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How Did UCLA Develop the World’s Largest Ground Magnetometer Network ~ An insider’s account ~

How Did UCLA Develop the World’s Largest Ground Magnetometer Network ~ An insider’s account ~. Peter Chi IGPP & ESS, UCLA Prof. Russell Symposium May 8-9, 2013. Once Upon a Time (circa 1992).

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How Did UCLA Develop the World’s Largest Ground Magnetometer Network ~ An insider’s account ~

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  1. How Did UCLA Develop the World’s Largest Ground Magnetometer Network~ An insider’s account ~ Peter Chi IGPP & ESS, UCLA Prof. Russell Symposium May 8-9, 2013

  2. Once Upon a Time (circa 1992) • Chris suggested me, a new graduate student from Taiwan, to study ground magnetometer data for my graduate research. • At that time UCLA was not operating ground magnetometers. • But a few sets of ground magnetometer data were studied with great interest (e.g. IGS data from UK; AFGL data from Howard Singer and Jeff Hughes) • Research using ground magnetometer data: Ultra-low-frequency (ULF) waves; Subsurface conductivity inferred from wave amplitude AFGL array Chi et al. [1996]

  3. Chris’ Advice on Scientific Research:Path to Discovery Imagination Reality

  4. List of UCLA Magnetometer Projects (both space-based and ground-based)

  5. 1995: Renewed Interest in Ground MagnetometersSMALL-type Fluxgate Magnetometers • Made use of desktop PC for housing electronics, acquiring and storing data • Included a GPS for accurate location and time • A low-cost system that made it economically feasible for many research projects

  6. 1995- early 2000s:SMALL & IGPP-LANL Arrays • PI: Guan Le • Chris organized a meeting with Chinese PIs at UCLA • A dozen stations were established in China • PI: V. Angelopoulos, C. T. Russell • Domestic ground observations since AFGL magnetometer project, paving the way for more ground projects in North America

  7. Detecting Field Line Resonance (FLR)from the Ground Russell et al. (1999): Using IGPP-LANL data Chi et al. (2000): Using IGPP-LANL data Chi and Russell (1998)

  8. (2005 -): Mid-continent Magnetoseismic Chain (McMAC) ● Field line resonance method requires close separation between ground stations in the north-south direction. ● The mean north-south separation between two adjacent McMAC stations is 275 Km. ● Joint operation with CANOPUS Churchill Line (Canada), IGPP-LANL (U.S.) and MAGDAS (Japan) provides the magnetic field data from L = 1.2to 11+ at one local time.

  9. Automated Detection of FLR Frequencies • We developed an algorithm to automated detection of FLR frequencies in cross-phase/cross-power spectrograms. • The algorithm is based on the criteria used by Berube et al. (2003) with additional constraints. • We examined the results in cross-phase spectrograms but rarely needed to make corrections. • Peaks in cross phase • Coherence • t-statistic • Positive slope in power ratio • Remove isolated selections

  10. FLR-inferred Equatorial Density:(July 2006-June 2007) Equatorial

  11. Local Time Dependence of Density Theremosphere Plasmasphere • Plasmasphere: Density increases in afternoon/evening hours are not predicted by models. • Thermosphere: Equatorial ionization anomaly peaks in local afternoon at low magnetic latitudes. • Reason: Neutral plasma coupling Equatorial Lühr et al. [2011]

  12. Other UCLA-built Ground Magnetometers Since Late 1990s MEASURE PI: Mark Moldwin Region: US East Coast PI: Martin Connors Region: Canada AMBER PI: EndawokeYizengaw Region: Africa SAMBA PI: EftyhiaZesta Region: South America/Antarctica

  13. THEMIS Ground Magnetometers (2003-) • System Features • • ±72KnT dynamic range @ 0.01nT Resolution (~23 bits) • • Offset DAC system for 256 possible ranges per axis • Sigma-delta modulator design • • 2 vectors per second data rate • • Low power < 4W • • Small size 22cm x 13cm x 5cm • • Ruggedized all weather sensor design • • USB interface for data retrieval and firmware upload • • GPS antenna and electronics Integrated into one package • • NTP compatible (1msec time accuracy)

  14. Effective Station Pairs for FLR Sounding in North America • Magnetometer Arrays: • McMAC • Falcon • THEMIS GBO/EPO • USGS • IGPP/LANL • GIMA • CARISMA • AUTUMN • CANMOS (During 23-26 October 2007)

  15. Monitoring Equatorial Density byGround Magnetometers 2007-Oct-25 log10 (neq) [a.m.u. cm3]

  16. Travel-time Magneto-seismology Spacecraft Ground stations

  17. Ultra Large TerrestrialInternational Magnetometer Array • An international consortium for ground-based magnetometers since 2006. • Provides a platform for ground-based magnetometer networks to collaborate. • ULTIMA and mini-GEM have been holding joint meeting sessions on an annual basis. ULTIMA looks forward to continuing this practice that helps interact with other scientists/projects. ULTIMA kick-off meeting at UCLA (2006)

  18. World Map of Magnetic Observatories(for Magnetospheric Research) L 10 8 6 4 2 1 2 4 6 8 10

  19. Lots of Babies (Ground Stations) to Look After

  20. Next Destination: Antarctica

  21. Conclusions • Since mid-1990s, UCLA and collaborators have developed the world’s largest ground magnetometer network in 15 years • What made it happen: • Persistent support and leadership by Prof. Russell • Engineering innovations and scientific quests • Joint ventures between UCLA Team and Collaborators • Unconditional love • Spirit of exploration

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