Published on November 5, 2007
Ground-based Magnetometry for IHY: UNBSS Small Instrument Array Opportunity: Ground-based Magnetometry for IHY: UNBSS Small Instrument Array Opportunity Ian R. Mann CANOPUS Magnetometer Array PI. Canada Research Chair in Space Physics Dept. of Physics, University of Alberta. E-mail: [email protected] IHY Magnetometer Array: IHY Magnetometer Array Magnetometer Arrays provide a relatively low-cost method for monitoring the solar-terrestrial interaction. Magnetometer stations provide monitoring of current systems local to monitoring station, as well as local wave populations. Multi-continental IHY array would provide excellent basis for meso- and global-scale monitoring of M-I disturbances. Excellent scientific targets for mid- and low-latitudes; perfect match for potential locations of the developing nations who may participate. Potential Science Targets: Potential Science Targets Primary Science Target: Use of latitudinal pairs of magnetometer stations and the “cross-phase technique” to remote-sense the temporal and spatial variations of magnetospheric, plasmaspheric and ionospheric plasma density: Field line geometry and magnetospheric density variations at mid-lat. Plasmaspheric dynamics and depletion and refilling processes at mid-lat. Ionospheric density variations and MI coupling at low-latitudes. Plasmapause dynamics – penetration to lower-L. Internal plasmaspheric density depletions at low-L. Diurnal and activity driven ionospheric profile variations, including F10.7 effects. Potential for link of IHY magnetometer derived density variations to those observed with GPS inversion technique during storms (cf. John Foster and co-workers). Secondary Science Targets: Local current systems: penetration of asymmetric ring current to mid- and low-latitudes, as well as mid-latitude field stretching and mid-latitude substorms (eg Pi2 location and timing). Radiation Belts: L-shell penetration of Ultra-low frequency wave power believed to transport and accelerate electrons to MeV energies in radiation belt. Cross-Phase Technique.: Cross-Phase Technique. Courtesy of Zoë Dent. The cross-phase technique uses the measurements from two latitudinally spaced magnetometers to identify the local field line resonance (FLR) frequency at the station mid-point. FLR frequency inverted with 1-D model to infer density variations: magnetospheric at mid-lat. and coupled M-I densities at low lat. Remote-sensing Plasma Density: Remote-sensing Plasma Density Recent observations by the IMAGE satellite have revealed a wealth of new dynamic structure in the coupled ionosphere-plasmasphere system. Dents, plumes, striations, bifurcations, internal depletions, MI coupling… Fundamental processes responsible for plasma injection, and redistribution and loss are not understood. Relationships between ionospheric and plasmaspheric plasma structure are also not understood. (From Adrian et al, 2004) (From Goldstein et al, 2004) Mass Density and Plasmapause Variations.: Mass Density and Plasmapause Variations. (From Dent et al, 2005) Mid-latitude Substorm Onset Diagnosis: Mid-latitude Substorm Onset Diagnosis Considerable interest in the location and timing of magnetotail instabilities and flows (substorms, BBFs, etc). Timing possible through Pi2 wave signatures (automation possible e.g., Nose et al., 1999). Substorm location possible through magnetic bay substorm current wedge analysis. H and D bays locate FAC elements. ULF Waves and Radiation Belt Acceleration: ULF Waves and Radiation Belt Acceleration Controversy surrounding MeV electron acceleration mechanism. ULF wave processes (e.g., ULF enhanced radial diffusion) considered important. Monitoring the global distribution of ULF power and its penetration to low-L is valuable. The ambient density and plasmapuase location are also important for a range of radiation belt acceleration and loss processes. Measurements from global ground arrays provide unique global view of ULF and EMIC disturbances along drift orbit. (From O’Brien et al, 2003) (From Elkington et al, 2003) Case Study: Halloween Storms 2003: Case Study: Halloween Storms 2003 (Loto’aniu et al, 2005) ULF Wave Penetration to Slot at Low-L: ULF Wave Penetration to Slot at Low-L L=1.6 L=6.6 Penetration of ULF Power: Lower Local FLR Frequency: Penetration of ULF Power: Lower Local FLR Frequency Suggests upflowing low energy ions Eigenfrequency Dynamics: Eigenfrequency Dynamics Density dynamics different at high and low latitudes. Plasmaspheric dynamics occur over wide range of activity levels. Anomalous Alfven Continuum: Anomalous Alfven Continuum Continental Global and Coverage…?: Continental Global and Coverage…? Extensive magnetometer coverage in north America. (apologies to GIMA, CANMOS, MACCS…) Coverage extends to low-latitudes with NSF funded SAMBA array. Co-ordinate magnetometer array operations on national, continental and global scales within IHY? Established IHY arrays (e.g., UBBSS IHY Mag. array) and co-ordination continuing their operations beyond IHY in 2007. Scientific Value in Continued IHYMag Operation Beyond 2007: Scientific Value in Continued IHYMag Operation Beyond 2007 (John Wygant, Personal Communication 2005) IHY Magnetometer Observatories: IHY Magnetometer Observatories Each observatory: magnetometer station pairs separated meridionally by ~200+km. 2 x 3-component fluxgate magnetometer, data logger, GPS timing, and power source (use solar panels/wind turbines for remote locations?). Data retrieval method depends on available infrastructure: Phone-line modem, or local internet where available. Cheapest option to just switch out USB pen-drives by hand (one day of uncompressed 1s magnetometer data is ~2MB). Approximate cost of each Observatory: ~ $20k US. 3 component fluxgate with RS232 output: ~$6k US Industrial grade data logger/PC with GPS ~$2k US. Solar Panel power system ~$2k US. Commercial fluxgates available from western nations. However, an excellent low-noise supplier also exists at the Lviv Institute in the Ukraine. The Ukraine benefits from export trade/tax agreements with some western nations to promote development in the former USSR (including Canada). The IHY magnetometer array could aid the development in nations such as the Ukraine where suitable expertise exists. For the CANOPUS Array, U. Alberta is developing a solar cell/wind generator stand-alone power source which could be modified for IHY use in developing nations with little infrastructure (also allows site deployment in environmentally magnetically quiet locations; avoids problems with local power grid stability). Potential IHY Magnetometer Array Operations: Funding from where?: Potential IHY Magnetometer Array Operations: Funding from where? Purchase of magnetometer sensor systems with RS output – perhaps from the developing nation of the Ukraine, or from elsewhere. UA together with other partner institutes could develop GPS timed PC data logger interface for the magnetometer. develop solar-cell/turbine power source for the IHY Mag. Observatories. integrate systems prior to delivery to participating nation scientists. Organize and run a number of regional/continent specific “deployment schools” whereby developing nation scientists attend a single deployment. They then deploy their own observatories in their own nation on their own. IHY array data are more powerful than data from single observatory alone, although science can be done with a single observatories data especially in combination with partner IHY data sets. Project involvement should require data delivery to IHY Magnetometer Array data centre (perhaps partner with eGY). Re-enforces the value and importance of having a central IHY data collection/storage archive/data centre. The scientific value of the collective IHY array data set encourages collaboration between participating nation IHY Mag. array scientists. Could provide the basis for IHY Science Workshops/Conference with active participation from the participating scientists.