David Milling

David Milling
University of Alberta | UAlberta · Department of Physics

PhD

About

113
Publications
21,685
Reads
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4,263
Citations
Additional affiliations
October 1986 - March 2003
University of York
Position
  • Research Assistant
January 2012 - present
University of Alberta
April 2003 - present
University of Alberta
Position
  • FSO
Education
September 1981 - September 1985
University of York
Field of study
  • Physics
September 1978 - July 1981
University of York
Field of study
  • Physics

Publications

Publications (113)
Article
Full-text available
Geoelectric fields produced by time‐varying magnetic fields during geomagnetic storms can result in potentially damaging geomagnetically induced currents (GICs) in long conductors at the Earth's surface. GICs can pose a significant risk to the integrity of grounded electrical infrastructure, particularly high‐voltage transformers. In this study, an...
Article
Full-text available
Magnetometers are a key component of heliophysics research providing valuable insight into the dynamics of electromagnetic field regimes and their coupling throughout the solar system. On satellites, magnetometers provide detailed observations of the extension of the solar magnetic field into interplanetary space and of planetary environments. At E...
Article
Full-text available
Estimating the effect of geomagnetic disturbances on power grid infrastructure is an important problem since they can induce damaging currents in electric power transmission lines. In this study, an array of magnetotelluric (MT) impedance measurements in Alberta and southeastern British Columbia are used to estimate the geoelectric field resulting...
Article
Full-text available
The Experimental Albertan satellite #1 (Ex-Alta 1) was a three-unit cube satellite (CubeSat) developed at the University of Alberta (UAlberta). As the first ‘made in Alberta’ spacecraft, the Ex-Alta 1 CubeSat was the Canadian contribution to the international QB50 CubeSat constellation mission (www.qb50.eu). Ex-Alta 1’s mission incorporated four sc...
Article
Full-text available
Fluxgate magnetometers are important tools for geophysics and space physics, providing high-precision magnetic field measurements. Fluxgate magnetometer noise performance is typically limited by a ferromagnetic element that is periodically forced into magnetic saturation to modulate, or gate, the local magnetic field. The parameters that control th...
Article
Full-text available
Fluxgate magnetometers are important tools for geophysics and space physics providing high precision magnetic field measurements. Fluxgate magnetometer noise performance is typically limited by a ferromagnetic element that is periodically forced into magnetic saturation to modulate, or gate, the local magnetic field. The parameters that control the...
Article
Full-text available
A proof-of-concept hybrid magnetometer is presented, which simultaneously operates as both a fluxgate and a search coil, allowing it to sense the magnetic field from DC to 2 kHz using a single sensor. Historically, such measurements would normally require two dedicated instruments, and each would typically require deployment on its own dedicated bo...
Article
Full-text available
A proof-of-concept hybrid magnetometer is presented which simultaneously operates as both a fluxgate and a search coil allowing it to sense the magnetic field from DC to two kHz using a single sensor. Historically, such measurements would normally require two dedicated instruments and each would typically require deployment on its own dedicated boo...
Article
We are pleased to address the comment on our paper from Shprits et al. since we believe it supports our conclusion that magnetopause shadowing and ultralow-frequency (ULF) wave outward transport can drive fast losses into the heart of the ultra-relativistic electron radiation belt and produce a remnant belt. As reported by Baker et al., the Septemb...
Article
Full-text available
Substorm onset is marked in the ionosphere by the sudden brightening of an existing auroral arc or the creation of a new auroral arc. Also present is the formation of auroral beads, proposed to play a key role in the detonation of the substorm, as well as the development of the large-scale substorm current wedge (SCW), invoked to carry the current...
Article
Full-text available
Fluxgate magnetometers are an important tool in geophysics and space physics but are typically sensitive to variations in sensor temperature. Changes in instrumental gain with temperature, thermal gain dependence, are thought to be predominantly due to changes in the geometry of the wire coils that sense the magnetic field and/or provide magnetic f...
Article
Full-text available
Fluxgate magnetometers are an important tool in geophysics and space physics but are typically sensitive to variations in sensor temperature. Changes in instrumental gain with temperature, thermal gain dependence, are thought to be predominantly due to changes in the geometry of the wire coils that sense the magnetic field. Scientific fluxgate magn...
Article
Difficulty in making low noise magnetic measurements is a significant challenge to the use of cube-satellite (CubeSat) platforms for scientific constellation class missions to study the magnetosphere. Sufficient resolution is required to resolve three-dimensional spatio-temporal structures of the magnetic field variations accompanying both waves an...
Article
Since the discovery of the Van Allen radiation belts over 50 years ago, an explanation for their complete dynamics has remained elusive. Especially challenging is understanding the recently discovered ultra-relativistic third electron radiation belt. Current theory asserts that loss in the heart of the outer belt, essential to the formation of the...
Article
Electromagnetic Ion Cyclotron Waves (EMIC) waves are believed to be an important source of pitch-angle scattering driven relativis-tic electron loss from the radiation belts. To date, investigations of this precipitation have been largely theoretical in nature, limited to calculations of precipitation characteristics based on wave observations and...
Article
We find that during a large geomagnetic storm in October 2011 the trapped fluxes of >30, >100, and >300 keV outer radiation belt electrons were enhanced at L=3-4 during the storm main phase. A gradual decay of the trapped fluxes was observed over the following 5–7 days, even though no significant precipitation fluxes could be observed in the Polar...
Article
On 31 May 2013 several rising tone electromagnetic ion cyclotron (EMIC) waves with intervals of pulsations of diminishing periods were observed in the magnetic local time afternoon and evening sectors during the onset of a moderate/large geomagnetic storm. The waves were sequentially observed in Finland, Antarctica, and western Canada. Coincident e...
Article
Very low frequency (VLF) transmissions propagating between the conducting Earth's surface and lower edge of the ionosphere have been used for decades to study the effect of space weather events on the upper atmosphere. The VLF response to these events can only be quantified by comparison of the observed signal to the estimated quiet-time or undistu...
Article
We present simulations of the outer electron radiation belt using a new ULF-wave driven radial diffusion model, including empirical representations of loss due to chorus and plasmaspheric hiss. With an outer boundary condition constrained by in-situ electron flux observations, we focus on the impacts of magnetopause shadowing and outward radial dif...
Article
Full-text available
study the effect of electromagnetic ion cyclotron (EMIC) waves on the loss and pitch angle scattering of relativistic and ultrarelativistic electrons during the recovery phase of a moderate geomagnetic storm on 11 October 2012. The EMIC wave activity was observed in situ on the Van Allen Probes and conjugately on the ground across the Canadian Arra...
Article
Full-text available
We present analytic expressions for ULF wave-derived radiation belt radial diffusion coefficients, as a function of L and Kp, which can easily be incorporated into global radiation belt transport models. The diffusion coefficients are derived from statistical representations of ULF wave power, electric field power mapped from ground magnetometer da...
Article
11 October 2012, during the recovery phase of a moderate geomagnetic storm, an extended interval (> 18 h) of continuous electromagnetic ion cyclotron (EMIC) waves was observed by Canadian Array for Real-time Investigations of Magnetic Activity and Solar-Terrestrial Environment Program induction coil magnetometers in North America. At around 14:15 U...
Article
[1] Pc5 (1.67–6.67 mHz) magnetic pulsations and the modulation of energetic electron precipitation are often observed simultaneously in the morning auroral-latitude data. Here we have investigated a conjunction event of Cluster spacecraft and Canadian auroral-latitude ground stations to identify the role of compressional Pc5 pulsations in modulatin...
Article
Full-text available
Although the Earth's Van Allen radiation belts were discovered over 50 years ago, the dominant processes responsible for relativistic electron acceleration, transport and loss remain poorly understood. Here we show evidence for the action of coherent acceleration due to resonance with ultra-low frequency waves on a planetary scale. Data from the CR...
Article
Ultra-low frequency (ULF) waves in the Pc4-5 band can be excited in the magnetosphere by the solar wind. Much recent work has shown how ULF wave power is strongly correlated with solar wind speed. However, little attention has been paid the dynamics of ULF wave power penetration onto low L-shells in the inner magnetosphere. We use more than a solar...
Article
We examine the global field-aligned current (FAC) topology associated with a clear substorm on the 16 February 2010. We show that for this particular substorm there is a clear and localised reduction in the FACs observed by AMPERE at least 6 minutes prior to auroral onset. A new auroral arc forms in the region of reduced FAC and on closed field lin...
Article
Full-text available
We present case studies of the evolution of Ultra-Low Frequency (ULF) magnetic wave amplitudes and auroral intensity through the late growth phase and the expansion phase of the substorm cycle. We present strong evidence that substorm-related auroral enhancements are clearly and demonstrably linked to ULF wave amplitudes observed at the same locati...
Article
Large amplitude Pc4-5 ULF waves can be excited in the magnetosphere during active times, including the excitation of field line resonances and fast magnetosonic waves during fast solar wind speeds and magnetospheric compressions. We present a statistical analysis of over 10 years of ground-based magnetometer data and map this into equatorial electr...
Article
Full-text available
Waves in the ultra-low-frequency (ULF) band have frequencies which can be drift resonant with electrons in the outer radiation belt, suggesting the potential for strong interactions and enhanced radial diffusion. Previous radial diffusion coefficient models such as those presented by Brautigam and Albert (2000) have typically used semiempirical rep...
Article
Full-text available
We present a statistical characterization of ground-based ultra-low-frequency (∼1–15 mHz) magnetic wave power spectral densities (PSDs) as a function of latitude (corresponding to dipole L-shells from L∼2.5–8), local time, and solar wind speed. We show a clear latitudinal dependence on the PSD profiles, with PSDs increasing monotonically from low-...
Conference Paper
This paper reviews the role of long-period ultralow frequency (ULF) waves in contributing to the acceleration, transport, and loss of electrons in the outer zone Van Allen radiation belt. We place particular emphasis on the mesoscale and global-scale characterization of ULF waves around electron drift orbits available from ground-based magnetometer...
Article
MeV energy electrons are thought to be transported inwards from the plasma sheet into the radiation belts under the action of radial diffusion. Waves in the ultra-low frequency (ULF) band have frequencies which can be drift resonant with these electrons in the outer zone suggesting the potential for strong interactions, and enhanced radial diffusio...
Article
Large amplitude Pc4-5 ULF waves can be excited in the magnetosphere during active times, including the excitation of field line resonances and fast magnetosonic waves during fast solar wind speeds and magnetospheric compressions. We present a statistical analysis of over 10 years of ground-based magmetometer, as well as in-situ electric field power...
Article
The formation of a substorm current wedge (SCW) is one of the fundamental processes in the expansion phase of the magnetospheric substorm [e.g. McPherron et al., 1973]. Uozumi et al. [2011] found that the ground Pi 2 timeseries had high coherencies with simultaneously observed AKR timeseries, regardless of whether the Pi 2 timeseries were associate...
Article
The temporal sequence of events at substorm onset requires the generation and propagation of electromagnetic waves as the system evolves from its pre- to post-onset state. Such waves offer a unique diagnostic for the dynamics of this system, and the important coupling between the equatorial magnetosphere and auroral onset dynamics in the ionosphere...
Article
The formation of the substorm current wedge (SCW) is an integral part of the substorm expansion phase. In general the SCW is viewed as an equivalent current system composed of net downward field aligned current (FAC) in the east, a westward electrojet and net upward field aligned current in the west; however, with increased coverage of the night-si...
Article
Full-text available
1] We present the results of a statistical analysis of ground‐based magnetometer Ultra Low Frequency (ULF) wave power and polarization during substorm expansion phase onset in three ULF wave bands, the longer‐period Pi1 (10–40 s) band, the Pi1‐2 (24–96 s) band, and Pi2 (40–150 s) wave band, in order to determine whether these wave bands are statist...
Article
Full-text available
Pi2s are a category of Ultra Low Frequency (ULF) waves associated with the onset of magnetic substorms. Recent work has suggested that the deceleration of bulk plasma flows in the central plasmasheet, known as bursty bulk flows (BBFs), are able to directly-drive Pi2 oscillations. Some of these studies have further shown evidence that there is a one...
Article
a b s t r a c t Utilising fifteen (1990–2005) years of ground-based magnetometer data from four magnetometer stations, we characterise the statistical dependence of the Pc5 ULF wave power spectra on variations in F10.7 solar radio flux and on solar cycle phase. We show that the median Pc5 ULF wave power spectra can be characterised as a power-law w...
Article
Ultra Low Frequency (ULF) wave power in the Pc5 period band is thought to play an important role in the dynamics, acceleration and transport of energetic electrons in the outer radiation belt. Current estimates of radial diffusion coefficients are typically derived empirically and characterised in terms of Kp. Using the results from a statistical a...
Article
Of critical importance to resolving the substorm problem is our understanding of the response of the ionosphere to a variety of magnetotail drivers. We present a series of case studies of the ionospheric response to substorm expansion phase onset and other auroral activations using both in-situ data from Cluster and THEMIS spacecraft and data from...
Article
Power in the Pc5 ULF wave band is believed to have strong impact on the acceleration and transport of MeV energy electrons in the outer radiation belt. Typically, radial belt diffusion coefficients are defined from empirical approaches, based on observed flux variations and param-eterised by geomagnetic indices. We report the results of new ULF wav...
Article
Full-text available
Despite the characterization of the auroral substorm more than 40 years ago, controversy still surrounds the processes triggering substorm onset initiation. That stretching of the Earth's magnetotail following the addition of new nightside magnetic flux from dayside reconnection powers the substorm is well understood; the trigger for explosive ener...
Article
The Outer Radiation Belt Injection, Transport, Acceleration, and Loss Satellite (ORBITALS) is a Canadian Space Agency small satellite mission proposed as a Canadian contribution to the satellite infrastructure for the International Living With a Star (ILWS) program. Planned to operate contemporaneously with the NASA Radiation Belt Storm Probes (RBS...
Article
One of the most important problems in solar-terrestrial physics concerns understanding the response of the ionosphere to a variety of physical drivers from the magnetotail. In particular, determining the ionospheric response to magnetotail disturbances such as current disruptions and Earthward-directed bursty bulk flows is key to understanding the...
Article
Despite the characterisation of the auroral substorm more than 40 years ago, controversy still surrounds the processes triggering substorm onset initiation. Using ground-based magnetometers from CARISMA and THEMIS and in-situ magnetic observations by THEMIS and GOES, we present the results obtained from an objective wavelet-based technique to deter...
Article
Full-text available
1] Using a discrete wavelet transform with a Meyer wavelet basis, we present a new quantitative algorithm for determining the onset time of Pi1 and Pi2 ULF waves in the nightside ionosphere with $20-to 40-s resolution at substorm expansion phase onset. We validate the algorithm by comparing both the ULF wave onset time and location to the optical o...
Article
Full-text available
Polar cap ionospheric measurements are important for the complete understanding of the various processes in the solar wind - magnetosphere - ionosphere (SW-M-I) system as well as for space weather applications. Currently the polar cap region is lacking high temporal and spatial resolution ionospheric measurements because of the orbit limitations of...
Article
Full-text available
1] In this paper, we present case studies of the optical and magnetic signatures of the characteristics of the first minute of substorm expansion phase onset observed in the ionosphere. We find that for two isolated substorms, the onset of magnetic pulsations in the 24–96 s period wavelet band are colocated in time and space with the formation and...
Article
Full-text available
This review describes the infrastructure and capabilities of the expanded and upgraded Canadian Array for Realtime InvestigationS of Magnetic Activity (CARISMA) magnetometer array in the era of the THEMIS mission. Formerly operated as the Canadian Auroral Network for the OPEN Program Unified Study (CANOPUS) magnetometer array until 2003, CARISMA ca...
Article
Full-text available
In this paper we introduce the field line resonance detector (FLRD), a wave telescope technique which has been specially adapted to estimate the spectral energy density of field line resonance (FLR) phase structures in a superposed wave field. The field line resonance detector is able to detect and correctly characterize several superposed FLR stru...
Article
Full-text available
1] We examine the initial ionospheric localisation and expansion of Pi1 pulsations associated with a substorm onset observed on 1st November 2006 with the combined CARISMA and THEMIS GMAG network of ground-based magnetometers. We demonstrate how the first ionospheric pulsation disturbance lies in the long-period Pi1 band. The long-period Pi1 pulsat...
Article
Impulsive Ultra-Low Frequency (ULF) waves known as Pi1s (1-40s period) and Pi2s (40-150s period) are predominantly observed during substorm onset. Primarily due a lack of high-fidelity and conjugate in-situ and ground-based observations, determining the excitation mechanism for these ULF waves and their role in magnetic substorms has proved to be c...
Article
With the successful launch of the THEMIS spacecraft, the expansion of the CARISMA magnetometer array, and the deployment of the THEMIS GBOs, there exist exceptional opportunities to study the initiation of ULF waves surrounding substorm onset during the first THEMIS tail season. In this talk, we outline a number of techniques with which to diagnose...
Article
With the successful launch of the THEMIS spacecraft, the expansion of the CARISMA magnetometer array, and the deployment of the THEMIS GBOs, there now exists an exceptional opportunity to study fundamental ULF wave science in the nightside magnetosphere around substorm onset. Traditionally, substorm onset is usually determined by location and timin...
Article
We present multi-instrument observations of ultra low frequency (ULF) wave activity from the dawn flank magnetosphere during the period 12:00–13:30 UT on the 16 December 2003. Optical, magnetic and riometer measurements from the Churchill line meridian in the Canadian sector are presented which demonstrate the presence of multiple discrete auroral...
Article
Full-text available
We present an interval on 7 th March 2004 whereby clear quasi-periodic Pi2 pulsations are observed following the onset of an isolated magnetospheric substorm. During this interval, we succesfully employ cross-phase analysis techniques to recreate discrete points along the Alfvén continuum for the first time following the substorm expansion phase on...
Article
The outer radiation belt injection, transport, acceleration and loss satellite (ORBITALS) is a small satellite mission proposed as a Canadian contribution to the satellite infrastructure for the International Living With a Star (ILWS) program. The ORBITALS will monitor the energetic electron and ion populations in the inner magnetosphere across a w...
Article
The Outer Radiation Belt Injection, Transport, Acceleration and Loss Satellite (ORBITALS) mission is proposed as a Canadian Space Agency satellite mission contribution to ILWS. The ORBITALS is currently approved by the CSA for Phase A, and the NASA LWS Mission of Opportunity 4-instrument payload MORE (Mission of Opportunity Radbelt Experiment) for...
Article
A study was undertaken to estimate the radial diffusion time-scale, tauLL, for relativistic electrons (2-6 MeV) to diffuse into the slot region due to drift-resonance with Pc5 ULF waves (2-10 mHz) on 29th October, 2003. Large amplitude ULF waves were observed by the CARISMA, SAMNET and IMAGE ground-based magnetometer arrays to penetrate deep into t...
Article
Using a two dimensional image of the Earth's plasmasphere taken by the Extreme Ultraviolet Imager (EUV) on the Imager for Magnetopause-to-Aurora Global Exploration (IMAGE) spacecraft, in-situ electron density measurements from the IMAGE Radio Plasma Imager (RPI) instrument, measurements of magnetospheric mass density inferred from field line resona...
Article
Transport of ULF wave energy via large-scale wave modes is extremely important in terms of solar wind-magnetosphere-ionosphere coupling In this paper we present a study in which we fully characterise and diagnose large-scale ULF wave dynamics on a near-global scale We present a study using a favourable radial alignment of the Cluster Polar and geos...
Article
Full-text available
We present an interval of extremely long-lasting narrow-band Pc5 pulsations during the recovery phase of a large geomagnetic storm. These pulsations occurred continuously for many hours and were observed throughout the magnetosphere and in the dusk-sector ionosphere. The subject of this paper is the favorable radial alignment of the Cluster, Polar,...
Article
Arrays of ground-based magnetometers provide the capability for the meso- and global-scale monitoring of current systems and waves in the coupled magnetosphere-ionosphere system. Recent advances in the processing of multiple time series magnetometer array data allows the inversion of standing Alfven eigenfrequencies for the purposes of monitoring d...
Article
There are a number of mechanisms by which global ULF oscillations can be produced in the magnetosphere. For example, during fast solar wind speed events, flow instabilities can drive surface waves on the magnetopause which in turn can drive compressional waves into the magnetosphere. Alternately, oscillations in solar wind parameters can also produ...
Article
Large amplitude Pc5 ULF waves observed by the CANOPUS, IMAGE and SAMNET magnetometer arrays are characterized during the Halloween 2003 storm. Following storm onset, very large ULF power in discrete frequencies penetrates to very low-L shells spanning in the entire outer radiation belt and into the slot region. This is especially pronounced during...
Article
The ground-based CANOPUS magnetometer array presently consists of 13 fluxgate magnetometers sampling at 5s. Following the award of \$1.3M from the Canada Foundation for Innovation, the array will be expanded through the deployment of an additional 15 3-component fluxgate magnetometers together with 8 two-component induction coil magnetometers. Data...
Article
The Outer Radiation Belt Injection, Transport, Acceleration and Loss Satellite (ORBITALS) mission is presently undergoing Concept Study as a Canadian Space Agency satellite mission contribution to ILWS. The ORBITALS will provide a unique view of the largely previously unexplored inner magnetosphere. Its mission goal to "understand the acceleration,...
Article
Full-text available
1] This paper discusses the use of ground magnetometer data to derive plasma mass density profiles of the dayside plasmapause region with spatial and temporal resolution in the range 0.15–0.4 R E and 20–60 min. This is achieved using cross-phase techniques to identify field line resonance signatures that are not apparent in power spectra. Under qui...