Sunday, August 22, 2010
Saturday, August 14, 2010
Friday, August 13, 2010
ARLP032 Propagation de NW7US
This week's bulletin was written by Tomas Hood, NW7US. Tomas is filling in for your regular reporter Tad Cook, K7RA.
Sunspot numbers and solar flux increased this week, with average daily sunspot numbers up over 32 points to 53, and the average daily
10.7-cm solar flux up over 3 points to 84.5. These are the numbers from last Thursday through this Wednesday, August 5 through August
The sunspot count on August 11 was 66, consisting of four active sunspot regions, NOAA Active Regions 1093, 1095, 1096, and 1097.
The largest of these was 1093 with a relative size of 130 millionths of a solar hemisphere. The sunspot count of 66 is the highest yet
recorded in Sunspot Cycle 24. Another note-worthy development this week is that five active sunspot regions were reported on August 12.
However, most of the spots were small, resulting in a daily sunspot count of 50.
Another news-worthy event was the M-class X-ray flare that erupted from active sunspot region 1093 on August 7. This flare was 10
times more powerful than the C-class flare on August 1 that caused so much News Media attention on August 3 through August 5. This
M1.0 magnitude solar flare peaked at 1824 UTC on August 7 and ejected a huge mass of coronal plasma. Many hoped that the coronal
mass ejection, or CME, originating from the sunspot region 1093 would trigger auroral displays around the world just like those that
occurred last week. However, because this CME was not fully Earth-directed, most of the CME missed the magnetosphere, resulting
in only the slightest increase in geomagnetic activity between August 10 and 11.
This flare, one of the biggest since the start of Cycle 24, also triggered a metric type II radio burst. This kind of radio burst
can be heard from a radio receiver tuned to, say, a six-meter frequency as the burst occurs. The burst sounds like rushing wind.
You can hear a recording of a type II radio burst as recorded on 50 MHz by Thomas Ashcraft on April 2, 2001 at 2151 UTC that occurred
during the X22.0-magnitude X-ray flare, by browsing to http://tinyurl.com/50MT2RB. Incidentally, the April 2, 2001 flare
is the second largest event on record after the X28.0-magnitude mega-flare that occurred on November 4, 2003.
A movie of the August 7 M-class flare showing a series of filtered views of the event as seen by the Solar Dynamics Observatory's
Atmospheric Imaging Assembly can be viewed at http://tinyurl.com/20100807mflare and is available in high
Thursday, August 12, 2010
SUNSET PLANET SHOW: When the sun goes down tonight, step outside and look west. Venus, Mars, Saturn and the crescent Moon are having a lovely 4-way conjunction. It's a great way to warm up for the Perseid meteor shower, which peaks on Thursday night, August 12th. Get the full story from Science@NASA. Sky maps: August 12, 13.
PERSEID METEOR SHOWER: The annual Perseid meteor shower is underway. According to the International Meteor Organization, dark-sky observers are now counting more than 35 Perseids per hour, including many fireballs. Be alert for Perseids from 10 pm on Thursday, Aug. 12th, until sunrise on Friday, Aug. 13th. The darkest hours before dawn are usually best.
Wednesday, August 11, 2010
August 2, 1972 – A solar storm caused a 230,000 volt transformer located at the British Columbia Hydro and Power Authority to explode
December 19, 1980 – A very expensive 735 kV transformer failed 8 days after the Great Red Aurora of 19 December at St. James Bay, Canada.
April 13, 1981 – A replacement 735 kV transformer at St. James Bay, Canada also failed the next year during another geomagnetic storm.
March 13, 1989 – At 02:45 EST on March 13, geomagnetically induced currents (GIC) inundated the transformers of the Hydro-Quebec power system and overloaded them with current. The voltage fluctuations that resulted prompted the tripping, or deactivation, of reactive power compensators at the Chibougamau, la Verendrye, Nemiscau and Albanel substations. A severe voltage drop resulted; the power lines from James Bay malfunctioned and the system collapsed. It was later determined that the power lines were substantially vulnerable due to their great length and the number of static compensators that ran along their distance. The Hydro Quebec outage resulted from the linked malfunction of more than 15 discrete
protective-system operations. From the initial event to complete blackout, only one-and-a-half minutes elapsed—hardly enough time to assess what was occurring, let alone to intervene.15 The blackout resulted in the loss of 21,500 megawatts of electricity generation. It took nine hours to restore 83% of that electrical load. The blackout affected 6 million people. The physical damage included a 1,200-ton capacitor failure at a Static VAR Compensator (SVC), overvoltage damage to two step-up transformers at the La Grande 4 generating station, surge arresters at the La Grande 2 and Churchill Falls generating stations, and to a shunt Figure 2. Earth ground resistivity based on underlying rock strata. Conductivity measurements from the Geomagnetic
Laboratory of the Geological Survey of Canada in Ottawa with Extension to the United States Completed by Electric Power Research Institute – Sunburst Project. Units – siemens per meter.
(regions in red are very non-conductive). reactor at the Nemiscau substation, and damage to the SVCs themselves.
March 13, 1989 – The solar storm destroyed a $12 million generator step-up transformer owned by the Public Service Electric and Gas Company of New Jersey. The transformer was a linchpin in converting electricity from the Salem Nuclear Generating Plant. The 288.8/24-kV single-phase shell-form transformers, which are rated at 406 MVA, are connected grounded-wye. The damage to the transformers included damage to the low-voltage windings, overheating, thermal degradation of the insulation of all three phases, and conductor melting.12 The utility asked the supplier for a replacement and was told thatthe order would receive top priority, but it would still take almost two years to fill. Fortunately a spare transformer was made available, but it still took 6 weeks to install.
October 30, 2003 – A power grid in southern Sweden located in Malmo experienced a 20-50 minute electrical blackout affecting 50,000 customers due to a strong solar storm. The same storm caused significant transformer damage in South Africa. Over 15 transformers in South Africa were damaged, some beyond repair.
Sunday, August 8, 2010
SOLAR BLAST JUST MISSES EARTH: On Saturday, August 7th, magnetic fields around sunspot 1093 erupted. NASA spacecraft and many amateur astronomers photographed the blast, which produced a strong M1-class solar flare and hurled a coronal mass ejection (CME) into space--apparently just missing the sun-Earth line. The explosion also made whooshing sounds in the loudspeakers of some shortwave radios. Visit http://spaceweather.com for audio recordings and movies of this latest solar event.
AURORA RECAP: Last week's geomagnetic storm sparked Northern Lights as far south as Iowa in the United States, and some nice Southern Lights over Antarctica. See photo above