Bibliography

New Measurement of the Vertical Atmospheric Density Profile From Occultations of the Crab Nebula With X-Ray Astronomy Satellites Suzaku and Hitomi

We present new measurements of the vertical density profile of the Earth s atmosphere at altitudes between 70 and 200 km, based on Earth occultations of the Crab Nebula observed with the X-ray Imaging Spectrometer onboard Suzaku and the hard X-ray Imager onboard Hitomi. X-ray spectral variation due to the atmospheric absorption is used to derive tangential column densities of the absorbing species, that is, N and O including atoms and molecules, along the line of sight. The tangential column densities are then inverted to obtain the atmospheric number density. The data from 219 occultation scans at low latitudes in both hemispheres from September 15, 2005 to March 26, 2016 are analyzed to generate a single, highly averaged (in both space and time) vertical density profile. The density profile is in good agreement with the Naval-Research-Laboratory s-Mass-Spectrometer-Incoherent-Scatter-Radar-Extended (NRLMSISE-00) model, except for the altitude range of 70–110 km, where the measured density is ∼50\% smaller than the model. Such a deviation is consistent with the recent measurement with the SABER aboard the TIMED satellite (Cheng et al., 2020, https://doi.org/10.3390/atmos11040341). Given that the NRLMSISE-00 model was constructed some time ago, the density decline could be due to the radiative cooling/contracting of the upper atmosphere as a result of greenhouse warming in the troposphere. However, we cannot rule out a possibility that the NRL model is simply imperfect in this region. We also present future prospects for the upcoming Japan-US X-ray astronomy satellite, X-Ray Imaging and Spectroscopy Mission (XRISM), which will allow us to measure atmospheric composition with unprecedented spectral resolution of ΔE ∼ 5 eV in 0.3–12 keV.

Katsuda, Satoru; Fujiwara, Hitoshi; Ishisaki, Yoshitaka; Yoshitomo, Maeda; Mori, Koji; Motizuki, Yuko; Sato, Kosuke; Tashiro, Makoto; Terada, Yukikatsu;

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

YEAR: 2021     DOI: 10.1029/2020JA028886

Crab Nebula; Hitomi; occultation; Suzaku; upper atmosphere; X-rays

Storm-Time Neutral Composition Changes in the Upper Atmosphere

During geomagnetic storms, energy inputs, such as particle precipitation and Joule heating from the magnetosphere and solar wind, create significant disturbances in the upper atmosphere in the form of changes in the thermospheric density and temperature and, more important, composition, such as O/N 2 column density ratio, nitric oxide (NO) density, and atomic nitrogen (N) density. The composition changes control the ionosphere and have a feedback effect on thermospheric temperature and density due to a cooling effect of enhanced NO 5.3 μm radiation. We review the methods of deriving the composition information from far ultraviolet (FUV) observations as well as the signatures of the major features in the storm-time composition variations such as O/N 2 depletion and enhancement, NO and N enhancement, corotation of the O/N 2 depletion, seasonal and hemispheric asymmetry, traveling atmospheric disturbance (TAD) and its connection to traveling ionosphere disturbance (TID), and temperature increase in O/N 2 depleted regions and their interaction with TADs. A FUV spectrograph imager is a cost-effective instrument suitable for low Earth orbit missions and can monitor the response of the near-Earth space environment including the thermosphere, ionosphere, and aurora (magnetosphere) to solar wind forcing as well as forcing from low atmosphere.

Zhang, Yongliang; Paxton, Larry;

Published by:       Published on:

YEAR: 2021     DOI: 10.1002/9781119815631.ch7

far ultraviolet observations; storm-time neutral composition changes; thermospheric nitric oxide variations; traveling atmospheric disturbance; traveling ionosphere disturbance; upper atmosphere

Exploring the Upper Atmosphere

In this chapter, we describe how we can understand the state of the upper atmosphere (the ionosphere, thermosphere, and aurora) using optical observations and how one produces a global view of the Earth s upper atmosphere from optical remote sensing, especially using far ultraviolet (FUV) wavelengths, to advance our understanding of the near Earth space environment. We examine the choice of optical signatures, the basic science behind the signatures, and the techniques for observations. Examples of the technique as applied to key geophysical processes are described and discussed for tracing the physical processes that alter the state variables (in particular, density, composition, and temperature) in the upper atmosphere. Applications of optical remote sensing will be discussed in terms of the challenges inherent in establishing a predictive capability of the global upper atmosphere system, including the high-latitude regions (such as the Arctic) where the structures of the thermosphere and ionosphere are complicated by strong coupling among the polar ionosphere, magnetosphere, and solar wind.

Paxton, Larry; Zhang, Yongliang; Kil, Hyosub; Schaefer, Robert;

Published by:       Published on:

YEAR: 2021     DOI: 10.1002/9781119815631.ch23

Earth space environment; far ultraviolet wavelengths; high-latitude regions; optical remote sensing; solar wind; upper atmosphere

On the Relationship of the O(1D) 630.0 nm Dayglow Emission to the F10.7 cm Solar Flux and the Solar Zenith Angle

The Wind Imaging Interferometer (WINDII) Empirical Model, which provides the characteristics of the O(1D) 630.0 nm atomic oxygen dayglow emission from the upper atmosphere has been reviewed and updated. It now includes the Integrated Emission Rate, the peak Volume Emission Rate, the Altitude of that peak and the Full Width at Half Maximum as functions of the F10.7 cm Solar Radio Flux and the solar zenith angle (SZA). The model employs 98,617 WINDII observations obtained between the years 1992 and 1996, and the model and observations of the Integrated Emission Rate agree well with one another within 2 standard deviations of 588.7 Rayleigh (R) (106 photons cm−2 sec−1). It is also demonstrated that the impact of latitude, longitude and day of year, independently of their contribution to the SZA, is very small. The WINDII Empirical Model is also shown to agree with results from the TRANSCAR photochemical model. The dayglow is challenging to measure with ground-based instruments, as the solar scattered light from the daytime sky must be accurately subtracted from the data. Ground-based measurements of the integrated emission rate have been made by others, with good agreement for observations from Hyderabad during the 2015 summer and winter, but mixed agreement with measurements made over Boston in 2003. The latter results are reviewed and assessed.

Shepherd, Gordon; Cho, Young-Min;

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

YEAR: 2021     DOI: 10.1029/2020JA028715

dayglow; empirical model; O(1D) Emission; solar radio flux; solar zenith angle; upper atmosphere

Explaining solar cycle effects on composition as it relates to the winter anomaly

The solar cycle variation of\ F₂\ region winter anomaly is related to solar cycle changes in the latitudinal winter-to-summer difference of O/N₂. Here we use the National Center for Atmospheric Research\textendashGlobal Mean Model to develop a concept of why the latitudinal winter-to-summer difference of O/N₂\ varies with solar cycle. The main driver for these seasonal changes in composition is vertical advection, which is expressed most simply in pressure coordinates. Meridional winds do not change over the solar cycle, so the vertical winds should also not change. The other component of vertical advection is the vertical gradient of composition. Is there any reason that this should change? At solar maximum vertical temperature gradients between 100 and 200 km altitude are strong, whereas they are weak at solar minimum. To maintain the same pressure, the weak vertical temperature gradients at solar minimum must be balanced by weak density gradients and the strong temperature gradients at solar maximum must be balanced by strong density gradients to obtain the same pressure profile. Changes in the vertical density gradients are species dependent: heavy species change more and light species change less than the average density change. Hence, vertical winds act on stronger O/N₂\ gradients at solar maximum than they do at solar minimum, and a stronger winter-to-summer difference of O/N₂\ occurs at solar maximum compared with solar minimum.

Burns, A.; Solomon, S.; Wang, W.; Qian, L.; Zhang, Y.; Paxton, L.; Yue, X.; Thayer, J.; Liu, H.;

Published by: Journal of Geophysical Research: Space Physics      Published on: 07/2015

YEAR: 2015     DOI: 10.1002/2015JA021220

composition; solar cycle; upper atmosphere

Recent investigation on the coupling between the ionosphere and upper atmosphere

Scientific attention has recently been focused on the coupling of the earth\textquoterights upper atmosphere and ionosphere. In the present work, we review the advances in this field, emphasizing the studies and contributions of Chinese scholars. This work first introduces new developments in the observation instruments of the upper atmosphere. Two kinds of instruments are involved: optical instruments (lidars, FP interferometers and all-sky airglow imagers) and radio instruments (MST radars and all-sky meteor radars). Based on the data from these instruments and satellites, the researches on climatology and wave disturbances in the upper atmosphere are then introduced. The studies on both the sporadic sodium layer and sporadic E-layer are presented as the main works concerning the coupling of the upper atmosphere and the low ionosphere. We then review the investigations on the ionospheric longitudinal structure and the causative atmospheric non-migrating tide as the main progress of the coupling between the atmosphere and the ionospheric F2-region. Regarding the ionosphere-thermosphere coupling, we introduce studies on the equatorial thermospheric anomaly, as well as the influence of the thermospheric winds and gravity waves to the ionospheric F2-region. Chinese scholars have made much advancement on the coupling of the ionosphere and upper atmosphere, including the observation instruments, data precession, and modeling, as well as the mechanism analysis.

Wan, Weixing; Xu, JiYao;

Published by: Science China Earth Sciences      Published on: 09/2014

YEAR: 2014     DOI: 10.1007/s11430-014-4923-3

Ionosphere; upper atmosphere; vertical coupling