A5053827038- Ionosphere and magnetosphere dynamics
- Solar and Space Plasma Dynamics
- Earthquake Detection and Analysis
- Geomagnetism and Paleomagnetism Studies
- Atmospheric Ozone and Climate
- Astro and Planetary Science
- Planetary Science and Exploration
- Atmospheric and Environmental Gas Dynamics
- Geophysics and Gravity Measurements
- Laser-induced spectroscopy and plasma
- GNSS positioning and interference
- Spacecraft Design and Technology
- Impact of Light on Environment and Health
- Aerospace Engineering and Energy Systems
- Atmospheric chemistry and aerosols
- Atomic and Subatomic Physics Research
- Astronomical Observations and Instrumentation
- Methane Hydrates and Related Phenomena
- Space Science and Extraterrestrial Life
- Space Exploration and Technology
- Scientific Research and Discoveries
- Plasma Diagnostics and Applications
- Meteorological Phenomena and Simulations
- Atmospheric aerosols and clouds
- Magnetic confinement fusion research
University of Alaska Fairbanks
2008-2022
Earth Science Institute of the Slovak Academy of Sciences
2006
Geophysical Laboratory
2006
University of Alaska System
2003
Boston University
2001
University of California, Berkeley
1997-1998
University of Oulu
1997
High Altitude Observatory
1991
Abstract. Auroral electron transport calculations are a critical part of auroral models. We evaluate numerical solution to the and energy degradation problem. The is verified by reproducing simplified problems which analytic solutions exist, internal self-consistency tests, comparison with laboratory experiments beams penetrating collision chamber, observations, particularly emission ratio N2 second positive N+2 first negative emissions. Our agree range measurements in chambers. calculated...
We report a new parameterization of ionization in the Earth's atmosphere by isotropically precipitating monoenergetic (100 eV to 1 MeV) electrons. This is first one based on sophisticated first‐principle models, and represents significant improvement accuracy, particularly for incident auroral lower energies. Without previous need interpolate over source energy atmospheric range, provides an easier implementation with robust fit model calculations wide range energies conditions. By...
The passage of an interplanetary magnetic cloud at Earth on January 10–11, 1997, induced significant geomagnetic disturbances, with a maximum AE in excess 2000 nT and minimum Dst about −85 nT. We use comprehensive set data collected from space‐borne instruments ground‐based facilities to estimate the energy deposition associated three major magnetospheric sinks during event. It is found that averaged over 2‐day period, total rate 400 GW, 190 GW going into Joule heating rate, 120 ring current...
It has recently been found that solar wind dynamic pressure changes can dramatically affect the precipitation of magnetospheric particles on high‐latitude ionosphere. We have examined effect large increases location, size, and intensity auroral oval using particle data from Defense Meteorological Satellite Program (DMSP) spacecraft. Three events selected for study during time period after 1997 when four DMSP spacecraft (F11–F14) were simultaneously operational. Interplanetary magnetic field...
We present a new parameterization of the altitude profile ionization rate in Earth's atmosphere due to precipitating energetic electrons. Precipitating electrons are assumed have Maxwellian energy distribution and an isotropic pitch angle above atmosphere. In this study, two electron transport models (whose validity has been verified by observations) employed calculate rate, which we fit our parameterization. To derive parameterization, follow similar scheme that Roble Ridley (1987) but take...
This paper is a companion to by Liang et al. (2011) which reports causal connection between the intensification of electrostatic ECH waves and postmidnight diffuse auroral activity in absence whistler mode chorus at L = 11.5 on basis simultaneous observations from THEMIS spacecraft NORSTAR optical instruments during 8–9 UT February 5, 2009. In this paper, we use particle wave measurements together with magnetically conjugate for event illustrate an example where electron cyclotron harmonic...
A combination of all‐sky imagers (ASTV) and meridian‐scanning photometers (MSP) was used to identify the optical signature growth phase, onset, expansion, recovery 33 auroral substorms in Alaskan sector. The discrete arc that brightens at substorm onset found be poleward diffuse aurora contains H emission by a distance between 10 300 km. average time 2215 magnetic local (MLT) geographic latitude 64.6° 63.6°, respectively. crossover peak occurs shortly after for intensification 2100 MLT....
Ultraviolet auroral images from the Imager (UVI) onboard POLAR satellite can be used as quantitative remote diagnostics of regions, yielding estimates incident energy characteristics, compositional changes, and other higher order data products. Here derived UVI are compared with in situ measurements same parameters an overflight by DMSP F12 coincident image times during substorm activity occurring on May 19, 1996. This event was simultaneously observed WIND, GEOTAIL, INTERBALL, NOAA...
Abstract. We present data from the sixth Cassini flyby of Titan (T5), showing that magnetosphere Saturn strongly interacts with moon's ionosphere and exo-ionosphere. A simple electron ionisation model provides a reasonable agreement altitude structure ionosphere. Furthermore, we suggest dense cold exo-ionosphere (from exobase at 1430 km outward to several radii surface) can be explained by magnetospheric forcing other transport processes whereas exospheric impacting low energy electrons...
It is well known that a persistent southward Interplanetary Magnetic Field (IMF) produces increased geomagnetic activity. has recently been shown sudden increase in solar wind pressure results poleward expansion of the auroral oval and closing polar cap over wide range MLTs, this effect more pronounced under IMF orientation. We show conditions combined with high dynamic immediately after front impact lead to enhanced coupling between terrestrial magnetosphere, significantly increasing...
Auroral images acquired by the Spin Scan Imager (SAI) on board DE 1 satellite are converted to geophysical parameters applying physical processes that produce from a precipitating electron flux response characteristics of instrument. The energy and characteristic basic derived which several ionospheric properties may be computed. Two spectral emissions required specify flux. With complement available filters photometers combination an ultraviolet channel one emission in visible wavelength...
Models of hydrogen‐proton transport in proton aurora predict the line profile hydrogen emissions from specified incident precipitation. We are using a model that includes collisional angular redistribution which leads to upward moving and fluxes. For ground‐based observation magnetic zenith this causes small Doppler broadening toward red profile. The precipitating energetic atoms responsible for prominent shift blue. resulting has thus both widened blue wing. Using spectrometer with...
The ultraviolet imager (UVI) on board the POLAR satellite offers opportunity to obtain high time resolution global auroral images. spectral discrimination of is sufficient separate far emissions from scattered sunlight, even when entire zone sunlit. energy flux precipitating electrons derived surface brightness through LBH‐long filter. Global images which have dayglow removed are spatially integrated yield total rate input into northern hemisphere. This parameter, hemispheric power, has...
Abstract. Recent work has shown that solar wind dynamic pressure changes can have a dramatic effect on the particle precipitation in high-latitude ionosphere. It also been noted preexisting interplanetary magnetic field (IMF) orientation significantly affect resulting size, location, and intensity of auroral oval. Here we focus pulses size We use data from up to four Defense Meteorological Satellite Program (DMSP) spacecraft simultaneous POLAR Ultra-Violet Imager (UVI) images examine three...
The overall objective of the particle environment monitor (PEM) is to provide comprehensive measurements both local and global energy inputs into Earth's atmosphere by charged particles Joule dissipation using a carefully integrated set instruments. PEM consists four instruments: atmospheric X ray imaging spectrometer (AXIS), high‐energy (HEPS), medium‐energy (MEPS), vector magnetometer (VMAG). AXIS provides scale images spectra 3‐ 100‐keV bremsstrahlung rays produced electron precipitation...
Using an electron transport model, we investigate the effect of precipitation on density and total content in nightside ionosphere Mars. As input use Mars Global Surveyor observations a typical tail spectrum auroral‐like spectrum. The accelerated increases maximum number by factor 3 over that produced Our calculations show secondary peak due to several keV electrons not seen previous modeling efforts. Regions enhanced ionization are expected be localized space, corresponding magnetic cusps...
A large increase in electron temperature measured filamentary aurora with the European incoherent scatter radar has been modeled a one‐dimensional transport and ion chemistry code. To account for observed changes temperature, while also reproducing E region density profiles, source of heating is required addition to local from energy degradation precipitating electrons. We show that ohmic strong field‐aligned current can heat source.
This paper presents a case study of ionospheric response to an interplanetary magnetic field (IMF) southward turning. It is based on comprehensive set observations, including global network ground magnetometers, auroral images, and SuperDARN HF radar. There clear evidence for two‐stage the IMF turning, namely, fast initial onset slow final reconfiguration. The manifested by nearly simultaneous (within 2 min) rise perturbations at all local times, corroborated sudden change in direction...
We present a coupled Monte Carlo and multistream model simulating primary ionization secondary electron ionization, respectively, from energetic proton precipitation in the Earth's upper atmosphere. Good agreement is obtained with previous results. It found that while electrons make negligible contribution to low‐energy (≤10 keV) auroral precipitation, their importance increases increasing incident energy, confirming earlier findings. becomes significant or even comparable protons generated...