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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 235 records · Page 13
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NASA NTRS1996

Compilation and Analysis of 20 and 30 GHz Rain Fade Events at the ACTS NASA Ground Station: Statistics and Model Assessment

The purpose of the propagation studies within the ACTS Project Office is to acquire 20 and 30 GHz rain fade statistics using the ACTS beacon links received at the NGS (NASA Ground Station) in Cleveland. Other than the raw, statistically unprocessed rain fade events that occur in real time, relevant rain fade statistics derived from such events are the cumulative rain fade statistics as well as fade duration statistics (beyond given fade thresholds) over monthly and yearly time intervals. Concurrent with the data logging exercise, monthly maximum rainfall levels recorded at the US Weather Service at Hopkins Airport are appended to the database to facilitate comparison of observed fade statistics with those predicted by the ACTS Rain Attenuation Model. Also, the raw fade data will be in a format, complete with documentation, for use by other investigators who require realistic fade event evolution in time for simulation purposes or further analysis for comparisons with other rain fade prediction models, etc. The raw time series data from the 20 and 30 GHz beacon signals is purged of non relevant data intervals where no rain fading has occurred. All other data intervals which contain rain fade events are archived with the accompanying time stamps. The definition of just what constitutes a rain fade event will be discussed later. The archived data serves two purposes. First, all rain fade event data is recombined into a contiguous data series every month and every year; this will represent an uninterrupted record of the actual (i.e., not statistically processed) temporal evolution of rain fade at 20 and 30 GHz at the location of the NGS. The second purpose of the data in such a format is to enable a statistical analysis of prevailing propagation parameters such as cumulative distributions of attenuation on a monthly and yearly basis as well as fade duration probabilities below given fade thresholds, also on a monthly and yearly basis. In addition, various subsidiary statistics such as attenuation rate probabilities are derived. The purged raw rain fade data as well as the results of the analyzed data will be made available for use by parties in the private sector upon their request. The process which will be followed in this dissemination is outlined in this paper.

Manning, Robert M.↗
NASA NTRS1996

Analysis of Cumulus Solar Irradiance Reflectance (CSIR) Events

Clouds are extremely important with regard to the transfer of solar radiation at the earth's surface. This study investigates Cumulus Solar Irradiance Reflection (CSIR) using ground-based pyranometers. CSIR events are short-term increases in solar radiation observed at the surface as a result of reflection off the sides of convective clouds. When sun-cloud observer geometry is favorable, these occurrences produce characteristic spikes in the pyranometer traces and solar irradiance values may exceed expected clear-sky values. Ultraviolet CSIR events were investigated during the summer of 1995 using Yankee Environmental Systems UVA-1 and UVB-1 pyranometers. Observed data were compared to clear-sky curves which were generated using a third degree polynomial best-fit line technique. Periods during which the observed data exceeded this clear-sky curve were identified as CSIR events. The magnitude of a CSIR event was determined by two different quantitative calculations. The MAC (magnitude above clear-sky) is an absolute measure of the difference between the observed and clear-sky irradiances. Maximum MAC values of 3.4 Wm(exp -2) and 0.069 Wm(exp -2) were observed at the UV-A and UV-B wavelengths, respectively. The second calculation determined the percentage above clear-sky (PAC) which indicated the relative magnitude of a CSIR event. Maximum UV-A and UV-B PAC magnitudes of 10.1% and 7.8%, respectively, were observed during the study. Also of interest was the duration of the CSIR events which is a function of sun-cloud-sensor geometry and the speed of cloud propagation over the measuring site. In both the UV-A and UV-B wavelengths, significant CSIR durations of up to 30 minutes were observed.

Laird, John L.↗
NASA NTRS1997

Solar energetic particle events and coronal mass ejections: New insights from SOHO

The scientific payload of SOHO, launched in December 1995, enables comprehensive studies of the sun from its interior, to the outer corona and solar wind. In its halo orbit around the Lagrangian point of the sun-earth system, the comprehensive suprathermal and energetic particle analyzer (COSTEP) measures in situ energetic partiles in the energy range 44 keV/particle to greater than 53 MeV/n. Although solar activity was at minimum, COSTEP detected from mid December 1995 until the end of July 1997, 30 solar energetic particle (SEP) events, including both gradual and implusive type SEPs. These minimum phase SEP events are unique in the sense that their associated solar source phenomena can be investigated in detail without interference by other simultaneous solar events as is usually the case at times around solar activity maximum. Simultaneous observations of the solar corona are provided by the large angle spectroscopic coronagraph (LASCO) and the extreme ultraviolet imaging telescope (EIT). From the correlated SOHO observations, a one to one correspondence of SEP events with coronal mass ejections (CMEs) was found. Most of the SEP events were associated with west-limb CMEs, some with halo CMEs that later passed the SOHO spacecraft and with Moreton-like disturbances in the lower solar atmosphere as observed by the EIT. Many SEP events were detected at sector boundaries of the interplanetary magnetic field (IMF) suggesting a magnetic connection to coronal streamers at the sun as supported by LASCO observations of mass ejections at the base of helmet streamers. Energetic particle and LASCO white-light observations yield evidence that CMEs often lead to large-scale disturbances of the sun's corona, probably affecting at times areas all around the sun.

Bothmer, V.↗
NASA NTRS1999

Inflight Medical Events in the Shuttle Program

Since the first launch of the Space Shuttle in 1981, the astronauts and their flight surgeons have dealt with a variety of inflight medical issues. A review will be provided of these issues as well as medications used in the treatment of these medical problems. Detailed medical debriefs are conducted by the flight ,surgeon with the individual crewmembers three days after landing. These debriefs were review for Shuttle flights from 1988 through 1999 to determine the frequency of inflight medical events. Medical events were grouped by ICD category and the frequency of medical events within those categories were reviewed. The ICD category of Symptoms, Signs and Ill-defined Conditions had the most medical events. Facial fullness and headache were the most common complaints within this category. The ICD category of Respiratory System had the next most common medical events with sinus congestion being the most common complaint. This was followed by Digestive System complaints and Nervous System/Sense Organ complaints. A variety of inflight medical events have occurred throughout the Shuttle program. Fortunately, the majority of these problems have been minor and have been well within the capability of the medical equipment flown and the skills of the Crew Medical Officers. Medical ,problems/procedures that are routine on the ground often present unique problems in the space flight environment. It is important that the flight surgeon understand the common medical problems encountered.

Baisden, Denise L.↗
NASA NTRS2000

Coupled Model Simulation of Snowfall Events Over the Black Hills

Although many long-term simulations of snow accumulation and oblation have been made using stand-alone land surface models and surface models coupled with GCMs, less research has focused on short-term event simulations. Actually, accurate event simulations of snow-related processes are the basis for successful long-term simulation. Three advantages of event simulations of snowfall and snow melting are availability of: (1) intensive observation data from field experiments for validation; (2) more physically-realistic precipitation schemes for use in atmospheric models to simulate snowfall; and (3) a more detailed analysis of the snow melting processes. In addition to the complexities of snow related processes themselves, terrain-induced effects on snowfall/snow melting make simulations of snow events more difficult. Climatological observations indicate that terrain features such as the Black Hills of South Dakota and Wyoming can exert important effects on snow accumulation and snow oblation processes. One of the primary effects is that the orography causes forced uplift of airflow and causes atmospheric waves to form both upwind and downwind of it. Airflow often splits around the obstacle, converging on the lee side. This convergence may lead to precipitation enhancement. It also provides an elevated heat and moisture source that enhances atmospheric instability. During the period of April 5-May 5, 1999, the Upper Missouri River Basin Pilot Project (UMRBPP) made intensive observations on precipitation events occurring in the Black Hills. Two moderate snowfall events were captured during the period. The resulting high temporal and spatial resolution data provides opportunities to investigate terrain effects on snowfall amount, distribution, and melting. Successful simulation of snowfall amount, distribution, and evolution using atmospheric models is important to subsequent modeling of snow melting using snow sub-models in land surface schemes. In this paper, a coupled model system, consisting of an atmosphere model (ARPS) and a land-surface model (revised NCAR LSM), is used to simulate one of these UMRBPP cases.

Wang, Jianzhong↗
NASA NTRS2001

The Evolution of Tropical and Extratropical Precipitation During ENSO Events

Many studies have tried to relate ENSO and global precipitation. This work examines changes in precipitation pattern, amount and intensity during ENSO events over the past 20+ years, using satellite-gauge merged data sets. ENSOs vary in duration and may peak at different times of the year. In this way, compositing events into seasons, such as onset, mature, and decay, is a challenge. This study will explore the sensitivity of using fixed versus variable month seasons to describe El Ninos and La Ninas. Global precipitation patterns will be shown. Both increases and decreases in rainfall are observed during ENSO, and there are more extreme and less 'normal' rain rates (i.e. a greater occurrence of drought and flood) in space and time. In the Southern Hemisphere during ENSO there is a spiral pattern of precipitation anomalies, centered at the pole, that agrees with previous studies looking at model-generated surface pressure. This study also examines the evolution of precipitation and SST in the tropical Pacific. The relation between the Maritime Continent convection center and the underlying surface temperatures of the islands will also be explored. An examination of the evolution of the 1997-98 El Nino and accompanying precipitation anomalies revealed that a dry area surrounding Indonesia, preceded the formation of positive SST anomalies in the eastern Pacific Ocean, 30-60 day oscillations in the winter of 1996/97 may have contributed to this lag relationship. A similar time line of onset was observed during the 1982-83 El Nino. These two events were comparable in strength and timing during the annual cycle. However, in the 1982-83 event the warming at the surface first appeared in the central Pacific, whereas in the 1997-98 event the warming first emerged off the coast of Peru. In both events the positive precipitation anomalies were first observed in the central Pacific, moving to the east Pacific within a month or two.

Curtis, W. R. Scott, III↗
NASA NTRS2001

A Study of Heavy Precipitation Events in Taiwan During 10-13 August, 1994: Mesoscale Model Simulations - Part 2

Several heavy precipitation episodes occurred over Taiwan from August 10 to 13, 1994. Precipitation patterns and characteristics are quite different between the precipitation events that occurred from August 10 and I I and from August 12 and 13. In Part I (Chen et al. 2001), the environmental situation and precipitation characteristics are analyzed using the EC/TOGA data, ground-based radar data, surface rainfall patterns, surface wind data, and upper air soundings. In this study (Part II), the Penn State/NCAR Mesoscale Model (MM5) is used to study the precipitation characteristics of these heavy precipitation events. Various physical processes (schemes) developed at NASA Goddard Space Flight Center (i.e., cloud microphysics scheme, radiative transfer model, and land-soil-vegetation surface model) have recently implemented into the MM5. These physical packages are described in the paper, Two way interactive nested grids are used with horizontal resolutions of 45, 15 and 5 km. The model results indicated that Cloud physics, land surface and radiation processes generally do not change the location (horizontal distribution) of heavy precipitation. The Goddard 3-class ice scheme produced more rainfall than the 2-class scheme. The Goddard multi-broad-band radiative transfer model reduced precipitation compared to a one-broad band (emissivity) radiation model. The Goddard land-soil-vegetation surface model also reduce the rainfall compared to a simple surface model in which the surface temperature is computed from a Surface energy budget following the "force-re store" method. However, model runs including all Goddard physical processes enhanced precipitation significantly for both cases. The results from these runs are in better agreement with observations. Despite improved simulations using different physical schemes, there are still some deficiencies in the model simulations. Some potential problems are discussed. Sensitivity tests (removing either terrain or radiative processes) are performed to identify the physical processes that determine the precipitation patterns and characteristics for heavy rainfall events. These sensitivity tests indicated that terrain can play a major role in determining the exact location for both precipitation events. The terrain can also play a major role in determining the intensity of precipitation for both events. However, it has a large impact on one event but a smaller one on the other. The radiative processes are also important for determining, the precipitation patterns for one case but. not the other. The radiative processes can also effect the total rainfall for both cases to different extents.

Tao, Wei Kuo↗
NASA NTRS2000

Multi-Satellite Measurements and Model Predictions of Mesospheric and Upper Stratospheric Influences from the Very Large July 14-16, 2000, Solar Proton Event

A large solar flare with an associated coronal mass ejection occurred in mid-July and caused a very large solar proton event at the earth in the time period July 14-16, 2000. So far this is the largest solar storm of solar cycle 23. The solar proton fluxes were measured by instruments aboard the GOES-10 satellite and used in our proton energy deposition model to help quantify the energy input to the middle atmosphere during this large solar event. Using this computed energy deposition in the GSFC 2D atmospheric model resulted in a prediction of $>$ 20\% increases in HO$-(x)$ (H, OH, HO$-(2)$) and $>$ 100\% increases in NO$-(x)$ (N, NO, NO$-(2)$) constituents in the mesosphere and upper stratosphere at polar latitudes ($>$ 60 degrees geomagnetic). Both the HO$-(x)$ and NO$_fx)$ increases impacted ozone. Large atmospheric impacts have been measured with the NOAA 14 SBUV/2 instrument (0$_(3)$), the UARS HALOE instrument (NO, NO$-(2)$, 0$-(3)$), and the POAM III instrument (0$_{3}$, NO$-(2)$). Preliminary analysis indicates that measured (SBUV/2) and modelled 0$_{3}$ decreases from this solar event are generally in agreement in the Northern Hemisphere. Short-term ozone changes (during the event) indicate $\sim$ 15% reduction at 2 hPa ($\sim$ 45 km) up to $\sim$ 40% reduction at 0.5 hPa ($\sim$ 55 km). A longer-term ozone depletion of $\sim$ 5% is indicated between 4 and 2 hPa ($\sim$ 40-45 km). The middle atmospheric changes caused by this solar event were very large and occurred fairly quickly ($\sim$ 1-2 days). Such a significant natural perturbation provides a good test of our understanding of the middle atmosphere. The measured and modelled impacts of this solar event will be compared and discussed in this paper.

Jackman, Charles H.↗
NASA NTRS2001

The Effect of Solar Proton Events on Ozone and Other Constituents in the Middle Atmosphere

Solar proton events (SPEs) can result in increases in both HO(x) (H, OH, HO2) and NO(x) (N, NO, NO2) constituents in the middle atmosphere polar region (>60 degrees geomagnetic). FlO(x) constituents produced by SPEs caused decreases in mesospheric and upper stratospheric ozone observed during several events. Recent SPEs in July and November of 2000 caused ozone decreases of over 30 percent during the event as measured by UARS HALOE and NOAA 14 SBUV/2. These HO(x)-driven ozone depletions last only during the SPEs (several hours to a few days) because of the short lifetimes of HO(x) constituents in the atmosphere. The NO(x) species feed into the entire odd nitrogen family NO(y) (N, NO, NO2, NO3, N2O5, HNO,14NO4, CIONO2, BrONO2) over a period of hours to weeks. The NO(y) family lasts several months or more in the stratosphere with low sun conditions. The two largest SPEs in the past 30 years, October 1989 and August 1972, caused polar stratospheric ozone depletions >10 percent for weeks past the events. The SPE in July 2000, third largest in 30 years, was measured by NOAA 14 SBUV/2 to decrease ozone by several percent for days past the event. Enhancements in mesospheric NO(x) of over 50 ppbv were also measured by UARS HALOE during this event. A review of the influence of SPEs on ozone and other constituents in the middle atmosphere will be given in this talk.

Jackman, Charles H.↗
NASA NTRS1998

Diagnostic yield and optimal duration of continuous-loop event monitoring for the diagnosis of palpitations. A cost-effectiveness analysis

BACKGROUND: Continuous-loop event recorders are widely used for the evaluation of palpitations, but the optimal duration of monitoring is unknown. OBJECTIVE: To determine the yield, timing, and incremental cost-effectiveness of each week of event monitoring for palpitations. DESIGN: Prospective cohort study. PATIENTS: 105 consecutive outpatients referred for the placement of a continuous-loop event recorder for the evaluation of palpitations. MEASUREMENTS: Diagnostic yield, incremental cost, and cost-effectiveness for each week of monitoring. RESULTS: The diagnostic yield of continuous-loop event recorders was 1.04 diagnoses per patient in week 1, 0.15 diagnoses per patient in week 2, and 0.01 diagnoses per patient in week 3 and beyond. Over time, the cost-effectiveness ratio increased from $98 per new diagnosis in week 1 to $576 per new diagnosis in week 2 and $5832 per new diagnosis in week 3. CONCLUSIONS: In patients referred for evaluation of palpitations, the diagnostic yield of continuous-loop event recording decreases rapidly after 2 weeks of monitoring. A 2-week monitoring period is reasonably cost-effective for most patients and should be the standard period for continuous-loop event recording for the evaluation of palpitations.

NASA Discipline Cardiopulmonary↗
NASA NTRS2005

Impacts and environmental catastrophes: A study of the effects of impact events on the climate system

The goal of this work is to investigate the perturbation of the climate system due to large impact events. Impacts are among the most important mechanisms for the evolution, distribution, and destruction of life in the universe. However, the possible climatic effects of an impact were not seriously considered until 1980, when Louis and Walter Alvarez suggested that the profound end-Cretaceous extinction might have been caused by the impact of an asteroid or comet about 10 km in diameter. Since then, the climatic change associated with the end-Cretaceous impact has become one of the most interesting and still unresolved questions in linking the well-known Chicxulub impact event and the end- Cretaceous mass extinction. While the end-Cretaceous impact offers the best-documented case of an impact affecting the Earth's climate and biota, even smaller (and more frequent in time) impacts could introduce significant perturbations of the climate comparable, if not larger, to the largest known volcanic perturbations. We propose to study the mechanical and thermal state of the atmosphere following an impact event. This will be done by using both one-dimensional and three-dimensional climate models. When necessary, modifications of the state-of-the-art general circulation models will b e carried out. We want to use the end-Cretaceous impact event as a case study. This allows us to take advantage of the extensive modeling of this impact event that has already been carried out through a previous Exobiology grant. Furthermore, a large experimental dataset, that can be used to constrain and test our models, is associated with the end-Cretaceous mass extinction (one of the largest of the Phanerozoic) and impact event.

Pierazzo, E.↗
NASA NTRS2007

Flux Transfer Events Simultaneously Observed by Polar and Cluster: Flux Rope in the Subsolar Region and Flux Tube Addition to the Polar Cusp

The phenomenon called flux transfer events (FTEs) is widely accepted as the manifestation of time-dependent reconnection. In this paper, we present observational evidence of a flux transfer event observed simultaneously at low-latitude by Polar and at high-latitude by Cluster. This event occurs on March 21, 2002, when both Cluster and Polar are located near local noon but with a large latitudinal separation. During the event, Cluster is moving outbound from the polar cusp to the magnetosheath, and Polar is in the magnetosheath near the equatorial magnetopause. The observations show that a flux transfer event occurs between the equator and the northern cusp. Polar and Cluster observe the FTE s two open flux tubes: Polar encounters the southward moving flux tube near the equator; and Cluster the northward moving flux tube at high latitude. The low latitude FTE appears to be a flux rope with helical magnetic field lines as it has a strong core field and the magnetic field component in the boundary normal direction exhibits a strong bi-polar variation. Unlike the low-latitude FTE, the high-latitude FTE observed by Cluster does not exhibit the characteristic bi-polar perturbation in the magnetic field. But the plasma data clearly reveal its open flux tube configuration. It shows that the magnetic field lines have straightened inside the FTE and become more aligned to the neighboring flux tubes as it moves to the cusp. Enhanced electrostatic fluctuations have been observed within the FTE core, both at low- and high-latitudes. This event provides a unique opportunity to understand high-latitude FTE signatures and the nature of time-varying reconnection.

Le, G.↗
NASA NTRS2007

Method and apparatus for detecting and determining event characteristics with reduced data collection

A method and apparatus for detecting and determining event characteristics such as, for example, the material failure of a component, in a manner which significantly reduces the amount of data collected. A sensor array, including a plurality of individual sensor elements, is coupled to a programmable logic device (PLD) configured to operate in a passive state and an active state. A triggering event is established such that the PLD records information only upon detection of the occurrence of the triggering event which causes a change in state within one or more of the plurality of sensor elements. Upon the occurrence of the triggering event, the change in state of the one or more sensor elements causes the PLD to record in memory which sensor element detected the event and at what time the event was detected. The PLD may be coupled with a computer for subsequent downloading and analysis of the acquired data.

Totman, Peter D.↗
NASA NTRS2008

The Solar Energetic Particle Event of December 14, 2006

We report on observations of a solar energetic particle event by instruments on five different spacecraft: the Advanced Composition Explorer (ACE), STEREO A and B, WIND, and GOES II. The event began with a class X1.5 .soft x-ray flare in AR930 on December 14 at 22:15 UT. At this time the two STEREO spacecraft were located outside the Earth's magnetosphere and were heading for their first lunar swing-by on December 15. The x-ray event was located on the sun at W46, a longitude which is nominally well-connected magnetically to the Earth. An interplanetary shock, associated with an earlier X3.4 event on December 13 (also from AR930), passed the Earth on December 14 at approx.13:56 (time at ACE). The corresponding magnetic cloud arrived at approx.22 UT on December 14, close to the time of the onset of the particle event associated with the X1.5 flare, and extended until approx.08 UT on December 15. The intensity of approx.14 MeV protons at STEREO A shows three dips by factors of approx.10 or more during the early stages of this event while the spacecraft was within the magnetic cloud. Similar dips are seen for protons to at least 100 MeV. In principle, these dips could have been caused by changes in the magnetic field direction with respect to the particle telescope's field of view while viewing a beamed particle distribution. However, this possibility can be ruled out because the magnetic field at the spacecraft shows no evidence of such directional variations, and similar particle intensity dips were seen by instruments on other spacecraft in the near-Earth solar wind. We shall present evidence that the dips were actually associated with varying magnetic connection to the Sun within the magnetic cloud. These dips were not observed at GOES II, suggesting they were somehow smoothed out by passage into the magnetosphere.

vonRosenvinge, T. T.↗
NASA NTRS1996

Patent Foramen Ovale: Association between the Degree of Shunt by Contrast Transesophageal Echocardiography and the Risk of Future Ischemic Neurologic Events

This study investigated whether there is an association between the degree of interatrial shunting across a patent foramen ovale, as determined by saline contrast transesophageal echocardiography, and the risk of subsequent systemic embolic events, including stroke. Thirty-four patients found to have patent foramen ovale during transesophageal echocardiography were divided into two groups on the basis of the maximum number of microbubbles in the left heart in any single frame after intravenous saline contrast injection: group 1 (n = 16) with a "large" degree of shunt (220 microbubbles) and group 2 (n = 18) with a "small" degree of shunt (23 but <20 microbubbles). Patients were followed up over a mean period of 21 months for subsequent systemic embolic events, including transient ischemic attack and stroke. Five (31%) of the patients with large shunts had subsequent ischemic neurologic events, whereas none of the patients with small shunts had embolic events (p= 0.03). These events occurred in spite of antiplatelet or anticoagulant therapy. We conclude that patients with a large degree of shunt across a patent foramen ovale, as determined by contrast transesophageal echocardiography, are at a significantly higher risk for subsequent adverse neurologic events compared with patients with a small degree of shunt.

Stone, David A.↗
NASA NTRS2009

Complex Event Recognition Architecture

Complex Event Recognition Architecture (CERA) is the name of a computational architecture, and software that implements the architecture, for recognizing complex event patterns that may be spread across multiple streams of input data. One of the main components of CERA is an intuitive event pattern language that simplifies what would otherwise be the complex, difficult tasks of creating logical descriptions of combinations of temporal events and defining rules for combining information from different sources over time. In this language, recognition patterns are defined in simple, declarative statements that combine point events from given input streams with those from other streams, using conjunction, disjunction, and negation. Patterns can be built on one another recursively to describe very rich, temporally extended combinations of events. Thereafter, a run-time matching algorithm in CERA efficiently matches these patterns against input data and signals when patterns are recognized. CERA can be used to monitor complex systems and to signal operators or initiate corrective actions when anomalous conditions are recognized. CERA can be run as a stand-alone monitoring system, or it can be integrated into a larger system to automatically trigger responses to changing environments or problematic situations.

Fitzgerald, William A.↗
NASA NTRS2009

Observation and Interpretation of Energetic Neutral Hydrogen Atoms from the December 5, 2006 Solar Event

We report the first observations of energetic neutral atoms (ENAs) from a solar flare/coronal mass ejection event. The observations were made during the December 5, 2006 X9 solar flare, located at E79, by the Low Energy Telescopes (LETs) on the STEREO A and B spacecraft. Within 1-2 hours of the flare onset, both LETs observed a sudden burst of 1.6 to 15 MeV protons arriving hours before the onset of the main solar energetic particle (SEP) event at Earth. More than 70% of these particles arrived from a longitude within +-10 degrees of the Sun. The derived emission profile at the Sun lasted for more than an hour and had a profile remarkably similar to the GOES soft X-ray profile. The observed arrival directions and energy spectrum argue strongly that the particle events <5 MeV were due to energetic neutral hydrogen atoms that were stripped of their electrons upon entering the LET sensor. To our knowledge, this is the first reported observation of ENA emission from a solar flare/coronal mass ejection. We discuss possible origins for the production of ENAs in solar events, including charge-transfer reactions involving both flare and shock-accelerated protons. Assuming isotropic emission, we find that ~2 x 10E28 ENAs escaped from the Sun in the upper hemisphere. Based on the 2.2 MeV gamma-ray emission observed by RHESSI in this event, and using measured and theoretical cross sections, we estimate that ~3 x 10E31 ENAs with 1.8 - 5 MeV could be produced by protons accelerated in the flare. CME-driven shock acceleration is also a possible ENA source, but unfortunately there were no CME observations available from this event. Taking into account ENA losses, we conclude that the observed ENAs were most likely produced in the high corona at heliocentric distances 1.6 solar radii.

Mewaldt, R. A.↗
NASA NTRS2010

Low-Frequency Type III Bursts and Solar Energetic Particle Events

We analyzed the coronal mass ejections (CMEs), flares, and type 11 radio bursts associated with a set of six low frequency (<14 MHz) extended type III bursts from active region 10588. The durations were measured at 1 and 14 MHz using high resolution data from Wind/WAVES and were within the range (>15 min) normally used to define these bursts. All but one of the type III bursts was not associated with a type 11 burst in the metric or longer wavelength domains. The burst without type 11 burst also lacked a solar energetic particle (SEP) event at energies >25 MeV. The 1-MHz duration of the type III burst (28 min) is near the median value of type III durations found for gradual SEP events and ground level enhancement (GLE) events. Yet, there was no sign of SEP events. On the other hand, two other type III bursts from the same active region had similar duration but accompanied by WAVES type 11 bursts; these bursts were also accompanied by SEP events detected by SOHO/ERNE. The CMEs were of similar speeds and the flares are also of similar size and duration. This study suggests that the type III burst duration may not be a good indicator of an SEP event.

Gopalswamy, Nat↗