Examining local time variations in the gains and losses of open magnetic flux during substorms

first_imgThe open magnetic flux content of the magnetosphere varies during substorms as a result of dayside and nightside reconnection. The open flux can be calculated from the area of the polar cap, delineated by the open‐closed field line boundary (OCB). This study presents a superposed epoch analysis of the location of the OCB and the change in the magnetic flux content in individual nightside MLT sectors during substorm growth, expansion and recovery phases. Far ultraviolet (FUV) observations from the IMAGE satellite are used to derive a proxy of the OCB location. In the hour prior to substorm onset, the total nightside flux content increases by up to 0.12 GWb on average, resulting in an equatorward expansion of the OCB. Following substorm onset, the OCB contracts towards the pole as the open magnetic flux content decreases by up to 0.14 GWb on average but the rate of decrease of the total nightside open flux content differs by 5‐66% between the three IMAGE FUV instruments. The OCB does not contract poleward uniformly in all nightside MLT sectors after substorm onset. Close to the substorm onset MLT sector, the OCB contracts immediately following substorm onset however the OCB in more dawnward and duskward MLT sectors continues to expand equatorward for up to 120 minutes after substorm onset. Despite the continued increase in flux in these sectors after substorm onset, the total nightside flux content decreases immediately at substorm onset, indicating that the nightside reconnection rate exceeds the dayside rate following substorm onset.last_img read more

2016 Hoopes Prize winners announced

first_imgThe Faculty of Arts and Sciences recently awarded the Hoopes Prize to 64 Harvard College seniors.Given in recognition of outstanding scholarly work or research, the prize is funded by the estate of Thomas T. Hoopes ’19, who established it to “promote excellence in the art of teaching.” Awards are given both to undergraduates and to faculty members who supervised them.In addition to the monetary prize, the winning papers or theses are bound and available at Lamont Library for two years.A full list of recipients may be found here.last_img

World Welcomes 4-H’ers

first_img“For high school and college age 4-H’ers, applications are due now for 4-Hinternational exchanges this summer,” says Greg Price. He directs these programsthrough the University of Georgia Extension Service. College-age 4-H’ers may apply for the three- to six-month IFYE Representativeprogram. The six-week IFYE Ambassador program or the month-long LABO programto Japan are for high school 4-H’ers. But there’s no time to delay. All applications aredue now. Virtual reality has its appeal. But nothing takes the place of being there. Just ask thosewho dreamed of the Olympics and finally came to Atlanta last summer. Doing beatsdreaming any day. “These programs help you learn about life,” Price says. “An international experiencecan be extremely valuable for an international career. It helps you develop abilities,including language skills. You can increase your knowledge and global awareness. Andyou can pursue your own study goals and career training.” That’s why Georgia 4-H’ers who dream about world travel need to do something abouttheir dreams. And they better do it fast. International 4-H programs offer exchanges from six weeks to six months. You cantravel to almost 30 countries. The list includes Australia, Botswana, Estonia andLatvia, India, Jamaica, Japan, Paraguay, Switzerland and Ukraine. “International programs have always been a strong part of Georgia 4-H,” he says. “Aninternational experience is an educational opportunity that’s equal to none. That’s truewhether you’re the traveler or the host family.” Families who would like to host a young international guest for a week or more shouldcontact their county agent. They have until March 15 to apply. Youths can apply to travel or to host an international visitor next summer through thecounty extension office.last_img read more