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Everything and anything => Interesting sites/links, ebooks/book, Reference papers, pdfs... => Topic started by: electrobleme on July 29, 2009, 16:54:57

Title: Global Electrical Weather System
Post by: electrobleme on July 29, 2009, 16:54:57

References, links and articles relating to the Earths Electric Weather Systems
Title: The Electrojet - (polar electric currents)
Post by: electrobleme on July 29, 2009, 16:59:43
Auroral Electrojet Research Studies


What is this Auroral Electrojet?

The term 'auroral electrojet' is the name given to the large horizontal currents that flow in the D and E regions of the auroral ionosphere. Although horizontal ionospheric currents can be expected to flow at any latitude where horizontal ionospheric electric fields are present, the auroral electrojet currents are remarkable for their strength and persistence. There are two main factors in the production of the electrojet. First of all, the conductivity of the auroral ionosphere is generally larger than that at lower latitudes. Secondly, the horizontal electric field in the auroral ionosphere is also larger than that at lower latitudes. Since the strength of the current flow is directly proportional to the vector product of the conductivity and the horizontal electric field, the auroral electrojet currents are generally larger compared to those at lower latitudes.

During magnetically quiet periods, the electrojet is generally confined to the auroral oval. However during disturbed periods, the electrojet increases in strength and expands to both higher and lower latitudes. This expansion results from two factors, enhanced particle precipitation and enhanced ionospheric electric fields.

Following picture shows the location of the auroral electrojet in general, and also shows subionospheric propagation paths used for VLF-based electrojet detection over North America and North Atlantic.

Location of the Auroral Electrojet

Energetic Electron Precipitation (EEP) represents a significant form of coupling between the ionosphere and magnetosphere, which is itself an important component of Space Weather. The magnetosphere can be thought of as a current generator which drives the ionosphere as an electrical 'load', in which significant energy dissipation takes place.

There is abundant evidence that during geomagnetic storms and substorms large fluxes of energetic electrons are directly injected into the auroral and subauroral regions from source regions in the magnetosphere. This precipitation is a major source of energy input into the lower ionosphere and cause substantial changes in the chemistry of this region. In addition these precipitating electrons produce secondary ionization in the D and E regions of both the auroral and subauroral ionospheres, significantly increasing the electrical conductivity of these regions. As a result of this increased conductivity, larger electric currents are produced there.

The importance of energetic particle precipitation in the electrojet expansion during disturbed periods has been demonstrated by Kikuchi and Evans [1983], who showed that the precipitation is completely correlated in time with the development of the electrojet current system.

VLF Measurements of the Auroral Electrojet

A key feature of E > 300 keV precipitation is the fact that it penetrates deeply into the D region of the ionosphere, well below the normal reflection height for VLF waves which propagate in the earth ionosphere waveguide. The enhanced ionization which is produced by the precipitated flux strongly perturbs the phase and amplitude of the propagation VLF waves. As shown by a number of studies [Kikuchi, 1981; Kikuchi and Evans, 1983; Kikuchi et al., 1983; Cummer et al., 1994 (AGU Outstanding Student Paper Award); Cummer et al., 1996] these perturbations are readily measurable with contemporary instruments.

Cummer et al. [1996] found that clear perturbations in both the VLF amplitude and phase data were associated with electrojet movements over the magnetometer stations.

The path configurations were such that any southward expansion of the electrojet during substorms could be remotely monitored by measuring the phase perturbations produced in the earth-ionosphere waveguide signals along the various paths.

Application of VLF Technique

VLF data over Eastern Canada has been studied for correlations with auroral electron precipitation regions over the path [Cummer et al., 1994]. It is well known that the E region conductivity enhancements caused by this precipitation are a major component in the increase of auroral electrojet currents, and as such the edge of the precipitation region is well-correlated with the edge of the elctrojet. X-ray images of the region were taken by the AXIS instrument on the UARS satellite, and from these it can easily be determined whether the precipitation region is over a VLF propagation path.

Following figure shows an example of simultaneous AXIS images, VLF data, and magnetometer data over the course of a single night. The VLF path studied was from the NLK transmitter to Gander, Newfoundland. Three x-ray images were taken over the region of interest, and it can clearly be seen that only during the third image was there electron precipitation occuring over the VLF path. Simultaneous with this last image is a significant amplitude drop in the NLK signal.

Early Warning

In many cases the VLF technique can provide hours of early warning of possible electrojet intrusion to mid-latitudes over the North American continent. The electrojet is a current system that is approximately fixed in inertial space with the earth rotating under it, and a strong electrojet activity is common in the local midnight sector of the auroral region. During major storms the electrojet can remain at mid-latitudes for as many as six hours. Since the VLF technique can detect the electrojet boundary over the Atlantic, it can provide 2 to 6 hours warning of possible strong electrojet activity when the North American continent enters the midnight sector.
VLF Group - Stanford University (http://www-star.stanford.edu/~vlf/ejet/electrojet.html[/url)
Title: The Electrojet (auroral electrojets)
Post by: electrobleme on July 29, 2009, 17:29:38
Space Weather Studies:
Continuous Monitoring of Intense Subauroral Relativistic Electron Precipitation and its Effects on the Ionosphere and Mesosphere

(http://www.everythingselectric.com/images/electron-precipitation-south-atlantic-anomaly-saa-forum.jpg) (http://www.electricyouniverse.com/eye/thumbs/lrg-1192-electron-precipitation-south-atlantic-anomaly-saa.jpg)



Space Weather Studies investigates key scientific questions concerning electron density enhancements in the lower ionosphere and middle atmosphere which are produced by relativistic electron precipitation from the Earth's outer radiation belts.

The ionospheric and mesospheric signatures of both steady and burst electron precipitation are to be measured at regular intervals via their effects on very low frequency (VLF) subionospheric signals transmitted from Maine (NAA), Washington (NLK), and Hawaii (NPM) and received at Fort Yukon and other ground stations in Alaska. (Figure 1).

Our proposed study will make use of relativistic electron data from the SAMPEX, UARS, and POLAR spacecraft. This
work is in association with Dr J. B. Blake, a Co-Investigator on SAMPEX associated with the Proton / Electron Telescope (PET) instrument, Dr. D. L. Chenette, a co-investigator on UARS associated with the High-Energy Particle Spectrometer (HEPS), and Dr. M. Walt, a Co-investigator on POLAR associated with the CEPPAD/SEPS instrument.
Space Weather Studies - Stanford University (http://www-star.stanford.edu/~vlf/spaceweather/spaceweather.htm)

Lots more information, results, graphs etc available with the full report (http://www-star.stanford.edu/~vlf/spaceweather/spaceweather.htm)

Title: Earths weather influenced by the Suns 11 year cycle
Post by: electrobleme on September 06, 2009, 23:55:04

Suns 11 year cycle (nucler powered?) affects Earths weather patterns

Connections among Solar Cycle, Stratosphere and Ocean Discovered - Work in sync to generate periodic global weather patterns

Subtle connections among the 11-year-solar cycle, the stratosphere and the tropical Pacific Ocean work in sync to generate periodic weather patterns that affect much of the globe, according to research results appearing this week in the journal Science.

The findings will help scientists get an edge on predicting the intensity of certain climate phenomena, such as the Indian monsoon and tropical Pacific rainfall, years in advance.

"It's been long known that weather patterns are well-correlated to very small variations in total solar energy reaching our planet during 11-year solar cycles," says Jay Fein, program director in the National Science Foundation (NSF)'s Division of Atmospheric Sciences, which funded the research. "What's been an equally long mystery, however, is how they are physically connected. This remarkable study is beginning to unravel that mystery."

An international team of authors led by the National Center for Atmospheric Research (NCAR) in Boulder, Colo., used more than a century of weather observations and three powerful computer models to tackle one of the more difficult questions in meteorology: if the total energy that reaches Earth from the Sun varies by only 0.1 percent across the approximately 11-year solar cycle, how can it drive major changes in weather patterns on Earth?

The answer, according to the study, has to do with the Sun's impact on two seemingly unrelated regions.

Chemicals in the stratosphere and sea surface temperatures in the Pacific Ocean respond during solar maximum in a way that amplifies the Sun's influence on some aspects of air movement.

This can intensify winds and rainfall, change sea surface temperatures and cloud cover over certain tropical and subtropical regions, and ultimately influence global weather.

"The Sun, the stratosphere, and the oceans are connected in ways that can influence events such as winter rainfall in North America," says NCAR scientist Gerald Meehl, the lead author of the paper. "Understanding the role of the solar cycle can provide added insight as scientists work over the next decade or two toward predicting regional weather patterns."

The results builds on recent papers by Meehl and colleagues exploring the link between the peaks in the solar cycle and events on Earth that resemble aspects of La Niña events, but are distinct from those larger patterns associated with changes in pressure and known as the Southern Oscillation.

The connection between peaks in solar energy and cooler water in the equatorial Pacific was first discovered by Harry Van Loon of NCAR and Colorado Research Associates, a co-author of the paper.

The contribution by Meehl and his colleagues is to document that two mechanisms that had been previously theorized in fact work together to amplify the response in the tropical Pacific.

The team first confirmed a theory that the slight increase in solar energy during the peak production of sunspots is absorbed by stratospheric ozone.

The energy warms the air in the stratosphere over the tropics where the sunlight is most intense, while also stimulating the production of additional ozone there that absorbs even more solar energy.

Since the stratosphere warms unevenly, with the most pronounced warming occurring at lower latitudes, stratospheric winds are altered and, through a chain of interconnected processes, end up strengthening tropical storms and precipitation.

At the same time, the increased sunlight at solar maximum causes a slight warming of ocean surface waters, especially across the subtropical Pacific, where Sun-blocking clouds are normally scarce.

That small amount of extra heat leads to more evaporation, producing additional water vapor. In turn, the moisture is carried by trade winds to the normally rainy areas of the western tropical Pacific, fueling heavier rains and reinforcing the effects of the stratospheric mechanism.

The top-down influence of the stratosphere and the bottom-up influence of the ocean work together to intensify this loop and strengthen the trade winds.

As more sunshine hits drier areas, these changes reinforce each other, leading to less clouds in the subtropics, allowing even more sunlight to reach the surface, and producing a positive feedback loop that further intensifies the climate response.

These stratospheric and ocean responses during solar maximum keep the eastern Pacific even cooler and drier than usual, producing conditions similar to a La Niña event.

However, the cooling of about 1-2 degrees Fahrenheit is focused further east than in a typical La Niña, is only about half as strong, and is associated with different wind patterns in the stratosphere.

Earth's response to the solar cycle continues over the year or two following peak sunspot activity. The La Niña-like pattern triggered by the solar maximum tends to evolve into a pattern similar to El Niño, as slow-moving currents replace the cool water over the eastern tropical Pacific with warmer water.

Again, the ocean response is only about half as strong as with El Niño, and the lagged warmth is not as consistent as the cold event-like pattern that occurs during peaks in the solar cycle.

Solar maximum could potentially enhance a true La Niña event or dampen a true El Niño event. The La Niña of 1988-89 occurred near the peak of solar maximum.

That La Niña became unusually strong and was associated with significant changes in weather patterns, such as an unusually mild and dry winter in the southwestern United States.

The Indian monsoon, Pacific precipitation and sea surface temperatures, and other regional climate patterns are largely driven by rising and sinking air in Earth's tropics and subtropics.

The new study could help scientists use solar-cycle predictions to estimate how that circulation, and the regional climate patterns related to it, might vary over the next decade or two.

To tease out the elusive mechanisms that connect the Sun and Earth, the study team needed three computer models that provided overlapping views of the climate system.

One model, which analyzed the interactions between sea surface temperatures and lower atmosphere, produced a small cooling in the equatorial Pacific during solar maximum years.

The second model, which simulated the stratospheric ozone response mechanism, produced some increases of tropical precipitation but on a much smaller scale than the observed patterns.

The third model contained ocean-atmosphere interactions as well as the role of ozone. It showed, for the first time, that the two combined to produce a response in the tropical Pacific during peak solar years that was close to actual observations.

"With the help of increased computing power and improved models, as well as observational discoveries, we are uncovering more of how the mechanisms combine to connect solar variability to our weather and climate," Meehl says.

The research was also funded by the U.S. Department of Energy.
The National Science Foundation (NSF) - Connections among Solar Cycle, Stratosphere and Ocean Discovered (http://www.nsf.gov/news/news_summ.jsp?cntn_id=115485&org=NSF&from=news)