Bibliography

Solar cycle, seasonal, and dawn-to-dusk variations of the hydrogen in the upper thermosphere

Atomic hydrogen is one of the least-understood atmospheric constituents whose distribution is important for the studies of aeronomy and magnetospheric physics. Using 6 years of space-based daytime Lyman-α observations from 2002 to 2007, we quantify the solar cycle, seasonal, and dawn-to-dusk variations of the H density in the upper thermosphere. Our results show evident dawn-dusk asymmetry of the exobase H density that decreases nearly linearly from dawn to dusk. The observed asymmetry in terms of the dawn-dusk density ratio decreases with declining solar activity and is larger in summer than in other seasons. Such variations are not predicted by the NRLMSISE-00 model and the NRLMSIS 2.0 model. Those models predict the opposite solar cycle trend and little seasonal variation of the degree of asymmetry.

Wan, Changan; Qin, Jianqi; Paxton, Larry;

Published by: Journal of Geophysical Research: Space Physics      Published on:

YEAR: 2022     DOI: 10.1029/2022JA030504

A Comparative Analysis of the OI 130.4-nm Emission Observed by NASA's TIMED Mission Using a Monte Carlo Radiative Transfer Model

Remote sensing of the OI 130.4-nm emission is potentially a useful means for routine monitoring of the atomic oxygen abundance in the upper atmosphere, especially for altitudes above urn:x-wiley:jgra:media:jgra55449:jgra55449-math-0001300 km where the OI 135.6-nm emission becomes too dim to be useful. However, to date, the interpretation of the OI 130.4-nm emission as a proxy for the O density remains ambiguous in that the relative contribution of the external and internal sources to the production of this emission has not been fully understood. In this study, we perform a comparative analysis of the OI 130.4-nm dayglow observed by NASA's Thermosphere Ionosphere Mesosphere Energetics and Dynamics (TIMED) mission using a Monte Carlo radiative transfer model to investigate the consistency between models and the TIMED/Global UltraViolet Imager (GUVI) data. T

Qin, Jianqi; Harding, Brian;

Published by: Journal of Geophysical Research: Space Physics      Published on:

YEAR: 2020     DOI: 10.1029/2019JA027520

Far Ultraviolet Remote Sensing of the Nighttime Ionosphere Using the OI 130.4-nm Emission

Qin, Jianqi;

Published by: Journal of Geophysical Research: Space Physics      Published on:

YEAR: 2020     DOI:

Research Progress on On-Orbit Calibration Technology for Far Ultraviolet Payload

Li-ping, Fu; Nan, Jia; Xiu-qing, Hu; Tian, Mao; Fang, Jiang; Yun-gang, Wang; Ru-yi, Peng; Tian-fang, Wang; Da-xin, Wang; Shuang-tuan, Dou; , others;

Published by:       Published on:

YEAR: 2019     DOI:

First radiative transfer analysis of the OI 130.4-nm emission observed by NASA's TIMED mission

observed by the Global UltraViolet Imager (GUVI) aboard NASA s TIMED mission. The solar O densities, and/or that the GUVI and SEE calibrations may need to be revisited. We will

Qin, Jianqi; Harding, Brian;

Published by:       Published on:

YEAR: 2019     DOI:

Nonparametric H Density Estimation Based on Regularized Nonlinear Inversion of the Lyman Alpha Emission in Planetary Atmospheres

Inversion of space-borne remote sensing measurements of the resonantly scattered solar Lyman alpha (121.6-nm) emission in planetary atmospheres is the most promising means of quantifying the H density in a vast volume of space near terrestrial planets. Owing to the highly nonlinear nature of the inverse problem and the lack of sufficient data constraints over the large volume of space where H atoms are present, previous inversion methods relied on physics-based parametric formulations of the H density distributions to guarantee solution uniqueness. Those physical formulations, such as the Chamberlain model, were developed with simple assumptions of the atmospheric conditions. The use of such formulations as constraints significantly limits the range of possible solutions, which might lead to large errors in the case when those assumptions are invalid. In this study, we demonstrate for the first time the feasibility of estimating the H density through regularized nonlinear inversion of the Ly-α emission in an optically thick atmosphere, without using parametric formulations. Specifically, Occam\textquoterights inversion algorithm is used to demonstrate that the H density can be estimated in a large volume of space near the planet, with accuracy in different atmospheric regions depending on the observation scheme. Two distinctly different schemes are examined, including a low-Earth orbit and a geostationary orbit. Modeling results show that the low-Earth orbit is better for H density estimation in the thermosphere, while the high-altitude orbit is better for estimation in the exosphere. Our results could provide useful information for designing the observation schemes of future missions.

Qin, Jianqi; Harding, Brian; Waldrop, Lara;

Published by: Journal of Geophysical Research: Space Physics      Published on: 09/2018

YEAR: 2018     DOI: 10.1029/2018JA025954

Inferring nighttime ionospheric parameters with the far ultraviolet imager onboard the ionospheric connection explorer

The Ionospheric Connection Explorer (ICON) Far Ultraviolet (FUV) imager, ICON FUV, will measure altitude profiles of OI 135.6 nm emissions to infer nighttime ionospheric parameters.

Kamalabadi, Farzad; Qin, Jianqi; Harding, Brian; Iliou, Dimitrios; Makela, Jonathan; Meier, RR; England, Scott; Frey, Harald; Mende, Stephen; Immel, Thomas;

Published by: Space science reviews      Published on:

YEAR: 2018     DOI:

Empirical quantification of the vertical transport and escape of atomic hydrogen in the terrestrial upper atmosphere

Waldrop, Lara; Phal, Yamuna; Kerr, Robert; Qin, Jianqi;

Published by:       Published on:

YEAR: 2018     DOI:

Redistribution of H atoms in the upper atmosphere during geomagnetic storms

Geocoronal H emission data acquired by NASA\textquoterights Thermosphere Ionosphere Mesosphere Energetics and Dynamics mission are analyzed to quantify the H density distribution over the entire magnetosphere-ionosphere-thermosphere region in order to investigate the response of the atmospheric system as a whole to geomagnetic storms. It is shown that at low and middle latitudes the H density averaged over storm times in the thermosphere-exosphere transition region decreases by \~30\%, while the H density at exospheric altitudes above \~1\textendash2\ R_E increases by up to \~40\% relative to quiet times. We postulate that enhanced ion-neutral charge exchange in the topside ionosphere and inner plasmasphere is the primary driver of the observed H redistribution. Specifically, charge exchange reactions between H atoms and ionospheric/plasmaspheric O⁺ lead to direct H loss, while those between thermal H and H⁺ yield kinetically energized H atoms which populate gravitationally bound satellite orbits. The resulting H density enhancements in the outer exosphere would enhance the charge exchange rates in the ring current and the associated energetic neutral atom production. Regardless of the underlying mechanisms, H redistribution should be considered as an important process in the study of storm time atmospheric evolution, and the resultant changes in the geocoronal H emissions potentially could be used to monitor geomagnetic storms.

Qin, Jianqi; Waldrop, Lara; Makela, Jonathan;

Published by: Journal of Geophysical Research: Space Physics      Published on: 08/2017

YEAR: 2017     DOI: 10.1002/jgra.v122.1010.1002/2017JA024489

Non-thermal hydrogen atoms in the terrestrial upper thermosphere

Model predictions of the distribution and dynamical transport of hydrogen atoms in the terrestrial atmosphere have long-standing discrepancies with ultraviolet remote sensing measurements, indicating likely deficiencies in conventional theories regarding this crucial atmospheric constituent. Here we report the existence of non-thermal hydrogen atoms that are much hotter than the ambient oxygen atoms in the upper thermosphere. Analysis of satellite measurements indicates that the upper thermospheric hydrogen temperature, more precisely the mean kinetic energy of the atomic hydrogen population, increases significantly with declining solar activity, contrary to contemporary understanding of thermospheric behaviour. The existence of hot hydrogen atoms in the upper thermosphere, which is the key to reconciling model predictions and observations, is likely a consequence of low atomic oxygen density leading to incomplete collisional thermalization of the hydrogen population following its kinetic energization through interactions with hot atomic or ionized constituents in the ionosphere, plasmasphere or magnetosphere.

Qin, Jianqi; Waldrop, Lara;

Published by: Nature Communications      Published on: 12/2016

YEAR: 2016     DOI: 10.1038/ncomms13655

Thermal structure of the ITM: old challenges and new insights

Waldrop, Lara; Qin, Jianqi;

Published by:       Published on:

YEAR: 2016     DOI:

Climatology of neutral hydrogen in the terrestrial thermosphere

Qin, Jianqi; Waldrop, Lara;

Published by:       Published on:

YEAR: 2016     DOI:

Radiative transfer modeling of the OI 135.6~nm emission in the nighttime ionosphere

Remote sensing of the nighttime OI 135.6\ nm emissions has been a widely used method for measuring the\ F\ region ionospheric plasma densities. In this work, we first develop a comprehensive radiative transfer model from first principles to investigate the effects of different physical processes on the production and transport of the 135.6\ nm photons in the ionosphere and then propose a new approach for estimating electron densities from the nightglow. The forward modeling investigation indicates that under certain conditions mutual neutralization can contribute up to \~38\% of the total production of the nighttime 135.6\ nm emissions. Moreover, depending on the ionospheric conditions, resonant scattering by atomic oxygen and pure absorption by oxygen molecules can reduce the limb brightness observed by satellite-borne instruments by up to \~40\% while enhancing the brightness viewing in the nadir direction by typically \~25\%. Further analysis shows that without properly addressing these effects in the inversion process, the peak electron density in the\ F\ region (NmF2) obtained using limb observations can be overestimated by up to \~24\%. For accurate estimation of the ionospheric electron density, we develop a new type of inverse model that accounts for the effects of mutual neutralization, resonant scattering, and pure absorption. This inversion method requires the knowledge of O and O₂\ densities in order to solve the radiative transfer equations. Application of the inverse model to the nighttime ionosphere in the noiseless cases demonstrates that the electron density can be accurately quantified with only \~1\% error in NmF2 and hmF2.

Qin, Jianqi; Makela, Jonathan; Kamalabadi, Farzad; Meier, R.;

Published by: Journal of Geophysical Research: Space Physics      Published on: 11/2015

YEAR: 2015     DOI: 10.1002/jgra.v120.1110.1002/2015JA021687

OI 135.6-nm Emission; onosphere; Radiative transfer; remote sensing

Radiative transfer modeling of the OI 135.6 nm emission in the nighttime ionosphere

Qin, Jianqi; Makela, Jonathan; Kamalabadi, Farzad; Meier, RR;

Published by: Journal of Geophysical Research: Space Physics      Published on:

YEAR: 2015     DOI:

Research on thermospheric densities derived from two-line element sets

Two-line Orbital Element Sets (TLEs) consist of mean orbital elements at epoch, along with the NORAD (North American Aerospace Defence Command) catalog number, international designator, epoch and additional fitting parameters. These information can be used to derive thermospheric densities through integration of differential equation for mean motion. For near-circular orbit satellites, derived thermospheric density can be seen as real density because of their stable orbit height, while for elliptical orbit satellites, thermospheric density at perigee and apogee can be different as much as several orders.

Tingling, Ren; Juan, Miao; Siqing, Liu; Zhitao, Li;

Published by: Journal of Space Science      Published on:

YEAR: 2014     DOI:

Optical System Design of a Spaceborne Broadband Far Ultraviolet Hyperspectral Imager

According to the application requirements for remote sensing of upper atmosphere,a reflective optical system of spaceborne far ultraviolet hyperspectral imager is designed.Which is composed of a scan mirror,an off-axis parabolic telescope and a toroidal grating spectrometer.An aberration-correction method for concave toroidal grating is developed.The initial parameters are solved based on the geometrical aberration theory of concave grating and then optimized using the optical design software Zemax,and the toroidal gating spectrometer is designed.The root mean square of spot radius is less than 16 μm in the working waveband.Aberration is corrected simultaneously in broadband and the requirement of spectral resolution of 0.6 nm is satisfied,which indicates the aberration-correction method is feasible.Ray tracing and analysing are performed by Zemax software.Analyzed results demonstrate that the modulation transfer function for different wavelength is more than 0.8,which satisfies the design requirements.The construction is compact and suitable for application in space remote sensing.

Qingsheng, Xue;

Published by: Acta Optica Sinica      Published on:

YEAR: 2012     DOI:

optical design hyperspectral imager toroidal grating far ultraviolet geometrical aberration