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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 NTRS1969

Vegetation changes caused by fire in the Florida flatwoods as observed by remote sensing

The nature of the flatwoods and the role that ground fires have played in maintaining them are discussed. Emphasis is placed on the areal and temporal extent of burns as recorded uniformly by remote sensors. Thermal infrared, color infrared, and Ektachrome imagery were obtained from sensors flown by a NASA aircraft at 15,000 feet over a test site in Osceola County, Florida, in March 1968. The overall pattern of burning can be sequenced and mapped uniformly from the imagery. By comparing the various imagery, areal and temporal extent of burned areas can be determined. It was concluded that remote sensed imagery provides more accurate and areally comprehensive media for assessing the impact of ground fires on the landscape of the flatwoods region than are available from any other data source.

Mealor, W. T., Jr.↗
NASA NTRS1973

Satellite imagery for assessing range fire damage in the Sandhills of Nebraska

The author has identified the following significant results. Initial imagery from the first ERTS indicates that satellite-acquired data is of value in determining the location and extent of range fire in the Sand Hills region of Nebraska. Preliminary results suggest that it can also provide a tool for monitoring soil erosion by wind and evaluating the recovery of vegetation in burned areas.

Drew, J. V.↗
NASA NTRS1974

SO2 damage to forests recorded by ERTS-1

Sulfur dioxide fumes have been affecting the forests around Wawa, Ontario, which have been under surveillance for a number of years and were recently covered by ultra-small-scale (1:160,000) air photography for damage-assessment purposes. Image interpretation supported by electronic color enhancement was used to delineate on ERTS imagery three damage zones (total-kill, heavy-kill and medium-damage zones). The zones delineated on ERTS imagery are similar to the results of aerial sketch-mapping and air photo interpretation. Band 5 provided the greatest detail for assessing the damage to the forests, followed in successive order by bands 4, 6 and 7. Comparison with ERTS images obtained in the winter showed that even though the total-kill could be separated from heavy-kill damage zones, total-kill could not be consistently separated from clear-cut logging, burned areas, frozen lakes and bogs.

Murtha, P. A.↗
NASA NTRS1974

Predict ephemeral and perennial range quantity and quality during normal grazing season

The author has identified the following significant results. Collection and update of resource inventory data has historically been a difficult, time consuming task. Accurate resource data is necessary as a basis for wise management decisions made by a resource management agency such as the Bureau of Land Management. Black and white and color infrared composites of ERTS satellite imagery at 1:1,000,000 and enlarged scales can be used as data gathering tools. No investment in expensive sophisticated equipment is necessary. A photointerpreter can map boundaries of soils, plant communities, levels of forage production, areas revegetated by man, and areas burned by wildlife directly from satellite imagery. The ERTS system of producing and distributing imagery must be improved greatly before satellite imagery can be useful to the resource manager.

Bentley, R. G., Jr.↗
NASA NTRS1974

Mapping a recent forest fire with ERTS-1 MSS data

Accurate fire boundary delineation provides essential information to forest managers in allocating suppression costs and planning regeneration efforts. The objective of this study was to test the capability of computer-aided analysis of ERTS-1 MSS data to accurately define the boundary of a recent forest fire and to discriminate spectral classes within the perimeter. Two frames of ERTS-1 MSS data were selected for analysis of the Moccasin Mesa Fire in Mesa Verde National Park. Data sets were collected one-half growing season and one full growing season after the fire. Results indicate that computer-aided analysis of ERTS-1 MSS data has the capability for accurately delineating fire boundaries and determining acreage of the burned area. Distinct spectral classes may also be defined within the fire perimeter.

Hitchcock, H. C.↗
NASA NTRS1976

A stop-restart solid propellant study with salt quench

Experiments were conducted to gain insight into the unsatisfactory performance of the salt quench system of solid propellants in earlier studies. Nine open-air salt spray tests were conducted and high-speed cinematographic coverage was obtained of the events. It is shown that the salt spray by the detonator is generally a two-step process yielding two different fractions. The first fraction consists of finely powdered salt and moves practically unidirectionally at a high velocity (thousand of feet per second) while the second fraction consists of coarse particles and moves randomly at a low velocity (a few feet per second). Further investigation is required to verify the speculation that a lower quench charge ratio (weight of salt/propellant burning area) than previously employed may lead to an efficient quench

Kumar, R. N.↗
NASA NTRS1977

An application of LANDSAT digital technology to forest fire fuel type mapping

The role of digital classifications suitable as fuel maps was examined. A Taylor enhancement was produced for an 8 million hectare fire control region showing water, muskeg, coniferous, deciduous and mixed stands, clearcut logging, burned areas, regeneration areas, nonforested areas and large forest roads. Use of the map by fire control personnel demonstrated its usefulness for initial attack decision making.

Kourtz, P. H.↗
NASA NTRS1984

The direct effects of strain on burning rates of composite solid propellants

A mathematical model is developed to predict burn rate augmentation due to strain in a composite solid propellant. The model assumes the effect is due to the ability of the flame to penetrate the small fissures and voids that form when a propellant is strained. The number and size of these fissures is obtained by applying a flaw propagation analysis to randomly distributed flaws that form when the binder-oxidizer particle bonds break under stress. A flame height is calculated with Summerfield's burn rate equation and is used to compute the burn rate augmentation based upon the additional burn area created when the flame penetrates the fissures. Comparisons are made with data obtained from published sources. The existence of threshold pressure and strains, above which augmentation occurs, is verified although the model predicts a lower threshold pressure and higher threshold strain than expected. Further results and applications of the model are discussed.

Langhenry, M. T.↗
NASA NTRS1990

Aerospace video imaging systems for rangeland management

This paper presents an overview on the application of airborne video imagery (VI) for assessment of rangeland resources. Multispectral black-and-white video with visible/NIR sensitivity; color-IR, normal color, and black-and-white MIR; and thermal IR video have been used to detect or distinguish among many rangeland and other natural resource variables such as heavy grazing, drought-stressed grass, phytomass levels, burned areas, soil salinity, plant communities and species, and gopher and ant mounds. The digitization and computer processing of VI have also been demonstrated. VI does not have the detailed resolution of film, but these results have shown that it has considerable potential as an applied remote sensing tool for rangeland management. In the future, spaceborne VI may provide additional data for monitoring and management of rangelands.

Everitt, J. H.↗
NASA NTRS1992

Mapping continental-scale biomass burning and smoke palls from the space shuttle

Space shuttle photographs have been used to map the areal extent of Amazonian smoke palls associated with biomass burning. Areas covered with smoke have increased from approximately 300,000 sq km to continental-size smoke palls of approximately 3,000,000 sq km. The smoke palls interpreted from the STS-48 data indicate that this phenomenon is persistent. Astronaut observations of such dynamic and vital environmental phenomena indicate the possibility of intergrating the earth observation capabilities of all space platforms in future modeling of the earth's dynamic processes.

Lulla, Kamlesh↗
NASA NTRS1993

Time-Accurate Unsteady Flow Simulations Supporting the SRM T+68-Second Pressure Spike Anomaly Investigation (STS-54B)

Time-accurate unsteady flow simulations are being performed supporting the SRM T+68sec pressure 'spike' anomaly investigation. The anomaly occurred in the RH SRM during the STS-54 flight (STS-54B) but not in the LH SRM (STS-54A) causing a momentary thrust mismatch approaching the allowable limit at that time into the flight. Full-motor internal flow simulations using the USA-2D axisymmetric code are in progress for the nominal propellant burn-back geometry and flow conditions at T+68-sec--Pc = 630 psi, gamma = 1.1381, T(sub c) = 6200 R, perfect gas without aluminum particulate. In a cooperative effort with other investigation team members, CFD-derived pressure loading on the NBR and castable inhibitors was used iteratively to obtain nominal deformed geometry of each inhibitor, and the deformed (bent back) inhibitor geometry was entered into this model. Deformed geometry was computed using structural finite-element models. A solution for the unsteady flow has been obtained for the nominal flow conditions (existing prior to the occurrence of the anomaly) showing sustained standing pressure oscillations at nominally 14.5 Hz in the motor IL acoustic mode that flight and static test data confirm to be normally present at this time. Average mass flow discharged from the nozzle was confirmed to be the nominal expected (9550 lbm/sec). The local inlet boundary condition is being perturbed at the location of the presumed reconstructed anomaly as identified by interior ballistics performance specialist team members. A time variation in local mass flow is used to simulate sudden increase in burning area due to localized propellant grain cracks. The solution will proceed to develop a pressure rise (proportional to total mass flow rate change squared). The volume-filling time constant (equivalent to 0.5 Hz) comes into play in shaping the rise rate of the developing pressure 'spike' as it propagates at the speed of sound in both directions to the motor head end and nozzle. The objectives of the present analysis are to: (1) capture the dynamic responses of the motor combustion gas flow to correlate with available low-frequency (less than 12.5 sample/sec) data and (2) observe the high-frequency (up to 50 Hz) characteristics of the response to determine any potentials for dynamic coupling.

Dougherty, N. S.↗
NASA NTRS1994

Factors influencing atmospheric composition over subarctic North America during summer

Elevated concentrations of hydrocarbons, CO, and nitrogen oxides were observed in extensive haze layers over northeastern Canada in the summer of 1990, during ABLE 3B. Halocarbon concentrations remained near background in most layers, indicating a source from biomass wildfires. Elevated concentrations of C2Cl4 provided a sensitive indicator for pollution from urban/industrial sources. Detailed analysis of regional budgets for CO and hydrocarbons indicates that biomass fires accounted for approximately equal to 70% of the input to the subarctic for most hydrocarbons and for acetone and more than 50% for CO. Regional sources for many species (including CO) exceeded chemical sinks during summer, and the boreal region provided a net source to midlatitudes. Interannual variations and long-term trends in atmospheric composition are sensitive to climatic change; a shift to warmer, drier conditions could increase the areas burned and thus the sources of many trace gases.

Wofsy, Steven C.↗
NASA NTRS2000

The Application of TOMS Ozone, Aerosol and UV-B Data to Madagascar Air Quality Determination

Total Ozone Mapping Spectrometer (TOMS) data products for the area of Madagascar are presented. In addition to total ozone, aerosols and UV-B tropospheric ozone results are shown from 1979 to the present. Tropospheric ozone over Africa and Madagascar is enhanced by 10 to 15 DU in October. This maximum coincides with the time of maximum biomass area burning in Africa and Madagascar. Ozone observations were made from 1979 to 1999 using the TOMS tropospheric ozone convective cloud differential method. As a result of easterly trade winds, ozone originating on Madagascar is transported to the west over the Mozambique Channel. In El Nino years higher level westerly winds descend to transport low level ozone easterly. This results in African continental ozone being transported east of Madagascar. Long range transport of African ozone is observed during El Nino periods. The potential of TOMS and other space data for use in public education and research on Madagascar air quality is demonstrated.

Aikin, A.C.↗
NASA NTRS1995

Mapping Fire Scars in the Brazilian Cerrado Using AVHRR Imagery

The Brazilian cerrado, or savanna, spans an area of 1,800,000 square kilometers on the great plateau of Central Brazil. Large fires covering hundreds of square kilometers, frequently occur in wildland areas of the cerrado, dominated by grasslands or grasslands mixed with shrubs and small trees, and also within area in the cerrado used for agricultural purposes, particularly for grazing. Smaller fires, typically extending over arm of a few square kilometers or less, are associated with the clewing of crops, such as dry land rice. A method for mapping fire scars and differentiating them from extensive areas of bare sod with AVHRR bands 1 (.55 -.68 micrometer) and 3 (3.5 - 3.9 micrometers) and measures of performance based on comparison with maps of fires with Landsat imagery will be presented. Methods of estimating total area burned from the AVHRR fire scar map will be discussed and related to land use and scar size.

Hlavka, C. A.↗
NASA NTRS2001

Fires and Smoke Observed from the Earth Observing System MODIS Instrument: Products, Validation, and Operational Use

The MODIS sensor, launched on NASA's Terra satellite at the end of 1999, was designed with 36 spectral channels for a wide array of land, ocean, and atmospheric investigations. MODIS has a unique ability to observe fires, smoke, and burn scars globally. Its main fire detection channels saturate at high brightness temperatures: 500 K at 4 microns and 400 K at 11 microns, which can only be attained in rare circumstances at the I kin fire detection spatial resolution. Thus, unlike other polar orbiting satellite sensors with similar thermal and spatial resolutions, but much lower saturation temperatures (e.g. AVHRR and ATSR), MODIS can distinguish between low intensity ground surface fires and high intensity crown forest fires. Smoke column concentration over land is for the first time being derived from the MOMS solar channels, extending from 0.41 microns to 2.1 microns. The smoke product has been provisionally validated both globally and regionally over southern Africa and central and south America. Burn scars are observed from MODIS even in the presence of smoke, using the 1.2 to 2.1 micron channels. MODIS burned area information is used to estimate pyrogenic emissions. A wide range of these fire and related products and validation are demonstrated for the wild fires that occurred in northwestern United States in the summer of 2000. The MODIS rapid response system and direct broadcast capability is being developed to enable users to obtain and generate data in near real time. It is expected that health and land management organizations will use these systems for monitoring the occurrence of fires and the dispersion of smoke within two to six hours after data acquisition.

Kaufman, Y. J.↗
NASA NTRS2001

Comparative Analysis of Daytime Fire Detection Algorithms, Using AVHRR Data for the 1995 Fire Season in Canda: Perspective for MODIS

Two fixed-threshold Canada Centre for Remote Sensing and European Space Agency (CCRS and ESA) and three contextual GIGLIO, International Geosphere and Biosphere Project, and Moderate Resolution Imaging Spectroradiometer (GIGLIO, IGBP, and MODIS) algorithms were used for fire detection with Advanced Very High Resolution Radiometer (AVHRR) data acquired over Canada during the 1995 fire season. The CCRS algorithm was developed for the boreal ecosystem, while the other four are for global application. The MODIS algorithm, although developed specifically for use with the MODIS sensor data, was applied to AVHRR in this study for comparative purposes. Fire detection accuracy assessment for the algorithms was based on comparisons with available 1995 burned area ground survey maps covering five Canadian provinces. Overall accuracy estimations in terms of omission (CCRS=46%, ESA=81%, GIGLIO=75%, IGBP=51%, MODIS=81%) and commission (CCRS=0.35%, ESA=0.08%, GIGLIO=0.56%, IGBP=0.75%, MODIS=0.08%) errors over forested areas revealed large differences in performance between the algorithms, with no relevance to type (fixed-threshold or contextual). CCRS performed best in detecting real forest fires, with the least omission error, while ESA and MODIS produced the highest omission error, probably because of their relatively high threshold values designed for global application. The commission error values appear small because the area of pixels falsely identified by each algorithm was expressed as a ratio of the vast unburned forest area. More detailed study shows that most commission errors in all the algorithms were incurred in nonforest agricultural areas, especially on days with very high surface temperatures. The advantage of the high thresholds in ESA and MODIS was that they incurred the least commission errors.

Ichoku, Charles↗
NASA NTRS2003

Use of MODIS-Derived Fire Radiative Energy to Estimate Smoke Aerosol Emissions over Different Ecosystems

Biomass burning is the main source of smoke aerosols and certain trace gases in the atmosphere. However, estimates of the rates of biomass consumption and emission of aerosols and trace gases from fires have not attained adequate reliability thus far. Traditional methods for deriving emission rates employ the use of emission factors e(sub x), (in g of species x per kg of biomass burned), which are difficult to measure from satellites. In this era of environmental monitoring from space, fire characterization was not a major consideration in the design of the early satellite-borne remote sensing instruments, such as AVHRR. Therefore, although they are able to provide fire location information, they were not adequately sensitive to variations in fire strength or size, because their thermal bands used for fire detection saturated at the lower end of fire radiative temperature range. As such, hitherto, satellite-based emission estimates employ proxy techniques using satellite derived fire pixel counts (which do not express the fire strength or rate of biomass consumption) or burned areas (which can only be obtained after the fire is over). The MODIS sensor, recently launched into orbit aboard EOS Terra (1999) and Aqua (2002) satellites, have a much higher saturation level and can, not only detect the fire locations 4 times daily, but also measures the at-satellite fire radiative energy (which is a measure of the fire strength) based on its 4 micron channel temperature. Also, MODIS measures the optical thickness of smoke and other aerosols. Preliminary analysis shows appreciable correlation between the MODIS-derived rates of emission of fire radiative energy and smoke over different regions across the globe. These relationships hold great promise for deriving emission coefficients, which can be used for estimating smoke aerosol emissions from MODIS active fire products. This procedure has the potential to provide more accurate emission estimates in near real-time, providing opportunities for various disaster management applications such as alerts, evacuation and, smoke dispersion forecasting.

Ichoku, Charles↗
NASA NTRS2004

Estimation of Fire Emissions from Satellite-Based Measurements

Biomass burning is a worldwide phenomenon affecting many vegetated parts of the globe regularly. Fires emit large quantities of aerosol and trace gases into the atmosphere, thus influencing the atmospheric chemistry and climate. Traditional methods of fire emissions estimation achieved only limited success, because they were based on peripheral information such as rainfall patterns, vegetation types and changes, agricultural practices, and surface ozone concentrations. During the last several years, rapid developments in satellite remote sensing has allowed more direct estimation of smoke emissions using remotely-sensed fire data. However, current methods use fire pixel counts or burned areas, thereby depending on the accuracy of independent estimations of the biomass fuel loadings, combustion efficiency, and emission factors. With the enhanced radiometric range of its 4-micron fire channel, the Moderate Resolution Imaging Spectroradiometer (MODIS) sensor, which flies aboard both of the Earth Observing System EOS) Terra and Aqua Satellites, is able to measure the rate of release of fire radiative energy (FRE) in MJ/s (something that older sensors could not do). MODIS also measures aerosol distribution. Taking advantage of these new resources, we have developed a procedure combining MODIS fire and aerosol products to derive FRE-based smoke emission coefficients (C(e), in kg/MJ) for different regions of the globe. These coefficients are simply used to multiply FRE from MODIS to derive the emitted smoke aerosol mass. Results from this novel methodology are very encouraging. For instance, it was found that the smoke total particulate mass emission coefficient for the Brazilian Cerrado ecosystem (approximately 0.022 kg/MJ) is about twice the value for North America, Western Europe, or Australia, but about 50% lower than the value for southern Africa.

Ichoku, Charles↗