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Le, Guan

Publications and source records attributed to Le, Guan.

At least 19 records
All sourcesNASA NTRSDOE OSTI
NASA NTRS2017

The Scintillation Prediction Observations Research Task (SPORT): an International Science Mission Using a Cubesat

The Scintillation Prediction Observations Research Task (SPORT) is a 6U CubeSat mission to address the compelling but difficult problem of understanding the preconditions leading to equatorial plasma bubbles. The scientific literature describes the preconditions in both the plasma drifts and the density profiles related to bubble formations that occur several hours later in the evening. Most of the scientific discovery has resulted from observations at a single site, within a single longitude sector, from Jicamarca, Peru. SPORT will provide a systematic study of the state of the pre-bubble conditions at all longitudes sectors to enhance understanding between geography and magnetic geometry. SPORT is an international partnership between National Aeronautics and Space Administration (NASA), the Brazilian National Institute for Space Research (INPE), and the Technical Aeronautics Institute under the Brazilian Air Force Command Department (DCTA/ITA), and encouraged by U.S. Southern Command. This talk will present an overview of the SPORT mission, observation strategy, and science objectives to improve predictions of ionospheric disturbances that affect radio propagation of telecommunication signals. The science goals will be accomplished by a unique combination of satellite observations from a nearly circular middle inclination orbit and the extensive operation of ground based observations from South America near the magnetic equator.

Scintillation Prediction Observations↗
NASA NTRS2017

The Scintillation Prediction Observations Research Task (SPORT) Mission

SPORT is a science mission using a 6U CubeSat and integrated ground network that will (1) advance understanding and (2) enable improved predictions of scintillation occurrence that impact GPS signals and radio communications. This is the science of Space Weather. SPORT is an international partnership with NASA, U.S. institutions, the Brazilian National Institute for Space Research (INPE), and the Technical Aeronautics Institute under the Brazilian Air Force Command Department (DCTA/ITA).

SPORT↗
NASA NTRS2016

Near-Earth Magnetic Field Effects of Large-Scale Magnetospheric Currents

Magnetospheric currents play an important role in the electrodynamics of near- Earth space. This has been the topic of many space science studies. Here we focus on the magnetic fields they cause close to Earth. Their contribution to the geomagnetic field is the second largest after the core field. Significant progress in interpreting the magnetic fields from the different sources has been achieved thanks to magnetic satellite missions like Ørsted, CHAMP and now Swarm. Of particular interest for this article is a proper representation of the magnetospheric ring current effect. Uncertainties in modelling its effect still produce the largest residuals between observations and present-day geomagnetic field models. A lot of progress has been achieved so far, but there are still open issues like the characteristics of the partial ring current. Other currents discussed are those flowing in the magnetospheric tail. Also their magnetic contribution at LEO orbits is non-negligible. Treating them as an independent source is a more recent development, which has cured some of the problems in geomagnetic field modelling. Unfortunately there is no index available for characterizing the tail current intensity. Here we propose an approach that may help to properly quantify the magnetic contribution from the tail current for geomagnetic field modelling. Some open questions that require further investigation are mentioned at the end.

Magnetospheric currents↗
NASA NTRS2016

Electrodynamic Context of Magnetopause Dynamics Observed by Magnetospheric Multiscale

Magnetopause observations by Magnetospheric Multiscale (MMS) and Birkeland currents observed by the Active Magnetosphere and Planetary Electrodynamics Response Experiment are used to relate magnetopause encounters to ionospheric electrodynamics. MMS magnetopause crossings on 15 August and 19 September 2015 occurred earthward of expectations due to solar wind ram pressure alone and coincided with equatorward expansion of the Birkeland currents. Magnetopause erosion, consistent with expansion of the polar cap, contributed to the magnetopause crossings. The ionospheric projections of MMS during the events and at times of the magnetopause crossings indicate that MMS observations are related to the main path of flux transport in one case but not in a second. The analysis provides a way to routinely relate in situ observations to the context of in situ convection and flux transport.

Anderson, Brian J.↗