How Did UCLA Develop the Worlds Largest Magnetometer Network

How Did UCLA Develop the Worlds Largest Ground Magnetometer Network~ An insiders account ~Peter ChiIGPP & ESS, UCLA

Prof. Russell SymposiumMay 8-9, 20131Once 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

Chi et al. [1996]AFGL array2Chris Advice on Scientific Research:Path to Discovery

ImaginationReality3List of UCLA Magnetometer Projects (both space-based and ground-based)

1995: Renewed Interest in Ground MagnetometersSMALL-type Fluxgate MagnetometersMade use of desktop PC for housing electronics, acquiring and storing dataIncluded a GPS for accurate location and timeA low-cost system that made it economically feasible for many research projects

51995- early 2000s:SMALL & IGPP-LANL ArraysPI: Guan LeChris organized a meeting with Chinese PIs at UCLAA dozen stations were established in ChinaPI: V. Angelopoulos, C. T. RussellDomestic ground observations since AFGL magnetometer project, paving the way for more ground projects in North America

Get maps (check IGPP website)6Detecting Field Line Resonance (FLR)from the Ground

Chi and Russell (1998)Russell et al. (1999):Using IGPP-LANL dataChi et al. (2000): Using IGPP-LANL data8 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.(2005 -): Mid-continent Magnetoseismic Chain (McMAC)

8Automated Detection of FLR FrequenciesWe 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 phaseCoherencet-statisticPositive slope in power ratioRemove isolated selections9

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

Equatorial10Local Time Dependence of DensityPlasmasphere: 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 coupling11

Equatorial

Lhr et al. [2011]PlasmasphereTheremosphereOther UCLA-built Ground Magnetometers Since Late 1990s

SAMBAPI: Eftyhia ZestaRegion: South America/Antarctica

PI: Martin ConnorsRegion: Canada

MEASUREPI: Mark MoldwinRegion: US East CoastAMBERPI: Endawoke YizengawRegion: Africa12THEMIS 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)

Add image of THEMISAdd PI and Co-I names13

Effective Station Pairs for FLR Sounding in North America(During 23-26 October 2007)Magnetometer Arrays:McMACFalconTHEMIS GBO/EPOUSGSIGPP/LANLGIMACARISMAAUTUMNCANMOS14Monitoring Equatorial Density byGround Magnetometerslog10 (neq)[a.m.u. cm3]

2007-Oct-25(movie) 2-D FLR sounding1516Travel-time Magneto-seismology

SpacecraftGround stations

16Imagine an impulse propagating in the magnetosphereobserved by satellite and ground stations at different locationsTwo critical things to know:Travel speedTravel pathThese two pieces of information lead to travel time

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.

Ultra LargeTerrestrial International Magnetometer Array

ULTIMA kick-off meeting at UCLA (2006)Count # of stations involved17World Map of Magnetic Observatories(for Magnetospheric Research)

L

10864

2

1

2

46810Lots of Babies (Ground Stations) to Look After

A photo of ~100 babies19

Next Destination:Antarctica20ConclusionsSince mid-1990s, UCLA and collaborators have developed the worlds largest ground magnetometer network in 15 yearsWhat made it happen:Persistent support and leadership by Prof. RussellEngineering innovations and scientific questsJoint ventures between UCLA Team and CollaboratorsUnconditional loveSpirit of exploration