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NASA NTRS1992

Motions of particle microstructures in the magnetopause boundary layer

Particle flux data acquired by the ISEE 1 and 2 spacecraft reveal many of magnitude changes within the magnetopause boundary layer that occur during less than 1/4 s of time. These changes define small-scale particle structure, or microstructures within the region, many of which are apparently inclusions of plasma from adjacent regions. Particle structures resolved by the high time resolution data include groups with periods as short as 0.375 s. An estimate is derived for the motion of the microstructures with respect to an oscillatory inner boundary for four afternoon sector boundary layer crossings by measuring interspacecraft time differences as the features propagate past the satellites. On average the microstructures move toward the tail of the magnetosphere in concert with the wavy large-scale inner boundary. Furthermore, the orientations of the edges of the structures maintain an aspect similar to that of the boundary. These characteristics are expected for magnetohydrodynamic plasma flows that generate vorticity due to velocity shear stresses.

Larson, Nels R.↗

NASA NTRS1983

Energetic particle microsignatures of Saturn's satellites

During Voyager's 1980 and 1981 encounters with Saturn, the low energy charged particle experiment observed satellite microsignatures in ions and electrons. Each of the five major satellites within Titan's orbit were associated with at least one absorption feature in the high time resolution data. Microsignatures are usually observed in the corotational wake region within about 25 deg in azimuth of a satellite, and do not generally occur at times predicted by a centered, aligned dipole. A better predictive model seems to be that of an aligned, axisymmetric field with significant quadrupole and octupole terms.

Carbary, J. F.↗

NASA NTRS1977

Microstructure of a magnetotail fireball

We use high time resolution data from the magnetometer, LEPEDEA and plasma wave analyzer on IMP-7 to examine the microstructure of a long-duration magnetotail fireball event observed during an extended quiet period on November 9, 1972. We demonstrate that the magnetic field is turbulent with fluctuation time scales down to several seconds. These findings suggest that the magnetic merging process may be a highly turbulent one, possibly associated with a form of the tearing mode instability.

Coroniti, F. V.↗

NASA NTRS2011

Relativistic Electron Losses in the Outer Radiation Belts

Relativistic electrons in the magnetosphere are both energized and lost via their interaction with plasma waves such as whister chorus, plasmaspheric hiss and EMIC waves. These waves are usually localized in different regions of the magnetosphere as well as being located either inside or outside the plasmapause. We study relativistic electron losses in the outer radiation belts by characterizing decay times scales at low and high altitudes and their relationship to microbursts. We use data collected by SAMPEX, a low Earth orbiting spacecraft in a highly inclined polar orbit and the HEO spacecraft in a high altitude Molniya orbit. The sensors onboard these spacecraft measure electrons of energies > 0.6 MeV, > 1 MeV, > 3 MeV, 2-6 MeV, 3-16 MeV. High time resolution data enable identifying and characterizing electron microbursts observed at low altitudes.

Kanekal, Shrikanth G.↗

DOE OSTI2025

Examining the Ice-Nucleating Particles from the North Slope of Alaska (ExINP-NSA) (Final Campaign Report)

The Examining the Ice-Nucleating Particles from the North Slope of Alaska (ExINP-NSA) campaign was conducted at the National Oceanic and Atmospheric Administration’s (NOAA) Barrow Atmospheric Baseline Observatory (71.3230° N, 156.6114° W, “BRW” hereafter), next to the Atmospheric Radiation Measurement (ARM) user facility NSA site and ~ 6 km northeast of the town of Utqiaġvik. The location of the NSA site is shown in Figure 1. Our observing period began in October 2021 and continued until May 2024. This campaign was funded by the U.S. Department of Energy (DOE) Office of Science Early Career Research Program through grant number DE-SC001879. This grant contains funding for three ARM field campaigns. The previous field campaigns were performed at ARM’s Southern Great Plains atmospheric observatory in Oklahoma (SGP; 36.6073° N, 97.4876° W) and the ARM’s Eastern North Atlantic atmospheric observatory on Graciosa Island, Azores (ENA; 39.0916° N, 28.0257° W). The ExINP-NSA campaign aims included: • Determining the number concentration of ice-nucleating particles (n INPs ) active at temperatures spanning the range of heterogeneous freezing processes (from ≈−30 °C to 0 °C) using a combination of online and offline measurements, • Determining whether local meteorological conditions and/or synoptic scale air mass transport impact INP abundance and/or ice nucleation efficiency, • Examining if the physicochemical properties of INPs relate to aerosol chemistry, and • Assessing if there is a similarity in INP properties across three ARM sites Multi-seasonal datasets of INP abundance in the NSA region were delivered from this campaign. This campaign also allowed researchers to perform a comprehensive analysis of atmospheric INPs based on long- term ground-based measurements in the Alaskan Arctic. Our data and results from the ExINP-NSA campaign will help refine current earth system models. One of the stated goals of ARM is to advance aerosol-cloud ice interaction, which will be a direct result of this campaign. Current earth system models poorly represent INPs, and the 15-minute time resolution data over several seasons generated during this campaign will provide an invaluable resource, especially combined with the datasets generated during two previous ARM ExINP campaigns. These datasets will allow for a greater understanding of ice nucleation processes as they may (or may not) relate to local meteorological processes and aerosol chemistry and will eventually help further the understanding of the Earth’s atmospheric processes and energy balance.

54 ENVIRONMENTAL SCIENCES↗

NASA NTRS2000

The Spectral Evolution of Solar Flare Hard X-Ray Emission Observed with BATSE

We present a more detailed characterization of spectral evolution in solar flare hard X-ray emission than has been previously described. Our characterization is consistent with some earlier results but utilizes higher time resolution data and reveals nuances in spectral evolution that have never been reported. We employ an underutilized data set, the Burst and Transient Source Experiment (BATSE) solar flare catalog, for our investigation and different methodology than previous studies. Our findings support the conclusion that properties of the particle Abstract: acceleration mechanism in flares, such as the acceleration rate or efficiency, are indeed important to understanding spectral evolution. On the other hand, time-of-flight models, which assume accelerator properties to be negligible, cannot explain the observed detailed spectral evolution, and correlations that we would expect to exist between spectral evolution patterns and parameters derived from time-of-flight model inversions are not supported by the data. In this fashion, we establish an observational context in which to interpret future High Energy Solar Spectroscopic Imager (HESSI) observations and delineate some constraints for theoretical models of particle acceleration.

Newton, Elizabeth K.↗

NASA NTRS2002

Monitoring Global Precipitation Using Satellite Observations: Status and Future

The current status of monitoring global precipitation amounts and patterns is described using data sets from the Global Precipitation Climatology Project (GPCP) of the World Climate Research Program (WCRP) and from recent research satellites, especially the Tropical Rainfall Measuring Mission (TRMM). The GPCP monthly (and pentad) data set is a 23-year, globally complete precipitation analysis that is used to explore global and regional variations and trends. The data set is a blend of data mainly from low-orbit microwave satellites and geosynchronous infrared satellites, with additional input from satellite sounder data, Outgoing Longwave Radiation (OLR) data and raingauges. The monthly GPCP data set shows no significant global trend in precipitation over the twenty years, unlike the positive trend in global surface temperatures over the past century. Regional trends are also analyzed. A trend pattern that is a combination of both El Nino and La Nina precipitation features is evident in the 23-year data set. This pattern is related to an increase with time in the number of combined months of El Nino and La Nina during the 23-year period. This apparent trend may be a short-term variation, but also might be related to the increase with time of extreme precipitation events reported elsewhere. Patterns of precipitation variation related to ENSO and other phenomena are shown with clear signals extending from the Tropics into middle and high latitudes of both hemispheres. Also shown, as an example of higher time resolution data is the GPCP daily analysis, which is available for the last six years. A second focus of the talk is on TRMM precipitation data and how these newer data sets incorporating information from the first space-borne meteorological radar compare with the established GPCP data sets.

Adler, Robert F.↗

DOE OSTI2025

SQuaD: Smart Quantum Detection for Photon Recognition and Dark Count Elimination

Quantum detectors of single photons are an essential component for quantum information processing across computing, communication and networking. Today's quantum detection system, which consists of single photon detectors, timing electronics, control and data processing software, is primarily used for counting the number of single photon detection events. However, it is largely incapable of extracting other rich physical characteristics of the detected photons, such as their wavelengths, polarization states, photon numbers, or temporal waveforms. This work, for the first time, demonstrates a smart quantum detection system, SQuaD, which integrates a field programmable gate array (FPGA) with a neural network model, and is designed to recognize the features of photons and to eliminate detector dark-count. The SQuaD is a fully integrated quantum system with high timing-resolution data acquisition, onboard multi-scale data analysis, intelligent feature recognition and extraction, and feedback-driven system control. Our \name experimentally demonstrates 1) reliable photon counting on par with the state-of-the art commercial systems; 2) high-throughput data processing for each individual detection events; 3) efficient dark count recognition and elimination; 4) up to 100% accurate feature recognition of photon wavelength and polarization. Additionally, we deploy the SQuaD to an atomic (erbium ion) photon emitter source to realize noise-free control and readout of a spin qubit in the telecom band, enabling critical advances in quantum networks and distributed quantum information processing.

Linne, Karl C. [U. Chicago (main)] (ORCID:00090009↗

NASA NTRS1974

Magnetotail variations associated with the southward interplanetary magnetic field

Ten weeks of simultaneous fine time resolution data on the interplanetary magnetic field (IMF), the solar wind parameters observed by the Explorer 33 and Vela 3 satellites, the magnetic field, and the particle fluxes in the magnetotail from the Imp 3 satellite are examined together with auroral zone magnetograms monitoring substorm activity to study the magnetotail variations associated with the latitudinal changes of the IMF. It is found that the magnetotail magnetic field magnitude often increases when the north-south component of the IMF is southward; this increment is generally observed throughout the entire high-latitude tail (outside the plasma sheet). The increment is about 10% of the background field, and it increases to 20% or higher when the north-south component of the IMF increases from the usual 2 or 3 gamma to 7 or 8 gamma.

Meng, C.-I.↗

NASA NTRS1978

Imp 6 measurements in the distant polar cusp during substorms

High time-resolution data from the magnetic field, plasma, energetic particle, and VLF wave experiments performed aboard Imp 6 in a study of the distant dayside cusp during substorms are described. The cusp was studied when its location was slightly equatorward of its normal location and the geomagnetic dipole was tilted in the appropriate direction. The data support both reconnection and diffusion as methods of particle entry to the magnetosphere. The evidence (1) indicates an acceleration process to explain enhancements of 400 to 600-km/sec protons above their magnetosheath intensities, and (2) suggests convection of field lines over the polar cap as a means of explaining the lack of low-energy protons near the low-latitude boundary of the cusp. Magnetic field fluctuations, a perturbation vector, ion cyclotron waves, and an abrupt change in the intensity of both whistler waves and electrostatic waves are characterized.

Fairfield, D. H.↗

NASA NTRS1979

Time structure of postmidnight energetic electron precipitation and the limit of stable trapping

The paper examines the detailed time structure of high-energy (over 30 keV) electron precipitation along the morningside and dayside of the auroral zone. To this end, available high time resolution data from the Ogo 6 energetic electron experiment are analyzed. The relationship between trapped flux levels and degree of precipitation observed is studied from an observational standpoint and compared with the critical flux levels estimated by Kennel and Petschek (1966). A possible explanation within the general framework of the Kennel-Petschek theory of the observed burstlike precipitation episodes is presented, and the implications of these features for the average lifetime of electrons in drifting clouds are discussed.

Trefall, H.↗

NASA NTRS1981

Solar Maximum Mission experiment - Early results from the soft X-ray polychromator experiment

It is pointed out that the X-ray polychromator experiment has been in operation on the Solar Maximum Mission satellite for more than three months. Using a number of different modes, the polychromator is observing flares and active regions in the wavelength range 1-23 A. These modes include polychromatic imaging, high resolution line profiles, high dispersion spectra, and light curves with high time-resolution. Data are described and some of the early analysis and interpretation is presented. All the interpretations are based on simple approximate methods; it is noted, however, that in most cases more elaborate and reliable methods are close to being applied.

Gabriel, A. H.↗

NASA NTRS1982

Plasma waves near the magnetopause

Plasma waves associated with the magnetosphere from the magnetosheath to the outer magnetosphere are investigated to obtain a clear definition of the boundaries and regions, to characterize the waves observed in these regions, to determine which wave modes are present, and to determine their origin. Emphasis is on high time resolution data and a comparison between measurements by different antenna systems. It is shown that the magnetosheath flux transfer events, the magnetopause current layer, the outer magnetosphere, and the boundary layer can be identified by their magnetic field and plasma wave characteristics, as well as by their plasma and energetic particle signatures. The plasma wave characteristics in the current layer and in the boundary layer are very similar to the features in the flux transfer events, and upon entry into their outer magnetosphere, the plasma wave spectra are dominated by intense electromagnetic chorus bursts and electrostatic emissions.

Anderson, R. R.↗

NASA NTRS1983

Upstream electron oscillations and ion overshoot at an interplanetary shock wave

During the passage of a large interplanetary shock on Oct. 13, 1981, the ISEE-1 and -2 spacecraft were in the solar wind outside of the upstream region of the bow shock. The high time resolution data of the University of California particle instruments allow pinpointing the expected electron spike as occurring just before the magnetic ramp. In addition, two features that occur at this shock have not been observed before: electron oscillations associated with low frequency waves upstream of the shock and sharp 'overshoot' (about 1 sec) in the ion fluxes that occur right after the magnetic ramp. This interplanetary shock exhibits many of the same characteristics that are observed at the earth's bow shock.

Potter, D. W.↗

NASA NTRS1983

Meteorological and dynamical requirements for MST radar networks: Waves

Studies of wave motions using the MST radar have concentrated on single station time series analyses of gravity waves and tides. Since these radars collect high time resolution data they have the potential to become a significant tool for mesoscale research. In addition, radars are operated almost continuously unattended and, consequently, data sets are available for analyzing longer period wave motions such as tides and planetary scale waves. Although there is much to learn from single station data, the possibilities of new knowledge from a network of radars is exciting. The scales of wave motions in the atmosphere cover a broad range. Consequently the choice of a radar network depends to a large extent on the types of wave motions that are studied. There are many outstanding research problems that would benefit from observations from a MST radar network. In particular, there is a strong need for measurements of gravity wave parameters and equatorial wave motions. Some of the current problems in wave dynamics are discussed.

Avery, S. K.↗

NASA NTRS1984

High time resolution measurements of rocket potential changes induced by electron beam emission

The transient charging and photon emission from the vacuum chamber testing of the Cooperative High Altitude Rocket Gun Experiment are studied. Graphs of the mother-daughter voltage versus time and high time resolution data related to the return current to the vehicle are examined. It is observed that for average sounding rocket densities of 10 to the -6th torr the slope of the voltage rise of the rocket begins to flatten 40 microsec after the onset of electron beam emission, and for higher gas pressure the rocket reaches a maximum voltage of 25 or 30 microsec after the onset of electron beam emission. The data reveal that the return current mechanism for the higher gas pressure is through the sheath.

Raitt, W. J.↗

NASA NTRS1987

Electric field measurements at subcritical, oblique bow shock crossings

ISEE-1 electric field measurements at three oblique, subcritical dispersive bow shock crossings are presented. The potential drops across the shock due to the large spatial scale normal component of the electric field were found to vary between 340 and 520 V. The measurements provide the first observations in a space plasma of the oscillations in the normal component of the electric field connected with the whistler precursor phase standing at a collisionless shock. Intense, rapidly varying electric fields with peak amplitudes ranging up to 100 mV/m were observed at the magnetic ramp of the shock in the high time resolution data.

Wygant, J. R.↗

NASA NTRS1992

Cloud motions on Neptune from Voyager 2 images

The puzzle presented by Neptune's circulation is evidenced by its wide spectrum of wind speeds and differences between the drift rate of its longest lived features and its finer scale cloud forms, unlike Jupiter or Saturn. Neptune's clouds appear dynamic and show strong evidence of atmospheric waves, making cloud motion measurements somewhat difficult and requiring some departures from the methods which have been traditionally used to determine atmospheric circulations. New measurements of cloud motions of Neptune that confirm the general characteristics reported by Smith et al. (1989) are presented below. Besides greater number of measurements from a higher time resolution data set, the new results reveal the shape of the westerly jet at 72 deg S latitude.

Limaye, S. S.↗