DEUTSCHE WELLE SOLAR GEOPHYSICAL ACTIVITY REPORT FEBRUARY 2007

Transcription

1 SOLAR GEOPHYSICAL ACTIVITY REPORT FEBRUARY 2007 Steffen Hilbig Mess- und Kontrollzentrale

2 SOLAR GEOPHYSICAL ACTIVITY REPORT February 2007 Aurora Borealis Steffen Hilbig

3 Solar Geophysical Activity Summary 2 Contents... 2 Introduction.. 3 Review.. 4, 5 Solar Images of January , 7, 8 Diagram: Solar Indices (Solar Flux, Sunspot Numbers, Ap-Index) 9 Diagram: Solar Wind Velocity (daily values) Diagram: Solar Wind (development). 11 Diagram: Solar Wind Density (daily values) Diagram: Solar Wind Density (development) Diagram: Planetary A - Indices (daily values).. 14 Diagram: Planetary A - Indices (development) Diagram: Planetary K - Indices (daily values).. 16 Diagram: Planetary K - Indices (development) Diagram: Geomagnetic Activity Diagram: IMF Field B-Components (daily max values)... 19, 20 Northern Auroral Oval Images 21, 22, 23 Northern Auroral Oval Description 24 Space Weather Scales (Ap - Indices) Space Weather Scales (Kp - Indices).. 26 Space Weather Scales (correlation of Ap to Kp Indices) Space Weather Scales (Solar Flares) Diagram: Solar Flares (daily values) Diagram: Solar Flares (development) Long Distance Propagation Summary.. 31, 32 Diagram: Solar Cycles 22 and Glossary... 34, 35 Abbreviations 36 Disclaimer... 37

4 Solar Geophysical Activity Summary 3 Introduction This monthly Solar Geophysical Activity Report summarizes solar- and geomagnetic activities observed during the previous period. It s purpose is to provide an overview of solar events e.g. the changing number of sunspots (on the Earth directed visible disk of the Sun), the planetary A- and K-indices, and to give information of the Sun s activity, the development of solar wind, the velocity, energetic particle enhancements etc., and their influence to the geomagnetic field, especially to propagation mechanism for long- and short range hf radio circuits. Significant sunspots or sunspot groups as well as solar active regions are always identified by the solar region number, to make it more easy to observe their development and movement. If not otherwise stated, please be advised, that all data provided are daily maximum (not smoothed) values. Important sunspots or sunspot groups with particularly high geoeffectivity are always shown as solar images of the corresponding day. All images of the Sun shown in this summary have been issued by Stanford University, Stanford, California, USA, and based on SOHO Michelson Doppler Imager (MDI) 6767 A observations. All information concerning shortwave propagation conditions are based on observations of a global shortwave beacon network project (NCDXF) and selected broadcasting stations. Please don t hesitate to forward any kind of critisism as well as proposals. Those information will be most welcome to rise the level of quality of this report. Steffen Hilbig Direktion Distribution Ausstrahlungskoordination Kurt Schumacher Str. 3 D Bonn TF +49 (0) FAX +49 (0) Steffen.Hilbig@dw-world.de

5 Solar Geophysical Activity Summary 4 Solar Geophysical Activity Summary for February 2007 Space weather conditions are currently extremely quiet. Basically the x-ray corona of the sun has vanished, as well as any geomagnetic activity. Review of solar and geomagnetic events First period of observation, (01 07 February 2007). Solar activity was at very low to low levels during the first period of observation. Region NOAA 0940 produced isolated B- and C-class flares during 01 February No flares were observed during February. The geomagnetic field ranged from quiet to minor storm levels at middle latitudes, while high latitudes experienced quiet to severe storm levels. A recurrent coronal hole high-speed stream disturbed the field during 29 January until 01 February Activity ranged from quiet to minor storm levels during the disturbance with major storm periods detected at higher latitudes. During the disturbance solar wind speeds reached maximum velocities of about 720 km/s early on 31 January, while the Bz component of the Interplanetary Magnetic Field IMF fluctuated between +/- 18 nt on 29 January Activity decreased to quiet levels during the latter half of 01 February and remained so for the balance of the period. By 30 January the IMF Bz component relaxed and did not vary much beyond +/- 5 nt for the remainder of the period. Solar wind speed gradually decreased after 31 January and ended the period near 325 km/s. Second period of observation, (08 14 February 2007). Solar activity again was at very low to low levels. Region 0940 produced an isolated C-class flare at 08 February 2007 as the region rotated around the western limb. The geomagnetic field was generally at quiet to unsettled levels at all latitudes. High latitudes experienced isolated active to minor storm conditions on 04, 07 and 08 February 2007 due to a southward directed Bz component of the IMF. Solar wind speed ranged from a low of 330 km/s on 05 February to a high around 475 km/s on 09 February. The Bz component of the IMF fluctuated between +/- 8 nt for about 24 hours beginning early on 06 February. Thereafter and through the balance of the period Bz did not vary much beyond +/-5 nt. Activity decreased to quiet levels during the latter half of 10 February. On 13 February a solar wind stream hit Earth, leading to a geomagnetic storm (Kp=5) and aurorae borealis visible as southward as southern Skandinavia.

6 Solar Geophysical Activity Summary 5 Solar Geophysical Activity Summary for February 2007 Third period of observation, (15 21 February 2007). Solar activity was at very low to low levels. Isolated, optically uncorrelated B- and C-class flares occurred during the period. The geomagnetic field was disturbed during February due to a recurrent coronal hole high-speed stream. Activity ranged from quiet to minor storm levels during the disturbance with a brief period of major storm at high latitudes on 14 February. Solar wind data indicated the recurrent high-speed stream commenced on 12 February by a brief density increase. Velocity reached a peak of 778 km/s at 14/0830 UTC. Maximum IMF Bz variations occurred during February with a peak southward Bz on minus 11 nt at 13/1400 UTC. Field activity decreased to quiet to unsettled levels during February as coronal hole effects subsided. Fourth period of observation (22 28 February 2007). Solar activity was low and decreased to very low levels for the rest of the period with no flares. The geomagnetic field was quiet at all latitudes during the summary period. Ap-Index The maximum Ap-Index number was of 39 (minor storm conditions) on 28 February Sunspots The maximum Sunspot number was of 36 on 02 February and of 27 spots on 20 February Otherwise just a small number of spots have been seen during the entire period. Solar winds Maximum Solar winds have been measured with values of approximately 645 km/s on 01 February 2007, of around 840 km/s to 780 km/s from 15 to 16 February and of around 700 km/s on 28 February Solar Flux Maximum Solar Flux has been observed on 01 and 02 February 2007 with values of around 90. Significant activities The most significant solar event was a

7 Solar Geophysical Activity Summary 6 Solar Geophysical Activity Summary for February 2007 Solar Image Solar disk of 05 February 2007 showing groups NOAA 0940 and 0941

8 Solar Geophysical Activity Summary 7 Solar Geophysical Activity Summary for February 2007 Solar Image Solar Disk of 15 February 2007 appears almost spotless Mess- u.kontrollzentrale

9 Solar Geophysical Activity Summary 8 Solar Geophysical Activity Summary for February 2007 Solar Image Solar Disk of 20 February 2007 showing Regions NOAA 0942 and NOAA 0943 Mess- u.kontrollzentrale

10 9 SOLAR - GEOPHYSICAL ACTIVITY SUMMARY FOR FEBRUARY 2007 NOAA / SEC SOLAR INDICES SFl SSN A-Index Date d

11 10 SOLAR WIND DEVELOPMENT FOR FEBRUARY max min 800 VELOCITY (km/sec) Date d

12 11 SOLAR WIND DAILY VALUES FOR FEBRUARY max min VELOCITY (km/sec) Date d

13 12 SOLAR WIND DENSITY DURING FEBRUARY Protons/ccm 12 Protons / ccm Date d

14 13 SOLWIND DENSITY DEVELOPMENT FOR FEBRUARY Protons / ccm Date d

15 14 DAILY Ap-INDICES DURING FEBRUARY Ap-Indices Ap-Indices Date d

16 15 Ap-INDICES DEVELOPMENT FOR FEBRUARY max min Ap-Indices Date d

17 16 DAILY Kp-INDICES FOR FEBRUARY Kp-Indices Date d

18 17 9 DEVELOPMENT OF K-INDICES DURING FEBRUARY K-Indices 7 6 Kp-Indices Date d

19 18 12 GEOMAGNETIC ACTIVITY OVERVIEW FOR FEBRUARY 2007 Geomagnetic Events quiet - unsett active minor - moderate s. major - severe storm Date d

20 19 IMF - ORIENTATION AND STRENGTH. DAILY B and Bz COMPONENTS FOR FEBRUARY B total Bz south Bz north nt Date d

21 20 30 IMF - ORIENTATION AND STRENGTH. DEVELOPMENT DURING FEBRUARY B total Bz south Bz north Date d

22 Solar Geophysical Activity Summary 21 Solar Geophysical Activity Summary for February 2007 Northern Auroral Region Northern Auroral Oval of 05. February 2007

23 Solar Geophysical Activity Summary 22 Solar Geophysical Activity Summary for February 2006 Northern Auroral Region Northern Auroral Oval of 27 February 2007

24 Solar Geophysical Activity Summary 23 Solar Geophysical Activity Summary for February 2007 Northern Auroral Region Northern Auroral Oval of 28 February 2007

25 Solar Geophysical Activity Summary 24 Image of the Northern Polar Auroral Oval During intensive geomagnetic disturbance, the geomagnetic field structure is deeply affected by high-energy particles released by the Sun. The plots of Northern Polar Auroral Oval estimate the visibility of activity from any location of the northern hemisphere. Images show the potential auroral luminosity from the current solar wind stream conditions and are destined to provide an estimate of the visibility of auroral activity. Colour Levels of activity green NIL - low brown / orange low - moderate red moderate - high The brighter the colour, the more intense the activity. Images and maps of the Polar Auroral Oval provided are based on NOAA data and have been issued by STD Solar Terrestrial Dispatch.

26 Solar Geophysical Activity Summary 25 Space Weather Scales Ap - Index Category Descriptor 0-7 Quiet 8-15 Unsettled Active Minor Storm Major Storm Severe Storm Ap-Indices The geomagnetic Ap Index describes the activity of the geomagnetic field in a given time.

27 Solar Geophysical Activity Summary 26 Space Weather Scales Planetary K Indices (Kp); describe geomagnetic storm levels Category Effects 0-1 Kp-Index values of 0 and 1 represent Inactive to Very quiet magnetic conditions and imply very good to good hf radio signal propagation conditions. 2-4 Represent Quiet to Unsettled and Active magnetic conditions and generally correspond to less-impressive hf radio propagation conditions. 5 Represent Minor Storm conditions and are usually associated with fair to poor propagation for many hf paths. 6 Generally represents Major Storm conditions and are almost always associated with poor hf radio propagation conditions. 7 Represents Severe Storm conditions and are often accompanied by hf radio blackout conditions lasting from minutes to < 6 hours, particularly over high latitudes. 8-9 Represents Very Severe Storm to Extreme Severe Storm conditions and are rarely encountered (except during exceptional periods of solar activity). Kp Indices of values around 8 9 most often produce hf radio blackouts for periods lasting in excess of 6 to >10 hours, depending upon intensity of the solar event. Kp-Indices Planetary K - Index NOAA Geomagnetic storm levels * Indices Descriptor Values 0 Inactive G0 1 Very quiet G0 2 Quiet G0 3 Unsettled G0 4 Active G0 5 Minor storm G1 6 Major storm G2 7 Severe storm G3 8 Very severe storm G4 9 Extremely severe storm G5 * broadcast as voice announcements by WWV and WWVH

28 Solar Geophysical Activity Summary 27 Space Weather Scales Correlation of Kp Indices to Ap Indices Correlation Kp - Indices Ap - Indices Kp-Indices / Ap-Indices

29 Solar Geophysical Activity Summary 28 Space Weather Scales Solar Flares Solar flares are classified according their x-ray brightness in the wavelength range 1 to 8 Ångstrøms. Flare Category Peak (W/m²) between 1 and 8 Ångstrøms Descriptor X - class 1.0 x 10E-4 X-class flares are big. They are major events that can trigger planet-wide radio blackouts and long-lasting radiation storms. M class 1.0 x 10E-5 M-class flares are medium-sized events. They generally cause brief radio blackouts that effect Earth s high latitude regions. C class 1.0 x 10E-6 C-class flares are small events with only few noticeable consequences on Earth. B class 1.0 x 10E-7 B-class flares are very small events with no noticeable consequences on Earth. A class 1.0 x 10E-8 A-class flares are extreme small events with no noticeable consequences on Earth. Classification of solar flares Solar Flares A solar flare is an explosion on the Sun that happens when high energy stored in twisted magnetic fields (usually above sunspots or sunspot areas) is suddenly released. Flares produce a burst of radiation across the entire electromagnetic spectrum from radio waves to x-rays and gamma-rays and has major, minor, small or no consequences to hf propagation. Flares are classified according to the table. Mess- u. Empfangsstation

30 29 10 DAILY NUMBER AND CATEGORY OF SOLAR FLARES FOR FEBRUARY X-flares M-flares C-flares Date d

31 30 SOLAR FLARES - DEVELOPMENT DURING FEBRUARY X-flares M-flares C-flares Cathegory Date d

32 Solar Geophysical Activity Summary 31 Date Solar Activity (Flares) Geomagnetic Field Recent propagation conditions for February 2007 according to observations of a global HF beacon network and selected broadcasting stations obtained by means of s receiving station Bockhacken Remarks 045 NE 090 E 135 SE Great Circle Paths* 01. eruptive minor storm n.o. n.o. n.o. n.o. n.o. n.o. n.o. n.o. 02. quiet minor storm fair good fair good fair - good fair -good fair - poor poor 03. quiet active warning fair fair - good fair fair - good fair fair - poor poor poor 04. quiet quiet fair -good fair - good fair good fair -good fair fair fair - poor 05. quiet quiet n.o. n.o. n.o. n.o. n.o. n.o. n.o. n.o. 06. quiet quiet n.o. n.o. n.o. n.o. n.o. n.o. n.o. n.o. 07. quiet quiet fair fair fair fair - good fair - good poor poor - unus unusable 08. quiet quiet fair - poor fair - good poor fair - good fair fair fair - poor fair - poor 09. quiet quiet fair - good good fair - good good fair - good fair fair - poor unusable 10. quiet quiet n.o. n.o. n.o. n.o. n.o. n.o. n.o. n.o. 11. quiet quiet n.o. n.o. n.o. n.o. n.o. n.o. n.o. n.o. 12. quiet unsettled warning fair fair - good fair - good good fair fair fair - poor poor - unus 13. quiet unsettled warning fair good fair fair - good fair fair - poor poor poor 14. quiet unsettled warning fair good fair good fair fair fair - poor poor 15. quiet quiet fair fair - good fair - good good fair fair fair - poor poor - unus 180 S 225 SW 270 W 315 NW 360 N * directions as from location of remote controlled Receiving Station Bockhacken (lat. 51N06.40, long 07E16.45)

33 Solar Geophysical Activity Summary 32 Mess- u.kontrollzentrale Date Solar Activity (Flares) Geomagnetic Field (Status) Recent propagation conditions for February 2007 according to observations of a global HF beacon network and selected broadcasting stations taken by means of s receiving station Bockhacken Remarks 045 NE 090 E 135 SE Great Circle Paths* 16. quiet quiet fair fair - good fair good fair fair fair - poor poor 17. quiet quiet fair - good good fair good fair fair fair - poor fair - poor 18. quiet quiet fair fair - good fair good - fair fair Fair - poor poor poor 19. quiet quiet n.o. n.o. n.o. n.o. n.o. n.o. n.o. n.o. 20. quiet quiet poor - fair fair - good fair good fair fair poor unusable 21. quiet quiet n.o. n.o. n.o. n.o. n.o. n.o. n.o. n.o. 22. quiet quiet fair fair - good fair good fair fair fair fair - poor 23. quiet quiet fair good fair - good good fair - good fair - good fair fair 24. quiet quiet fair fair - good fair - good good fair fair - good fair fair - poor 25. quiet active warning n.o. n.o. n.o. n.o. n.o. n.o. n.o. n.o. 26. quiet minor warning n.o. n.o. n.o. n.o. n.o. n.o. n.o. n.o. 27. quiet active warning n.o. n.o. n.o. n.o. n.o. n.o. n.o. n.o. 28. quiet active warning n.o. n.o. n.o. n.o. n.o. n.o. n.o. n.o. 180 S 225 SW 270 W 315 NW 360 N * Directions as from location of remote controlled receiving station Bockhacken (lat 51N06.40, long 07E16.46)

34 SOLAR CYCLE PROGRESSION CYCLES 22, 23 & 24 CYCLE 22 CYCLE 23 February 2007 d

35 Solar Geophysical Activity Summary 34 Glossary of Solar Terms Ap Index: The geomagnetic Ap-Index describes the activity of the geomagnetic field in a given time. It can vary up to values around 100. During very severe geomagnetic storms it can reach values up to 200 and very occasionally more. Aurora: A sporatic, faint visual phenomenon (Polar Lights, Aurorae Borealis, Aurorae Australis), associated with high geomagnetic activity that occurs mainly in the high latitude night skies of the northern and southern hemisphere. Auroral Oval: An elliptical band around each geomagnetic pole ranging from about 75 degrees magnetic latitude to about 65 degrees magnetic latitude under average magnetic conditions. It is the area of those locations of the maximum occurrence of auroras and widens to both higher and lower latitudes during the expansion phases of magnetic substorms. Geomagnetic Activity: Natural variations in the geomagnetic field, classified into: quiet, unsettled, active and geomagnetic storm levels. There are two indices that are used to determine the level of geomagnetic activity: the Ap-index and the Kp-index. Geomagnetic Latitudes: Low latitudes range from 0 20 degrees, middle latitudes range from degrees, high latitudes range from degrees geomagnetic latitude to the north and/or the south of the equator. Geomagnetic Storm: A worldwide disturbance of Earth s magnetic field (magnetosphere), inducted by direct connection to the Sun s interplanetary magnetic field (IMF), distinct with the arrival at Earth of a shock front of the solar wind, which compresses the front of the magnetosphere. A storm occurs when: Ap > (minor storm), Ap (major storm), Ap (severe storm). Interplanetary Magnetic Field (IMF): The interplanetary magnetic field (IMF) is a part of the Sun s magnetic field that is carried into the interplanetary space by the solar wind. The IMF s field varies in strength near Earth from 1 to 37 nt, with an average value on ~6nT. IMF Bz: The IMF is a vector quantity with three directional components, two of which (Bx and By) are orientated parallel to the ecliptic, the third component (Bz) is perpendicular to the ecliptic and is created by waves and other disturbances in the solar wind. When the IMF and geomagnetic field lines are orientated opposite or antiparallel to each other, they can in some cases merge or reconnect, resulting in transfer of energy, mass and momentum from the solar wind flow to the magnetosphere. The strongest coupling with the most dramatic magnetospheric effect occurs, when the Bz-component is orientated southward. Ionospheric Storm: A disturbance of the ionosphere (F-layer), which occurs in connection with geomagnetic activity, usually causing high absorption of hf radio signals. Kp Index: The Kp-Index describes geomagnetic activity and storm levels. This planetary 3 hour range index Kp is an index taken from 13 geomagnetic observatories between 044 degrees and 060 degrees northern or southern geomagnetic latitude and is designed to measure solar particles radiation by its magnetic effects. The scale is 0 9. nt: Nano Tesla, Unit of magnetism, (1nT = 10E-5 Gauss). Mess- u.kontrollzentrale

36 Solar Geophysical Activity Summary 35 Glossary of Solar Terms Solar Activity: Transient perturbations of the solar atmosphere as measured by enhanced x-ray emissions of the sun. Solar Flares: Solar Flares are tremendous explosions on the Sun s surface. They occur in vicinity of sunspots and usually along the dividing line between areas of opposite fields. Flares release many forms of energy (s. Solar wind). Solar Flux (SFl): The solar flux is used as the basic indicator of solar activity and to determine the level of radiation being received from the sun. The solar flux is measured in solar flux units (SFU) and is the amount of radio noise or flux that is emitted at a frequency of 2800 MHz (10.7 cm). The solar flux is closely related to the amount of ionization and hence the electron concentration in the F-region of the ionosphere. As a result it gives a good indication of conditions especially for long distance radio communication on hf circuits. Solar Wind: A stream of charged particles and magnetic fields emanating from the sun. Under undisturbed conditions this winds velocity is measured with approximately 250 to 450 kilometers per second. In cases of severe or extreme disturbance its tremendous velocity is measured with > km/s. Sunspots: Areas seen as dark spots, in contrast with it surroundings on the Suns surface. Sunspots are areas with extreme concentrations of energy (magnetic flux). Sunspot Number (SSN): The sunspot number summarizes the number of sunspots to be seen on the (Earth directed) visible disc of the Suns surface and gives an index of sunspot activity (R). Sudden Ionospheric Disturbance (SID): One of the different hf radio propagation anomalies due to ionospheric changes resulting from solar activities. Anomalies include short wave fades (or fadeouts), enhancements of atmospherics, phase shifts of electromagnetic radio waves, absorptions, cosmic noise etc. Solar Cycle or Sunspot Cycle: The approximately 11-year quasi periodic variation in the sunspot number. (see diagram of solar cycles 22 and 23). Space Weather: Describes the conditions in space that effect Earth and its technological systems. It is a consequence of the behavior of the Sun, the nature of Earth s magnetic field and atmosphere, and our location in the solar system. Mess- u.kontrollzentrale

37 Solar Geophysical Activity Summary 36 Abbreviations and Terms: ACE = Advanced Composition Explorer Satellite AGU = American Geophysical Union Ap = Planetary A-Index AIP = American Institutes of Physics Bx, By, Bz = B-Components of the IMF CME = Coronal Mass Ejection DK0WCY = Auroa-Beacon DK0WCY, Scheggerott HSS = High Solar Stream IMF = Interplanetary Magnetic Field IARU = International Amateur Radio Union IPS = Radio & Space Services, The Australian Space Weather Agency Kp = Planetary K-Index lat = Latitude long = Longitude minor = minor geomagnetic storm major = major geomagnetic storm NCDXF = Northern California DX-Foundation Inc. NGDC = National Geophysical Data Center n.o. = not observed NOAA = National Oceanic and Atmospheric Administration nt = NanoTesla PCA = Polar Cap Absorption R = Index of Sunspot activity SEC = Space Weather Environment Center SFl = Solar Flux SFU = Solar Flux Units SI = Sudden Impulse SID = Sudden Ionospheric Disturbance SIDC = Solar Influence Data Analysis Center SSN = Sunspot Number STD = Solar Terrestrial Dispatch unsett = unsettled unus = unusable WWV = National Bureau of Standards, Fort Collins, Colorado WWVH = National Bureau of Standards, Maui, Hawaii

38 Solar Geophysical Activity Summary 37 Disclaimer This Solar Geophysical Activity and Propagation Summary has been prepared and compiled by Steffen Hilbig,, Bonn, Germany. Results are based on own observations and numerous valuable data provided by different services and institutions as mentioned below. I herewith reserve the rights not to be responsible for completeness and quality of the information. Liability claims regarding damage caused by the use of any information given in this summary will therefore be rejected. shall be under no liability whatsoever resulting from any use of the given information. AGU, American Geophysical Union, Washington, DC, USA AIP, American Institutes of Physics Aurora-Beacon DK0WCY, Scheggerott, Germany IonoProbe, Realtime Space Weather Monitor IPS Radio & Space Services, Haymarket, NSW, Australia Joint USAF/NOAA, Propagation Bulletin Max Planck Institut für Aeronomie, Göttingen - Lindau, Germany NCDXF/IARU Northern California International Beacon Transmission Network NGDC, National Geophysical Data Center, Boulder, Colorado, USA NOAA, National Oceanic and Atmospheric Administration, Boulder, Colorado, USA Real Time Propagation Monitor, SM5AJV, Stockholm, Sweden SEC, US Space Weather Environment Services Center, Boulder, Colorado, USA SIDC, Solar Influence Data Analysis Center, RWC, Belgium STD, Solar Terrestrial Dispatch WWV, National Bureau of Standards, Fort Collins, Colorado, USA WWVH, National Bureau of Standards, Maui, Hawaii, USA and others