Multiple Electron Acceleration Instances during a Series of Solar Microflares Observed Simultaneously at X-Rays and Microwaves

Even small solar flares can display a surprising level of complexity regarding their morphology and temporal evolution. Many of their properties, such as energy release and electron acceleration can be studied using highly complementary observations at X-ray and radio wavelengths. We present X-ray observations from the Reuven Ramaty High Energy Solar Spectroscopic Imager and radio observations from the Karl G. Jansky Very Large Array (VLA) of a series of GOES A3.4–B1.6 class flares observed on 2013 April 23. The flares, as seen in X-ray and extreme ultraviolet, originated from multiple locations within active region NOAA 11726. A veritable zoo of different radio emissions between 1 GHz and 2 GHz was observed cotemporally with the X-ray flares. In addition to broadband continuum emission, broadband short-lived bursts and narrowband spikes, indicative of accelerated electrons, were observed. However, these sources were located up to 150″ away from the flaring X-ray sources but only some of these emissions could be explained as signatures of electrons that were accelerated near the main flare site. For other sources, no obvious magnetic connection to the main flare site could be found. These emissions likely originate from secondary acceleration sites triggered by the flare, but may be due to reconnection and acceleration completely unrelated to the cotemporally observed flare. Thanks to the extremely high sensitivity of the VLA, not achieved with current X-ray instrumentation, it is shown that particle acceleration happens frequently and at multiple locations within a flaring active region.

Environmental Implication of Thermal Radiation on the Physiochemical Properties of Soil around Gas Flare Sites in the Niger Delta Region of Nigeria

The effect of thermal radiation on the Physiochemical properties of soil around gas flare site in the Niger Delta region was assessed in Emuoha Local Government Area of River State, Nigeria, for a period of twelve months. Radiation profile was determined at different times (hours) – 6, 10, 14, 18 and 22, in the four seasons (early dry, early wet, late dry and late wet) of the year. Soil samples were taken at different depths (cm) (0-15 and 15-30) for physicochemical attributes at different distances (m) (0-150, 150-300, 300-450, 450-600 and 1000 -2000) from the flare site and thermal radiation was also determined at the respective distances. Results of effect of time and seasonal variations on radiation profile showed that environmental temperature (oC) ranged from 29.2 ± 0.3 at 22 hours of early wet season to 33.0 ± 0.4 at 14 hours of late dry season; radiation temperature ranged from 35.4 ± 1.2 at 22 hours of late wet season to 42.0 ± 1.4 at 14 hours of late dry season, while thermal radiation (w/m2) ranged from 490.83 ± 7.7 at 22 hours of late wet season to 535.69 ± 9.69 at 14 hours of late dry season. Results of effect of flare distance on physicochemical properties of soil showed that as the distance (m) from flare site increases from 0 – 150 to 1000 – 2000, the radiation intensity (w/m2) decreases from 603.84 ± 5.7 – 428.83 ± 0.75, and values of pH, OC, N, P, and exchangeable cations - K+, Na+, Ca2+, Mg2+ increases in the range {pH (4.94 ± 0.02 – 5.50 ± 0.00), OC (1.09 ± 0.01 – 2.05 ± 0.00), N (0.07 ±0.01 – 0.09 ± 0.00), P (10.90 ± 0.03 – 12.10 ± 5.19), K+ (0.28 ± 0.01 – 1.86 ± 0.01), Na+ (0.48 ± 0.00 – 1.04 ± 0.00), Ca2+ (1.65 ± 0.01 – 2.85 ± 0.00), Mg2+ (0.73 ± 0.01 – 1.24 ± 0.01)}, These values seemed not to be affected by the thermal radiation and flare distance , oil and grease and THC decreases in the range 203.30 ± 0.88 – 61.33 ± 0.33 and 352.90 ± 2.08 – 10.04 ± 0.04 respectively. Similar trend was observed with soil samples taken at 15-30cm depth. Statistical analysis showed there is significant difference (p<0.001) in soil attributes as distance from flare distance increases. Further studies should be carried out to investigate the relationship between soil around flare site and crop performance on different agro-ecological zone of Rivers State.

Assessment of Association between Gas Flaring and Prevalence of Diseases: Delineation of Opinion from Perception

Background: Pollutants are released into the atmosphere by gas flaring, and these cause a range of health problems, including heart disease and respiratory disorders. This article assesses the opinion and perception of the community regarding association between gas flaring and prevalence of diseases. Methodology: This research followed a descriptive quantitative approach. Purposive survey using 2 Likert scale questionnaires was adopted, and the first questionnaire collected data on distance to gas flare site, health status and family health history, amongst others. The second collected data on perception and knowledge-based opinions regarding association and correlation. Summated Likert scale were collated and descriptive and correlation analysis between distance to gas flare site and number of diseases in respondents and their families were done. Results: In this purposive survey, there is no correlation between nearness to gas flare and prevalence of diseases. There appears no difference in communities proximal to flare sites compared to non-host communities farther from site. Multivariate analysis further shows that no statistically significant difference between groups, except in comparison of perceptions. Conclusion: This investigation shows a variation from previous observation in this series i.e. that distance to gas flare site is a potential factor influencing community members’ perception about their health impact, but the surveyed opinion of healthcare workers differs. This implies that nearness to gas flare sites mediate perception of negative health impact and this calls for further research to delineate perception from knowledge-based opinion.

Air Pollution Assessment of a Gas Flare Site in the Niger Delta Region

Aim: The aim of this research was to investigate the level of air pollutants generated from a gas flaring plant in Ogbogu and Ebocha communities of Rivers State, Port Harcourt, Nigeria. Study design: Seven monitoring stations were selected for Air quality monitoring, which involved measurement of basic air quality index and meteorological parameters using standard meteorological Equipment. Monitoring locations were selected with respect to the prevailing wind direction from the flare point. The following measurements were conducted; Gas emission: CO, SO2, NO2, VOC, CH4, H2S, NH3 Meteorological: Humidity, Wind Velocity, Wind direction, Atmospheric Pressure, Heat Radiation and Smoke density. Place and duration of study: This study was carried out in Ogba/Egbema/Ndoni Local Government Area of Rivers State. This area was chosen for this study because of the high volume of petroleum activities. Oil and gas processing, production, transportation and utilization for power generation occur daily in the area resulting in numerous cases of environmental degradation and pollution. Methodology: A multigas Detector MSA Orion is used to monitor the different gases at 20m, 50m, 100m, 500m, and 700m. A Krestel Extech model 45112 mutli-parameter air quality equipment is used to determine the direction of wind flow and speed at a particular location. Results: The gases flared are in decreasing order of NOx,>SOx,>CO>VOC >SMP at increasing distance. This implies that the health of the people in the study area is affected negatively especially those living very close at 20- 100m distance to the flare site since the gases are occurring at levels higher towards the allowable limits of FEPA. The quantity of carbon emitted by these flares is about 2,525,000.00 tons of carbon per day. These values portray a bad omen for the affected communities. This study recommends that gas flaring should be seen as violent action against the people and that the flared gas should be channeled to meeting the ever increasing demand for energy in the industrial sector of the economy. Conclusion: It is safe to conclude that gas flaring not only produces excessive heat which alters the temperature of the environment, but also causes gaseous pollutants to be present in the environment and this may have adverse effects on the inhabitants and thus on the socio-economic activities of Ebocha community. The temperature of the environment returns to normal at about 450m away from the flare stack. Residential buildings should therefore be located and agricultural activities should be encouraged within this range of distance.

Remote coronal dimmings related to a circular-ribbon flare

Aims. In this paper, we report multiwavelength observations of remote coronal dimmings related to an M1.1 circular-ribbon flare in active region (AR) 12434. Methods. The confined flare without a coronal mass ejection was observed by the Atmospheric Imaging Assembly (AIA) and the Helioseismic and Magnetic Imager on board the Solar Dynamics Observatory on 2015 October 16. We obtained global three-dimensional (3D) magnetic fields before the flare using the potential field source surface modeling. Results. A few minutes before the flare hard X-ray peak time (06:13:48 UT), small-scale, weak dimming appeared ∼240″ away from the flare site, which can be observed by AIA only in 131 and 171 Å. Afterward, long and narrow dimmings became evident in all AIA extreme-ultraviolet passbands except 304 Å, while localized core dimming was not clearly observed near the flare site. The large-area dimmings extended southeastward and the areas increased gradually. The total area of dimmings reaches (1.2 ± 0.4) × 104 Mm2 in 193 Å. The maximal relative intensity decreases in 171 and 193 Å reach 90% and 80%, respectively. Subsequently, the dimmings began to replenish and the area decreased slowly, lasting for ≥3 h. The remote dimmings and AR 12434 are connected by large-scale coronal loops. The remote dimmings are associated with the southwest footpoints of coronal loops with weak negative polarities. Possible origins of remote dimmings are discussed.

Gamma-Ray Solar Flares and In Situ Particle Acceleration

At present two concurrent paradigms of solar energetic particle (SEP) origin exist: acceleration directly in the flare site or by the shock wave of coronal mass ejection (CME). Active discussions on a relative role of flares and coronal mass ejections for SEP acceleration and propagation are continuous until now. In my opinion only future observations of solar high energy γ–emission with better spectral, spatial and temporal resolution may clarify this issue. In my report I discuss possible signatures of the flare and shock acceleration processes. What is a picture provided by the current instruments? What can we expect to observe with a perfect instrument in high energy gamma rays in one or another case on a time scale of impulsive and long decay flare phases?

Searching for failed eruptions interacting with overlying magnetic field

It is well known that not all solar flares are connected with eruptions followed by coronal mass ejection (CME). Even strongest X-class flares may not be accompanied by eruptions or are accompanied by failed eruptions. One of important factor that prevent eruption from developing into CME is strength of the magnetic field overlying flare site. Few observations show that active regions with specific magnetic configuration may produce many CME-less solar flares. Therefore, forecasts of geoeffective events based on active region properties have to take into account probability of confining solar eruptions. Present observations of SDO/AIA give a chance for deep statistical analysis of properties of an active region which may lead to confining an eruption. We developed automated method which can recognize eruptions in AIA images. With this tool we will be able to analyze statistical properties of failed eruptions observed by AIA telescope.

Observations of IMF coherent structures and their relationship to SEP dropout events

The solar energetic particle (SEP) events from impulsive solar flares are often characterized by short-timescale modulations affecting, at the same time, particles with different energies. Several models and simulations suggest that these modulations are observed when SEPs propagate through magnetic structures with a different connection with the flare site. However, in situ observations rarely showed clear magnetic signatures associated with these modulations. In this paper we used the Grad–Shafranov reconstruction to perform a detailed analysis of the local magnetic field topology during the SEP event of 9–10 January 1999, characterized by several SEP dropouts. An optimization procedure is used to identify, during this SEP event, the magnetic structures which better satisfy the Grad–Shafranov assumptions and to evaluate the direction of their invariant axis. We found that these two-dimensional structures, which are flux ropes or current sheets with a more complex field topology, are generally associated with the maxima in the SEP counts. This association suggests that the SEPs propagate within these structures and, since their gyration radii is much smaller than the transverse dimension of these structure, cannot escape from them.