The SI Weather

3:00 PM | The Carrington Event of 1859 – a solar superstorm that took place 155 years ago

[Sunspots sketched by Richard Carrington on Sept. 1, 1859. Copyright: Royal Astronomical Society]


It was this time of year 155 years ago when the solar superstorm, now known as the Carrington Event, took place during solar cycle 10. The event has been named for the British astronomer, Richard Carrington, as he observed from his own private observatory the largest solar flare during this event which caused a major coronal mass ejection (CME) to travel directly toward Earth. The 33-year-old astronomer - widely acknowledged at the time to be England’s best - also recorded in detailed fashion the appearance of the sunspot regions that he saw at the time.

From August 28, 1859 to September 2, 1859 numerous sunspots and solar flares were observed on the sun and auroras were being observed in different parts of the world. Just before noon on September 1st, Richard Carrington was using his telescope to project an 11-inch wide image of the sun on a screen and he carefully drew the sunspots that he saw. Suddenly, two brilliant beads of blinding white light appeared over the sunspots and he realized that he was witnessing something unprecedented. He left for about one minute to find another witness and found upon their return that much had already subsided.

Just before dawn the next day, skies all over Earth erupted in red, green and purple auroras - even in tropical locations like Cuba, the Bahamas and Hawaii. The massive solar flare caused a major CME that reached the Earth some 17.6 hours later. Normally such a journey takes 3 or 4 days, but an earlier CME actually cleared the way of the ambient solar plasma for the second blast to move so quickly. The auroras were so bright over the Rocky Mountains that their glow awoke gold miners who began preparing breakfast because they thought it was morning. People in the northeastern US could read a newspaper by the aurora’s light. Telegraph systems all over Europe and North America went haywire and, in some cases, telegraph operators were literally shocked as sparks were flying and telegraph paper was often set on fire. Some systems continued to work despite being disconnected from their power supplies as aurora-induced electric currents still allowed messages to be transmitted.

Now we know that solar flares happen frequently, especially during solar sunspot maximums, but in those days there were no X-ray satellites or radio telescopes and no one knew flares existed until that September morning. “It is rare that one can actually see the brightening of the solar surface which takes a lot of energy to heat up the surface of the sun” says a modern day NASA astronomer. “In the 160-year record of geomagnetic storms, the Carrington event is the biggest.” In fact, going back farther in time by examining Arctic ice (energetic particles leave nitrates in ice cores), it is estimated that this event may have been the biggest in 500 years and nearly twice as big as the runner-up.

In today’s world, electronic technologies have become embedded into everyday life and are, of course, quite vulnerable to solar activity. Power lines, long-distance telephone cables, radar, cell phones, GPS, satellites – all could be significantly affected by an event like this one. The good news is that observations of the sun are a constant in today’s world with a fleet of spacecraft in position to monitor the sun and gather data on solar flares. The bad news is that the Carrington Event occurred during a weak solar cycle (10) which actually resembles rather closely our current solar cycle (24) so we always have to stay on guard for a potential powerful solar storm - even during times of weak solar cycles.

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2:45 PM | The Iceland volcano erupts, but a far bigger explosion occurs on the other side of the world

[Ash plume from Rabaul volcano in Papua New Guinea]


The Bardarbunga volcano in Iceland that we have been tracking in recent days has finally erupted, but it was not a big explosive event. Meanwhile, there has actually been a far bigger eruption in Papua New Guinea at the Rabaul volcano on Mount Tavurvur and this has the potential to do more damage to nearby population centers. In addition to the direct threat to people in nearby locations, volcano eruptions can produce ash that is extremely hazardous to jet aircraft that inadvertantly fly through it. The ash is composed primarily of silicate particles that melt when ingested into the combustion chamber of a jet engine, causing severe loss of engine performance and perhaps, a complete shutdown of the engine.

The Iceland volcano which sits beneath a glacier has been receiving most of the attention lately and last night it finally started erupting as lava emerged from a fissure. A fissure eruption is one in which lava essentially flows up through vents in the ground spread out over a larger area. The eruption lasted about four hours and came after weeks of earthquakes in the region. The eruption did not spew ash into the atmosphere and has had minimal effects on flights and it is in a relatively remote area of Iceland. Even though the eruption has stopped for the time being, earthquakes continue to rumble indicating magma is still on the move, and this volcano will continue to be closely monitored. By the way, in an odd twist of fate by Mother Nature, the remains of Hurricane Cristobal raced from off the US east coast into the North Atlantic during the past couple of days and actually dumped some serious snow on Iceland as well as on eastern sections of Greenland.

Papua New Guinea
Meanwhile, on the other side of the world, the large Rabaul volcano began erupting earlier today and it has spewed out plenty of ash into the atmosphere. The ash plume has apparently reached about 11 miles into the air and has indeed disrupted air travel in that part of the world. This was the first major eruption of this volcano – one of the most active in Papua New Guinea - in about twenty years. In 1994, an eruption there nearly destroyed Rabaul altogether, forcing residents to flee.

Volcanic eruptions along with oceanic and solar cycles play crucial roles in our global climate. The most substantive climatic effect from volcanoes results from the production of atmospheric haze. Large eruption columns inject ash particles and sulfur-rich gases into the troposphere and stratosphere and these clouds can circle the globe within weeks of the volcanic activity. The small ash particles decrease the amount of sunlight reaching the surface of the earth and lower average global temperatures. The sulfurous gases combine with water in the atmosphere to form acidic aerosols that also absorb incoming solar radiation and scatter it back out into space. In fact, the formation of atmospheric sulfur aerosols has a more substantial effect on global temperatures than simply the volume of ash produced during an eruption.

Not only does the type and amount of ash from volcanic eruptions play a critical role in its potential effect on global temperatures, but the location of the eruption is also very important. Volcanic eruptions in the tropics, for example, can be much more important than those in the mid-latitudes for a couple of reasons. First, the sun heats equatorial regions more than in mid-latitude or polar regions; therefore, any disruption to solar radiation in the tropics can have more serious effects on global temperatures. Second, upper level winds - which act to spread and disperse ash plumes – are typically weak over tropical regions as compared with the mid-latitudes, for example, and this could impact the longevity of any ash cloud in a particular region.

The atmospheric effects of volcanic eruptions were confirmed by the 1991 eruption of Mount Pinatubo, in the Philippines. Pinatubo’s eruption cloud reached over 40 kilometers into the atmosphere and ejected about 17 million tons of SO2, just over two times that of the El Chichon, Mexico volcano in 1982. The sulfur-rich aerosols circled the globe within three weeks and produced a global cooling effect approximately twice that of El Chichon. The Northern Hemisphere cooled by up to 0.6 degrees C during 1992 and 1993.

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3:00 PM | The first half of September looks quite warm in the Mid-Atlantic region

[Euro computer model forecast at 500 millibars for September 7th]


August has brought a continuation of below normal temperatures to the Mid-Atlantic region following a slightly cooler-than-normal month of July, but it looks like at least the first half of September will be on the warmer-than-normal side. The persistent upper air pattern of recent months featuring numerous troughs of low pressure centered over the Midwest and Great Lakes will change over the next several days to one with strong high pressure ridging centered in the Southeast US. Indeed, the 500 millibar forecast map from the latest European computer forecast model run (above) depicts high pressure in the Southeast US about 10 days from now. From this position, high pressure over the Southeast US will pump in warm, humid air from the Gulf of Mexico region to the Mid-Atlantic which until now this summer has not been sustainable by the atmosphere for more than a couple of days at a time. Supporting evidence for this warm outlook during the first half of September comes from NOAA’s Climate Forecast System (CFS version 2) forecast model which shows warmer-than-normal conditions during the first 10 days of September in much of the eastern half of the nation (orange/red areas in two maps below). Looking even farther ahead, I believe it is possible that the warmer-than-normal weather pattern that develops next week may end up continuing into October, but there is likely to be a transition back to colder-than-normal conditions before the winter locks in.

[NOAA/Climate Forecast System forecast maps for temperature departures from normal for the next two weeks]

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1:00 PM | Northern lights, an update on the Iceland volcano, and mysterious lights from the Napa earthquake


Northern Lights
[Northern lights earlier today as seen in Devil's Tower, Wyoming; courtesy]

A coronal mass ejection (CME) reached the Earth’s upper atmosphere early today sparking bright auroras around the North and South Poles and in high latitudes. In fact, reports of northern lights have poured in today from across the northern US including such states as Maine, Michigan, Wisconsin, Idaho, North Dakota and Washington. The CME that instigated today’s display was launched toward Earth on August 22nd. According to “”, the solar wind speed did not change much when the slow-moving CME arrived. However, the storm cloud was still “effective” because it contained a south-pointing magnetic field that opened a crack in Earth’s magnetosphere. Solar wind is pouring in to fuel the on-going display. High latitude sky watchers should remain on alert tonight for auroras as solar wind conditions continue to favor geomagnetic activity.

[NOAA POES satellite data shows the extent of this morning’s "statistical aurora oval" well down into the mid-latitudes; courtesy NOAA Space Prediction Center].

Iceland Volcano
Earthquakes are rocking Iceland’s Bardarbungo volcano, adding to concerns that magna movements may trigger an eruption that could hinder air traffic. Two earthquakes measuring over 5.0 shook the volcano under the vast Vatnajokull glacier earlier today and over 500 quakes have hit the area since midnight. Scientists say that 50 million cubic meters of molten rock has moved in a 24 hour period. If it continues to head north, it could link up with the Askja system and trigger a large eruption. In 2010, Iceland's Eyjafjallajokul volcano erupted and sparked a week of international aviation chaos. Some 100,000 flights were cancelled after aviation officials closed Europe's air space for five days out of fears that volcanic ash could harm jet engines.

[The ash cloud from the Eyjafjallajokull eruption in 2010 created a major disruption for air travel]

Mysterious Lights
Mysterious flashes of light in the sky were reported by several people during last Sunday’s magnitude 6.0 earthquake in the Napa region of northern California. Witnesses said the strange phenomenon looked like lightning and similar flashes of light have been reported in earthquakes around the world from Japan to Peru. One scientist called this phenomenon “earthquake lights” and suggested they are a consequence of the stresses building up deep below the earth that cause an electric current to flow to the surface and burst through the earth. This typically happens before or during an earthquake. Most reports said there were one to two seconds between the light flashes. Research continues in this area - many seismologists do not believe such things are real.

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