Bibliography

Deducing Non-Migrating Diurnal Tides in the Middle Thermosphere With GOLD Observations of the Earth's far Ultraviolet Dayglow From Geostationary Orbit

The global-scale observations of the limb and disk (GOLD) Mission images middle thermosphere temperature and the vertical column density ratio of oxygen to molecular nitrogen (O/N2) using its far ultraviolet imaging spectrographs in geostationary orbit. Since GOLD only measures these quantities during daylight, and only over the ∼140° of longitude visible from geostationary orbit, previously developed tidal analysis techniques cannot be applied to the GOLD data set. This paper presents a novel approach that deduces two specified non-migrating diurnal tides using simultaneous measurements of temperature and O/N2. DE3 (diurnal eastward propagating wave 3) and DE2 (diurnal eastward propagating wave 2) during October 2018 and January 2020 are the focus of this paper. Sensitivity analyses using TIE-GCM simulations reveal that our approach reliably retrieves the true phases, whereas a combination of residual contributions from secondary tides, the restriction in longitude, and random uncertainty can lead to ∼50\% error in the retrieved amplitudes. Application of our approach to GOLD data during these time periods provides the first observations of non-migrating diurnal tides in measurements taken from geostationary orbit. We identify discrepancies between GOLD observations and TIE-GCM modeling. Retrieved tidal amplitudes from GOLD observations exceed their respective TIE-GCM amplitudes by a factor of two in some cases.

Krier, Christopher; England, Scott; Greer, Katelynn; Evans, Scott; Burns, Alan; Eastes, Richard;

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

YEAR: 2021     DOI: 10.1029/2021JA029563

airglow; composition; temperature; thermosphere; tides

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

A new technique for remote sensing of O ₂ density from 140 to 180 km

Observations of molecular oxygen are difficult to make in the Earth\textquoterights atmosphere between 140 and 200 km altitude. Perhaps the most accurate measurements to date have been obtained from satellite instruments that measure solar occultations of the limb. These do provide height-resolved O₂ density measurements, but the nature of this technique is such that the temporal/spatial distribution of the measurements is uneven. Here a new space-based technique is described that utilizes two bright dayglow emissions, the (0,0) transition of the O₂ atmospheric band and the O I (630 nm), to derive the height-resolved O₂ density from 140 to 180 km. Data from the Remote Atmospheric and Ionospheric Detection System, which was placed on the International Space Station in late 2009, are used to illustrate this technique. The O₂ density results for periods in May 2010 that were geomagnetically quiet and disturbed are compared to model predictions.

Hecht, James; Christensen, Andrew; Yee, Jeng-Hwa; Crowley, Geoff; Bishop, Rebeeca; Budzien, Scott; Stephan, Andrew; Evans, Scott;

Published by: Geophysical Research Letters      Published on: 01/2015

YEAR: 2015     DOI: 10.1002/2014GL062355

composition; technique; thermosphere

Quasi two day wave-related variability in the background dynamics and composition of the mesosphere/thermosphere and the ionosphere

Dissipating planetary waves in the mesosphere/lower thermosphere (MLT) region may cause changes in the background dynamics of that region, subsequently driving variability throughout the broader thermosphere/ionosphere system via mixing due to the induced circulation changes. We report the results of case studies examining the possibility of such coupling during the northern winter in the context of the quasi two day wave (QTDW)\textemdasha planetary wave that recurrently grows to large amplitudes from the summer MLT during the postsolstice period. Six distinct QTDW events between 2003 and 2011 are identified in the MLT using Sounding of the Atmosphere using Broadband Emission Radiometry temperature observations. Concurrent changes to the background zonal winds, zonal mean column O/N₂ density ratio, and ionospheric total electron content (TEC) are examined using data sets from Thermosphere Ionosphere Mesosphere Energetics and Dynamics Doppler Interferometer, Global Ultraviolet Imager, and Global Ionospheric Maps, respectively. We find that in the 5\textendash10 days following a QTDW event, the background zonal winds in the MLT show patterns of eastward and westward anomalies in the low and middle latitudes consistent with past modeling studies on QTDW-induced mean wind forcing, both below and at turbopause altitudes. This is accompanied by potentially related decreases in zonal mean thermospheric column O/N₂, as well as to low-latitude TECs. The recurrent nature of the above changes during the six QTDW events examined point to an avenue for vertical coupling via background dynamics and chemistry of the thermosphere/ionosphere not previously observed.

Chang, Loren; Yue, Jia; Wang, Wenbin; Wu, Qian; Meier, R.;

Published by: Journal of Geophysical Research: Space Physics      Published on: 06/2014

YEAR: 2014     DOI: 10.1002/jgra.v119.610.1002/2014JA019936

composition; Ionosphere; mesosphere; quasi two day wave; thermosphere

Effect of IMF BY on thermospheric composition at high and middle latitudes: 1. Numerical experiments

Magnetic storms and their effects on the thermosphere and ionosphere have been studied for many years, yet there are many aspects of the thermospheric and ionospheric responses that are not understood. The purpose of this paper is to show how the high-latitude composition depends on the sign of the IMF BY component, using controlled simulations with a global first principles model. Because the high-latitude convection and neutral wind systems are strongly controlled by the IMF BY component, it seems likely that the compositional response that is driven by high-latitude forcing should also be sensitive to the BY component. To date, no first-principles modeling has been performed to test the idea of IMF BY effects on composition. Numerical experiments using model simulations provide insight into this important scientific question, since the thermospheric compositional response to the convection patterns for different IMF BZ and BY can be studied in isolation in a model. In this paper we use a first-principles model to determine the effect of the IMF BY component on the compositional response of the high-latitude thermosphere. We show for the first time that a clockwise rotation of the potential pattern resulting from a change from BY-negative to BY-positive drives a corresponding rotation in the wind, neutral density, and composition distributions. BY control of thermospheric composition has been invoked in the literature to explain an apparent variability in the effectiveness of auroral activity in causing thermospheric storm effects at middle latitudes, as observed in global images of the far-ultraviolet (FUV) OI 130.4-nm emission from the DE-1 auroral imager. However, the effect in the simulations presented here is opposite from that suggested by earlier work based on DE data, indicating another explanation must be sought for the DE results. These simulations are highly relevant for interpreting data being provided by more modern UV imaging instruments on the DMSP, TIMED, and IMAGE satellites.

Crowley, G.; Immel, T.; Hackert, C.; Craven, J.; Roble, R.;

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

YEAR: 2006     DOI: https://doi.org/10.1029/2005JA011371

composition; thermospheric