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Forecasting Large Solar Flares: Possibilities and Restrictions

This presentation discusses the emerging magnetic fields and their role in solar flares, the conditions leading to unconditional realization of solar flares, essential observational peculiarities, and the period of flare energy release. It also explores the possibilities and restrictions of the technique used for forecasting large solar flares.

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Forecasting Large Solar Flares: Possibilities and Restrictions

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  1. THE FORECAST OF THE LARGE SOLAR FLARE EVENTS:POSSIBILITIES AND RESTRICTIONSV. Ishkov,ishkov@izmiran.ru

  2. Outline of Presentation 1. Emerging magnetic fields and their role in realization of solar flares. 2. The conditions leading to unconditional realization of LFE. 3. The some essential observational peculiarities of the solar flare realization. 4. THE PERIOD OF FLARE ENERGY RELEASE ”(PFER); 5. Possibilities and restrictions of the given technique of the large solar flare forecast. 6. Classification the flare phenomena on a magnetic field in which its occur.

  3. The recent observations with high temporal and spatial resolution have shown that solar flare occurrences are closes related to the emergence of new MF. The growth of flare productivity is always preceded by the emergence of new MF in already existing AR as well as in the background solar magnetic field regions. These results have something in common with the results of SA observations in the early days, where it has been shown the realization of large solar flares was preceded by the appearance of new sunspots or increasing of the sunspot number in AR. &$ Every so often the observers could not link the emergence of new MF with large flare occurences and even with growth of theflare productions. In all likelihood the reason is in obserations of theemergent fluxes just before flare onset (within some hours). But thebegining of flux emergence, entirely controlling of large flareproduction, comes within 1–3 days before the onset ofrealizing large solar flares.

  4. The solar large flare event forecasting is presently based on observations of: * the process of new MF emergencies; * their evolution: the magnitude growth and rate of emergence; * their localization and interaction with already existing magnetic fields of the AR or outside of them. &$ The most successful attempt to classify the EFR phenomena inrelation to the time of life and flareactivity was madeGolovko, 1986, 1988.Inaccordance toEFRmagnitude and therate ofemergenceof MF,theauthor revealedthe three branchesreflect the presence ofthree maindifferent magnetic structures onthe Sun and, that is very significantly,marked out EFR with a fast evolution (II).These papers provide sufficient reasons toconsider the process ofsolar flare occurenceas anoriginal independent process withincommon AR evolution. Limited on time, such process of a new MFE can accelerate AR evolution, but, generally, such influence it is possible to consider insignificant since AR continues to exist for the account of internal evolutionary changes. Golovko, 1986

  5. This physicalprocess has the concrete begining – the emergence of a new MF within an active region, the maximum – the period of time when moderateand large flares occur, and the end –when the energy of new MF arerealized fully. This time-limited process of new MF emergencemay accelerate theevolution of AR but in general case suchinfluence may be concideredas notimportant.The emergences of new MF may occur in all phases of active region evolution. Their interactions with overlying magnetic fields will always cause the flare activity increasing. For normal AR: the fluxes magnitude is Ф≈ 1012 –1013 Wb, and the rate of emergence is V ≈ 107 – 108 Wb/s. For flare EFR: the magnitude is Ф ≥ 1013 Wb and the rate of emergence is V ≥ 109 Wb/s. AR10930 (S06L009;CMP 11,0.12.2006; Sp max = 680 м.д.п., DKI, δ); XRI=20.8: X49.0+M5+C42; 41+31+23+14+S49; ПВЭ I (36h) – 5 – 6.12 – X29.0+M4; ПВЭ II (43h) – 13 – 14.12 – X2

  6. The quantity of the energy that is taken out the new magnetic flux, predetermines a course of the subsequent flare energy release. The example of AR XII 2006 once again underlines that for realization of the large solar flares complexity of a magnetic configuration AR is not important, but dynamics, fast evolution of the new magnetic fluxes.

  7. The observational evidences of large new MF emergences manifestations: – rapid growth of sunspot areas, usually it is greater than a factor 2 or more at the first day for sunspot groups with areas up to 300 m.v.h. and greater than a factor of 1.5 on the second and third days (time of evolution is about 1- 3 days); – appearance of new large umbrae within the same penumbra for large and complexes sunspot groups with area >1000 m.v.h. (time of evolution is about 1-3 days); – fast complication of magnetic structure of a sunspot group at the expense of new spots and umbrae with gamma and delta-configurations appearance (time of evolution is from several hours to 1.5 days); – rapid evolution of the sunspot groups to D, E, F (ki, kc) Mc-Intosh classes (time of evolution is from several hours to 1.5 days); – appearance of compact arch filament systems (AFS) which visualize EFR within active regions; the observations in the wings of Hα spectral line (±1 Å) indicate the large number of microflares in the arch footpoints; – rapid increase of soft X-ray background (1 – 12,5 keV) – most essential for minimum solar activity phase. – rapid proper motions of one or more spots, umbrae or pores (Dejo et al, 1980); – appearance of sheared magnetic configuration (“shear“) in regions immediately adjacent to the line of polarity reversal in the active region, (Tanaka, 1980), etc.

  8. AR10720 (N09L177; CMP15,7.01.2001; Sp=1630m.v.h.,EKC, δ; XRI=21.5X57.1+M19+C65; 31+28+19+S58; ПВЭ1 14-15.01(17h):(Х2+М9) [4], ПВЭ216-17.01 (9h): (Х1+М3) – [1], ПВЭ318-20.01 (39h): (Х2+М4) – [3] The some essential observational peculiarities of the solar flare realization: – all large flares are necessarily accompanied by middle importance flares; – solar flares of large and middle importance are distributed not at random in time, but they form the successions;Obashev et al., (1973), Ishkov, (1989); – in most cases they occur within a certain limited temporal interval,Ishkov, (1998, 1999). The temporal interval during which the bulk of large and moderate solar flares occur we will call as “THE PERIOD OF FLARE ENERGY RELEASE” (PFER); – PFER occurs on 2nd–3rd day after the first evidences of the emergence of a new sufficiently powerful magnetic flux; – PFER may last from 16 to 80 hours depending on the degree of AR evolution, parameters of its magnetic field and characteristics of a new emerging flux. The average duration is about 55h±20h or 5–25% of whole the time of AR passage across the solar disk. &$

  9. It is the most important to notice that ALL large flares and the most of moderate flares of given active region occur in this temporal interval if the given sunspot group area is no more ~1000 m.v.h. (Ishkov, 1998). To occur other large solar flares in given active region a new large magnetic flux emergence must take place.

  10. Two cases are the most complexity: • 1. The passage of very large ( Sp > 1500m.v.h.) complex sunspot groups over visible disk of the Sun. In this case it is practically impossible to separate a new magnetic flux emergence by the messages and the direct observations in real time, that now give daily pictures KA SOHO, TRACE, and, especially, HINODE are needed . It is necessary to watch for the appearance of new large umbrae within the same penumbra. • 2. An appearance from behind east limb of an active region in time of PFER preparation or occurrence. The main features of FAR appearance from behind east limb are as follows: • – active region is formed within the longitudes which are active for given solar cycle phase and during preceding rotation has gone beyond west limb in violent growth stage; • – during active region passage over the Sun's backside the radio bursts of the type II and IV not associated with observed flares and unidentified solar proton events are registered; • – within 4–2 days before appearance of an active region on the east limb significant enhancement of green and red coronal line intensities is registries; • – steady elevation of soft X-ray background in the range of 12,5 – 1 keV; • – gradual decreasing down to 3% of the galactic cosmic ray intensity by neutron monitors. • All these features allow estimating the probability of large flare occurrences close to east limb.

  11. The passage of sunspot groups on March 1989 is a good example of suchsituation whenmajor flares have taken place during all time of passingthe sunspot group over visible disk of the Sun. The following analysisof observation data was shown that scheme of our forecast was performedwith superior accuracy but it wasimpossible to reveal a new fluxemergence, occuring at each 3 days, by service messages. It should be notedthat sunspot group of such flare activity concentration appeared inthree solar cycles for the 4 time. Март1989 г. AR5395 (N34L257, CMP 12,7.03.1989;Sp max = 3600 м.д.п., FКС, δ)XRI=32.6 X11>12.5+M48+C47; 35+221+137+S132;ПВЭ I (83h) – 6 – 7.03 – X2>12.5+M5;ПВЭ II (74h) – 9– 11.03 – X44.3+M15ПВЭ III (14h) – 13– 14.03 – X21.1+M6 ПВЭ IV (50h) – 15– 17.03 – X36.5+M7 8.4 From the scheme one can recognize that the given AR represented superposition of 4 sunspot groups consistently appearing at passage of a solar disk in small area.

  12. ------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------ AR lat long CMP Sp max McI PFER1 Fl TOTAL m.v.h./date cls PFER2 PFER Fl ------------------------------------------------------------------------------------------------------- 1203 N18 L170 15.07.78 1330/11.07 EKC 09-12/82h X4+M18X4+M30+C44 18-19/70h M4 1781 N20 L181 05.06.79 1150/03.06 EKI 03-05/44h X2+M3 X3+M5+C14 09-10/31h X1+M1 2372 N12 L104 06.04.80 1200/08.04 EKI 05-07/69h X1+M8X1+M14+C11 10-13/67h M5 2470 S17 L177 25.05.80 1040/21.05 DKI 28-29/27h X1+M5 X1+M5+C11 3234 S12 L289 27.07.81 2100/24.08 FKI 25-27/52h X3+M16X3 +M26+C57 3576 S13 L323 01.02.82 1360/1.02 FKC 31-03/78 h X3 + M3X6+ M14 +C32 06-09/>56h X3 + M3 3804 N11 L322 15.07.82 2963/12.07 FKC 09-12/74h X3 + M36X5+ M67 +C32 17-19/65h X2 + M9 *4025 S08 L89 16.12.82 583/17.12 DKI* 15-18/85h X6 + M9X3+ M2 +C12 * *4026 S12 L77 16.12.82 494/13.12 DKI* 15-18/85h X6 + M9X4+ M12 +C22* 4173 S11 L349 09.05.83 1787/15.05 EKI 14-15/25h X1 +M2X1+ M7 +C30 4201 S09 L353 04.06.83 1800/06.06 FKC 05-06/26h X1 + M7X1+ M14 +C69 4617 S08 L073 19.01.85 750/21.01 EKI 20-23/27h X1 + M7X1+ M8 +C18 4647 N04 L235 26.04.85 900/24.04 EKI 22-24/40h X1 + M1X1+ M2 +C25 5533 S19 L072 15.06.89 920/12.06 FKI 15-16/26h X2 + M6X2 + M16 +C23 5747 S26 L211 19.10.89 1160/18.10 EKC 18-19/18h X1 + M2X5 + M22+C27 25-28/61h X1 + M5 21-24/65h X3 + M6

  13. ARlatlong СМРSpMcIPFER-1, 2, 3FL PFER Σ вспышек 9591 S19 L295 28.08.01 740 FKI24-25/36h X1+M5X1+M9+C49 9661 N15L357 17.10.01 800 EKI 19/14h; X2; X2+M2+C16 9672 S18 L268 24.10.01590 DKI22-25/87hX2+M2 X2+M5+C16 10017 S18L235 29.06.02 610EKI02-05/65hX1+M5 X1+M6+C16 10030N18 L012 15.07.02 1350 EKC11-12/34h M3X2+M6+C40 15-18/59hX2+M3 10039S12 L204 28.07.02 940FKC 20-23/51hX2X3+M4+C28 02-04/46hX1+M1 10069 S08 L298 17.08.02 1990 EKC16/12h; M3X2+M17+C55 20-22/48hX1+M2 23-24/17hX+M2 10314 S15 L061 15.03.03 500EKI17-18/40hX2+M6 X2+M9+C17 10365 S07 L182 26.05.03 880 DKC27-29/27hX2+M2X2+M9+C17 31-2/56hM5 10375 N13 L022 7.06.03 1250 FKC09-12/62h X3+M24 X2+M16+C28 10486S17L283 29.10.03 2610FKC 22-24/59hХ2+М6X7+M16+C16 26-29/59hХ3+М4 01-5/85hХ2+М6 10488 N08 L291 28.10.03 1750 FKC 02-04/41hX2+M2 X3+M7+C17 10649S10L044 19.07.04 510 FKC13-14/29h M6 X6+M10+C6 15-17/55hX6+M2 10656 S13 L083 12.08.041360FKC 13-15/54hX1+M15 X2+M23+C94 17-18/34hX1+M6 10696N08L026 06.11.04 910EKC 03-04/44hМ6X2+M13+C37 06-7/39hХ1+М4 09-10/9hХ1+М1 10720 N09L177 15.01.05 1630 EKI 14–15/32hX2+M7X5+M19+C 16-17/09hX1+M2 18-20/39hX2+M4 10930 S06 L009 11.12.06 680 DKI 05-06/36h X2+M4; X4+M5 13-14/43hX2

  14. By technique working out the problem was put to give forecasts on the basis of the accessible daily data about a condition of solar activity which can be received on lines Space Weather Prognostic Center Joint NOAA-USAF (http://www.swpc.noaa.gov) and, in last solar cycle, systems of tracing and data processing Solar Soft of analytical department of the NASA Goddard Space Flight Center's Solar Data Analysis Center solar data (http://www.solarmonitor.org/). Thus the question on was in passing studied what possibilities and restrictions such forecast without attraction of special observations. In connection with impossibility now to have the data about EFR in real time the given technique it is constructed on an estimation of magnetic fluxes on size of an increment of the sunspot area for days. Calculation of new emerging magnetic fluxes is carried out under the estimated formula received from the observational data: F = (0.031Sp)13 Wb (Obridko, 1985), where Sp – the sunspot group area in m.v.h., and average size of a sunspot magnetic field ~2500 E. In forecast PFER additional marker of new emerging magnetic fluxes after which there comes growth flare activity, i.e. realizations of large and middle flares are considered. For occurrence of such flares it is necessary, that new MF was ≥1013 Wb and speed of its emergence was ≥109 Wb/s. The period of flares realization comes in 1–2 days after occurrence new MF within AR.

  15. POSSIBILITIES: At observation of new significant magnetic fluxes in active area * – Forecast PFER beginning for 48 – 24h; * – Preliminary a geoefficiency estimation flare events on localization and surrounding structures of AR; At observation of flare events: * – On a X-ray class – R (SID, blackouts); * – On a radio emission and localization flare events and to CME characteristics – S (SPE), G (MS); RESTRICTIONS: Impossibility of the time forecast and importance of individual flare event during PFER; Real difficulties of a new MF observations in complex compact AR with areas Sp> 1500 m.v.h.; Difficulties of an estimation flare potential in AR which placed near solar limb.

  16. On sample PFER with the large flares, occurrences on a visible disk of the Sun in 23 solar cycle (1996-2008), to check of the considered technique working capacity has been spent: Samples Σ in cycle EL, WL Σ in work No Yes % PFER 145 35 1102684 76 % LSF 272 57 215 36 179 83 % In 26 cases of a new magnetic flux emergence visible signs it is not revealed. It, apparently, is connected by that in the forecast technique is used indirect criteria of a new magnetic flux emergence revealing

  17. Мf (Gs) МCPha Imp.max F 10.7маx Хh, γ CME AFFS <50 –DSF; <SF/≤C7<50 –+ + <500 – SFl 4N/≤M7≤300 – + + ≤2000 γ, δ SFl 3B/>X17.5 >10000 + + + >2500δ SFl 1B/≤M5 <10000 + – – Table has presented some maximal characteristics of solar flare productions in according to magnitude of already existing magnetic field in which the new magnetic fluxes emerge. First column presents typical values of the magnetic field magnitudes. Second one (MC) presents a type of magnetic configuration, which depends on the magnetic field magnitude. Third column (Pha) is defining a type of solar flare event. Columns 4 – 7 present maximum event intensity in different ranges of electromagnetic spectra (Imp – maximal importance of solar flare (optical and soft X-ray); F – maximal fluxes in radio wave on 10 cm; Xh, γ – the availability of hard X-ray and gamma ray bursts). Columns 8 – present the possibility of coronal mass ejection. Columns 8 – present the possibility of visible arch filament flare systems.

  18. From this standpoint it is possible to consider the solar filament eruption as a flare processes in a weak magnetic field (from units up to several tens of gauss). In this case a new emergence MF interacts with the overlying background solar magnetic field and it can emerge in the vicinity of the polarity inversion line, where a filament is located. Filament eruptions or “disparition brusque” are the two-ribbon “flare-like brightening” event with slower rise times (about 1 hour), considerably longer lifetimes (up to 3 hours) beyond solar sunspot groups. No evidence of any impulsive phase microwave or hard X-ray emissions. These events are accompanied by weak gradual thermal soft x-ray (≤C7) microwave flux (≤50 s.f.u.) and cool loop arcades at last stage of event evolution.

  19. As an example I show the fig. from Gopalswamy et al, 2006. In drawing we see a filament before ejection and after in various ranges of observation. A black arrow shows the place of emergence of small magnetic flux, which was the trigger of all process of a solar filament ejection. GOPALSWAMY ET AL.,2006

  20. THANKS FOR ATTENTION

  21. 19920625 1951 2014 2057 X3.9 2B 0.897 N09 W67 L313 7205 19920628 0445 0514 0620 X1.8 SF 0.742 N11 W90 L313 7205

  22. Conclusions • Long-term observations of radiation belt electrons generally show slow variations within the inner zone with much greater and more frequent changes in the outer zone • Remnants of the March 1991 storm were seen for years in the inner zone and the Halloween 2003 storm also produced dramatic, long-lasting effects • The largest average fluxes in the outer zone occurred for periods of several years in the approach to the 11-year solar minimum time (1993-95) • Solar wind speed variations constitute the most essential determinant of radiation belt enhancements • Acceleration of relativistic electrons involves enhanced radial diffusion and local (wave-particle) interactions • The present period of time is notable for the combined effects of remarkable CME-driven events and some recurrent solar wind streams: However, the space weather (deep-dielectric charging) consequences have not materialized because high-speed solar wind streams and coronal holes have not been well-organized (2004-06)

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