity. The topologically complicated instantaneous 'runaway surface' around the Sun, i.e., the surface which separates outgoing to the infinity streams from other finite flows in the solar atmosphere was not described in the literature and needs additional investigation. We conclude that a simple one-connected smooth and quasistationary 'critical surface' which is often supposed to be placed somewhere in the solar corona (say, at 4 solar radii) in reality does not exist. Observational and theoretical arguments favor instead of this a highly structured, disordered, patched and time-dependent sonic transition surface in the solar atmosphere permanently fluctuating at positional dependent heights starting sometimes from photospheric (and maybe subphotospheric) levels and more frequently from the chromosphenc network up to several solar radii in the solar corona.

Veselovsky, I. S.↗
NASA NTRS1994

Experiment K-7-23: Effect of Spaceflight on Level and Function of Immune Cells: Immunology Studies - Part 1

Two different experiments were carried out in this segment of the immunology protocol for samples received from rats flown on Cosmos 2044. Control groups included vivarium, synchronous and antiorthostatically suspended rats. In the first experiment, rat bone marrow cells were examined in Moscow for their response to recombinant murine colony stimulating factor-granulocyte / monocyte (CSF-GM). In the second experiment, rat spleen and bone marrow cells were stained in Moscow with a variety of antibodies directed against cell surface antigenic markers. These cells were preserved and shipped to the United States for analysis on a flow cytometer. The results of the studies indicated that bone marrow cells from flown and suspended rats showed a decreased response to CSF-GM as compared to bone marrow cells from control rats. Spleen cells from flown rats showed increased percentages of suppressor-cytotoxic-T and helper-T cells amongst the entire cell population. Bone marrow cells showed an increase in the percentage of helper-T cells in the myelogenous population and increased percentages of anti-asialo GM-1 bearing, interleukin-2 receptor bearing, pan-T and helper-T cells in the lymphocytic population. Cell populations from rats suspended antiorthostatically did not follow the same pattern of distribution of leukocytes as cell populations for flown rats. These results are similar, but not identical to, earlier results from Cosmos 1887, and confirm that space flight can have profound effects on immune system components and activities.

Sonnenfeld, G.↗
NASA NTRS1996

AIRSAR Data for Geological and Geomorphological Mapping in the Great Sandy Desert and Pilbara Regions of Western Australia

Enhancements of AIRSAR data have demonstrated the benefits of synthetic aperture radar (SAR) for revealing an additional and mich higher level of information about the composition of the terrain than enhancements f either SPOT-PAN or Landsat TM data. With appropriate image processing techniques, surface and near surface geological structures, hydrological systems (both current and ancient) and landform features, have been evidenced in a diverse range of landscapes. In the Great Sandy Desert region where spectral variability is minimal, radar's sensitivity to the micromorphology of sparse exposures of subcrop and lag gravels has provided a new insight into the region's geological framework, its landforms, and their evolution. In the Pilbara region, advanced processing of AIRSAR data to unmix the backscatter between and within the three frequencies of data has highlighted subsurface extensions of greenstone lithologies below sand cover and morphological evidence of past flow conditions under former climate regimes. On the basis of these observations, it is recommend that radar remote sensing technology involving the use of high resolution, polarimetric data be seriously considered as a viable tool for exploration in erosional and depositional environments located within Australia's mineral and oil-prospective provinces.

Tapley, Ian J.↗
NASA NTRS1994

Language in Comparative Perspective

The twentieth century will be noted for a wide variety of scientific and technological advancements, including powered flight, antibiotics, space travel, and the breaking of the genetic code. It also should be noted as the century in which major psychological, as well as biological, continuities between animal and human have been defined. Charles Darwin (1859) was quite right when he anticipated continuity in mental processes, some of which provide for language. Though none will argue that any animal has the full capacity of humans for language, none should deny that at least some animals have quite impressive competencies for language skills, including speech comprehension. The finding that the language skills in the bonobo and the chimpanzee are likely more fully and efficiently developed as a result of early rearing than by formal training at a later age declares a continuity even stronger than that defined by the language acquisition potential of the ape. To clarify, because early rearing facilitates the emergence of language in ape as well as in child, a naturalness to the familiar course of language acquisition, whereby comprehension precedes production, is also corroborated. In turn, the continuity and the shared naturalness of language acquisition serve jointly to define an advanced and critical point of linkage between the genera Pan and Homo - and, as concluded by Domjan (1993), one worthy of contributing to the series of reconceptions of ourselves as anticipated by Ploog and Melnechuk (1971).

Rumbaugh, Duane M.↗
NASA NTRS1997

Geophysical Characterization of Some Terranes and the Geophysical Modeling of Candidate Suture Zones

Indian participation in this project was terminated during the last year by a sudden withdrawal of support by the Department of Science and Technology, India, to the Indian Institute of Geomagnetism, Bombay. As a result, significant changes in the project focus had to be undertaken. Much of the work carried out at Southern Illinois University at Carbondale during the first year of the project anticipated the Indian participation and included development of computer programs to be used on gravity and magnetic data from the Indian subcontinent and preparations for fieldwork, tutorials, and workshops in India. Despite these setbacks, which were beyond our control, a number of significant tasks have been accomplished during the project period. These include: (1) Completion of digitization of the regional Bouguer gravity anomaly map of India and the regional ground total intensity magnetic anomaly map of India at an overdetermined spacing of 0.05 degrees. (2) We investigated and assessed the limitations of the Euler method using environmental examples because detailed aeromagnetic maps of parts of India were not available for interpretation by this method. (3) We also undertook an assessment of a suture zone between the Nyaza Craton (Archean) and the Mozambique Belt (Pan African) in the Kenya Rift, Africa, using gravity anomalies and the lithospheric seismological models. (4) We studied Magsat and high-altitude (approx. 4 km) aeromagnetic data over Canada.

Ravat, D.↗
NASA NTRS1997

Distributions of Beryllium 7 and Lead 210, and Soluble Aerosol-Associated Ionic Species Over the Western Pacific: PEM West B, February - March 1994

Aerosol sampling for the determination of the concentrations of soluble ionic species and the natural radionuclides Be-7 and Pb-210 was conducted from the NASA DC-8 over the western Pacific as part of GTE/PEM-West B during February - March 1994. Concentrations of most soluble ionic species in the free troposphere were higher in samples collected on flights originating from Hong Kong and Japan than those collected further east over the open ocean. In both regions the measured concentrations were higher than those found during PEM-West A (fall 1991). Activities of Pb-210, a tracer of air masses influenced by sources on the Asian continent, showed the same patterns. These data indicate the effect of stronger continental outflow from Asia over the western Pacific during the spring compared to fall season. For readily scavenged aerosol-associated species and soluble acidic gases the strongest indications of Asian outflow were restricted to altitudes below 6 km. The distribution of the continental tracer Pb-210 was also compared to those of a large number of gas phase species measured on the DC-8. Relatively strong correlations were found with O3, and peroxyacetylnitrate (PAN), but only during the flights over the remote Pacific. During PEM-West A, similar correlations were seen, but they were stronger near Asia. We believe that correlations are a signature of continental air that has been processed by deep wet convection over land before being advected over the ocean. One flight over the Sea of Japan provided the opportunity to sample upper troposphere/lower stratosphere air in and around a tropopause fold. Concentrations of Be-7 reached 7 pCi/cu m STP, and peak O3, mixing ratios of 480 ppb were encountered at 10.7 km. The Be-7 data are used to estimate the fraction of stratospheric air mixed down into the troposphere by circulation in the fold.

Dibb, J. E.↗
NASA NTRS1997

Airborne Measurements of NO, NO2, and NO(y) as Related to NASA's Pacific Exploratory Mission

The Tropospheric Trace Gas and Airborne Measurements Group's (TTGAMG) efforts on NASA GTE (Global Tropospheric Experiment) PEM (Pacific Exploratory Mission) West A & B field campaign primarily involved the acquisition of NO, NO2 and NO(y) measurements, as well as the subsequent analysis and interpretation of the data base obtained during the PEM West field campaign. These investigations focused on the distribution of trace gases, sources and sinks of ozone, ozone producing precursors with a heavy emphasize on ozone's photochemical state, and the partitioning of the molecules within the NO(y) family over the north western Pacific Ocean. The two components of PEM West were focused on observing air masses as they reached the Asian Continent (PEM West A) or as the air mass departed the Asian Continent (PEM West B). NO(x) concentrations play a pivotal role in controlling the photochemical lifetime of ozone in these environments, and understanding the NO(x) species partitioning is paramount. The transport of NO(x) into the regions, in the form of longer lived NO(y) family members, was examined in relation to the comparison of natural occurring sources of NO(x) (i.e., lightning and stratosphere/troposphere exchange) to those produced as a result of anthropogenic activity (i.e., biomass burning and aircraft emissions). The TTGAMG's measurements of NOx and NO(y), in conjunction with other investigators' measurements of PAN (H. B. Singh's group) and HNO3 (R. W. Talbot's group), have been used to assess the total reactive odd nitrogen levels over the study regions, the partitioning of the reactive odd nitrogen species in their various forms, and the usefulness of the NO, measurement and its measurement technique. The TTGAMG's primary PEM West objectives were the characterization of the factors controlling the distribution and fate of reactive odd nitrogen compounds over the western Pacific Ocean and an analysis of the concentration of various trace gases in the troposphere as the air mass aged by both dynamical mixing and photochemical processes in the troposphere.

Sandholm, Scott↗
NASA NTRS1997

Biochemical Assessment of Stress in Cardiac Tissue in Response to Weightless Space Travel

The absence of unit gravity may cause physiological changes in the cardiovascular system. For instance, in the absence of Earth's gravity, venous return to the heart may increase due, in pan, to decreased pooling of the blood in the extremities. We hypothesize that this would produce an increase in the heart's work load ultimately resulting in hypertrophy.

Brunton, Laurence L.↗
NASA NTRS1998

An Assessment of the Axial and Radial Dilation of a DPIMS Tantalum Cartridge for Space Shuttle Flight Experiments

Ground-based heat treatment tests are planned on an argon gas-filled tantalum cartridge developed as pan of a Diffusion Processes in Molten Semiconductors (DPIMS) experiment conducted on NASA's Space Shuttle. The possibility that the cartridge may creep during testing and touch the furnace walls is of real concern in this program. The present paper discusses the results of calculations performed to evaluate this possibility. Deformation mechanism maps were constructed using literature data in order to identify the creep mechanism dominant under the appropriate stresses and temperatures corresponding to the test conditions. These results showed that power-law creep was dominant when the grain size of the material exceeded 55 gm but Coble creep was the important mechanism below this value of grain size. Finite element analysis was used to analyze the heat treatment tWs assuming a furnace run away condition (which is a worst case scenario) using the appropriate creep parameters corresponding to grain sizes of 1 and 100 gm. Calculations were also conducted to simulate the effect of an initial 3 tilt of the cartridge assembly, the maximum possible tilt angle. The von Mises stress and su-ain distributions were calculated assuming that the cartridge was fixed at one end as it was heated from ambient temperature to 1823 K in 1.42 h, maintained at 1823 K for 9.5 h and then further heated to an over temperature condition of 2028 K in 0.3 h. The inelastic axial and radial displacements of the cartridge walls were evaluated by resolving the von Mises strain along the corresponding directions. These calculations reveal that the maximum axial and radial displacements are expected to be about 2.9 and 0.25 mm, respectively, for both fine and coarse-grained materials at 2028 K. It was determined that these displacements occur during heat-up to temperature and creep of the cartridge is likely to be relatively insignificant irrespective of grain size. Furthermore, with a 3' tilt of the cartridge, the deflection is increased by only 0.39 gm which is negligible. Since the gap between the furnace heating elements and the cartridge is about 7.5 mm and less than the maximum radial dilation of 0.25 mm at 2028 K, it is concluded that the cartridge is unlikely to touch the furnace walls during the experiments.

Raj, S.V.↗
NASA NTRS1997

Distributions of Beryllium 7 and Lead 210, and Soluble Aerosol-Associated Ionic Species Over the Western Pacific: PEM West B

Aerosol sampling for the determination of the concentrations of soluble ionic species and the natural radionuclides Be-7 and Pb-210 was conducted from the NASA DC-8 over the western Pacific as part of GTE/PEM-West B during February - March 1994. Concentrations of most soluble ionic species in the free troposphere were higher in samples collected on flights originating from Hong Kong and Japan than those collected further east over the open ocean. In both regions the measured concentrations were higher than those found during PEM-West A (fall 1991). Activities of Pb-210 tracer of air masses influenced by sources on the Asian continent, showed the same patterns. These data indicate the effect of stronger continental outflow from Asia over the western Pacific during the spring compared to fall season. For readily scavenged aerosol-associated species and soluble acidic gases the strongest indications of Asian outflow were restricted to altitudes below 6 km. The distribution of the continental tracer Pb-210 was also compared to those of a large number of gas phase species measured on the DC-8. Relatively strong correlations were found with O3 and peroxyacetylnitrate (PAN), but only during the flights over the remote Pacific. During PEM-West A, similar correlations were seen, but they were stronger near Asia. We believe that these correlations are a signature of continental air that has been processed by deep wet convection over land before being advected over the ocean. One flight over the Sea of Japan provided the opportunity to sample upper troposphere/lower stratosphere air in and around a tropopause fold. Concentrations of Be-7 reached 7 pCi/cu m STP, and peak O3, mixing ratios of 480 ppb were encountered at 10.7 km. The Be-7 data are used to estimate the fraction of stratospheric air mixed down into the troposphere by circulation in the fold.

Didd, J. E.↗
NASA NTRS1999

Measurements of Nitric Acid and Aerosol Species Aboard the NASA DC-8 Aircraft During the SASS OZone and Nitrogen Oxide Experiment (SONEX)

The SASS Ozone and Nitrogen Oxides Experiment (SONEX) over the north Atlantic during October/November 1997 offered an excellent opportunity to examine the budget of total reactive nitrogen (NO(y)) in the upper troposphere (8 - 12 km altitude). The median measured NO(y) mixing ratio was 425 parts per trillion by volume (pptv). Two different methods were used to measure HNO3: (1) the mist chamber technique and, (2) chemical ionization mass spectrometry. Two merged data sets using these HNO3 measurements were used to calculate NO(y) by summing the reactive nitrogen species (a combination of measured plus modeled results) and comparing the resultant values to measured NO(y) (gold catalytic reduction method). Both comparisons showed good agreement in the two quantities (slope greater than 0.9 and r(sup 2) greater than 0.9). Thus, the total reactive nitrogen budget in the upper troposphere over the North Atlantic can be explained in a general manner as a simple mixture of NO(x). (NO + NO2), HNO3, and PAN. Median values of NO(x)/NO(y) were approx. = 0.25, HNO3/NO(y) approx. = 0.35 and PAN/NO(y) approx. = 0.17. Particulate NO3 and alkyl nitrates together composed less than 10% of NO(y), while model estimated HNO4 averaged 12%.

Talbot, Robert W.↗
NASA NTRS1998

Creating a GIS-Based Decision-Support System

Tilting the Balance: Climate Variability and Water Resource Management in the Southwest, a regional conference hosted by the Pan American Center for Environmental Studies, will be held at The University of Texas at El Paso on March 2-4, 1998. The conference is supported through the US Global Change Research Program (USGCRP) established by the President in 1989, and codified by Congress in the Global Change Research Act of 1990. The NASA Mission to Planet Earth program is one of the workshops sponsors. The purpose of the regional workshops is to improve understanding of the consequences of global change. This workshop will be focused on issues along the border and the Rio Grande River and thus will bring together stakeholders from Mexico, California, Texas, New Mexico, Arizona and Colorado representing federal, state, and local governments; universities and laboratories; industry, agricultural and natural resource managers; and non-governmental organizations. This paper discusses the efforts of the NASA PACES center create a GIS-based decision-support system that can be used to facilitate discussion of the complex issues of resource management within the targeted international region.

Alvarado, Lori↗
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.↗