Oxygen Red Line Research Articles

Exploring Altitudinal Resolution of Twilight Airglow Red Lines Using Twilight Photometer

AbstractTwilight Photometer observations were carried out at low latitude station Kolhapur (16039’42.2”N, 74014’20.8”E) India, during the period 1 January 2009 to 31 December 2011 to yield a reasonable qualitative picture of the day‐to‐day variability of the vertical distribution of the atmospheric aerosols from about 6 km to a maximum of 350 km. In this study, one attempt was made to observe twilight airglow red lines having wavelengths in between 6100 Å and 7100 Å using the vertical profiles of aerosols. The rate of change of red light due to the twilight airglow shows narrow peaks with ∼600%–1000% rise in intensity than due to aerosol twilight glow. Our observations provides information about ionized Nitrogen (N2) emissions at 6482.05 Å, 6610.56 Å and 6482.70 Å, oxygen red emission lines of 6300 Å and 6364 Å, emission caused by formation of a molecule of nitric oxide (NO), metallic emissions of sodium four red lines between 6500 and 6700 Angstroms and lithium near 6708 Å, hydroxyl (OH) emission at 6329 Å and red sprites emissions (at altitudes 50–90 km). The principal aspiration of this study is to highlight the conspicuous capability of Semiautomatic twilight photometer to study the twilight airglow emission lines. This is the first attempt in India to obtain the twilight airglow data using Twilight photometer. Twilight Photometer, although currently seldom used, is still a very effective and the most appropriate ground based passive remote sensing tool for long‐term monitoring of different atmospheric components in a wide range of altitude for day‐to‐day basis. It is an efficient system having a simple and inexpensive underlying principle of operations, yet exhibits extremely accurate and precise usage and can be operated by even a person of average skill. However, it can be seen that the resultant data was consistent with nearest peer technologies, such as LIDARs, Balloon‐Borne instruments, rocket measurements, satellite observations etc.

The Mars Oxygen Visible Dayglow: A Martian Year of NOMAD/UVIS Observations

AbstractThe Ultraviolet and Visible Spectrometer Ultraviolet (UVIS UV) and Visible Spectrometer channel of the Nadir and Occultation for MArs Discovery spectrometer aboard the ExoMars Trace Gas Orbiter has made limb observations of the Martian dayglow during more than a Martian year. Two pointing modes have been applied: (a) In the inertial mode, the spectrometer scans the atmosphere twice down to near the surface and provides altitude profiles of the dayglow; (b) in the tracking mode, the atmosphere is scanned at varying latitudes at a nearly constant altitude through the entire observation. We present a statistical study of the vertical and seasonal distribution of the recently discovered oxygen green and red lines at 557.7 nm and 630 nm. It indicates that the brightness of the green line emission responds to changes in the Lyman‐α flux. The peak altitude of the green line emission increases seasonally when the Sun‐Mars distance decreases. The lower peak of the green line statistically drops by 15–20 km between perihelion and aphelion at mid‐to high altitude. The main lower peak intensity shows an asymmetry between the two hemispheres. It is significantly brighter and more pronounced in the southern hemisphere than in the north. This is a consequence of the stronger Lyman‐α solar flux near perihelion. The second component of the oxygen red line at 636.4 nm is also detected for the first time in the Martian atmosphere. A photochemical model is used to simulate the variations of the green dayglow observed along limb tracking orbits.

Errors From Asymmetric Emission Rate in Spaceborne, Limb Sounding Doppler Interferometry: A Correction Algorithm With Application to ICON/MIGHTI.

The Michelson Interferometer for Global High‐resolution Thermospheric Imaging (MIGHTI) on NASA's Ionospheric Connection Explorer (ICON) mission is designed to measure the neutral wind and temperature between 90 and 300 km altitude. Using the Doppler Asymmetric Spatial Heterodyne (DASH) spectroscopy technique, observations from MIGHTI can be used to derive thermospheric winds by measuring Doppler shifts of the atomic oxygen red line (630.0 nm) and green line (557.7 nm). Harding et al. (2017, https://doi.org/10.1007/s11214‐017‐0359‐3) (Harding17) describe the wind retrieval algorithm in detail and point out the large uncertainties that result near the solar terminators and equatorial arcs, regions of large spatial gradients in airglow volume emission rates (VER). The uncertainties originate from the assumption of a constant VER at every given altitude, resulting in errors where the assumption is not valid when limb sounders, such as MIGHTI, observe regions with significant VER gradients. In this work, we introduce a new wind retrieval algorithm (Wu20) with the ability to account for VER that is asymmetric along the line of sight with respect to the tangent point. Using the predicted ICON orbit and simulated global VER variation, the greatest impact of the symmetric airglow assumption to the ICON vector wind product is found within 30° from the terminator when the spacecraft is in the dayside, causing an error of at least 10 m/s. The new algorithm developed in this study reduces the error near the terminator by a factor of 10. Although Wu20 improves the accuracy of the retrievals, it loses precision by 75% compared to Harding17.

Mutual Allocation of the Artificial Airglow Patches and Large‐Scale Irregularities in the HF‐Pumped Ionosphere

AbstractThe paper reports first simultaneous observations of artificial emission of 630‐nm oxygen red line, along with perturbations of slant total electron content (STEC). They were induced by the high‐frequency (HF) ionospheric heating produced by the SURA facility situated near Nijniy Novgorod, Russia. The HF heating affects differently the optical emission and STEC. While the patches of the artificial airglow are close to the area of the reduced STEC, the STEC increases at the periphery of the patches. Thus, the artificial airglow occurs mostly inside the large plasma cavities.

Intensity Variations of OI 557.7 nm and OI 630.0 nm Lines before M5.0 and Greater Earthquakes in Tokyo Region, Japan, in 1979 to 1990

The intensity variation of 557.7 nm oxygen green line and 630.0 nm oxygen red line at Kiso observatory, Tokyo, and variations in critical frequency of the ionospheric F2 layer (foF2) and semi transparency coefficient related to the E layer before earthquakes with magnitude ≥ 5 are considered for 1979 to 1990. The intensity of both the lines increases within six days before earthquakes; foF2 and semi transparency coefficient abnormally increase before enhancement of airglow. The superposed epoch analysis of each variable is done for further confirmation. Some physical processes in atmosphere-ionosphere in pre-seismic days enhance the concentration of electron and neutral molecules in the ionospheric F and E regions. These events influence the dissociative recombination processes related to oxygen emission, and so the intensity of two line emissions show some special type of variations during earthquake events.

Multi-instrument observations of large-scale atmospheric gravity waves/traveling ionospheric disturbances associated with enhanced auroral activity over Svalbard

This study reports on observations of large-scale atmospheric gravity waves/traveling ionospheric disturbances (AGWs/TIDs) using Global Positioning System (GPS) total electron content (TEC) and Fabry–Perot Interferometer’s (FPI’s) intensity of oxygen red line emission at 630 nm measurements over Svalbard on the night of 6 January 2014. TEC large-scale TIDs have primary periods ranging between 29 and 65 min and propagate at a mean horizontal velocity of ∼749–761 m/s with azimuth of ∼345–347° (which corresponds to poleward propagation direction). On the other hand, FPI large-scale AGWs have larger periods of ∼42–142 min. These large-scale AGWs/TIDs were linked to enhanced auroral activity identified from co-located all-sky camera and IMAGE magnetometers. Similar periods, speed and poleward propagation were found for the all-sky camera (∼60–97 min and ∼823 m/s) and the IMAGE magnetometers (∼32–53 min and ∼708 m/s) observations. Joule heating or/and particle precipitation as a result of auroral energy injection were identified as likely generation mechanisms for these disturbances.

On the Connection Between the Spatial Behavior of the Total Electron Content of the Ionosphere on the GPS Signal Path and the Ionospheric Artificial Airglow in the 630 nm Line

We present the results of simultaneous measurements of the total electron content (TEC) of the ionosphere on the GPS signal path and the ionospheric artificial airglow in the atomic oxygen red line (λ = 630 nm) during HF pumping of the ionosphere by the Sura facility radiation. It is very likely that when the “navigation satellite—GPS receiver” path of a signal crosses the artificial airglow spot, the maximum brightness of the latter on the line of sight of the optical device at the navigation satellite was observed in the region of the TEC minimum.

Michelson Interferometer for Global High-resolution Thermospheric Imaging (MIGHTI): Instrument Design and Calibration.

The Michelson Interferometer for Global High-resolution imaging of the Thermosphere and Ionosphere (MIGHTI) instrument was built for launch and operation on the NASA Ionospheric Connection Explorer (ICON) mission. The instrument was designed to measure thermospheric horizontal wind velocity profiles and thermospheric temperature in altitude regions between 90km and 300km, during day and night. For the wind measurements it uses two perpendicular fields of view pointed at the Earth's limb, observing the Doppler shift of the atomic oxygen red and green lines at 630.0nm and 557.7nm wavelength. The wavelength shift is measured using field-widened, temperature compensated Doppler Asymmetric Spatial Heterodyne (DASH) spectrometers, employing low order échelle gratings operating at two different orders for the different atmospheric lines. The temperature measurement is accomplished by a multichannel photometric measurement of the spectral shape of the molecular oxygen A-band around 762nm wavelength. For each field of view, the signals of the two oxygen lines and the A-band are detected on different regions of a single, cooled, frame transfer charge coupled device (CCD) detector. On-board calibration sources are used to periodically quantify thermal drifts, simultaneously with observing the atmosphere. The MIGHTI requirements, the resulting instrument design and the calibration are described.

Modeling nightglow in atomic oxygen red and green lines under moderate disturbed geomagnetic conditions at midlatitudes

We present results of a study of mid-latitude auroras. The study is based on optical measurements and theoretical modeling. The modeling shows that precipitation can indirectly generate airglow in red and green lines of atomic oxygen by increasing rates of ion formation and heating of thermal electrons. This causes an increase in the rate of dissociative recombination and thermal-electron-collision excitation of the 1D and 1S levels.

The thermospheric auroral red line polarization: confirmation of detection and first quantitative analysis

The thermospheric atomic oxygen red line is among the brightest in the auroral spectrum. Previous observations in Longyearbyen, Svalbard, indicated that it may be intrinsically polarized, but a possible contamination by light pollution could not be ruled out. During the winter 2010/2011, the polarization of the red line was measured for the first time at the Polish Hornsund polar base without contamination. Two methods of data analysis are presented to compute the degree of linear polarization (DoLP) and angle of linear polarization (AoLP): one is based on averaging and the other one on filtering. Results are compared and are in qualitative agreement. For solar zenith angles (SZA) larger than 108° (with no contribution from Rayleigh scattering), the DoLP ranges between 2 and 7%. The AoLP is more or less aligned with the direction of the magnetic field line, in agreement with the theoretical predictions of . However, the AoLP values range between ±20° around this direction, depending on the auroral conditions. Correlations between the polarization parameters and the red line intensity I were considered. The DoLP decreases when I increases, confirming a trend observed during the observations in Longyearbyen. However, for small values of I , DoLP varies within a large range of values, while for large values of I , DoLP is always small. The AoLP also varies with the red line intensity, slightly rotating around the magnetic field line.

Excited oxygen states in the Venus nightglow 1This article is part of a Special Issue that honours the work of Dr. Donald M. Hunten FRSC who passed away in December 2010 after a very illustrious career.

In the absence of solar radiation, the most common photoexcitation process in the terrestrial planets results from atom recombination. Thus, in the Mars and Venus atmospheres recombination of O(3P) + O(3P) and O(3P) + N(4S) leads to emissions of excited states of O2 and NO, respectively. However, in the Earth’s atmosphere there are ionospheric emissions that depend on interactions of charged species, for example, the oxygen red and green lines arising from dissociative recombination (DR) of [Formula: see text]. In the case of the CO2 planets, the predominant ionospheric ion is also [Formula: see text], so that in principle DR is important in that environment, where the markers would also be the red and green lines. Whether these can be detected depends on DR rates and the radiating efficiencies of these species. In this report we discuss the history of green line detection in the Venus nightglow as well as the observations of excited O2 molecules, and the lack of appearance of the O2 (b–X) Atmospheric 0–0 band.

Photoabsorption in Ganymede’s atmosphere

In the framework of future space missions to Ganymede, a pre-study of this satellite is a necessary step to constrain instrument performances according to the mission objectives. This work aims at characterizing the impact of the solar UV flux on Ganymede’s atmosphere and especially at deriving some key physical parameters that are measurable by an orbiter. Another objective is to test several models for reconstructing the solar flux in the Extreme-UV (EUV) in order to give recommendations for future space missions.Using a Beer–Lambert approach, we compute the primary production of excited and ionized states due to photoabsorption, neglecting the secondary production that is due to photoelectron impacts as well as to precipitated suprathermal electrons. Ions sputtered from the surface are also neglected. Computations are performed at the equator and close to the pole, in the same conditions as during the Galileo flyby. From the excitations, we compute the radiative relaxation leading to the atmospheric emissions. We also propose a simple chemical model to retrieve the stationary electron density. There are two main results: (i) the modelled electron density and the one measured by Galileo are in good agreement. The main atmospheric visible emission is the atomic oxygen red line at 630nm, both in equatorial and in polar conditions, in spite of the different atmospheric compositions. This emission is measurable from space, especially for limb viewing conditions. The OH emission (continuum between 260 and 410nm) is also probably measurable from space. (ii) The input EUV solar flux may be directly measured or reconstructed from only two passbands solar observing diodes with no degradation of the modelled response of the Ganymede’s atmosphere. With respect to these results, there are two main conclusions: (i) future missions to Ganymede should include the measurement of the red line as well as the measurement of OH emissions in order to constrain the atmospheric model. (ii) None of the common solar proxies satisfactorily describes the level of variability of the solar EUV irradiance. For future atmospheric planetary space missions, it would be more appropriate to derive the EUV flux from a small radiometer rather than from a full-fledged spectrometer.

Polarisation in the auroral red line during coordinated EISCAT Svalbard Radar/optical experiments

Abstract. The polarisation of the atomic oxygen red line in the Earth's thermosphere is observed in different configurations with respect to the magnetic field line at high latitude during several coordinated Incoherent Scatter radar/optical experiment campaigns. When pointing northward with a line-of-sight nearly perpendicular to the magnetic field, we show that, as expected, the polarisation is due to precipitated electrons with characteristic energies of a few hundreds of electron Volts. When pointing toward the zenith or southward with a line-of-sight more parallel to the magnetic field, we show that the polarisation practically disappears. This confirms experimentally the predictions deduced from the recent discovery of the red line polarisation. We show that the polarisation direction is parallel to the magnetic field line during geomagnetic activity intensification and that these results are in agreement with theoretical work.

Is the Jovian auroral H\hbox{$_{3}^{+}$} emission polarised?

Context. Measurement of linear polarisation in Earth’s thermospheric oxygen red line can be a useful observable quantity for characterising conditions in the upper atmosphere; therefore, polarimetry measurements are extended to other planets. Since FUV emissions are not observable from the ground, the best candidates for Jupiter auroral emissions are infrared lines near 4 μm. This ion is created after a chemical process in the Jovian upper atmosphere. Thus the anisotropy responsible of the polarisation cannot be the particle impact as in the Earth case.

Remote Oxygen Sensing by Ionospheric Excitation (ROSIE)

Abstract. The principal optical observable emission resulting from ionospheric modification (IM) experiments is the atomic oxygen red line at 630 nm, originating from the O(1D–3P) transition. Because the O(1D) atom has a long radiative lifetime, it is sensitive to collisional relaxation and an observed decay faster than the radiative rate can be attributed to collisions with atmospheric species. In contrast to the common practice of ignoring O-atoms in interpreting such observations in the past, recent experimental studies on the relaxation of O(1D) by O(3P) have revealed the dominant role of oxygen atoms in controlling the lifetime of O(1D) at altitudes relevant to IM experiments. Using the most up-to-date rate coefficients for collisional relaxation of O(1D) by O, N2, and O2, it is now possible to analyze the red line decays observed in IM experiments and thus probe the local ionospheric composition. In this manner, we can demonstrate an approach to remotely detect O-atoms at the altitudes relevant to IM experiments, which we call remote oxygen sensing by ionospheric excitation (ROSIE). The results can be compared with atmospheric models and used to study the temporal, seasonal, altitude and spatial variation of ionospheric O-atom density in the vicinity of heating facilities. We discuss the relevance to atmospheric observations and ionospheric heating experiments and report an analysis of representative IM data.

Polarization in aurorae: A new dimension for space environments studies

The polarization of emission lines is a noteworthy observational parameter in astronomy. However, it has never been detected without ambiguity in planetary upper atmospheres. Theoretical considerations have suggested that the polarization of the thermospheric oxygen red line (630 nm) could exist in the polar cap region. We present here its first successful measurement at Svalbard in January 2007, during active geophysical conditions. We assign its origin and variability to complementary effects between permanent low‐energy electron precipitation and sporadic auroral events. Implications in physics, geophysics and planetary science are foreseen. In physics, it raises the question of the polarization of a forbidden transition by electron impact which is still unknown. In geophysics, it provides a new parameter to constrain the thermospheric models. In planetary science, it makes it possible to derive the local configuration of the magnetic fields. It therefore opens new perspectives for future space missions towards other planets

High time resolution measurements of the thermosphere from Fabry-Perot Interferometer measurements of atomic oxygen

Abstract. Recent advances in the performance of CCD detectors have enabled a high time resolution study of the high latitude upper thermosphere with Fabry-Perot Interferometers (FPIs) to be performed. 10-s integration times were used during a campaign in April 2004 on an FPI located in northern Sweden in the auroral oval. The FPI is used to study the thermosphere by measuring the oxygen red line emission at 630.0 nm, which emits at an altitude of approximately 240 km. Previous time resolutions have been 4 min at best, due to the cycle of look directions normally observed. By using 10 s rather than 40 s integration times, and by limiting the number of full cycles in a night, high resolution measurements down to 15 s were achievable. This has allowed the maximum variability of the thermospheric winds and temperatures, and 630.0 nm emission intensities, at approximately 240 km, to be determined as a few minutes. This is a significantly greater variability than the often assumed value of 1 h or more. A Lomb-Scargle analysis of this data has shown evidence of gravity wave activity with waves with short periods. Gravity waves are an important feature of mesosphere-lower thermosphere (MLT) dynamics, observed using many techniques and providing an important mechanism for energy transfer between atmospheric regions. At high latitudes gravity waves may be generated in-situ by localised auroral activity. Short period waves were detected in all four clear nights when this experiment was performed, in 630.0 nm intensities and thermospheric winds and temperatures. Waves with many periodicities were observed, from periods of several hours, down to 14 min. These waves were seen in all parameters over several nights, implying that this variability is a typical property of the thermosphere.

On the location and structure of the artificial 630-nm airglow patch over Sura facility

Abstract. Results are presented of the artificial optical emission of the atomic oxygen red line (the radiation of level O(1D) with a wavelength of 630 nm) from the HF-pumped ionosphere, obtained in September 2004 at the SURA heating facility situated near Nizhny Novgorod, Russia. For vertical pumping the airglow patch was increasingly displaced to the north, up to 7–8°, with increasing reflection altitude. For large brightness of the emission, the airglow patch started to develop at the northern edge of the pump beam and later expanded to the south. These effects are attributed to the precipitation of supra-thermal electrons from the pump wave upper hybrid resonance altitude to lower altitudes where excitation of the O(1D) level is more effective due to the larger density of atomic oxygen, and the O(1D) lifetime is shorter. For a pump beam inclination of 12° to the south, the optical spot was displaced by 4–5° to the south relative to the straight-line projection of the pump beam onto the sky. This exceeds that expected from the ray tracing and may be related, most probably, to the so-called "magnetic zenith" effect. In addition, mid-scale (1–10 km) magnetic field-aligned structures were observed in the pumped volume of the ionosphere. The east-west motions of the airglow patches are also analyzed.

Considering the polarization of the oxygen thermospheric red line for space weather studies

Space weather thermospheric monitoring requires real‐time and large‐scale measurements. In order to monitor the thermospheric variations due to geomagnetic activity, one relies mostly on the measurements of the intensity of the atomic oxygen green line and on the indirect measurement of the total electron content. These two parameters do not allow retrieving the full characteristics of the thermosphere, and a third proxy is required, for example, in orbitography. We propose to use the polarization of the atomic oxygen red line to fulfill this requirement. The first measurements of the polarization of thermospheric nightglow lines have been performed in the first part of the twentieth century and especially during the last International Geophysical Year. Amongst the oxygen visible lines, only the red one seems to be potentially polarized. However, there exists a disagreement between the different measurements. At the origin of the polarization, there is always a dissymmetric mechanism. It triggers either an emission process, a light scattering, or, in the case of the oxygen red line, a collision mechanism. This paper reviews the different experiments performed in the past and proposes to explore this matter with modern facilities. If successful, this investigation could lead to a systematic reanalysis of the previous red line interferometric measurements.

Review of tropical nightglow studies with astronomical instruments

Much of upper atmospheric chemistry and physics can be read in the detailed study of the nightglow. There are several classic observables—oxygen green line, oxygen red lines, OH, O 2 Atmospheric 0–1—but these are chosen for their convenient intensities, not necessarily because they reveal the most about the atmosphere. It has recently become evident that the sky spectra obtained at large telescopes show the nightglow and even glimpses of the dayglow with much more detail than has been previously available. Here we show examples of this new information, attempting to make the case that having such instruments for use by the aeronomic community would have great benefits. A recent review of this work has been published in conjunction with related laboratory experiments [Slanger, T.G., Copeland, R.A., 2003. Energetic oxygen in the upper atmosphere and the laboratory. Chemical Review Letters 103, 4731–4765].