Modeling the properties of plasmaspheric hiss: 1. Dependence on chorus wave emission

first_imgThere is increasing evidence that plasmaspheric hiss is formed by the evolution of a portion of chorus waves that are excited in the plasmatrough and propagate into the plasmasphere. Comparison between the statistical spatial distributions of these two emissions in the morning sector during active times from THEMIS over ∼3 years shows that the two emissions have comparable peak intensities but are distinct in their spatial distributions. We present a modeling study of the hiss spectrum, based on ray tracing, by taking the observed chorus source region as an input in the magnetosphere, which contains cold and suprathermal electrons. Our modeling results show that we are able to reproduce the main features of typical hiss, including the frequency spectrum, wave normal angle and spatial distribution. However, the simulated hiss intensity is weaker (∼15 dB less) than the observed intensity, which suggests some modest internal amplification inside the plasmasphere. The responses of hiss to variations in the spatial distribution, wave normal angle distribution and frequency distribution of the source chorus are examined. We find that the majority of hiss formation is due to a small portion of chorus emission originating within ∼3 RE from the plasmapause, with wave normal directions pointing toward the Earth at an angle of 30°–60°, and over a frequency range of 0.1–0.3 fce. If the chorus power is made to increase closer to the plasmapause, the hiss intensity and the peak frequency also increases, which roughly mimics active geomagnetic conditions. Variations of the chorus source distribution do not significantly affect the wave normal angle distribution and frequency distribution of hiss, but does impact the absolute intensity of the resulting hiss.last_img read more

New Vermont Hydro-Québec contract to start below current contract price

first_imgVermont utilities’ new contract with Hydro-Québec will begin in 2012 at rates below the existing contract, which phases out over the next five years. Central Vermont Public Service (NYSE-CV) and Green Mountain Power today filed information with the Vermont Public Service Board that shows a starting price of $58.07 per megawatt-hour. The PSB will hold technical hearings on the proposed contract beginning on Wednesday, Jan. 19, 2011.‘We are extremely pleased with the deal we negotiated and with the starting price we will pay,’ CVPS President Bob Young and GMP President Mary Powell said in a joint statement.  ‘We pride ourselves on providing a low-carbon, high-renewable power supply at affordable rates, and this contract will help us retain a competitive position in the region while helping control the air impacts of our supply.’Under the agreement, which the PSB is reviewing, Vermont utilities will purchase up to 225 megawatts of energy, predominantly hydroelectricity, from H.Q. Energy Services (U.S.) Inc. (HQUS) starting in November 2012 and ending in 2038. HQUS markets electricity from Hydro-Québec’s generating fleet, whose output is 98 percent hydroelectric.While the contract was negotiated by CVPS and GMP, HQUS is also selling energy in selected amounts to every other Vermont utility. Those utilities are Vermont Electric Cooperative Inc., Vermont Marble Power Division of Omya Inc., Washington Electric Cooperative, the Town of Stowe Electric Department, the City of Burlington, Vt., Electric Department, and Vermont Public Power Supply Authority on behalf of its 13 municipal electric utility members.The agreement includes a price-smoothing mechanism that will help shield Vermont customers from volatile market prices. This starting price, while for a somewhat different category of power service, is about 12 percent lower than the existing contract’s expected 2012 price. ‘Any time we can replace something that has served us exceedingly well for decades under pricing terms that are lower while being shielded from the market’s high volatility, that is an improvement and a significant accomplishment,’ Young and Powell said.‘The agreement will provide reasonable price stability and an initial small reduction in the cost of one slice of our power portfolio,’ Young and Powell said. ‘This is a very attractive deal for Vermont and a significant accomplishment on behalf of our customers and the customers of the other participating utilities.’Young and Powell thanked the Douglas Administration for its help in working with Québec in the months leading up to the contract signing this past summer, and the Shumlin Administration for its continued support to gain approval from the PSB. ‘Governor Douglas, Lt. Governor Dubie and Governor Shumlin have been uniformly supportive of our efforts to produce a valuable contract for Vermonters,’ Young and Powell said. ‘There has been a tremendous collaborative effort between utilities, the two administrations and officials in Québec.’Source: CVPS. GMP. 1.13.2011last_img read more

England’s Becca beats the pros – again

first_img27 Aug 2015 England’s Becca beats the pros – again England squad player Becca Earl has just beaten the pros for the second time in the space of one week. The 15-year-old from Bishop’s Stortford in Hertfordshire, scored her second win on the WPGA One Day Series in this week’s event at Three Rivers in Essex. Despite bad weather she shot level par 74, in a round which included three birdies, and she beat Sian Evans by a shot. “I couldn’t really believe it,” said Earl, whose latest success completes a winning treble in the space of a week. Earl, a member of the England Golf Thames Valley U16 squad, started her winning run in last week’s WPGA event at South Herts Golf Club. She scored four-under and won by three shots from Sian Evans and Danielle Anderson. The following day she won the Prince of Wales amateur challenge trophies at Woburn, scoring two over 76 and level par to take the U21 girls’ event by a stroke. Then it was back to the WPGA series, this time at Three Rivers in Essex, where she scored level par 74. Earl, who played through rain on the back nine, had a simple game plan: “I wanted to keep it steady and hit as many greens as I could,” she said. “I didn’t feel I’d played that well, but this has given me a lot of confidence. I know if I go out there and play steadily I can shoot a good round, even if I feel I’m not doing that well.” This is the second season that girls from the England Golf U16 and U18 regional squads have had the opportunity to enter the WPGA’s popular One Day Series and gain tournament experience. Click here for the WPGA scoreslast_img read more