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DOE OSTI2026

Multi‐Species Energy‐Banded Ions in the Ionosphere During the 21 January 2005 Magnetic Storm: Low‐Altitude Edge of the Warm Plasma Cloak

During the 21–22 January 2005 magnetic storm, the FAST satellite observed warm (< few keV) ions in discrete energy bands on the dayside at ∼3,000 km altitude for more than 6.5 hr. We suggest that the ionospheric energy-banded ions represent the low-altitude edge of the warm plasma cloak observed simultaneously by magnetospheric satellites. This is a clear example of the multi-species ion energy bands (10 eV to several keV) observed during strong magnetic storms by the FAST satellite, stretching from the diffuse auroral region to the plasmapause with lifetimes up to 12 hr. The close association of these energy-banded ions with magnetic storms, their broad latitudinal extent, and the presence of multiple ion species in the same energy band, rather than at the same velocity, indicate that this is a distinct phenomenon from other types of energy-banded ions. During the 21–22 January 2005 magnetic storm, the dayside ion energy band structures, centered at 10 eV (H + ), 40 eV (H + and He + ), and 160 eV (H + , He + , and O + ), were consistent with a “time-of-flight and velocity filter” formation process acting on a near-cusp, impulsive outflow of a <200 eV multi-species ion-source population, poleward and in the same hemisphere as FAST. Understanding the sources and dynamics of warm energy-banded ions and their linkage to the warm plasma cloak is important because during superstorms these ions are transported to L values as low as L ∼ 1.2 in the dawn sector, significantly altering the energetics of the mid-latitude ionosphere.

58 GEOSCIENCES↗

DOE OSTI2025

Evaluating Extreme Storm Events in an Ensemble of High‐Resolution Projections

This study uses different downscaling techniques and reference observations to investigate the characteristics of extreme storm events over the conterminous United States in historical and a projected future scenario. While previous studies agree on the projected changes in intensity and frequency of precipitation extremes, there is a lack of consensus regarding how their size will change in response to an increase in radiative forcing. Moreover, the influence of different downscaling techniques on their characteristics has not been thoroughly examined. This study employs an ensemble of high‐resolution projections derived from six CMIP6 GCMs, using dynamical, statistical and artificial intelligence based downscaling techniques and two reference observations. Overall, we find noticeable differences in the size, average depth, and total precipitation volume of these storms among the climate ensembles in the historical period. Despite these differences in the historical period, we find consistent future changes across various ensembles. We find a robust projected increase in storm size during Winter and Spring but a decrease in size during Summer in the East. Nevertheless, irrespective of changes in their size, extreme storms are projected to intensify across all the ensembles and seasons.

Rastogi, Deeksha [Oak Ridge National Laboratory (O↗

NASA NTRS1971

Geomagnetic storm particles in the high-latitude magnetotail.

Nearly monoenergetic positive ions flowing outward along magnetic-field lines in the high-latitude magnetotail, outside the plasma sheet, have been observed with Vela satellites. These ions, probably mainly protons, are detected only during geomagnetic storms. The ?storm particles' have average energies per charge ranging from about 0.3 to 3 kV, but at any instant the energy distribution is quite narrow, sometimes less than 10%. Their angular distribution is usually narrow, sometimes about 6 deg. Particles with storm-particle characteristics are not observed in the plasma sheet. Possible sources of the storm particles are considered, including the solar wind, magnetosheath, polar cusps, polar wind, or ionosphere, plasma sheet, solar neutral hydrogen streams, reconnection transfer of plasma into the magnetotail from the polar cusps, polar wind, or polar ionosphere, and parallel electric-field acceleration of the polar wind or ionosphere ions along the polar-cap magnetic-field lines. Of these possibilities, the electric-field acceleration is favored.

Bame, S. J.↗

NASA NTRS1972

The responses of the thermosphere due to a geomagnetic storm: A MHD model

A magnetohydrodynamics theory was used to study the dynamic response of the neutral atmosphere to a geomagnetic storm. A full set of magnetohydrodynamic equations appropriate for the present problem is derived and their various orders of approximation are discussed in some detail. In order to demonstrate the usefulness of this theoretical model, the May 1967 geomagnetic storm data were used in the resulting set of nonlinear, time dependent, partial differential magnetohydrodynamic equations to calculate variations of the thermosphere due to the storm. The numerical results are presented for wind speeds, electric field strength, and amount of joule heating at a constant altitude for the data recorded. Data show that the strongest thermospheric responses are at the polar region becoming weaker in the equatorial region. This may lead to the speculation that a thermospheric wave is generated in the polar region due to the geomagnetic storm which propagates towards the equator.

Wu, S. T.↗

NASA NTRS1974

Mars - Clearing of the 1971 dust storm

A semiquantitative analysis of clearing in the 1971 great dust storm on Mars is presented as a function of time and altitude, using Mariner 9 orange- and visual-light photos. Steady settling of dust approximately accounts for the decline of the storm after Dec. 22, 1971. Continuous settling cannot be invoked prior to that date; injection of dust into the atmosphere, i.e., a storm resurgence, occurred in mid-December 1971. Theoretical models of optical depth vs time are developed for various distributions of particles in the atmosphere. By interpreting settling in terms of Stokes' law, estimates of the maximum radii of dust particles throughout the atmosphere have been obtained. Models which best account for the dust-storm decline indicate particles less than 5 microns in diameter high in the atmosphere, with a concentration of larger particles near the ground in the lowest parts of Mars.

Hartmann, W. K.↗

NASA NTRS1974

Plasmaspheric hiss intensity variations during magnetic storms

The storm time intensity variations of ELF electromagnetic emissions have been studied by using the Ogo 6 search coil magnetometer. Low-latitude signals exhibit a sharp low-frequency cutoff and are identified as plasmaspheric hiss. Such waves show pronounced intensification during the recovery phase of magnetic storms but remain close to background levels during the storm main phase. This behavior is consistent with cyclotron resonant generation within the plasmasphere as the latter expands into the intensified belt of outer zone electrons during the storm recovery.

Smith, E. J.↗

NASA NTRS1974

Solar radio continuum storms

Radio noise continuum emission observed in metric and decametric wave frequencies is discussed. The radio noise is associated with actively varying sunspot groups accompanied by the S-component of microwave radio emissions. It is shown that the S-component emission in microwave frequencies generally occurs several days before the emission of the noise continuum storms of lower frequencies. It is likely that energetic electrons, 10 to 100 Kev, accelerated in association with the variation of sunspot magnetic fields, are the sources of the radio emissions. A model is considered to explain the relation of burst storms on radio noise. An analysis of the role of energetic electrons on the emissions of both noise continuum and type III burst storms is presented. It is shown that instabilities associated with the electrons and their relation to their own stabilizing effects are important in interpreting both of these storms.

Source record↗

NASA NTRS1975

The 1973 dust storm on Mars: Maps from hourly photographs

The hourly progress of the 1973 major Martian storm was mapped using photographic images from the International Planetary Patrol. Two series of 20 daily maps show the semi-hourly positions of the storm brightenings in red light and blue light. The maps indicate that the 1973 storm had many similarities to the 1971 storm.

Martin, L. J.↗

NASA NTRS1975

The Severe Storms Observation Satellite /SSOS/

The objective of the Severe Storms Observation Satellite (SSOS) is to continuously observe meteorological phenomena from geosynchronous altitude and to acquire data whose analysis will lead to a better understanding, early detection, and prediction of severe storms and other significant mesoscale events such as dust storms. Details are discussed as to the Advanced Atmospheric Sounding and Imaging Radiometer designed for SSOS, the use of a special spacecraft for an R&D mission, data acquisition, and data processing and analysis. The required accurate vertical temperature and moisture profiles as well as high temporal and spatial resolution images can best be obtained by a three-axis stabilized system, which offers approximately an order of magnitude sensing improvement over a comparable spinning system due to its capability to continuously view the earth. A block diagram of the severe storm analysis system is included.

Shenk, W. E.↗

NASA NTRS1975

Interplanetary field and plasma during initial phase of geomagnetic storms

A study has been conducted of a large number of geomagnetic storms occurring during the period from 1966 to 1970. Questions of data selection are discussed and the large-scale interplanetary magnetic field during the initial phase is examined. Small-scale interplanetary fields during the initial phase are also considered, taking into account important features of small-scale variations in the interplanetary field and plasma for three storms. Details concerning 23 geomagnetic storms and the interplanetary magnetic field are presented in a table. A study of the initial phase of these storms indicates that in most of these events, the solar-ecliptic Z component of the interplanetary magnetic field turns southward when the main phase decrease begins.

Patel, V. L.↗

NASA NTRS1976

The morphology of energetic O/+/ ions during two magnetic storms - Temporal variations

Results are presented for a statistical analysis of the temporal variations of precipitating O(+) and H(+) ions in the energy range 0.7-12 keV during the magnetic storms on Dec. 16-18, 1971. Emphasis is on the temporal variations of parameters describing the intensity, average energy, and spatial location of the precipitation zones of the two ionic species. It is shown that the intensity of the precipitating O(+) ions correlate well with the geomagnetic indices which measure the strength of magnetospheric substorm activity and the strength of the storm time ring current, indicating that a previously unknown strong coupling mechanism existed between the magnetosphere and the ionosphere during the storm period. Correlations are found between the locations of the O(+) and H(+) precipitation zones and between the average energies of the two ionic species. Precipitation is shown to be an important loss mechanism for ring current ions with energy less than 12 keV during the magnetic storm period studied.

Sharp, R. D.↗

NASA NTRS1976

Geomagnetic storm effects on the thermosphere and the ionosphere revealed by in situ measurements from OGO 6

The temporal response of the densities of upper-atmospheric ion and neutral constituents to a particular geomagnetic storm is studied using simultaneous ion and neutral-composition data obtained by the OGO 6 satellite during consecutive orbits at altitudes greater than 400 km. The investigated constituents include H(+), O(+), N2, O, He, and H. Derivation of the H density is reviewed, and the main effects of the storm are discussed, particularly temporal and global variations in the densities. It is found that: (1) the H and He densities began to decrease near the time of sudden commencement, with the decrease amounting to more than 40% of the quiet-time densities during the maximum stage at high latitudes; (2) the O and N2 densities exhibited an overall increase which began later than the change in H and He densities; (3) the H(+) density decreased differently in two distinct regions separated near the low-latitude boundary of the light-ion trough; and (4) the O(+) density showed an increase during earlier stages of the storm and decreased only in the Northern Hemisphere during the recovery phase. Certain physical and chemical processes are suggested which play principal roles in the ionospheric response to the storm

Marubashi, K.↗

NASA NTRS1978

Utilizing the dust streak-dryline intersection phenomenon in severe local storm forecasting

Several characteristics of a major dust storm on 20 February 1976 are presented. Four primary areas of discussion are considered: dust storm characteristics; comparisons between the cell detection capabilities of the geosynchronous satellite and radar; the use of the NASA Atmospheric and Oceanographic Information Processing System (an interactive image processing system) for interactive display of visual and IR digital data to obtain qualitative and quantitative results on specific dust cloud and cloud top characteristics; and evidence that the intersection downwind of dust clouds (streaks) with the dryline can be used to forecast the initial storm development on the dryline and that the dust clouds detected on 20 February 1976 are a reflection of upper tropospheric speed maxima, which according to McNulty (1978) and others, are associated with rapid severe convective local storm development.

Anthony, R. W.↗

NASA NTRS1979

Thermal tides and Martian dust storms - Direct evidence for coupling

Evidence for the coupling of diurnal and semidiurnal thermal tides, observed as surface pressure oscillations at the Viking Lander 1 and 2 landing sites, to Martian global dust storms is presented and the implications for models of dust storm generation are discussed. Local atmospheric opacity increases and jumps in atmospheric pressure ranges were found to be essentially simultaneous, and diurnal and semidiurnal components of the pressure and wind oscillations were observed to increase markedly after the onset of a dust storm. The semidiurnal wind component can be related to the observed surface pressure variations by means of a model of a semidiurnally forced Ekman boundary layer. However, a classical atmospheric tidal model shows that the preferential enhancement of the semidiurnal surface pressure oscillation observed at the Lander 1 site can be produced by a tidal heating distribution in which most of the heating is done at an altitude above 10 km. Observations suggest that various mechanisms are important for the generation and decay of global Martian dust storms.

Leovy, C. B.↗

NASA NTRS1979

Dynamics of severe storms through the study of thermospheric-tropospheric coupling

Atmospheric acoustic-gravity waves associated with severe local thunderstorms, tornadoes, and hurricanes can be studied through the coupling between the thermosphere and the troposphere. Reverse group ray tracing computations of acoustic-gravity waves, observed by an ionospheric Doppler sounder array, show that the wave sources are in the neighborhood of storm systems and the waves are excited prior to the storms. It is suggested that the overshooting and ensuing collapse of convective turrets may be responsible for generating the acoustic-gravity waves observed. The results of this study also show that the study of wave-wave resonant interactions may be a potential tool for investigating the dynamical behavior of severe storm systems using ionospheric observations of atmospheric acoustic-gravity waves associated with severe storms.

Hung, R. J.↗

NASA NTRS1980

A source for the geomagnetic storm main phase ring current

The paper considers a proposed source for the geomagnetic storm main phase ring current. It is shown that the flux increases of trapped ions and electrons observed by Explorer 45 at L below 4 during two large geomagnetic storms can be explained by inward radial displacement of the preexisting trapped particle distribution. The proposed source requires only the acceleration of the previously entrapped particle population by inward displacement under conservation of the first two adiabatic invariants. It is suggested that a significant difference between large geomagnetic storms and typical substorm activity may be the inward convection occurring over a large longitude range during storms, but only over a small longitude range during typical substorms.

Lyons, L. R.↗

NASA NTRS1980

Moisture convergence using satellite-derived wind fields - A severe local storm case study

Five-minute interval 1-km resolution SMS visible channel data were used to derive low-level wind fields by tracking small cumulus clouds on NASA's Atmospheric and Oceanographic Information Processing System. The satellite-derived wind fields were combined with surface mixing ratios to derive horizontal moisture convergence in the prestorm environment of April 24, 1975. Storms began developing in an area extending from southwest Oklahoma to eastern Tennessee 2 h subsequent to the time of the derived fields. The maximum moisture convergence was computed to be 0.0022 g/kg per sec and areas of low-level convergence of moisture were in general indicative of regions of severe storm genesis. The resultant moisture convergence fields derived from two wind sets 20 min apart were spatially consistent and reflected the mesoscale forcing of ensuing storm development. Results are discussed with regard to possible limitations in quantifying the relationship between low-level flow and between low-level flow and satellite-derived cumulus motion in an antecedent storm environment.

Negri, A. J.↗

NASA NTRS1982

Radar reflectivities and satellite imagery of severe storms 20 May 1977

Storms on 20 May 1977 generated a vast cirrus deck. Disturbed areas at storm top had equivalent black-body temperatures (T sub BB) much lower than the tropopause temperature, indicative of overshooting tops. The area of T sub BB not greater than -71 C represents the area of convective activity penetrating 2 km above the tropopause. This area was relatively large after cloud tops and radar reflectivities reached their maximum heights. It became much smaller during tornadoes when reflectivities were decreasing. T sub BB was at a minimum at the time of mesocyclone formation. The Del City storm had two periods of growth, as indicated both by reflectivities and the T sub BB areas. The mesocyclone was first detected during the second less intense period of growth; the tornado occurred during decreasing reflectivities. The maintenance of large areas of relatively low T sub BB after tornado dissipation is ascribed to continued convection on the flanks of the storm and to residual updrafts in a thick anvil cloud.

Wexler, R.↗