Technological advances have driven all aspects of Earth observation data, including improvements realized in sensor characteristics and capabilities, global data processing, near realtime monitoring, value-added products, and the distribution of global products. In particular, the growth of the World Wide Web is contributing to an increase in the global user base. The synergy of remote sensing, geographic information systems (GIS), Internet, and mobile phone technologies is revolutionizing the way in which satellite-derived information is archived and distributed to users. The Fire Information for Resource Management System (FIRMS), a NASA-funded application, is just one of many examples that illustrate the increasing ease with which Earth observation data are accessible to a broad range of users. This paper describes how the delivery of satellite-derived fire information has evolved over the last six years. By understanding user requirements and taking advantage of recent developments in areas such as information management, search, access, visualization, and enabling technologies, FIRMS has expanded the number and range of users that are able to access and utilize satellite-derived fire information. Specifically, we describe how satellite remote sensing and GIS technologies have been integrated to deliver MODIS active fire data to natural resource managers using Internet mapping services and customized e-mail alerts to users in more than 90 countries. We also describe how this web-based desktop application has been transitioned to a mobile service in South Africa to deliver fire information to field staff to warn of fires that may be potentially damaging to both natural resources and infrastructure.

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A pulsed drift tube has been used to measure the electron drift velocity in methane over the range of E/N from 10 to 1000 Td. In addition, measurements of the positive ion mobility and ionization coefficient have been made over the range of E/N from 80 to 1000 Td. Within the experimental sensitivity, no evidence of attachment has been observed in this range. A set of electron collision cross sections has been assembled and used in Monte Carlo simulations to predict values of swarm parameters. The cross-section set includes a momentum transfer cross section which is based primarily on the present and previous drift velocity measurements, cross sections for vibrational excitation and ionization based on published experimental cross-section measurements, and a cross section for dissociation into neutral products obtained by subtracting a measured dissociative ionization cross section from a measured total dissociation cross section. Isotropic scattering is assumed for all types of collisions in the Monte Carlo simulations. Good agreement between the predicted and measured values of swarm parameters is obtained without making any adjustments to these cross sections. A two-term Boltzmann equation method has also been used to predict swarm parameters using the same cross sections as input. The two-term results are in poor agreement with experiment and confirm the well-known inadequacy of two-term methods in the case of methane.

We have calculated α and η, the ionization and attachment coefficients, and (E/N) *, the limiting breakdown electric-field–to–gas-density ratio, in SF6 and SF6 mixtures by numerically solving the Boltzmann equation for the electron energy distribution. The calculations require a knowledge of several electron collision cross sections. Published momentum transfer and ionization cross sections for SF6 were used. We measured various attachment cross sections for SF6 using electron-beam techniques with mass spectrometric ion detection. We determined a total cross section for electronic excitation of SF6 by comparing the predicted values of α, η, and (E/N) * with our measured values obtained from spatial current growth experiments in SF6 in uniform fields over an extended range of E/N. With this self-consistent set of SF6 cross sections, together with published He and N2 cross sections, it was then possible to predict the dielectric properties of SF6-He and SF6-N2 mixtures. Published experimental values of α for the SF6-He mixtures lie between the values of α calculated with and without ionization of SF6 by excited He atoms. Published experimental values of (E/N) * agree with our calculations to within 5% in both the SF6-He and the SF6-N2 mixtures.

Abstract. We used the global fire detection record provided by the satellite-based Moderate Resolution Imaging Spectroradiometer (MODIS) to determine the number of fires detected inside 823 tropical and subtropical moist forest reserves and for contiguous buffer areas 5, 10, and 15 km wide. The ratio of fire detection densities (detections per square kilometer) inside reserves to their contiguous buffer areas provided an index of reserve effectiveness. Fire detection density was significantly lower inside reserves than in paired, contiguous buffer areas but varied by five orders of magnitude among reserves. The buffer : reserve detection ratio varied by up to four orders of magnitude among reserves within a single country, and median values varied by three orders of magnitude among countries. Reserves tended to be least effective at reducing fire frequency in many poorer countries and in countries beset by corruption. Countries with the most successful reserves include Costa Rica, Jamaica, Malaysia, and Taiwan and the Indonesian island of Java. Countries with the most problematic reserves include Cambodia, Guatemala, Paraguay, and Sierra Leone and the Indonesian portion of Borneo. We provide fire detection density for 3964 tropical and subtropical reserves and their buffer areas in the hope that these data will expedite further analyses that might lead to improved management of tropical reserves.

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Combined electrical, optical, and spectroscopic measurements have been used to determine the total flux, ion flux, particle flux, and neutral atom flux emitted from the cathode spot region of a copper vacuum arc of 80 A total current and 2-sec duration. It is found that the cathode erosion products consist predominantly of ions and particles, the emission of neutral atomic flux from the cathode being less than 1% of the total flux. The total and particle flux distributions are peaked in the direction of the cathode plane, whereas the ion-flux distribution is forward peaked. However, both ions and particles are detected in the cathode shadow, a result which is contrary to the hypothesis of purely collisionless transport of cathode erosion products. The neutral atom density measurements are consistent with a model assuming the source of the vapor to be evaporation in flight from the hot particles emitted from the cathode spot region. The size distribution of the particles has a maximum for particles of diameter in the range 0–1 μ.

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