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Peter Chi IGPP & ESS, UCLA Prof. Russell Symposium May 8-9, 2013

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Presentation on theme: "Peter Chi IGPP & ESS, UCLA Prof. Russell Symposium May 8-9, 2013"— Presentation transcript:

1 Peter Chi IGPP & ESS, UCLA Prof. Russell Symposium May 8-9, 2013
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 Magnetometers SMALL-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
Get maps (check IGPP website) PI: V. Angelopoulos, C. T. Russell Domestic ground observations since AFGL magnetometer project, paving the way for more ground projects in North America PI: Guan Le Chris organized a meeting with Chinese PIs at UCLA A dozen stations were established in China

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 = 1.2 to 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)

11 Local Time Dependence of Density
Plasmasphere Theremosphere Equatorial Lühr et al. [2011] 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

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

13 THEMIS Ground Magnetometers (2003-)
System Features • ±72KnT dynamic 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) Add image of THEMIS Add PI and Co-I names

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 October 2007)

15 Monitoring Equatorial Density by Ground Magnetometers
2007-Oct-25 log10 (neq) [a.m.u. cm3] (movie) 2-D FLR sounding

16 Travel-time Magneto-seismology
Spacecraft Ground stations Imagine an impulse propagating in the magnetosphere observed by satellite and ground stations at different locations Two critical things to know: Travel speed Travel path These two pieces of information lead to travel time

17 Terrestrial International Magnetometer Array
Ultra Large Terrestrial International 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. Count # of stations involved ULTIMA kick-off meeting at UCLA (2006)

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

19 Lots of Babies (Ground Stations) to Look After
A photo of ~100 babies

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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