Interplanetary magnetic field control of polar ionospheric equivalent current system modes

first_imgWe analyse the response of different ionospheric equivalent current modes to variations in the interplanetary magnetic field (IMF) components By and Bz. Each mode comprises a fixed spatial pattern whose amplitude varies in time, identified by a month‐by‐month empirical orthogonal function separation of surface measured magnetic field variance. Here we focus on four sets of modes that have been previously identified as DPY, DP2, NBZ and DP1. We derive the cross‐correlation function of each mode set with either IMF By or Bz for lags ranging from ‐10 to +600 mins with respect to the IMF state at the bow shock nose. For all four sets of modes, the average correlation can be reproduced by a sum of up to three linear responses to the IMF component, each centered on a different lag. These are interpreted as the statistical ionospheric responses to magnetopause merging (15‐20 mins lag) and magnetotail reconnection (60 mins lag), and to IMF persistence. Of the mode sets, NBZ and DPY are the most predictable from a given IMF component, with DP1 (the substorm component) the least predictable. The proportion of mode variability explained by the IMF increases for the longer lags, thought to indicate conductivity feedbacks from substorms. In summary, we confirm the postulated physical basis of these modes and quantify their multiple reconfiguration timescales.last_img read more

Women of Troy look to get back on track in Texas

first_imgIntent on rebounding from a frustrating 1-0 season-opening loss to San Diego, the USC women’s soccer team must bear the Texas heat this weekend as it squares off against Texas Christian University and the University of Texas at Austin in two non-conference matchups.Moving on · Junior midfielder Carly Butcher looks to continue her strong play as the soccer team travels to Texas for two games this weekend. – Sundaram Kuppuswamy | Daily Trojan On Friday, the Women of Troy will kick off their road schedule against TCU (1-1); from there, they will travel farther south to face Texas (1-0) on Sunday.Despite the disheartening beginning to the season, which included being dropped unceremoniously from the top 25 rankings, the team is not dwelling on its opponents. When asked about the challenges TCU and Texas pose, coach Ali Khosroshahin turned his focus to the Women of Troy.“To be honest, the biggest challenge is ourselves,” Khosroshahin said. “Right now, the biggest challenge is the ball and ourselves.”Evident in Khosroshahin’s response was not only the frustration that accompanies an unexpected early-season loss, but also his steadfast confidence in his team.During practices, he has emphasized maintaining formation as the team progresses down the field and staying connected. And as senior striker Megan Ohai pointed out, by staying in their own lanes, the Women of Troy can stretch the field and make themselves more difficult to defend.“We weren’t doing the little things,” Ohai said. “Everyone needs to work together and get on the other side of some of these crosses.”Undoubtedly, teamwork is how the Women of Troy will generate more offense and enjoy sustained success this season.“If we don’t connect, we won’t generate anything. It’s all based on the same thing,” Khosroshahin said.In TCU and Texas, USC faces two unfamiliar opponents, both unranked and coming off of mediocre seasons. The Horned Frogs opened their season with a 3-0 loss to Texas Tech, but soon rebounded, beating Texas Southern 7-0. The Longhorns won their only game 2-1 against North Carolina State, but also beat Louisiana State by the same score in an exhibition game.last_img read more

All eyes on the Magpies tonight.

first_imgThey aim for a Premier League win at Stoke.Club owner Mike Ashley is reported to have said that Pardew will lose his job if they suffer a defeat tonight, though later insisted those comments were “tongue in cheek”.Burnley replaced the Tynesiders at the bottom of the table after losing 4-0 at West Brom.last_img