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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 217 records · Page 12
All sourcesNASA NTRSDOE OSTI
NASA NTRS2019

The Magnetosphere Ionosphere Electron Precipitation Dynamics and Their Geospace Consequences During the 17 March 2013 Storm

During geomagnetic storms and substorms, the magnetosphere and ionosphere are strongly coupled by precipitating magnetospheric electrons from the Earth's plasma sheet and driven by both magnetospheric and ionospheric processes. Magnetospheric wave activity initiates electron precipitation, and the ionosphere and upper atmosphere further facilitate this process by enhancing the value of precipitated energy uxes via connection of two magnetically conjugate regions and multiple atmospheric reections. This paper focuses on the resulting electron energy uxes and afliated heightintegrated Pedersen and Hall conductances in the auroral regions produced by multiple atmospheric reections during the 17 March 2013 geomagnetic storm and their effects on the inner magnetospheric electric eld and ring current. Our study is based on the magnetically and electrically selfconsistent Rice ConvectionModelEquilibrium of the inner magnetosphere with SuperThermal Electron Transport modied electron energy uxes that take into account the electron energy interplay between the two magnetically conjugate ionospheres. SuperThermal Electron Transportmodied energy ux in the Rice ConvectionModelEquilibrium leads to a signicant difference in the global conductance pattern, ionospheric electric eld formation, Birkeland current structure, ring current energization and its energy content, subauroral polarization drifts intensications and their spatial locations, interchange instability redistribution, and overall energy interplay on the global scale.

Khazanov, George V.↗
NASA NTRS2016

Geomagnetically Induced Currents Around the World During the 17 March 2015 Storm

Geomagnetically induced currents (GICs) represent a significant space weather issue for power grid and pipeline infrastructure, particularly during severe geomagnetic storms. In this study, magnetometer data collected from around the world are analyzed to investigate the GICs caused by the 2015 St. Patricks Day storm. While significant GIC activity in the high-latitude regions due to storm time substorm activity is shown for this event, enhanced GIC activity was also measured at two equatorial stations in the American and Southeast Asian sectors. This equatorial GIC activity is closely examined, and it is shown that it is present both during the arrival of the interplanetary shock at the storm sudden commencement (SSC) in Southeast Asia and during the main phase of the storm approximately 10 h later in South America. The SSC caused magnetic field variations at the equator in Southeast Asia that were twice the magnitude of those observed only a few degrees to the north, strongly indicating that the equatorial electrojet (EEJ) played a significant role. The large equatorial magnetic field variations measured in South America are also examined, and the coincident solar wind data are used to investigate the causes of the sudden changes in the EEJ approximately 10 h into the storm. From this analysis it is concluded that sudden magnetopause current increases due to increases in the solarwind dynamic pressure, and the sudden changes in the resultant magnetospheric and ionospheric current systems, are the primary drivers of equatorial GICs.

Carter, B. A.↗
NASA NTRS2016

On the Reduced Geoeffectiveness of Solar Cycle 24: A Moderate Storm Perspective

The moderate and intense geomagnetic storms are identified for the first 77 months of solar cycles 23 and 24. The solar sources responsible for the moderate geomagnetic storms are indentified during the same epoch for both the cycles. Solar cycle 24 has shown nearly 80% reduction in the occurrence of intense storms whereas it is only 40% in case of moderate storms when compared to previous cycle. The solar and interplanetary characteristics of the moderate storms driven by coronal mass ejection (CME) are compared for solar cycles 23 and 24 in order to see reduction in geoeffectiveness has anything to do with the occurrence of moderate storm. Though there is reduction in the occurrence of moderate storms, the Dst distribution does not show much difference. Similarly, the solar source parameters like CME speed, mass, and width did not show any significant variation in the average values as well as the distribution. The correlation between VBz and Dst is determined, and it is found to be moderate with value of 0.68 for cycle 23 and 0.61 for cycle 24. The magnetospheric energy flux parameter epsilon (epsilon) is estimated during the main phase of all moderate storms during solar cycles 23 and 24. The energy transfer decreased in solar cycle 24 when compared to cycle 23. These results are significantly different when all geomagnetic storms are taken into consideration for both the solar cycles.

Selvakumaran, R.↗
DOE OSTI2025

Impact assessment of geomagnetic induced current neutral blocking devices with power electronics sources on distance relay for 230 kV transmission lines

Electrical grids increased the integration of power electronics sources onto transmission lines. In addition, recent reports show a significant rise in geomagnetic storms occurring in 2024. These geomagnetic storms can affect transmission lines by inducing electrical currents within them, potentially causing power outages due to overloaded power transformers. Geomagnetic induced current neutral blocking devices (GIC-NBDs) are capacitors on the ground of wye power transformers, to avoid damage caused by geomagnetic storms. The integration of distance relays and transmission lines with power electronics sources and GIC-NBDs needs to be studied to observe if GIC-NBDs and power electronics sources could adversely affect operation of the electrical grid. In this analysis, the effect of 2 MW power electronics sources and GIC-NBDs on distance relays is assessed for different 230 kV transmission line lengths in radial and nonradial power systems. The simulations measured the apparent impedances, with different electrical faults. Results for a typical 2,650 μF GIC-NBD application were presented on impedance plots, and the distance relay model operations were assessed. In conclusion, the tests for radial and nonradial power systems showed the behavior of the distance elements and source impedance ratios, assessing the effect of power electronics sources and GIC-NBDs on 230 kV transmission lines.

Distance relays↗
NASA NTRS2009

Multifluid Block-Adaptive-Tree Solar Wind Roe-Type Upwind Scheme: Magnetospheric Composition and Dynamics During Geomagnetic Storms-Initial Results

The magnetosphere contains a significant amount of ionospheric O+, particularly during geomagnetically active times. The presence of ionospheric plasma in the magnetosphere has a notable impact on magnetospheric composition and processes. We present a new multifluid MHD version of the Block-Adaptive-Tree Solar wind Roe-type Upwind Scheme model of the magnetosphere to track the fate and consequences of ionospheric outflow. The multifluid MHD equations are presented as are the novel techniques for overcoming the formidable challenges associated with solving them. Our new model is then applied to the May 4, 1998 and March 31, 2001 geomagnetic storms. The results are juxtaposed with traditional single-fluid MHD and multispecies MHD simulations from a previous study, thereby allowing us to assess the benefits of using a more complex model with additional physics. We find that our multifluid MHD model (with outflow) gives comparable results to the multispecies MHD model (with outflow), including a more strongly negative Dst, reduced CPCP, and a drastically improved magnetic field at geosynchronous orbit, as compared to single-fluid MHD with no outflow. Significant differences in composition and magnetic field are found between the multispecies and multifluid approach further away from the Earth. We further demonstrate the ability to explore pressure and bulk velocity differences between H+ and O+, which is not possible when utilizing the other techniques considered

Glocer, A.↗
NASA NTRS1998

Magnetic Storms

One of the oldest mysteries in geomagnetism is the linkage between solar and geomagnetic activity. The 11-year cycles of both the numbers of sunspots and Earth geomagnetic storms were first noted by Sabine. A few years later, speculation on a causal relationship between flares and storms arose when Carrington reported that a large magnetic storm followed the great September 1859 solar flare. However, it was not until this century that a well-accepted statistical survey on large solar flares and geomagnetic storms was performed, and a significant correlation between flares and geomagnetic storms was noted. Although the two phenomena, one on the Sun and the other on the Earth, were statistically correlated, the exact physical linkage was still an unknown at this time. Various hypotheses were proposed, but it was not until interplanetary spacecraft measurements were available that a high-speed plasma stream rich in helium was associated with an intense solar flare. The velocity of the solar wind increased just prior to and during the helium passage, identifying the solar ejecta for the first time. Space plasma measurements and Skylab's coronagraph images of coronal mass elections (CMES) from the Sun firmly established the plasma link between the Sun and the Earth. One phenomenon associated with magnetic storms is brilliant "blood" red auroras, as shown.

Tsurutani, Bruce T.↗
NASA NTRS2005

Eyewitness Reports of the Great Auroral Storm of 1859

The great geomagnetic storm of 1859 is really composed of two closely spaced massive worldwide auroral events. The first event began on August 28th and the second began on September 2nd. It is the storm on September 2nd that results from the Carrington-Hodgson white light flare that occurred on the sun September l&. In addition to published scientific measurements; newspapers, ship logs and other records of that era provide an untapped wealth of first hand observations giving time and location along with reports of the auroral forms and colors. At its height, the aurora was described as a blood or deep crimson red that was so bright that one "could read a newspaper by." Several important aspects of this great geomagnetic storm are simply phenomenal. Auroral forms of all types and colors were observed to latitudes of 25deg and lower. A significant portion of the world's 125,000 miles of telegraph lines were also adversely affected. Many of - which were unusable for 8 hours or more and had a small but notable economic impact. T h s paper presents only a select few available first hand accounts of the Great Auroral Event of 1859 in an attempt to give the modern reader a sense of how this spectacular display was received by the public from many places around the globe and present some other important historical aspects of the storm.

Green, James L.↗
NASA NTRSDate not supplied

Temporal and Spatial Dynamics of Nitric Oxide Production at High Latitudes During an ICME-driven Storm on Dec. 14, 2006

During geomagnetic storms driven by interplanetary coronal mass ejections (ICMEs), Earth’s upper atmosphere neutral mass density is directly driven by the geomagnetic storm cycle from intense driving and subsequent recovery. The neutral density heating and cooling times are shorter for stronger storms and longer for weaker storms. The influx of energy (Joule Heating and precipitation) into Earth’s upper atmosphere during the storm main phase allows for the enhanced production of nitric oxide (NO) at high latitudes, which in turn cools the thermosphere by radiating away excess energy. As a result, greater NO production results in quicker thermospheric cooling. Yet while the production of NO on a global scale has been examined in detail, the space and time evolution of NO is not well-known. In this study, we investigate the effects of a particular ICME-driven storm, which occurred on Dec. 14th, 2006, on the production of NO at high latitudes. We compare NO measurements from the Thermosphere, Ionosphere, Mesosphere Dynamics (TIMED) spacecraft to neutral mass density measurements from the Challenging Minisatellite Payload (CHAMP) spacecraft and find that the impact of the shock prior to the storm, not just the onset of the storm itself, is responsible for an increase in NO production. We also observe a dawn-dusk asymmetry in high-latitude NO production and discuss how the geometry of the solar wind driver may play a role in creating this asymmetry. Finally, we discuss how the improved hemispheric and local time coverage provided by the GDC and DYNAMIC missions will enable more robust studies of the spatiotemporal evolution of NO during storms. Since NO is an important factor in regulating the neutral density of the thermosphere, such studies will be relevant for more accurate orbital drag calculations.

Kevin Delano↗
NASA NTRS1990

Procedures for minimizing the effects of high solar activity on satellite tracking and ephemeris generation

We are currently experiencing a period of high solar radiation combined with wide short-term fluctuations in the radiation. The short-term fluctuations, especially when combined with highly energetic solar flares, can adversely affect the mission of U.S. Space Command's Space Surveillance Center (SSC) which catalogs and tracks the satellites in orbit around the Earth. Rapidly increasing levels of solar electromagnetic and/or particle radiation (solar wind) causes atmospheric warming, which, in turn, causes the upper-most portions of the atmosphere to expand outward, into the regime of low altitude satellites. The increased drag on satellites from this expansion can cause large, unmodeled, in-track displacements, thus undermining the SSC's ability to track and predict satellite position. On 13 March 1989, high solar radiation levels, combined with a high-energy solar flare, caused an exceptional amount of short-term atmospheric warming. The SSC temporarily lost track of over 1300 low altitude satellites--nearly half of the low altitude satellite population. Observational data on satellites that became lost during the days following the 13 March 'solar event' was analyzed and compared with the satellites' last element set prior to the event (referred to as a geomagnetic storm because of the large increase in magnetic flux in the upper atmosphere). The analysis led to a set of procedures for reducing the impact of future geomagnetic storms. These procedures adjust selected software limit parameters in the differential correction of element sets and in the observation association process and must be manually initiated at the onset of a geomagnetic storm. Sensor tasking procedures must be adjusted to ensure that a minimum of four observations per day are received for low altitude satellites. These procedures have been implemented and, thus far, appear to be successful in minimizing the effect of subsequent geomagnetic storms on satellite tracking and ephemeris computation.

Bredvik, Gordon D.↗