Flare Emission Research Articles

EvryFlare. III. Temperature Evolution and Habitability Impacts of Dozens of Superflares Observed Simultaneously by Evryscope and TESS

Abstract Superflares may provide the dominant source of biologically relevant UV radiation to rocky habitable-zone M-dwarf planets (M-Earths), altering planetary atmospheres and conditions for surface life. The combined line and continuum flare emission has usually been approximated by a 9000 K blackbody. If superflares are hotter, then the UV emission may be 10 times higher than predicted from the optical. However, it is unknown for how long M-dwarf superflares reach temperatures above 9000 K. Only a handful of M-dwarf superflares have been recorded with multiwavelength high-cadence observations. We double the total number of events in the literature using simultaneous Evryscope and Transiting Exoplanet Survey Satellite observations to provide the first systematic exploration of the temperature evolution of M-dwarf superflares. We also increase the number of superflaring M dwarfs with published time-resolved blackbody evolution by ∼10×. We measure temperatures at 2 minutes cadence for 42 superflares from 27 K5–M5 dwarfs. We find superflare peak temperatures (defined as the mean of temperatures corresponding to flare FWHM) increase with flare energy and impulse. We find the amount of time flares emit at temperatures above 14,000 K depends on energy. We discover that 43% of the flares emit above 14,000 K, 23% emit above 20,000 K and 5% emit above 30,000 K. The largest and hottest flare briefly reached 42,000 K. Some do not reach 14,000 K. During superflares, we estimate M-Earths orbiting <200 Myr stars typically receive a top-of-atmosphere UV-C flux of ∼120 W m−2 and up to 103 W m−2, 100–1000 times the time-averaged X-ray and UV flux from Proxima Cen.

Evolution of the OH and H2O Maser Emission in the Active Star-Forming Region IRAS 05358+3543 (S231)

We present the results of our observations of the star-forming region located in the Perseus arm and associated with the Sharpless nebula S231 in the lines of H2O at a wavelength of 1.35 cm and OH at a wavelength of 18 cm obtained with the Pushchino 22-m radio telescope (Russia) and the Nancay Large Radio Telescope (France), respectively. We provide a catalog of H2O maser spectra in the period from March 2003 to March 2020. The variability of the integrated flux that we have calculated based on the monitoring by Felli et al. (1987–2007) and our monitoring (2003–2020) has a quasi-cyclic pattern with a cycle duration from 4.3 to 7.7 yr. Flares of maser emission of both single and several features occurred in each activity cycle. The mean rise and decay times of the flare emission were $$0.30 \pm 0.02$$ and $$0.35 \pm 0.02$$ yr, respectively. The observed radial velocity drift and jumps of the H2O emission features can be a consequence of the impact of shocks emerging as the protostar activity rises on them. The complex pattern of variability shows that the H2O masing medium is fragmented and small-scale turbulent motions of matter can occur in it. We have observed the OH maser emission in the 1665 and 1667 MHz main lines and the 1720 MHz satellite line. A large number of OH emission features and their variability have been detected. We have found one Zeeman pair at ‒9.2 km/s with a small splitting, with the longitudinal magnetic field in the period 2008–2020 having decreased monotonically from 0.24 to 0.10 mG. For the three most intense features we have calculated the degrees of linear polarization and position angles. A correlation between the H2O and OH maser activities has been found.

LOW-POWER SOLAR FLARES OF OPTICAL AND X-RAY WAVELENGTHS FOR SOLAR CYCLES 21–24

Using data obtained in optical and X-ray wavelengths, we have analyzed solar flare activity for cycles 21–24. Over the last three cycles, solar activity is shown to decrease significantly. As compared to solar cycle 21 (the most active over the last 50 years), in cycle 24 2–4-class large optical flares are 4.4 times rarer; 1-class flares, 8.2 times; and S-class small flares, 4.1 times. The number of X-class flares decreased 3.7 times; M-class flares, 3.2 times. This confirms that secular solar activity trends affect peak values of 11-year cycles. It is shown that optical low-power flares can be accompanied by proton fluxes and X-ray bursts of different intensity, including X-class ones. Ranges of small flare emission in soft X-rays largely overlap with emission ranges of flares of high optical classes. We have confirmed that X-ray emission from solar flares appears on average 2 min before the optical emission. The X-ray maximum for small optical flares and 1-class flares occurs approximately 1 min later; for 2–4-class flares, 2 min.

Солнечные вспышки малой мощности в оптическом и рентгеновском диапазонах длин волн в 21–24-м солнечных циклах

Using data obtained in optical and X-ray wavelengths, we have analyzed solar flare activity for cycles 21–24. Over the last three cycles, solar activity is shown to decrease significantly. As compared to solar cycle 21 (the most active over the last 50 years), in cycle 24 2–4-class large optical flares are 4.4 times rarer; 1-class flares, 8.2 times; and S-class small flares, 4.1 times. The number of X-class flares decreased 3.7 times; M-class flares, 3.2 times. This confirms that secular solar activity trends affect peak values of 11-year cycles. It is shown that optical low-power flares can be accompanied by proton fluxes and X-ray bursts of different intensity, including X-class ones. Ranges of small flare emission in soft X-rays largely overlap with emission ranges of flares of high optical classes. We have confirmed that X-ray emission from solar flares appears on average 2 min before the optical emission. The X-ray maximum for small optical flares and 1-class flares occurs approximately 1 min later; for 2–4-class flares, 2 min.

Impact of intrinsic polarization of Sgr A* historical flares on (polarization) properties of their X-ray echoes

ABSTRACT Reflection of X-ray emission on molecular clouds in the inner ∼100 pc of our Galaxy reveals that, despite being extremely quiet at the moment, our supermassive black hole Sgr A* should have experienced bright flares of X-ray emission in the recent past. Thanks to the improving characterization of the reflection signal, we are able to infer parameters of the most recent flare(s) (age, duration, and luminosity) and relative line-of-sight disposition of the brightest individual molecular complexes. We show that combining these data with measurements of polarization in the reflected X-ray continuum will not only justify Sgr A* as the primary source but also allow deriving intrinsic polarization properties of the flare emission. This will help to identify radiation mechanisms and underlying astrophysical phenomena behind them. For the currently brightest reflecting molecular complex, Sgr A, the required level of sensitivity might be already accessible with upcoming X-ray polarimeters.

Magnetic Reconnection during the Post-impulsive Phase of a Long-duration Solar Flare: Bidirectional Outflows as a Cause of Microwave and X-Ray Bursts

Abstract Magnetic reconnection plays a crucial role in powering solar flares, production of energetic particles, and plasma heating. However, where the magnetic reconnections occur, how and where the released magnetic energy is transported, and how it is converted to other forms remain unclear. Here we report recurring bidirectional plasma outflows located within a large-scale plasma sheet observed in extreme-ultraviolet emission and scattered white light during the post-impulsive gradual phase of the X8.2 solar flare on 2017 September 10. Each of the bidirectional outflows originates in the plasma sheet from a discrete site, identified as a magnetic reconnection site. These reconnection sites reside at very low altitudes (<180 Mm, or 0.26 R ⊙) above the top of the flare arcade, a distance only <3% of the total length of a plasma sheet that extends to at least 10 R ⊙. Each arrival of sunward outflows at the loop-top region appears to coincide with an impulsive microwave and X-ray burst dominated by a hot source (10–20 MK) at the loop top and a nonthermal microwave burst located in the loop-leg region. We propose that the reconnection outflows transport the magnetic energy released at localized magnetic reconnection sites outward in the form of kinetic energy flux and/or electromagnetic Poynting flux. The sunward-directed energy flux induces particle acceleration and plasma heating in the post-flare arcades, observed as the hot and nonthermal flare emissions.

An Eruptive Circular-ribbon Flare with Extended Remote Brightenings

Abstract We study an eruptive X1.1 circular-ribbon flare on 2013 November 10, combining multiwavelength observations with a coronal field reconstruction using a non-force-free field method. In the first stage, a filament forms via magnetic reconnection between two mildly twisted sheared arcades, which are embedded under the fan dome associated with a null point (NP). This reconnection seems to be driven by photospheric shearing and converging flows around the inner two arcade footpoints, consistent with the flare-related changes of the transverse field. The southern portion of the filament rises upward due to torus instability and pushes against the NP. The induced NP reconnection then generates the circular ribbon and the initial remote brightening in the west, as accelerated electrons precipitate along the fan and propagate outward along quasi-separatix surfaces with high values of the squashing factor (Q) in the envelope fields, which have a curtain-like shape here. In the second stage, the southern end of the flux rope breaks away from the surface, sequentially disrupts the dome and overlying fields, and erupts in a whipping-like fashion to become a partial halo coronal mass ejection. This leads to an enhanced flare emission and fast-moving remote brightenings at the footpoints of the magnetic curtain, which span a remarkably broad region and are also associated with coronal dimmings. This is a rare example of eruptive circular-ribbon flares, in which the evolution of a flux rope from its formation to successful eruption out of the dome and the resulting unusually extended remote brightenings are completely observed.

Ambient methane functionalization initiated by electrochemical oxidation of a vanadium (V)-oxo dimer

The abundant yet widely distributed methane resources require efficient conversion of methane into liquid chemicals, whereas an ambient selective process with minimal infrastructure support remains to be demonstrated. Here we report selective electrochemical oxidation of CH4 to methyl bisulfate (CH3OSO3H) at ambient pressure and room temperature with a molecular catalyst of vanadium (V)-oxo dimer. This water-tolerant, earth-abundant catalyst possesses a low activation energy (10.8 kcal mol‒1) and a high turnover frequency (483 and 1336 hr−1 at 1-bar and 3-bar pure CH4, respectively). The catalytic system electrochemically converts natural gas mixture into liquid products under ambient conditions over 240 h with a Faradaic efficiency of 90% and turnover numbers exceeding 100,000. This tentatively proposed mechanism is applicable to other d0 early transition metal species and represents a new scalable approach that helps mitigate the flaring or direct emission of natural gas at remote locations.

An integrated flare minimization methodology for simultaneous turnaround operations of two chemical plants

Current flare minimization studies were exclusively focusing on single facility/plant under normal or abnormal operating conditions. Systematic studies are still lacking for simultaneous flare minimizations of multiple plants, which are all under their turnaround operations. In this paper, a novel methodology has been developed for simultaneous flare minimizations of two olefin plants under their turnarounds: one is to start up and the other is to shut down. Based on plant-wide dynamic modeling and simulation, new flare minimization opportunities coupling both start-up and shutdown operations have been explored and examined. Eventually, an integrated duo-plant flare minimization strategy has been identified and virtually demonstrated. A key merit of this study is that through the interplant material exchange, flaring sources from Plant A could be utilized by Plant B instead of being flared; meanwhile, flaring sources from Plant B could also be significantly reduced. Thus, the integrated flare minimization strategy has created a win-win situation that can simultaneously reduce flare emissions from both plants to their extreme potentials. Compared with conventional turnaround strategies, the case study performed in this paper shows that the total flaring amount for both olefin plants can be significantly reduced by 69.47%. Compared with a previous study, the flaring amount of the single plant has also been reduced by an extra of 18.18%. The development suggests potentially significant economic, environmental, and societal benefits. It has also laid a solid foundation for future studies and applications on simultaneous multi-plant flare minimizations through optimal design and scheduling of multi-plant interplant material exchanges.

The STIX Aspect System (SAS): The Optical Aspect System of the Spectrometer/Telescope for Imaging X-Rays (STIX) on Solar Orbiter

The Spectrometer/Telescope for Imaging X-rays (STIX) is a remote sensing instrument on Solar Orbiter that observes the hard X-ray bremsstrahlung emission of solar flares. This paper describes the STIX Aspect System (SAS), a subunit that measures the pointing of STIX relative to the Sun with a precision of pm 4'', which is required to accurately localize the reconstructed X-ray images on the Sun. The operating principle of the SAS is based on an optical lens that images the Sun onto a plate that is perforated by small apertures arranged in a cross-shaped configuration of four radial arms. The light passing through the apertures of each arm is detected by a photodiode. Variations of spacecraft pointing and of distance from the Sun cause the solar image to move over different apertures, leading to a modulation of the measured lightcurves. These signals are used by ground analysis to calculate the locations of the solar limb, and hence the pointing of the telescope.

Global Energetics of Solar Flares. XI. Flare Magnitude Predictions of the GOES Class

Abstract In this study we determine scaling relationships of observed solar flares that can be used to predict upper limits of the Geostationary Orbiting Earth Satellite (GOES)–class magnitude of solar flares. The flare prediction scheme is based on the scaling of the slowly varying potential energy E p (t), which is extrapolated in time over an interval of Δt ≤ 24 hr. The observed scaling of the dissipated energy E diss scales with the potential field energy as . In addition, the observed scaling relationship of the flare volume, , the multi-thermal energy, E th ∝ V 0.76, the flare emission measure , the EM-weighted temperature T w , and the GOES flux, , allows us then to predict an upper limit of the GOES-class flare magnitude in the extrapolated time window. We find a good correlation (cross-correlation coefficient (CCC) ≈ 0.7) between the observed and predicted GOES-class flare magnitudes (in 172 X- and M-class events). This is the first algorithm that employs observed scaling laws of physical flare parameters to predict GOES flux upper limits, an important capability that complements previous flare prediction methods based on machine-learning algorithms used in space-weather forecasting.

Effect of industrial flare DREs derived by CFD and WERF on ozone pollution through CAMx simulation

Abstract Flare is the last safety measure for daily operations in oil, gas & chemical process industries (OGCPI). However, an excessive flaring releases large quantity of emissions of VOCs and NOx, which may suddenly enhance local ozone as a secondary pollution. Normally, the flare destruction and removal efficiency (DRE) of 98% or 99% is regulated as the national standard and presumed for industrial practices in the U.S. Unfortunately, real DRE values could be much lower than the standard due to impact factors including various meteorological and operating conditions such as the cross-wind speed, flare jet velocity and heating value of combustion. Thus, it is critically important to explore the sensitivity of the regional ozone impact due to low DREs of OGCPI flare combustions. In this paper, a systematic methodology has been developed to examine ozone impacts due to the low flare DREs, which have never been systematically studied before. The DRE formulas were derived from computational fluid dynamic (CFD) modeling and Water Environment Research Foundation (WERF) results and then employed to recompile the point source emission inventory. After that, comprehensive air quality model with extensions (CAMx) was employede to simulate and quantify local ozone changes impacted by flare emissions of OGCPI. Case studies indicate that the maximum hourly ozone increments due to the low DRE through CFD and WERF modeling is 0.18 ppb and 1.3 ppb, respectively. This study could enrich fundamental understandings of industrial point source emissions and provide the quantitative and valuable support for the ozone pollution caused by OGCPI flare emissions under low DRE instead of standard values.

Morphology of the Flare-Productive Active Region NOAA 9087

Evolution and morphological properties of the active region NOAA 9087 are analyzed based on space and ground observational data. Data on hard X-ray (HXR) and soft X-ray (SXR) were obtained from Yohkoh Telescopes (HXT and SXT) and the Geostationary Operational Environmental Satellite. Magnetograms and images in far ultraviolet were obtained from the Michelson Doppler Imager (MDI) and Extreme ultraviolet Imaging Telescope (EIT) of the Solar and Heliospheric Observatory (SOHO). White light images from the Big Bear Observatory (BBSO) and Hα-filtergrams from the Meudon Observatory were used. Data on the 2.69 GHz radio flux were taken from the World Data Center of the Learmonth Observatory (Australia). The investigated active region (AR) was observed on the solar disk from July 15 to 27, 2000, and showed a complex multipolar magnetic field configuration. A high flare activity and emissions were observed in this AR. According to Solar Geophysical Data (SGD), the 3N/M6.4 two-ribbon flare occurred on July 19, 2000, and lasted 2.5 h. The energy was released sequentially in different locations in the AR. All observational data indicate a continuous change in the structure and power of the flare at different wavelengths. HXR and type III radio bursts were observed at the initial phase of the flare. The HXR coronal source was above the line of magnetic polarity inversion of the AR. Observational evidence of magnetic reconnections during the main phase of the flare is obtained based on the analysis of sequential images of loops in the ultraviolet wavelength band. Postflare loops were observed in the 19.5 nm passband at the gradual phase, which is a manifestation of the EUV late phase. These extended loops connect the primary and secondary energy release sites of the flare. There was an additional energy transfer and heating mechanism during the main phase of the flare.

Electromagnetic Precursors to Gravitational-wave Events: Numerical Simulations of Flaring in Pre-merger Binary Neutron Star Magnetospheres

Abstract The detection of gravitational waves from neutron star merger events has opened up a new field of multimessenger astronomy linking gravitational-wave events to short gamma-ray bursts and kilonova afterglows. A further—yet to be discovered—electromagnetic counterpart is a precursor emission produced by the nontrivial interaction of the magnetospheres of the two neutron stars prior to merger. By performing special-relativistic force-free simulations of orbiting neutron stars we discuss the effect of different magnetic field orientations and show how the emission can be significantly enhanced by differential motion present in the binary, either due to stellar spins or misaligned stellar magnetospheres. We find that the buildup of twist in the magnetic flux tube connecting the two stars can lead to the repeated emission of powerful flares for a variety of orbital configurations. We also discuss potential coherent radio emission mechanisms in the flaring process.

QUASI-PERIODIC PULSATIONS IN SOLAR AND STELLAR FLARES. REVIEW

This paper provides an overview of the state-of-the-art studies of oscillatory processes in solar and stellar flares, based on modern observational data from ground-based and space-borne instruments with high temporal, spatial, and spectral resolution in different bands of the electromagnetic spectrum. We examine the mecha-nisms that generate flare emission and its quasi-periodic modulation. We discuss similarities and differences be-tween solar and stellar flares, and address associated problems of superflares on the Sun and space weather. Quasi-periodic pulsations (QPPs) of flare emission are shown to be an effective tool for diagnosing both the flare processes themselves and the parameters of flaring plasmas and accelerated particles. We consider types of QPPs, their statistical properties, and methods of analysis, taking into account the non-stationarity of the QPPs’ parameters. We review the proposed mechanisms of QPPs and summarize open questions.

An X-ray activity cycle on the young solar-like star ɛ Eridani

Chromospheric Ca II activity cycles are frequently found in late-type stars, but no systematic programs have been created to search for their coronal X-ray counterparts. The typical time scale of Ca II activity cycles ranges from years to decades. Therefore, long-lasting missions are needed to detect the coronal counterparts. The XMM-Newton satellite has so far detected X-ray cycles in five stars. A particularly intriguing question is at what age (and at what activity level) X-ray cycles set in. To this end, in 2015 we started the X-ray monitoring of the young solar-like star ɛ Eridani, previously observed on two occasions: in 2003 and in early 2015, both by XMM-Newton. With an age of 440 Myr, it is one of the youngest solar-like stars with a known chromospheric Ca II cycle. We collected the most recent Mount Wilson S-index data available for ɛ Eridani, starting from 2002, including previously unpublished data. We found that the Ca II cycle lasts 2.92 ± 0.02 yr, in agreement with past results. From the long-term XMM-Newton lightcurve, we find clear and systematic X-ray variability of our target, consistent with the chromospheric Ca II cycle. The average X-ray luminosity is 2 × 1028erg s−1, with an amplitude that is only a factor of 2 throughout the cycle. We apply a new method to describe the evolution of the coronal emission measure distribution of ɛ Eridani in terms of solar magnetic structures: active regions, cores of active regions, and flares covering the stellar surface at varying filling fractions. Combinations of these three types of magnetic structures can only describe the observed X-ray emission measure of ɛ Eridani if the solar flare emission measure distribution is restricted to events in the decay phase. The interpretation is that flares in the corona of ɛ Eridani last longer than their solar counterparts. We ascribe this to the lower metallicity of ɛ Eridani. Our analysis also revealed that the X-ray cycle of ɛ Eridani is strongly dominated by cores of active regions. The coverage fraction of cores throughout the cycle changes by the same factor as the X-ray luminosity. The maxima of the cycle are characterized by a high percentage of covering fraction of the flares, consistent with the fact that flaring events are seen in the corresponding short-term X-ray lightcurves predominately at the cycle maxima. The high X-ray emission throughout the cycle of ɛ Eridani is thus explained by the high percentage of magnetic structures on its surface.

Evidence for a Coronal Shock Wave Origin for Relativistic Protons Producing Solar Gamma-Rays and Observed by Neutron Monitors at Earth

Abstract We study the solar eruptive event on 2017 September 10 that produced long-lasting >100 MeV γ-ray emission and a ground level enhancement (GLE72). The origin of the high-energy ions producing late-phase gamma-ray emission (LPGRE) is still an open question, but a possible explanation is proton acceleration at coronal shocks produced by coronal mass ejections. We examine a common shock acceleration origin for both the LPGRE and GLE72. The γ-ray emission observed by the Fermi-Large Area Telescope exhibits a weak impulsive phase, consistent with that observed in hard X-and γ-ray line flare emissions, and what appear to be two distinct stages of LPGRE. From a detailed modeling of the shock wave, we derive the 3D distribution and temporal evolution of the shock parameters, and we examine the shock wave magnetic connection with the visible solar disk. The evolution of shock parameters on field lines returning to the visible disk mirrors the two stages of LPGRE. We find good agreement between the time history of >100 MeV γ-rays and one produced by a basic shock acceleration model. The time history of shock parameters magnetically mapped to Earth agrees with the rates observed by the Fort Smith neutron monitor during the first hour of GLE72 if we include a 30% contribution of flare-accelerated protons during the first 10 minutes, having a release time following the time history of nuclear γ-rays. Our analysis provides compelling evidence for a common shock origin for protons producing the LPGRE and most of the particles observed in GLE72.

Квазипериодические пульсации в солнечных и звездных вспышках. Обзор

This paper provides an overview of the state-of-the-art studies of oscillatory processes in solar and stellar flares, based on modern observational data from ground-based and space-borne instruments with high temporal, spatial, and spectral resolution in different electro-magnetic spectrum ranges. We examine the mechanisms that generate flare emission and its quasi-periodic modulation. We discuss similarities and differences between solar and stellar flares, and address associated problems of superflares on the Sun and space weather problems. Quasi-periodic pulsations (QPPs) of flare radiation are shown to be an effective tool for diagnosing both the flare processes themselves and the parameters of flare plasma and accelerated particles. We consider types of QPPs, their statistical properties, and methods of analysis, taking into account the non-stationarity of the QPPs’ parameters. We review the proposed mechanisms of QPPs and address open questions.

X-ray study of high-and-low luminosity modes and peculiar low-soft-and-hard activity in the transitional pulsar XSS J12270−4859

XSS J12270−4859 (henceforth J12270) is the first low-mass X-ray binary to exhibit a transition, taking place at the end of 2012, from an X-ray active state to a radio pulsar state. The X-ray emission based on archival XMM-Newton observations is highly variable, showing rapid variations (∼10 s) from a high X-ray luminosity mode to a low mode and back. A flaring mode has also been observed. X-ray pulsations have been detected during the high mode only. In this work we present two possible interpretations for the rapid swings between the high and low modes. In the first scenario, this phenomenon can be explained by a rapid oscillation between a propeller state and a radio-ejection pulsar state, during which the pulsar wind prevents matter from falling onto the neutron star surface. In the second scenario, a radio pulsar is always active, the intra-binary shock is located just outside the light cylinder in the high mode, while it expands during the low mode. At variance with other transitional pulsars, J12270 shows two instances of the low mode: a low-soft and low-hard mode. Performing an X-ray spectral analysis, we show that the harder component, present in the low-hard spectra, is probably related to the tail of the flare emission. This supports the understanding that the flare mechanism is independent of the high-to-low mode transitions.

WITHDRAWN: Effect of Flare destruction and removal efficiencies on regional ozone pollution from oil, gas and chemical process industries in Southeast of Texas through CAMx modeling and simulation

Flare is the last safety measure for daily operations in oil, gas & chemical process industries (OGCPI). However, an excessive flaring releases large quantity of emissions of VOCs and NOₓ, which may suddenly enhance local ozone as a secondary pollution. Normally, the flare destruction and removal efficiency (DRE) of 98% or 99% is regulated as the national standard and presumed for industrial practices in the U.S. Unfortunately, real DRE values could be much lower than the standard due to impact factors including various meteorological and operating conditions such as the cross-wind speed, flare jet velocity and heating value of combustion. Thus, it is critically important to explore the sensitivity of the regional ozone impact due to low DREs of OGCPI flare combustions. In this paper, a systematic methodology has been developed to examine ozone impacts due to the low flare DREs, which have never been systematically studied before. The DRE formulas were derived from computational fluid dynamic (CFD) modeling and Water Environment Research Foundation (WERF) results and then employed to recompile the point source emission inventory. After that, comprehensive air quality model with extensions (CAMx) was employede to simulate and quantify local ozone changes impacted by flare emissions of OGCPI. Case studies indicate that the maximum hourly ozone increments due to the low DRE through CFD and WERF modeling is 0.18 ppb and 1.3 ppb, respectively. This study could enrich fundamental understandings of industrial point source emissions and provide the quantitative and valuable support for the ozone pollution caused by OGCPI flare emissions under low DRE instead of standard values.