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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 NTRS2003

Doppler Radar and Lightning Network Observations of a Severe Outbreak of Tropical Cyclone Tornadoes

Data from a single WSR-88D Doppler radar and the National Lightning Detection Network are used to examine in detail the characteristics of the convective storms that produced a severe tornado outbreak within Tropical Storm Beryl's remnants on 16 August 1994. Comparison of the radar data with reports of tornadoes suggests that only 13 cells produced the 29 tornadoes that were documented in Georgia and the Carolinas on that date. Six of these cells spawned multiple tornadoes, and the radar data confirm the presence of miniature supercells. One of the cells was identifiable on radar for 11 hours, spawning tornadoes over a time period spanning approximately 6.5 hours. Several other tornadic cells also exhibited great longevity, with cell lifetimes greater than ever previously documented in a landfalling tropical cyclone tornado event, and comparable to those found in major midlatitude tornadic supercell outbreaks. Time-height analyses of the three strongest tornadic supercells are presented in order to document storm kinematic structure and to show how these storms appear at different ranges from a WSR-88D radar. In addition, cloud-to-ground (CG) lightning data are examined for the outbreak, the most intense tropical cyclone tornado event studied thus far. Although the tornadic cells were responsible for most of Beryl's CG lightning, flash rates were only weak to moderate, even in the most intense supercells, and in all the tornadic storms the lightning flashes were almost entirely negative in polarity. A few of the single-tornado storms produced no detectable CG lightning at all. In the stronger cells, there is some evidence that CG lightning rates decreased during tornadogenesis, as has been documented before in some midlatitude tornadic storms. A number of the storms spawned tornadoes just after producing their final CG lightning flashes. Surprisingly, both peak currents and positive flash percentages were larger in Beryl s nontornadic storms than in the tornadic ones. Despite some intriguing patterns, the CG lightning behavior in this outbreak remains mostly inconsistent and ambiguous, and offers only secondary value for warning guidance. The present findings argue in favor of the implementation of observing systems capable of continuous monitoring of total lightning activity in storms.

McCaul, Eugene W., Jr.↗
NASA NTRS2004

Doppler Radar and Lightning Network Observations of a Severe Outbreak of Tropical Cyclone Tornadoes

Data from a single Weather Surveillance Radar-1988 Doppler (WSR-88D) and the National Lightning Detection Network are used to examine the characteristics of the convective storms that produced a severe tornado outbreak, including three tornadoes that reached F3 intensity, within Tropical Storm Beryl s remnants on 16 August 1994. Comparison of the radar data with reports of tornadoes suggests that only 13 cells produced the 29 tornadoes that were documented in Georgia and the Carolinas on that date. Six of these cells spawned multiple tornadoes, and the radar data confirm the presence of miniature supercells. One of the cells was identifiable on radar for 11 h. spawning tornadoes over a time period spanning approximately 6.5 h. Several other tornadic cells also exhibited great longevity, with cell lifetimes longer than ever previously documented in a landfalling tropical cyclone (TC) tornado event. This event is easily the most intense TC tornado outbreak yet documented with WSR-88Ds. Time-height analyses of the three strongest tornadic supercells are presented in order to document storm kinematic structure and to show how these storms appear at different ranges from a WSR-88D. In addition, cloud-to-ground (CG) lightning data are examined in Beryl s remnants. Although the tornadic cells were responsible for most of Beryl's CG lightning, their flash rates were only weak to moderate, and in all the tornadic storms the lightning flashes were almost entirely negative in polarity. A few of the single-tornado storms produced no detectable CG lightning at all. There is evidence that CG lightning rates decreased during the tornadoes, compared to 30-min periods before the tornadoes. A number of the storms spawned tornadoes just after producing their final CG lightning flashes. Contrary to the findings for flash rates, both peak currents and positive flash percentages were larger in Beryl's nontornadic storms than in the tornadic ones.

Mccaul, Eugene W., Jr.↗
NASA NTRS1983

VAS temperature retrievals for NASA special network observations of 6 March 1982

VAS retrieval capability was studied. A mesoscale event consisting of a rapidly moving temperature perturbation with strong horizontal wind shear but shallow vertical extent occurred over Texas. The mesoscale event passed through the special radiosonde network and was documented with three hourly measurements. The event occurred behind a cold frontal cloud band during clear conditions. The event was accompanied by large skin temperature changes as the day progressed. This combination allows the testing of two important aspects of the retrieval algorithms with minimal cloud contamination and good ground truth. The first aspect concerns the horizontal and vertical resolving power of the retrievals and the second aspect concerns sensitivity to the boundary term. The NASA special network radiosonde is proven to be useful. It is demonstrated that: the VAS is capable, of delineating a mesoscale, normal retrieval procedure has the deficiency of oversmoothing, but this can be corrected, to document first quess dependence, and a superior data set to evolve better techniques for treating the surface boundary problem.

Hayden, C. M.↗
NASA NTRS2015

Meteor Shower Forecast Improvements from a Survey of All-Sky Network Observations

Meteoroid impacts are capable of damaging spacecraft and potentially ending missions. In order to help spacecraft programs mitigate these risks, NASA's Meteoroid Environment Office (MEO) monitors and predicts meteoroid activity. Temporal variations in near-Earth space are described by the MEO's annual meteor shower forecast, which is based on both past shower activity and model predictions. The MEO and the University of Western Ontario operate sister networks of all-sky meteor cameras. These networks have been in operation for more than 7 years and have computed more than 20,000 meteor orbits. Using these data, we conduct a survey of meteor shower activity in the "fireball" size regime using DBSCAN. For each shower detected in our survey, we compute the date of peak activity and characterize the growth and decay of the shower's activity before and after the peak. These parameters are then incorporated into the annual forecast for an improved treatment of annual activity.

Moorhead, Althea V.↗
DOE OSTI2025

Integration and Quantitative Comparison of Up-Scaled Molecular Observation Network Data with Existing Soil Databases

MONet provides novel soil molecular data to the research community for understanding biogeochemical processes and complementing other soil datasets. This study assesses MONet's ability to replicate known soil patterns via a comparative analysis of soil respiration (Rs), pH, and clay content against benchmark datasets. Results show moderate agreement for pH and clay content, highlighting MONet's strengths in capturing soil biogeochemical variation in underrepresented regions like urban areas. Rs data are marked by the appropriate trends relative to other datasets, but direct comparison is impractical due to methodological differences in underlying data. Strategic sampling is recommended to improve MONet's coverage and eventual utility in bridging molecular observations with global datasets.

54 ENVIRONMENTAL SCIENCES↗
NASA NTRS1976

The quiet sun chromospheric network observed from Skylab

The paper analyzes spectra of a supergranulation cell interior and cell boundary obtained near the solar center at wavelengths between 1200 and 1560 A with a normal-incidence spectrograph aboard Skylab. Absolute intensities, relative intensities, and profiles are given for selected optically thin and optically thick lines over the cell interior, the boundary, and intermediate positions; the results are compared with spectra obtained at the limb. Characteristic lengths along the line of sight are derived for the Si III emitting region, and these are compared with the predictions of Gabriel's (1975) model. It is concluded that the present data are representative of a fairly typical cell interior and boundary, that nonthermal motions are isotropic and the same for the interior and boundary, and that the electron-density ratio between the interior and the boundary is about a factor of two or less.

Feldman, U.↗
NASA NTRS1983

Operational radio interferometry observation network (ORION) mobile VLBI station

The design and current status of the ORION mobile VLBI station is described. The station consists of a five-meter antenna, a receiving and recording system installed in a mobile antenna transporter, and an electronics transporter. The station is designed for field operation by a two-person crew at the rate of two sites per week. The various subsystems are described in detail, including the antenna, housing facilities for electronics and crew, microwave equipment, receiver, data acquisition subsystem, frequency and timing subsystem, phase calibration, monitoring and control, water vapor radiometer, and communications.

Renzetti, N. A.↗
NASA NTRS1989

An evaluation of the Barnes objective analysis response - Two-dimensional theoretical response, sensitivity to observing networks, and 'actual' response

A principal advantage of the Barnes (1964, 1973) scheme is its theoretical response function through which the response of the analysis at a particular wavelength can be predicted. The objective of this paper is to examine the accuracy and efficiency of the Barnes scheme for different data distributions. Then, the 'actual' response is used to estimate the true attenuation of a wave in the filtered field.

Wu, Xiaohua↗
NASA NTRS1966

The Archive of the Amateur Observation Network of the International Halley Watch: Comet Giacobini-Zinner - Volume 1

The International Halley Watch (IHW) was organized for the purpose of gathering and archiving the most complete record of the apparition of a comet, Halley's Comet (1982i = 1986 III = 1P/Halley), ever compiled. The redirection of the International Sun-Earth Explorer 3 (ISEE-3) spacecraft, subsequently renamed the International Cometary Explorer (ICE), toward Comet Giacobini-Zinner (1984e = 1985 XIII = 21P/Giacobini-Zinner) prompted the initiation of a formal watch on that comet. All the data collected on P/Giacobini-Zinner and P/Halley have been published on CD-ROM in the Comet Halley Archive. This document contains a printed version of the archive data, collected by amateur astronomers, on these two comets. Volume 1 contains the Comet Giacobini-Zinner data archive and Volume 2 contains the Comet Halley archive. Both volumes include information on how to read the data in both archives, as well as a history of both comet watches (including the organizing of the network of astronomers and lessons learned from that experience).

Edberg, Stephen J.↗
NASA NTRS1996

The Archive of the Amateur Observation Network of the International Halley Watch: Comet Halley - Volume 2

The International Halley Watch (IHW) was organized for the purpose of gathering and archiving the most complete record of the apparition of a comet, Halley's Comet (1982i = 1986 III = 1P/Halley), ever compiled. The redirection of the International Sun-Earth Explorer 3 (ISEE-3) spacecraft, subsequently renamed the International Cometary Explorer (ICE), toward Comet Giacobini- Zinner (1984e = 1985 XIII = 21P/Giacobini-Zinner) prompted the initiation of a formal watch on that comet. All the data collected on P/Giacobini-Zinner and P/Halley have been published on CD-ROM in the Comet Halley Archive. This document contains a printed version of the archive data, collected by amateur astronomers, on these two comets. Volume 1 contains the Comet Giacobini-Zinner data archive and Volume 2 contains the Comet Halley archive. Both volumes include information on how to read the data in both archives, as well as a history of both comet watches (including the organizing of the network of astronomers and lessons learned from that experience).

Edberg, Stephen J.↗
NASA NTRS1996

The Archive of the Amateur Observation Network of the International Halley Watch: Comet Giacobini-Zinner - Volume 1

The International Halley Watch (IHW) was organized for the purpose of gathering and archiving the most complete record of the apparition of a comet, Comet Halley (1982i = 1986 III = 1P/Halley), ever compiled. The redirection of the International Cometary Explorer (ICE), toward Comet Giacobini-Zinner (1984e = 1985 XIII = 21P/Giacobini-Zinner) prompted the initiation of a formal watch on that comet. All the data collected on P/Giacobini-Zinner and P/Halley have been published on CD-ROM in the Comet Halley Archive. This document contains a printed version of the archive data, collected by amateur astronomers, on these two comets. Volume 1 contains the Comet Giacobini-Zinner data archive and Volume 2 contains the Comet Halley archive. Both volumes include information on how to read the data in both archives, as well as a history of both comet watches (including the organizing of the network of astronomers and lessons learned from that experience).

Edberg, Stephen J.↗
NASA NTRS2022

The Marine Biodiversity Observation Network Plankton Workshops: Plankton Ecosystem Function, Biodiversity, and Forecasting—Research Requirements and Applications

Plankton functional diversity is at the core of various ecological processes, including productivity, carbon cycling and sequestration, nutrient cycling, interspecies interactions, food web dynamics and structure. Through these functions, plankton play a critical role in the health of the coastal and open ocean and provide essential ecosystem services. Yet, at present, our understanding of plankton dynamics is insufficient to project how climate change and other human-driven impacts affect the functional diversity of plankton. That limits our ability to predict how critical ecosystem services will change in the future and develop strategies to adapt to these changes.

Plankton↗
NASA NTRS1992

Near-Earth asteroids: Observer alert network and physical observations

This project strives to obtain physical observations on newly discovered Near-Earth Objects (NEO's) in order to provide fundamental data needed to assess the resources available in the population. The goal is acquiring data on all objects brighter than magnitude V= 17.0. To accomplish this, an electronic mail alert and observer information service that informs observers around the world as to the status of physical observations on currently observable NEO's was established. Such data is also acquired ourselves through a cooperative program with European colleagues that uses telescopes on La Palma to obtain spectra of NEO's and through observations made from a local telescope on Tumamoc Hill. This latter telescope has the advantage that large amounts of observing time are available, so that whenever a new NEO's discovered, we can be assured of getting time to observe it.

Davis, Donald R.↗