Solar flare induced ionospheric D-region enhancements from VLF amplitude observations

first_imgEnhancements of D-region electron densities caused by solar flares are determined from observations of VLF subionospheric amplitude changes and these enhancements are then related to the magnitudes of the X-ray fluxes measured by the GOES satellites. The electron densities are characterised by the two traditional parameters, H′ and β (being measures of the ionospheric height and the rate of increase of electron density with height, respectively), which are found by VLF radio modelling of the observed amplitudes using the NOSC Earth-ionosphere waveguide programs (LWPC and Modefinder) mainly on two paths, one short and one long. The short path measurements were made near Cambridge, UK, on the signals from the French transmitter to the south while the long path measurements were made near Dunedin, NZ, on the signals from NLK in Seattle, USA, across the Pacific Ocean. The observations include flares up to a magnitude of about M5 at 0.1–) which gave VLF amplitude enhancements up to about ; these corresponded, under near solar maximum conditions (1992), to a reduction in H′ from about down to about and an increase in β from up to about . The increased values of β during a flare are caused by the solar X-rays dominating all sources of ionisation during the flare in contrast with the normal unperturbed daytime values of β which are significantly lower than for a single solar UV or X-ray source due to the extra electrons from the normal galactic cosmic ray ionisation in the lowest parts of the D-region. This steady, normal (unperturbed) cosmic ray influence on β, and hence unperturbed VLF attenuation, is more marked at times of reduced solar Lyman-α flux in the D-region such as at solar minimum, high latitudes or early or late in the day, thus explaining the normal (unperturbed) higher VLF attenuation rates previously reported in these conditions.last_img read more

Poppy seed stars

first_imgWith their unusual shape and pretty design, these will draw customers to the bakery counter, especially if they are displayed next to other breadsticks and rolls. They are perfect at Christmas.Makes 36 starsWholemeal flour – 900gStrong white flour – 600gSalt – 30gYeast – 30gWater – 1,050mlPoppy seeds – 150gPreheat the oven to 250°C. Mix the flours, yeast, salt and water into a dough in a spiral mixer on a slow speed for four minutes and fast for six to eight minutes. Rest the dough for one hour. Turn out the dough and divide into 12 pieces (about 70g each) and roll into balls. Scatter the poppy seeds on a plate and fill a shallow bowl with water. Flatten one of the rolls with the palm of your hand, dip the top into the water, then immediately into the seeds and press them in with your hand. Place on a lightly floured work surface, seed side up, and flatten a little with your hand. Make a diagonal cut across the centre of the dough – the cut should not reach the edges of the roll but should go all the way through it to the work surface. Then make two other diagonal cuts that intersect the first one equally, so that the three cuts form a star shape. Carefully push the roll from underneath, with your fingertips, and turn it inside out, so that the points of the star push upwards and outwards, resulting in the points being on the outside. Place the star on a baking tray, seed-side up, cover and prove for about 45 minutes until the stars have nearly doubled in volume. Place in the pre-heated oven and bake for 10-12 minutes.last_img read more

Football: Voltz unexpectedly retires, leaves left guard spot vacant

first_imgA mere week and a half from the beginning of the 2016 season, and the University of Wisconsin football team has already been dealt a serious blow.Head coach Paul Chryst announced Tuesday at the Badgers’ fall camp that fifth-year senior Dan Voltz will retire from the game.Voltz, a key offensive lineman, suffered a torn ACL during last season’s game against Illinois.Football Notebook: Center Dan Voltz done for season with right knee injuryThe mantra of the Wisconsin football team’s offensive line has been “next man up” for the entire 2015 season. The Read…“It’s been a hard decision to make,” Voltz said on Tuesday. “Something I’ve dealt with pretty much my whole career is injuries. For physical reasons, (that’s) the main reason that it kind of forced me to start thinking about this.”The injury kept him from six games total last season, including the final five of the season. Sophomore Michael Deiter covered for the Badger veteran at center those games and is likely to remain at the position this season.With Voltz’s retirement, the left guard spot he was slotted to will likely be given to redshirt sophomore Micah Kapoi. The 6-foot-3, 334-pound lineman adds some size over the 6-foot-3, 294-pound Voltz.Football: O-line shuffles continue for BadgersFor the fourth time in six games this season, the Wisconsin football team trotted out a different offensive line combination Read…Kapoi played in 12 games last season, but it is likely that redshirt freshman Jon Dietzen will also be in the mix to start at left guard.This story will be updated as more information is released.last_img read more