Saturday, November 29, 2008

The paradox of a quiet sun

In a recent article in Movosti there is discussion on the problems from flare and cme activity during the new solar cycle

Our Sun is muscling up again. According to NASA, it is beginning another 11-year cycle of activity. Considering that the Sun is to blame for some unfavorable climate changes on the Earth, the coming decade could spell more trouble for our planet.

The first measuring instruments made their appearance 440 years ago. They showed that our nearest star treats the Earth to more than just solar eclipses. Sunspots, solar flares, faculae and other phenomena affect everything on the Earth: from atmospheric events to human behavior. These phenomena are known collectively as solar activity.

This activity, expressing itself through bursts of solar radiation, magnetic storms or fiery flares, can vary in intensity, from very low to very strong. It is the storms that pose the greatest danger to civilization.

On August 28, 1859, polar lights glowed and shimmered all over the American continent as darkness fell. Many people thought their city was aflame. The instruments used to record this magnetic fluctuation across the world went off their scales. Telegraph systems malfunctioned, hit by a massive surge in voltage.

This was an actual solar storm. Its results for humankind were small, because civilization had not yet entered a hi-tech phase of development. Had something similar happen in our nuclear space age, destruction would have been catastrophic.

Meanwhile, according to scientific data, storms of such size occur relatively seldom: once in five centuries. But events with half the intensity happen every 50 years. The last one took place on November 13, 1960 and disturbed the Earth's geomagnetic fields, upsetting the operation of radio stations.

We have already discussed this here and here

A basic outline is here.

Society reliance on electricity for meeting essential needs has steadily increased for many years. This unique energy service requires coordination of electrical supply, demand, and delivery—all occurring at the speed of light. Disturbances caused by solar activity can disrupt these complex power grids. When the Earth's magnetic field captures ionized particles carried by the solar wind, Geomagnetically-induced currents (GIC) can flow through the power system, entering and exiting the many grounding points on a transmission network. GICs are produced when shocks resulting from sudden and severe magnetic storms subject portions of the Earth's surface to fluctuations in the planet's normally stable magnetic field. These fluctuations induce electric fields in the Earth that create potential differences in voltage between grounding points—which causes GICs to flow through transformers, power system lines, and grounding points. Only a few amps are needed to disrupt transformer operation, but over 200 amps have been measured in the grounding connections of transformers in affected areas. Unlike threats due to ordinary weather, Space Weather can readily create large-scale problems because the footprint of a storm can extend across a continent. As a result, simultaneous widespread stress occurs across a power grid to the point where widespread failures and even regional blackouts may occur. Systems in the upper latitudes of the Northern Hemisphere are at increased risk because Auroral activity and its effects center on the magnetic poles. North America is particularly exposed to these storm events because the Earth’s magnetic north pole tilts toward this region and therefore brings it closer to the dense critical power grid infrastructure across the continent.

Routine grid and transformer failures can be expected fom moderate to severe the frequency and severity (which obeys a powerlaw ie the larger the event the less frequency) can be seen here

Climatically there will be seen similar cooling events as linked above and seen in SH summer 2006.As these are essentially random prediction is not possible,

Friday, November 21, 2008


In an interesting paper K. G. Pavlakis et al have found that changes in downward shortwave radiation (by changes in cloud cover) are a significant forcing in the enso oscillation.

Abstract. We have studied the spatial and temporal variation of the downward shortwave radiation (DSR) at the surface of the Earth during ENSO events for a 21-year period over the tropical and subtropical Pacific Ocean (40_ S–40_ N, 90_ E–75_ W). The fluxes were computed using a deterministic model for atmospheric radiation transfer, along with satellite data from the ISCCP-D2 database, reanalysis data from NCEP/NCAR for the key atmospheric and surface input parameters,and aerosol parameters from GADS (acronyms explained in main text). A clear anti-correlation was found between the downward shortwave radiation anomaly (DSR-A) time-series, in the region 7_ S–5_ N 160_ E–160_W located west of the Ni˜no-3.4 region, and the Ni˜no-3.4 index timeseries. In this region where the highest in absolute value DSR anomalies are observed, the mean DSR anomaly values range from −45Wm−2 during El Ni˜no episodes to +40Wm−2 during La Ni˜na events. Within the Ni˜no-3.4 region no significant DSR anomalies are observed during the cold ENSO phase in contrast to the warm ENSO phase. A high correlation was also found over the western Pacific (10_ S–5_ N, 120–140_ E), where the mean DSR anomaly values range from +20Wm−2 to −20Wm−2 during El Ni˜no and La Ni˜na episodes, respectively. There is also convincing evidence that the time series of the mean downward shortwave radiation anomaly in the off-equatorial western Pacific region 7– 15_ N 150–170_ E, precedes the Ni˜no-3.4 index time-series by about 7 months and the pattern of this anomaly is indicative of ENSO operating through the mechanism of the western Pacific oscillator. Thus, the downward shortwave radiation anomaly is a complementary index to the SST anomaly for the study of ENSO events and can be used to assess whether or not El Ni˜no or La Ni˜na conditions prevail.

Whilst this is an additional indicator,the enso oscillation is a highly coupled mechanism that is both internally driven(self organized far from equilibrium) and externally forced,both the fluctuations and inversions are a result of highly coupled
feedbacks both positive(amplifying) and negative(dissipative),this is a well understood open problem for long term predictive modelling.

Web Counters