Nitric Oxide Density Research Articles

Investigation of Thermospheric Response to Geomagnetic Storms Using GITM‐OVATION Prime and ‐FTA Model With Comparison to GOLD and SABER Observations

AbstractGlobal Ionosphere Thermosphere Model (GITM) results have been compared with measurements from Global‐scale observations of the limb and disk (GOLD) and Sounding of the Atmosphere using Broadband Emission Radiometry (SABER). For the first time, GOLD‐derived exospheric temperature and column‐integrated ratio measurements have been used to validate GITM model results. We examine two geomagnetic storm events for which we drive GITM with space weather conditions to understand how well the model reproduces the thermospheric responses to geomagnetic activity. In this paper, a recently developed auroral model, the Feature Tracking of Aurora (FTA) model, has been employed to calculate auroral electron precipitation in GITM (GITM w/FTA), and results are compared with the OVATION prime (OP) driven GITM model (GITM w/OP). GITM w/FTA simulated temperature, neutral density, and nitric oxide (NO) density are generally higher compared to the GITM w/OP model. During the geomagnetic storm, the GITM model and GOLD‐derived exospheric temperature agree between and N latitude in the equatorial region. GOLD measurements show strong peaks on either side of the equator during the geomagnetic storm period, which is also observed in our model results. The NO cooling peaks estimated by GITM models are 20 km lower than SABER observations during geomagnetic storms. GITM w/FTA better matches SABER observations than GITM w/OP except at low latitudes during storm time. Our model‐model/data comparisons show that improved auroral models are needed to better capture the thermospheric variations during geomagnetic storms.

Quantum Calculation of the Vibrational Excitation of Nitrogen Molecules by Fast Ions: Can It Contribute to STEVE Formation?

AbstractThe vibrational‐translational (VT) excitation of nitrogen molecules led by collisions with fast ions in subauroral ion drifts (SAID) has been conceived as a potential underlying mechanism contributing to the formation of the Strong Thermal Emission Velocity Enhancement (STEVE) phenomenon (Harding et al., 2020, https://doi.org/10.1029/2020gl087102). In this study, we perform quantum calculations of the VT excitation rates of N2 led by fast‐drifting ions, and evaluate the resulting vibrational distribution of N2 with ionospheric/thermospheric parameters expected under intense SAID condition. We conclude that, while the VT energy transfer led by SAID plays a distinguishable role in the vibrational excitation of N2, it is incapable of populating the high vibrational levels to the required concentration (Harding et al., 2020, https://doi.org/10.1029/2020gl087102) to produce adequate nitric oxide density, and in turn the nitrogen‐dioxide continuum intensity, to account for the STEVE brightness.

Energetic Electron Precipitation During Slot Region Filling Events

AbstractThe slot region marks the equatorward boundary of the energetic electron precipitation (EEP). There are, however, numerous reports where energetic electrons cross these boundaries and fill the slot region. The ensuing EEP will occur long after the geomagnetic activity subsides. This is a missing energy input in current EEP estimates scaled by geomagnetic indices. This study explores the occurrence rate, duration, and local time dependence of slot region filling events using observations from the National Oceanic and Atmospheric Administration/Polar Orbiting Environmental Satellites over a full solar cycle from 2004 to 2014. The EEP flux estimates are based on the Medium Energy Proton Electron Detector 0° and 90° detectors and the theory of pitch angle diffusion by wave‐particle interaction. The occurrence rates of >43, >114, and >292 keV events are found to be strongly energy and solar cycle dependent. Higher energy events are more likely to be associated with Coronal Mass Ejections and stronger geomagnetic deflections compared to lower energy events. Solar wind speed, Bz, and Ey reveal a calm period before the events, potentially important for preconditioning the ensuing magnetospheric mass convection. The slot region reforms more efficiently closer to the plasmapause, which creates a double EEP band throughout the recovery period. The slot region EEP maximizes around noon throughout the afternoon/evening sector, consistent with pitch angle scattering from plasmaspheric hiss and lightning induced whistler mode waves. Concurrent with slot region filling events, the Michelson Interferometer for Passive Atmospheric Sounding/Envisat nitric oxide density show an increase at <55° corrected geomagnetic latitudes. This demonstrates the importance of including slot region EEP when assessing the EEP impact on the atmosphere.

Nonequilibrium effects in high enthalpy gas flows expanding through nozzles

An approach based on the direct simulation Monte Carlo method is proposed to model a core flow in a converging–diverging nozzle. The area of applicability of this approach is defined by the Boltzmann equation, which allows fully kinetic models that accurately capture thermal and chemical nonequilibrium to be applied to gas flows where the flow regime rapidly changes from continuum to transitional. The approach is validated through comparison with available experimental data. The examination of nonequilibrium and reaction rate effects for Caltech's T5 shock tunnel condition has shown little impact of nonequilibrium but demonstrated significant sensitivity of nitric oxide (NO) density to all exchange reaction and NO recombination rates. The use of the most recent theoretical and experimental rates results in a factor of two lower NO density at the nozzle exit as compared to the conventional Park rates, which indicates that re-visiting of the latter may be necessary. Multi-parametric sensitivity study of T5 conditions has not provided an explanation for a large drop in free-stream temperature and NO density over time, under constant flow velocity, observed recently in T5. Modeling of High Enthalpy Shock Tunnel Göttingen conditions has demonstrated considerable nonequilibrium between vibrational modes of N2, NO, and O2; it has also shown that the vibration–dissociation coupling strongly influences mole fractions of NO and O2.

Measurement of nitrogen dioxide and nitric oxide densities by using CEAS (cavity‐enhanced absorption spectroscopy) in nonthermal atmospheric pressure air plasma

AbstractNonthermal atmospheric pressure plasmas are widely used in biomedicine and agriculture. Currently, radical density is used as an important parameter for the development of plasma biomedicine and agriculture. Especially, nitrogen dioxide (NO2) and nitric oxide (NO) radicals are significant species in these applications. These could be measured by using the cavity‐enhanced absorption spectroscopy (CEAS) technique. For the NO2 and NO radical density measurement, we used a visible LED (light‐emitting diode) of 660 nm and a mid‐infrared LD (laser diode) of 5238.6 nm, respectively. Radical densities can be calculated with the transmission ratio using Beer–Lambert law, which is obtained by the absorbed amount of laser intensity passed through the gas from the plasma jet in an optical cavity of CEAS.

Tuning of operational parameters for effective production of nitric oxide using an ambient air rotating glow discharge jet

In this work, we have improved the structural design of the previously reported rotating arc jet and tuned the operational parameters to achieve effective production of nitric oxide from ambient air. Tuning of parameters was performed using a statistical approach. Absolute density of nitric oxide was estimated using threshold ionization mass spectroscopy (TIMS) and deep ultraviolet absorption spectroscopy (DUVAS) and after a validation experiment it was concluded that it is possible to produce nitric oxide with densities up to 5 × 1017 cm−3 using the present setup. Low level contamination by metal sputtered from the electrodes and small concentration of ozone and other harmful species was confirmed by TIMS and DUVAS. It has been found that the energy cost for forming a nitric oxide molecule using the developed plasma jet is about 78 eV, which is considerably low compared to conventional plasma jets. This work is a step towards the practical use of plasmas in medicine and agriculture.

Reproductive, antioxidant and metabolic responses of Ossimi rams to kisspeptin

The aim of this study was to evaluate the potential reproductive, antioxidant and metabolic effects of kisspeptin-10 (KP-10) on Ossimi rams. Twelve Ossimi rams (1.5–2 years old) were divided randomly into two groups (six per group). The first one served as a control group, while the second one served as a treated group. Rams of the treated group were injected once weekly with KP-10 (5 μg/kg body weight) for one month. There were no significant differences in all measured parameters between rams of control group at pre-treatment period and those at post-treatment period. However, most examined parameters in the same rams in the treated group were affected by injection of KP-10 when comparing pre-treatment values in treated group with its post-treatment values. At the pre-treatment period, there were no significant differences between the treated and control groups regarding semen pH, mass motility, sperm concentration/mL, live and dead spermatozoa, total sperm abnormality, testosterone and oxidative stress and metabolic parameters. However, all semen characteristics were significantly improved in the treated group compared with the control group at the post-treatment period and in the treated group at the post-treatment period compared with that at the pre-treatment period. In addition, scrotal circumference, ejaculate volume and total sperm concentration/ejaculate showed higher significant improvements when comparing the treated group with the control one at the post-treatment period than when comparing the two groups at the pre-treatment period and also when comparing the treated group at the post-treatment period with that at the pre-treatment period. Serum testosterone, total antioxidant capacity, lipid peroxides, nitric oxide, total protein, albumin, glucose and high density lipoprotein-cholesterol levels significantly increased when comparing the treated group with the control one at the post-treatment period and also when comparing the treated group at the post-treatment period with that at the pre-treatment period. In conclusion, KP-10 led to potential improvement in the reproductive efficacy and metabolic capacity of Ossimi ram.

Detection of the Nitric Oxide Dayglow on Mars by MAVEN/IUVS

AbstractWe report the first remote observation of nitric oxide (NO) densities on Mars. The Imaging Ultraviolet Spectrograph (IUVS) on NASA's Mars Atmosphere and Volatile Evolution (MAVEN) satellite observes NO γ band solar resonance fluorescence between 213.0 and 225.5 nm. We invert an average dayglow limb radiance profile to retrieve a number density profile between 80 and 130 km. The retrieved IUVS NO number density at 117 km is 5 times smaller than those measured by Viking mass spectrometers over 40 years ago but consistent with photochemical model results within the IUVS statistical uncertainty. These observations may therefore help to reconcile a longstanding problem in our understanding of NO photochemistry in the Martian upper atmosphere. We also report the first detection of the CO+ First Negative bands in the Martian dayglow near 219 nm.

Estimated nitric oxide density in auroras from ground-based photometric data

In this paper, we numerically estimate the nitric oxide density in auroras, using photometric data on 427.8, 557.7, and 630.0 nm emission intensities. The data were obtained at midnight at observatories of the Polar Geophysical Institute. These estimates were made using a numerical modeling procedure with a time-dependent model of the auroral ionosphere [Dashkevich et al., 2017]. It is shown that the NO density in the maximum of the altitude profile is between (1÷3.3)∙10^8 cm–3. The obtained estimates indicate the absence of a correlation between the [NO]max values and 427.8 nm emission intensities.

Оценка содержания окиси азота в полярных сияниях по данным наземных фотометрических наблюдений

In this paper, we numerically estimate the nitric oxide density in auroras, using photometric data on 427.8, 557.7, and 630.0 nm emission intensities. The data were obtained at midnight at observatories of the Polar Geophysical Institute. These estimates were made using a numerical modeling procedure with a time-dependent model of the auroral ionosphere [Dashkevich et al., 2017]. It is shown that the NO density in the maximum of the altitude profile is between (1÷3.3)∙10^8 cm–3. The obtained estimates indicate the absence of a correlation between the [NO]max values and 427.8 nm emission intensities.

Impact of nitric oxide, solar EUV and particle precipitation on thermospheric density decrease

Recent studies have revealed that the post-storm thermospheric mass density at a fixed altitude could be lower than the pre-storm mass density. This phenomenon has been attributed to an overcooling effect caused by enhanced infrared emissions from nitric oxide (NO). Here we report that thermospheric density decrease can take place under both storm and non-storm conditions. Relevant observations are presented during two superstormes, one intense storm, and one non-storm case. Thermospheric neutral density variations observed by GOCE and CHAMP satellites are investigated along with simultaneous measurements of thermospheric nitric oxide density and emissions from TIMED/GUVI and TIMED/SABER, respectively, together with auroral hemispheric power from DMSP, Joule heating rate from the Assimilative Mapping of Ionospheric Electrodynamics (AMIE) algorithm, and solar extreme ultraviolet (EUV) flux from SOHO/SEM and TIMED/SEE. It was found that the apparent storm-time density decrease or “overcooling” is a result of combined effects: an increase in NO cooling and a decrease in both the solar EUV flux and the auroral energy input. It was also found that whether or not a density decrease exists depends on whether there are auroral activities prior to the pre-storm reference day and how the reference day is chosen. The relative contributions of the different drivers (namely, enhanced NO cooling and variations in auroral hemispheric power, Joule heating, and solar EUV at the pre-storm and post-storm days) to thermospheric density decrease remain to be determined.

An Intercomparison of VLF and Sounding Rocket Techniques for Measuring the Daytime D Region Ionosphere: Theoretical Implications

AbstractWe compare the two approaches that have been used to measure the lowermost ionosphere, the measurement of the propagation of very low frequency (VLF) radio waves and the in situ sampling by sounding rockets. We focus on the altitude, latitude, and zenith angle variation of the electron density profiles inferred from these two observational techniques as compared with a theoretical photochemical model. Our results show that below 68–70 km, the VLF data and the model agree better with each other than with the sounding rocket profile. At the lowest altitudes, near 60 km, both the VLF data and the model show a greater electron density at higher latitudes, consistent with a cosmic ray flux that increases with latitude, whereas the limited rocket data show a maximum at the tropics. Above 68–70 km, the VLF data and the sounding rockets agree better and at tropical latitudes, the model fails to reproduce the observations. Specifically, the calculated electron density is lower than the data by up to a factor of 2. Possible reasons for the model deficit include underestimates of the solar Lyman alpha flux, the solar X‐ray flux and the mesospheric nitric oxide density. Once these three factors are mitigated, the model is in agreement with the observations between 60 and 80 km.

Study of plasma-chemical NO-containing gas flow for treatment of wounds and inflammatory processes

This work is aimed at exhaustive and detailed study of chemical, physical and physico-chemical characteristics of NO-containing gas flow (NO-CGF) generated by a plasma-chemical generator of Plason device, which has been used in medical practice for more than 15 years for effectively healing wound and inflammatory conditions with exogenous nitric oxide (NO-therapy). Data was obtained on spatial structure of the gas flow, and values of its local parameters in axial and radial directions, such as nitric oxide content, velocity, temperature and mass flow density of nitric oxide, providing altogether the effectiveness of treatment by the exogenous NO-therapy method, were determined experimentally and by computations. It was demonstrated that plasma-chemical synthesis of NO from atmospheric air in a low direct current (DC) arc provides a high mass flow of nitric oxide at the level of 1.6-1.8mg/s, while in the area of impact of NO-CGF on the biological tissue, on its axis, NO content is 400-600ppm, flow velocity about 5m/s, nitric oxide mass flow density 0.25-0.40 mg/(s·cm2), temperature 40-60°C. Tendencies were determined for designing new devices for further experimental biological and medical research in the field of NO-therapy: lowering the temperature of NO-CGF to ambient temperature will enable variation, in experiments, of the affecting flow parameters in a wide range up to their maximum values: NO content up to 2000ppm, velocity up to 20m/s, nitric oxide mass flow density up to 2.5 mg/(s·cm2).

High-spatial resolution measurements of NO density and temperature by Mid-IR QCLAS in open-air confined plasmas

Radial distributions of absolute nitric oxide (NO) density and gas temperature are measured in atmospheric confined plasmas using Mid-IR quantum cascade laser absorption spectroscopy (QCLAS). Two ro-vibrational transitions of the fundamental band are probed in the electronic ground state NO(X) at 1900.076 cm−1 and 1900.517 cm−1, respectively. Plasmas are generated using nanosecond repetitively pulsed (NRP) discharges in air at atmospheric pressure. The spatial measurements are radially performed halfway between the discharge electrodes with a resolution down to 0.3 mm by the Abel inversion technique. The gas temperature is determined using two methods: (i) based on the ratio of the two ro-vibrational absorption lines and (ii) based on the collisional broadening line shape. The local NO density is obtained from local absorption coefficients and temperature dependent line strengths. The results were found in good agreement. The time averaged gas temperature and density at the discharge center are found at 800(±100) K and 2(±0.2) × 1015 cm−3, respectively. The FWHM of the NO density radial profile is found at 6–7 mm. This is large compared to the discharge channel width, i.e. typically below 0.5 mm, which is explained mainly by hot reactive jets induced in the post-discharge.

Electron density variability of nighttime D region ionosphere in Vietnamese and Japanese sectors

AbstractRecording tweek atmospherics on geomagnetically quiet days in 2014 at Tay Nguyen University (TNU) (12.65°N, 108.02°E), Vietnam, and at Kagoshima (KAG) (31.48°N, 130.72°E), Japan, we investigated the nighttime electron density variability of the D region ionosphere between the equatorial‐low‐latitude Vietnamese and the low‐ to middle‐latitude Japanese sectors. We estimated the reflection height and electron density of the D region ionosphere using the first‐order mode cutoff frequency of tweek atmospherics. The results observed at both stations show that the mean electron density at the reflection height during winter season was higher than that during summer and equinox seasons. The electron density observed at TNU gradually decreased from 20:15 to 4:15 LT from winter to equinox and to summer. The electron density observed at KAG increased from 20:20 to 4:20 LT during summer and winter seasons. The mean electron density during 2014 observed at TNU (25.0 cm−3) was higher by 2.1 cm−3 than that observed at KAG (22.9 cm−3). During 2014, the nighttime electron density variations show a moderate positive correlation with the sunspot number but show weak to no correlation with the galactic cosmic rays. We suggest that the seasonal variations in the nighttime electron density could be significantly caused by the enhancement of geocoronal hydrogen Lyman α intensity and seasonal variation of nitric oxide density in the lower ionosphere.

Production of nitric oxide using a microwave plasma torch and its application to fungal cell differentiation

The generation of nitric oxide by a microwave plasma torch is proposed for its application to cell differentiation. A microwave plasma torch was developed based on basic kinetic theory. The analytical theory indicates that nitric oxide density is nearly proportional to oxygen molecular density and that the high-temperature flame is an effective means of generating nitric oxide. Experimental data pertaining to nitric oxide production are presented in terms of the oxygen input in units of cubic centimeters per minute. The apparent length of the torch flame increases as the oxygen input increases. The various levels of nitric oxide are observed depending on the flow rate of nitrogen gas, the mole fraction of oxygen gas, and the microwave power. In order to evaluate the potential of nitric oxide as an activator of cell differentiation, we applied nitric oxide generated from the microwave plasma torch to a model microbial cell (Neurospora crassa: non-pathogenic fungus). Germination and hyphal differentiation of fungal cells were not dramatically changed but there was a significant increase in spore formation after treatment with nitric oxide. In addition, the expression level of a sporulation related gene acon-3 was significantly elevated after 24 h upon nitric oxide treatment. Increase in the level of nitric oxide, nitrite and nitrate in water after nitric oxide treatment seems to be responsible for activation of fungal sporulation. Our results suggest that nitric oxide generated by plasma can be used as a possible activator of cell differentiation and development.

Nitric oxide density distributions in the effluent of an RF argon APPJ: effect of gas flow rate and substrate

The effluent of an RF argon atmospheric pressure plasma jet, the so-called kinpen, is investigated with focus on the nitric-oxide (NO) distribution for laminar and turbulent flow regimes. An additional dry air gas curtain is applied around the plasma effluent to prevent interaction with the ambient humid air. By means of laser-induced fluorescence (LIF) the absolute spatially resolved NO density is measured as well as the rotational temperature and the air concentration. While in the laminar case, the transport of NO is attributed to thermal diffusion; in the turbulent case, turbulent mixing is responsible for air diffusion. Additionally, measurements with a molecular beam mass-spectrometer (MBMS) absolutely calibrated for NO are performed and compared with the LIF measurements. Discrepancies are explained by the contribution of the and to the MBMS NO signal. Finally, the effect of a conductive substrate in front of the plasma jet on the spatial distribution of NO and air diffusion is also investigated.

Ground‐based observations of nitric oxide in the mesosphere and lower thermosphere over Antarctica in 2012–2013

AbstractWe report temporal variations of the partial column density of nitric oxide (NO) in an altitude range 75–105 km at Syowa Station, Antarctica, from January 2012 to September 2013. We found two patterns of NO temporal variation: (1) a seasonal cycle with a maximum in winter and a minimum in summer, and (2) short‐term enhancements on a time frame of 5–10 days associated with solar activities. In the seasonal cycle, the variation pattern of NO showed good agreement with scotoperiod of solar radiation rather than the downwelling atmospheric transport, suggesting that photodissociation is the main driver of the seasonal variation. To study the short‐term enhancements, we compared the NO column density with the proton and electron fluxes obtained by the POES/METOP (Polar Orbiting Environmental Satellite/Meteorological Operational) satellites. There is a weak but significant correlation between the NO and the electron flux, but no correlation between the NO and the proton flux. We also made a detailed comparison of the time series of NO and proton/electron fluxes for 12 selected 25‐day time frames, and found that at least two remarkable NO enhancements occurred without any solar proton events (SPEs). During electron precipitation, the NO column density peaked 1–5 days after the commencement of geomagnetic storms, whereas the relationship between NO and the solar proton is not clear because the electron flux also increased at the same time. These results suggest that energetic electron precipitation may be a major cause of NO enhancements above Syowa Station in the auroral region, even during SPEs.

Odin observations of Antarctic nighttime NO densities in the mesosphere–lower thermosphere and observations of a lower NO layer

The Optical Spectrograph and Infrared Imaging System (OSIRIS) on the Odin satellite currently has an eight‐year dataset of nighttime Antarctic nitric oxide densities, [NO], in the mesosphere–lower thermosphere (MLT) region. In this work, the OSIRIS data are compared with a similar data set from the Sub‐Millimeter Radiometer (SMR), also on the Odin satellite. Both of the Odin data sets are compared with twilight [NO] from the Atmospheric Chemistry Experiment–Fourier Transform Spectrometer (ACE‐FTS) on the SciSat‐I satellite. Direct comparisons of OSIRIS and SMR profiles show large differences, indicating that the individual [NO] profiles of one or both data sets may not be valid. However, when comparing averaged [NO], variations on timescales of weeks‐years in all three data sets are in good agreement and correspond to the 27 day and 11 year solar cycles. The averaged OSIRIS values are typically 10% greater than SMR and 30% greater than ACE‐FTS, which are within the estimated OSIRIS systematic uncertainties. These results suggest that the satellite‐derived data sets can be used for determining polar‐mean NO climatology and variations on timescales of weeks‐years. The OSIRIS and SMR nighttime data sets show that the [NO] peak height in the MLT decreases throughout the autumn, from an altitude near or above 100 km to a minimum altitude ranging from 90 to 95 km around winter solstice. A similar decrease in [NO] peak height is observed in modeled NO climatology from the Specified Dynamics–Whole Atmosphere Community Climate Model (SD‐WACCM), although the SD‐WACCM climatology exhibits a decrease throughout autumn from 107 km down to 102 km. The results suggest that global climate models require more sophisticated auroral forcing simulations in order to reproduce observed NO variations in this region.

NO concentrations in laminar premixed CH4/O2/N2 flames with varying equivalence ratio

Number density and concentration of nitric oxide have been investigated in laminar premixed CH4/O2/N2 flames using laser-induced fluorescence technique. Emphasis was placed on quantitative measurements, which were taken in flames at various equivalence ratios ranging from 0.9 ∼ 3.0. The flow rate was fixed at 2 SLPM. The NO A-X (0,0) vibrational band around 226 nm was excited using a XeCl excimer-pumped dye laser. By selecting an appropriate NO transition, the interferences from elastic scattering and O2 fluorescence were minimized. Results show that the maximum NO concentration increased at the range of equivalence ratio from ϕ = 0.9 to 1.6, decreased from ϕ = 1.6 to 2.0 and slowly increased with increasing equivalence ratio above ϕ = 2.0. Also, the maximum NO concentration was at around the reaction zone.