Weekly Highlights and Forecasts
:Product: Weekly Highlights and Forecasts :Issued: 2012 Jan 31 2314 UTC # Prepared by the US Dept. of Commerce, NOAA, Space Weather Prediction Center # Product description and SWPC contact on the Web # http://www.swpc.noaa.gov/weekly.html # # Weekly Highlights and Forecasts # Highlights of Solar and Geomagnetic Activity 23 - 29 January 2012 Solar activity ranged from low to high levels. Region 1402 (N28, L=214, class/area=Eko/630 on 17 January) produced a long duration M8/2b flare at 23/0359 UTC. Multiple radio emissions from 25 MHz to 15.4 GHz, including a 5100 sfu Tenflare, and a Type IV sweep were also observed. Finally, an approximately 1600 km/s asymmetric full-halo coronal mass ejection (CME) was seen in SOHO/LASCO C2 imagery beginning at 23/0412 UTC. Activity returned to low levels as Region 1402 made its way across the visible solar disk producing occasional low to mid level C-class flares. On 27 January, Region 1402 moved to N29W71 before producing an X1/1f flare at 27/1837 UTC. Radio phenomena, including a Type II (1523 km/s) and a Type IV radio sweep with an 810 sfu Tenflare accompanied this flare. An asymmetric halo CME was later observed in LASCO C2 coronagraph imagery with an estimated plane-of-sky speed near 2000 km/s. Region 1402 rotated off the west limb on 28 January. Region 1402’s counterpart, Region 1401 (N18, L=213, class/area=Eki/540 on 19 January) was the second largest and most magnetically complex (beta-gamma) region on the disk during the period. Region 1401 was only responsible for a couple of low level C-class flares during the period. Region 1401 decayed to spotless plage on 26 January. Energetic proton flux levels reached strong levels during the period as two proton events energized the Earth's magnetosphere. The first event began minutes after the M8/2b flare on 23 January. The 10 MeV proton flux crossed the 10 pfu event threshold at 23/0530 UTC. The 10 MeV protons increased steadily to a peak flux of 6310 pfu at 24/1530 UTC, following the arrival of the interplanetary shock. This 10 MeV proton event ended at 27/1025 UTC when the enhancement dropped below the 10 pfu level. This 10 MeV proton event was the largest enhancement since Oct 29, 2003 (29,526 pfu) and the 11th largest since January, 1975. Also with this event, the 100 MeV proton flux exceeded the 1 pfu threshold. The 100 MeV flux began at 23/0445 UTC, increased to a peak of 2 pfu at 23/0750 UTC, then steadily declined until it dropped below the 1 pfu threshold at 23/2050 UTC. The second event began on 27 January, after the X1.7/1f flare. The 10 MeV proton flux crossed the 10 pfu event threshold at 27/1905 UTC. The 10 MeV protons increased steadily to a peak flux of 796 pfu at 28/0205 UTC. The 10 MeV proton event was still in progress at the time of this report. The associated 100 MeV event began at 27/1900 UTC, reached a maximum of 11 pfu at 27/2140 UTC and ended on 28/2120 UTC. The greater than 2 MeV electron flux at geosynchronous orbit began at background levels, but increased to moderate levels late on 23 January. Values increased to high levels on 27-28 January, before decreasing to moderate levels through the end of the period. Geomagnetic field activity ranged from quiet to minor storm levels at mid-latitudes and briefly reached severe storm conditions at high latitudes. The magnetic field was mostly quiet on 23 January with an isolated minor storm observed at high latitudes from waning effects from a CME. On 24-25 January, activity increased to isolated minor storms at low latitudes and severe storms at high latitudes, due to the arrival of a CME, associated with the 23 January M8/2b flare. An interplanetary shock was observed at the ACE spacecraft at 24/1431 UTC followed by a 37 nT increase in total field, as measured by the ACE spacecraft, at 24/1439 UTC. A corresponding sudden impulse was observed in the Boulder magnetometer with a 22 nT deviation at 24/1504 UTC. Solar wind speed, as measured by the SOHO spacecraft, was approximately 750 km/s at the time of the shock passage before decreasing to approximately 650 km/s. The geomagnetic field decreased to predominantly quiet levels for the remainder of the period. Forecast of Solar and Geomagnetic Activity 01 February - 27 February 2012 Solar activity is expected to be at very low to low levels from 01-09 February until old Regions 1401 and 1402 are due to return. Solar activity is expected to increase to low levels with a chance for M-class flares and a slight chance for X-class flares for the remainder of the period. The greater than 10 MeV proton flux at geosynchronous orbit is expected to remain elevated from 01-02 February but below the 10 pfu threshold values. A return to background levels is expected from 03- 08 February. On 09 February, old Regions 1401 and 1402 are due to return to the visible disk. From 09 February until the end of the forecast period, there will be a slight chance for a proton event. The greater than 2 MeV electrons at geosynchronous orbit are expected to be at normal to moderate levels for the entire forecast period. The geomagnetic field is expected to be at predominantly quiet levels for the entire period. Quiet to unsettled levels are expected on days 03-04 February, 09 February, 12 February, and 23 February. This increased activity can be attributed to multiple, recurrent coronal hole, high speed wind streams.
