HO2 enhancements due to sprite discharges - observations and model simulations

2020 ◽  
Author(s):  
Holger Winkler ◽  
Takayoshi Yamada ◽  
Yasuko Kasai ◽  
Justus Notholt
Keyword(s):  
Plasma Chemistry ◽  
Submillimeter Wave ◽  
Electrical Discharges ◽  
Model Simulations ◽  
Direct Observations

<p>We present first observational evidences of an HO<sub>2 </sub>production in the mesosphere above sprite‐producing thunderstorms derived from low‐noise SMILES (Submillimeter-Wave Limb-Emission Sounder) observation spectra in relation with sprite detections by the ISUAL (Imager of Sprites and Upper Atmospheric Lightning) instrument. Three events were identified with enhanced HO<sub>2</sub> levels of approximately 10<sup>25</sup> molecules at altitudes of 75-80 km a few hours after sprite occurrence. These first direct observations of chemical sprite effects are compared to results of plasma chemistry model simulations of electrical discharges in the mesosphere, and processes which can lead to an increase of mesospheric HO<sub>2</sub> on timescale of a few hours after a sprite event are analysed.</p>

scholarly journals Model simulations of chemical effects of sprites in relation with satellite observations

2021 ◽  
Author(s):  
Holger Winkler ◽  
Takayoshi Yamada ◽  
Yasuko Kasai ◽  
Uwe Berger ◽  
Justus Notholt
Keyword(s):  
Dispersion Model ◽  
Plasma Chemistry ◽  
Water Molecules ◽  
Streamer Discharge ◽  
Model Simulations ◽  
Direct Observations ◽  
Chemical Effects ◽  
Production Of Hydrogen ◽  
Hydrogen Radicals ◽  
The Impact

Abstract. Recently, measurements by the Superconducting Submillimeter-Wave Limb Emission Sounder (SMILES) satellite instrument have been presented which indicate an increase of mesospheric HO2 above sprite producing thunderstorms. These are the first direct observations of chemical sprite effects, and provide an opportunity to test our understanding of the chemical processes in sprites. In the present paper, results of numerical model simulations are presented. A plasma chemistry model in combination with a vertical transport module was used to simulate the impact of a streamer discharge in the altitude range 70–80 km, corresponding to one of the observed sprite events. Additionally, a horizontal transport and dispersion model was used to simulate advection and expansion of the sprite volumes. The model simulations predict a production of hydrogen radicals mainly due to reactions of proton hydrates formed after the electrical discharge. The net effect is a conversion of water molecules into H + OH. This leads to increasing HO2 concentrations a few hours after the electric breakdown. According to the model simulations, the HO2 enhancements above sprite producing thunderstorms observed by the SMILES instrument can not solely be attributed to the detected one sprite event for each thunderstorm. The main reason is that the estimated amount of HO2 released by a sprite is much smaller than the observed increase. Furthermore, the advection and dispersion simulations of the observed sprites reveal that in most cases only little overlap of the expanded sprite volumes and the field of view of the SMILES measurements is expected.

scholarly journals Model simulations of chemical effects of sprites in relation with observed HO<sub>2</sub> enhancements over sprite-producing thunderstorms

2021 ◽  
Vol 21 (10) ◽  
pp. 7579-7596
Author(s):  
Holger Winkler ◽  
Takayoshi Yamada ◽  
Yasuko Kasai ◽  
Uwe Berger ◽  
Justus Notholt
Keyword(s):  
Dispersion Model ◽  
Plasma Chemistry ◽  
Water Molecules ◽  
Streamer Discharge ◽  
Air Masses ◽  
Model Simulations ◽  
Chemical Effects ◽  
Production Of Hydrogen ◽  
Hydrogen Radicals ◽  
The Impact

Abstract. Recently, measurements by the Superconducting Submillimeter-Wave Limb Emission Sounder (SMILES) satellite instrument have been presented which indicate an increase in mesospheric HO2 above sprite-producing thunderstorms. The aim of this paper is to compare these observations to model simulations of chemical sprite effects. A plasma chemistry model in combination with a vertical transport module was used to simulate the impact of a streamer discharge in the altitude range 70–80 km, corresponding to one of the observed sprite events. Additionally, a horizontal transport and dispersion model was used to simulate advection and expansion of the sprite air masses. The model simulations predict a production of hydrogen radicals mainly due to reactions of proton hydrates formed after the electrical discharge. The net effect is a conversion of water molecules into H+OH. This leads to increasing HO2 concentrations a few hours after the electric breakdown. Due to the modelled long-lasting increase in HO2 after a sprite discharge, an accumulation of HO2 produced by several sprites appears possible. However, the number of sprites needed to explain the observed HO2 enhancements is unrealistically large. At least for the lower measurement tangent heights, the production mechanism of HO2 predicted by the model might contribute to the observed enhancements.

scholarly journals Influence of clouds on the oxidising capacity of the troposphere

2014 ◽  
Vol 14 (16) ◽  
pp. 23763-23796
Author(s):  
L. K. Whalley ◽  
D. Stone ◽  
I. J. George ◽  
S. Mertes ◽  
D. van Pinxteren ◽  
...  
Keyword(s):  
Surface Area ◽  
Droplet Surface ◽  
Atmospheric Composition ◽  
Uptake Coefficient ◽  
Transport Models ◽  
Cloud Droplets ◽  
Model Simulations ◽  
Direct Observations ◽  
Ho2 Radical ◽  
Good Agreement

Abstract. The potential for chemistry occurring in cloud droplets to impact atmospheric composition has been known for some time. However, the lack of direct observations and uncertainty in the magnitude of these reactions, led to this area being overlooked in most chemistry transport models. Here we present observations from Mt. Schmücke, Germany, of the HO2 radical made alongside a suite of cloud measurements. HO2 concentrations were depleted in-cloud by up to 90% with the rate of heterogeneous loss of HO2 to clouds necessary to bring model and measurements into agreement demonstrating a dependence on droplet surface area and pH. This provides the first observationally derived assessment for the uptake coefficient of HO2 to cloud droplets and was found to be in good agreement with theoretically derived parameterisations. Global model simulations, including this cloud uptake, showed impacts on the oxidizing capacity of the troposphere that depended critically on whether the HO2 uptake leads to production of H2O2 or H2O.

Direct observations of radiation-enhanced transformations in glass

1983 ◽  
Vol 41 ◽  
pp. 354-355
Author(s):  
J. F. DeNatale ◽  
D. G. Howitt
Keyword(s):  
Glass Matrix ◽  
Diffusion Mechanism ◽  
Bubble Formation ◽  
Silicate Glasses ◽  
Phase Decomposition ◽  
Direct Observations ◽  
Thin Foils ◽  
Oxygen Bubble ◽  
Electron Energy Loss ◽  
Kinetics Of

The electron irradiation of silicate glasses containing metal cations produces various types of phase separation and decomposition which includes oxygen bubble formation at intermediate temperatures figure I. The kinetics of bubble formation are too rapid to be accounted for by oxygen diffusion but the behavior is consistent with a cation diffusion mechanism if the amount of oxygen in the bubble is not significantly different from that in the same volume of silicate glass. The formation of oxygen bubbles is often accompanied by precipitation of crystalline phases and/or amorphous phase decomposition in the regions between the bubbles and the detection of differences in oxygen concentration between the bubble and matrix by electron energy loss spectroscopy cannot be discerned (figure 2) even when the bubble occupies the majority of the foil depth.The oxygen bubbles are stable, even in the thin foils, months after irradiation and if van der Waals behavior of the interior gas is assumed an oxygen pressure of about 4000 atmospheres must be sustained for a 100 bubble if the surface tension with the glass matrix is to balance against it at intermediate temperatures.

Effects of Electrical Discharges in Low Pressure Gases on the Morphology of Polyethylene Crystals

1974 ◽  
Vol 32 ◽  
pp. 544-545
Author(s):  
L.H. Bolz ◽  
D.H. Reneker
Keyword(s):  
Power Distribution ◽  
Electrical Discharge ◽  
Dielectric Breakdown ◽  
Ionic Species ◽  
Low Pressure ◽  
Polymer Surfaces ◽  
Electrical Discharges ◽  
Adhesive Bonds ◽  
Power Distribution Lines ◽  
Modification Of The Surface

The attack, on the surface of a polymer, by the atomic, molecular and ionic species that are created in a low pressure electrical discharge in a gas is interesting because: 1) significant interior morphological features may be revealed, 2) dielectric breakdown of polymeric insulation on high voltage power distribution lines involves the attack on the polymer of such species created in a corona discharge, 3) adhesive bonds formed between polymer surfaces subjected to such SDecies are much stronger than bonds between untreated surfaces, 4) the chemical modification of the surface creates a reactive surface to which a thin layer of another polymer may be bonded by glow discharge polymerization.

Metallurgical Effects of Grain Boundary Ledges

1977 ◽  
Vol 35 ◽  
pp. 126-129
Author(s):  
L.E. Murr
Keyword(s):  
Grain Boundary ◽  
Quantitative Data ◽  
Mechanical Treatment ◽  
Unit Length ◽  
Physical And Mechanical Properties ◽  
Direct Observations ◽  
Transmission Electron ◽  
Properties Of Materials ◽  
Thermo Mechanical Treatment ◽  
Ledge Density

Ledges in grain boundaries can be identified by their characteristic contrast features (straight, black-white lines) distinct from those of lattice dislocations, for example1,2 [see Fig. 1(a) and (b)]. Simple contrast rules as pointed out by Murr and Venkatesh2, can be established so that ledges may be recognized with come confidence, and the number of ledges per unit length of grain boundary (referred to as the ledge density, m) measured by direct observations in the transmission electron microscope. Such measurements can then give rise to quantitative data which can be used to provide evidence for the influence of ledges on the physical and mechanical properties of materials.It has been shown that ledge density can be systematically altered in some metals by thermo-mechanical treatment3,4.

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