BEGIN:VCALENDAR
VERSION:2.0
PRODID:-//Talks.cam//talks.cam.ac.uk//
X-WR-CALNAME:Talks.cam
BEGIN:VEVENT
SUMMARY:The Importance to Solar-Terrestrial Physics of Amundsen’s and Sc
 ott’s Conjugate Observations of the Earth’s Magnetic Field - Alv Egela
 nd (Department of Physics\, University of Oslo)
DTSTART:20141015T153000Z
DTEND:20141015T163000Z
UID:TALK55017@talks.cam.ac.uk
CONTACT:Poul Christoffersen
DESCRIPTION:The ships Gjøa and Discovery sailed to the opposite ends of t
 he Earth during the years 1902-06.  Among the scientific goals of the two 
 expeditions\, was that of documenting the nature of the high latitude geom
 agnetic field and especially the location of the respective north and sout
 h magnetic dip poles (MDP).  Both expeditions overwintered within 200 km o
 f their respective poles\, and\, unwittingly\, at nearly the same geomagne
 tic longitude\, 240°.  Thus\, they were camped at opposite ends of the sa
 me geomagnetic field line.  Their unique magnetic observations at Gjøahav
 n and Cape Armitage more than 100 years ago were at the same local geomagn
 etic time\, but they were separated in local solar time by ~6 hours becaus
 e  of the tilt of the geomagnetic axis with respect to the geographic axis
 . This is important to the interpretation of the data\, especially when th
 e relationship of the high latitude geomagnetic field to the interplanetar
 y magnetic field (IMF)\, is examined.  \n\nIndeed\, the combined observati
 ons offer a glimpse of the solar wind fifty years before it was known to e
 xist.  After a brief review of the characteristics of the Earth’s magnet
 ic field\, the main facts found on diurnal and seasonal variations of the 
 field at Gjøahavn will be compared with similar observations at Cape Armi
 tage.  These are unique observations of the geomagnetic field in the polar
 -regions decades before modern polar observatories were established.  Afte
 r comparing the data sets of the two expeditions and subjecting the data t
 o modern analysis\, we reached the following conclusions: \n\nAmundsen and
  Scott were the first to demonstrate that the north and south magnetic dip
 -poles do not have a permanent location\, but move their position in a reg
 ular manner on average. The activity was more intense in the local summer 
 than in the local winter.  The wavelike\, diurnal variation in the field a
 t Cape Armitage mimics the Gjøahavn data almost exactly. \n\nThe quality 
 of these magnetic observations may be shown to be equal to that of the lat
 e 20th century observations by subjecting them to analytical techniques sh
 owing the newly discovered relationship between the diurnal variation of h
 igh latitude magnetic observations and the direction of the interplanetary
  magnetic field in the solar wind called the .Svalgard-Mansurov effect (SM
 E). From this comparison\, we found that the solar wind and its temporal v
 ariations were similar to what we observe today. For stations near 80 degr
 ees magnetic latitude we conclude that the SME is not a UT effect\, but ma
 ximizes near magnetic noon.\n\nOur motivation for this study has been to i
 lluminate the contributions of Amundsen and Scott as scientists.  Their co
 ntributions are important to the world-wide survey of the Earth’s magnet
 ic field in the early 20th century.\n
LOCATION:Scott Polar Research Institute\, main lecture theatre
END:VEVENT
END:VCALENDAR