Imperial College London

DrMartinArcher

Faculty of Natural SciencesDepartment of Physics

Stephen Hawking Fellow
 
 
 
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Contact

 

m.archer10 Website

 
 
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Location

 

720BHuxley BuildingSouth Kensington Campus

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Summary

 

Publications

Publication Type
Year
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55 results found

Desai R, Eastwood J, Horne R, Allison H, Allanson O, Watt C, Eggington J, Glauert S, Meredith N, Archer M, Staples F, Mejnertsen L, Tong J, Chittenden Jet al., 2021, Drift orbit bifurcations and cross-field transport in the outer radiation belt: global MHD and integrated test-particle simulations, Journal of Geophysical Research: Space Physics, ISSN: 2169-9380

Energetic particle fluxes in the outer magnetosphere present a significant challenge to modellingefforts as they can vary by orders of magnitude in response to solar wind driving conditions. In thisarticle, we demonstrate the ability to propagate test particles through global MHD simulations to ahigh level of precision and use this to map the cross-field radial transport associated with relativisticelectrons undergoing drift orbit bifurcations (DOBs). The simulations predict DOBs primarily occurwithin an Earth radius of the magnetopause loss cone and appears significantly different for southwardand northward interplanetary magnetic field orientations. The changes to the second invariant areshown to manifest as a dropout in particle fluxes with pitch angles close to 90◦and indicate DOBsare a cause of butterfly pitch angle distributions within the night-time sector. The convective electricfield, not included in previous DOB studies, is found to have a significant effect on the resultant longterm transport, and losses to the magnetopause and atmosphere are identified as a potential methodfor incorporating DOBs within Fokker-Planck transport models.

Journal article

Archer M, Hartinger M, Plaschke F, Southwood D, Rastaetter Let al., 2021, Magnetopause ripples going against the flow form azimuthally stationary surface waves, Nature Communications, ISSN: 2041-1723

Journal article

Desai RT, Freeman M, Eastwood J, Eggington J, Archer M, Shprits Y, Meredith N, Staples F, Ian R, Hietala H, Mejnertsen L, Chittenden J, Horne Ret al., 2021, Interplanetary shock-induced magnetopause motion: Comparison between theory and global magnetohydrodynamic simulations, Geophysical Research Letters, Vol: 48, Pages: 1-11, ISSN: 0094-8276

The magnetopause marks the outer edge of the Earth’s magnetosphere and a distinct boundary between solar wind and magnetospheric plasma populations. In this letter, we use global magneto-hydrodynamic simulations to examine the response of the terrestrial magnetopause to fast-forward interplanetary shocks of various strengths and compare to theoretical predictions. The theory and simulations indicate the magnetopause response can be characterised by three distinct phases; an initial acceleration as inertial forces are overcome, a rapid compressive phase comprising the majority of the distance travelled, and large-scale damped oscillations with amplitudes of the order of an Earth radius. The two approaches agree in predicting subsolar magnetopause oscillations with frequencies2–13 mHz but the simulations notably predict larger amplitudes and weaker damping rates. This phenomenon is of high relevance to space weather forecasting and provides a possible explanation for magnetopause oscillations observed following the large interplanetary shocks of August 1972 and March 1991.

Journal article

Archer MO, 2021, Schools of all backgrounds can do physics research – on the accessibility and equity of the Physics Research in School Environments (PRiSE) approach to independent research projects, Geoscience Communication, Vol: 4, Pages: 189-208, ISSN: 2569-7110

Societal biases are a major issue in school students' access to and interaction with science. School engagement programmes in science from universities, like independent research projects, which could try and tackle these problems are, however, often inequitable. We evaluate these concerns applied to one such programme, Physics Research in School Environments (PRiSE), which features projects in space science, astronomy, and particle physics. Comparing the schools involved with PRiSE to those of other similar schemes and UK national statistics, we find that PRiSE has engaged a much more diverse set of schools with significantly more disadvantaged groups than is typical. While drop-off occurs within the protracted programme, we find no evidence of systematic biases present. The majority of schools that complete projects return for multiple years with the programme, with this repeated buy-in from schools again being unpatterned by typical societal inequalities. Therefore, a school's ability to succeed in independent research projects appears independent of background within the PRiSE framework. Qualitative feedback from teachers shows that the diversity and equity of the programme, which they attribute to the level of support offered through PRiSE's framework, is valued, and they have highlighted further ways of making the projects potentially even more accessible. Researcher involvement, uncommon in many other programmes, along with teacher engagement and communication are found to be key elements to success in independent research projects overall.

Journal article

Archer MO, DeWitt J, 2021, “Thanks for helping me find my enthusiasm for physics”: the lasting impacts “research in schools” projects can have on students, teachers, and schools, Geoscience Communication, Vol: 4, Pages: 169-188, ISSN: 2569-7110

Using 6 years of evaluation data, we assess the medium- and long-term impacts upon a diverse range of students, teachers, and schools from participating in a programme of protracted university-mentored projects based on cutting-edge space science, astronomy, and particle physics research. After having completed their 6-month-long projects, the 14–18-year-old school students report having substantially increased in confidence relating to relevant scientific topics and methods as well as having developed numerous skills, outcomes which are corroborated by teachers. There is evidence that the projects helped increase students' aspirations towards physics, whereas science aspirations (generally high to begin with) were typically maintained or confirmed through their involvement. Longitudinal evaluation 3 years later has revealed that these projects have been lasting experiences for students which they have benefited from and drawn upon in their subsequent university education. Data on students' destinations suggest that their involvement in research projects has made them more likely to undertake physics and STEM degrees than would otherwise be expected. Cases of co-created novel physics research resulting from Physics Research in School Environments (PRiSE) has also seemed to have a powerful effect, not only on the student co-authors, but also participating students from other schools. Teachers have also been positively affected through participating, with the programme having influenced their own knowledge, skills, and pedagogy, as well as having advantageous effects felt across their wider schools. These impacts suggest that similar “research in schools” initiatives may have a role to play in aiding the increased uptake and diversity of physics and/or STEM in higher education as well as meaningfully enhancing the STEM environment within schools.

Journal article

Archer MO, DeWitt J, Thorley C, Keenan Oet al., 2021, Evaluating participants' experience of extended interaction with cutting-edge physics research through the PRiSE “research in schools” programme, Geoscience Communication, Vol: 4, Pages: 147-168, ISSN: 2569-7110

Physics in schools is distinctly different from, and struggles to capture the excitement of, university research-level work. Initiatives where students engage in independent research linked to cutting-edge physics within their school over several months might help mitigate this, potentially facilitating the uptake of science in higher education. However, how such initiatives are best supported remains unclear and understudied. This paper evaluates a provision framework, Physics Research in School Environments (PRiSE), using survey data from participating 14–18-year-old students and their teachers to understand their experience of the programme. The results show that PRiSE appears to provide much more positive experiences than typical university outreach initiatives due to the nature of the opportunities afforded over several months, which schools would not be able to provide without external input. The intensive support offered is deemed necessary, with all elements appearing equally important. Based on additional feedback from independent researchers and engagement professionals, we also suggest the framework could be adopted at other institutions and applied to their own areas of scientific research, something which has already started to occur.

Journal article

Archer MO, Day N, Barnes S, 2021, Demonstrating change from a drop-in space soundscape exhibit by using graffiti walls both before and after, Geoscience Communication, Vol: 4, Pages: 57-67, ISSN: 2569-7110

Impact evaluation in public engagement necessarily requires measuring change. However, this is extremely challenging for drop-in activities due to their very nature. We present a novel method of impact evaluation which integrates graffiti walls into the experience both before and after the main drop-in activity. The activity in question was a soundscape exhibit, where young families experienced the usually inaudible sounds of near-Earth space in an immersive and accessible way. We apply two analysis techniques to the captured before and after data – quantitative linguistics and thematic analysis. These analyses reveal significant changes in participants' responses after the activity compared to before, namely an increased diversity in language used to describe space and altered conceptions of what space is like. The results demonstrate that the soundscape was surprisingly effective at innately communicating key aspects of the underlying science simply through the act of listening. The impacts also highlight the power of sonification in stimulating public engagement, which, through reflection, can lead to altered associations, perceptions, and understanding. Therefore, we show that this novel approach to drop-in activity evaluation, using graffiti walls both before and after the activity and applying rigorous analysis to this data, has the power to capture change and, thus, have a short-term impact. We suggest that commonly used evaluation tools suitable for drop-in activities, such as graffiti walls, should be integrated both before and after the main activity in general, rather than only using them afterwards as is typically the case.

Journal article

Archer M, DeWitt J, Davenport C, Keenan O, Coghill L, Christodoulou A, Durbin S, Campbell H, Hou Let al., 2021, Going beyond the one-off: How can STEM engagement programmes with young people have real lasting impact?, Research for All, Vol: 5, Pages: 67-85, ISSN: 2399-8121

A major focus in the STEM public engagement sector concerns engaging withyoung people, typically through schools. The aims of these interventions areoften to positively affect students' aspirations towards continuing STEMeducation and ultimately into STEM-related careers. Most schools engagementactivities take the form of short one-off interventions that, while able toachieve positive outcomes, are limited in the extent to which they can havelasting impacts on aspirations. In this paper we discuss various differentemerging programmes of repeated interventions with young people, assessing whatimpacts can realistically be expected. Short series of interventions appearalso to suffer some limitations in the types of impacts achievable. However,deeper programmes that interact with both young people and those that influencethem over significant periods of time (months to years) seem to be moreeffective in influencing aspirations. We discuss how developing a Theory ofChange and considering young people's wider learning ecologies are required inenabling lasting impacts in a range of areas. Finally, we raise severalsector-wide challenges to implementing and evaluating these emergingapproaches.

Journal article

Archer M, 2021, Comment on gc-2020-35, Publisher: Copernicus GmbH

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Archer M, 2020, Reply to RC5, Publisher: Copernicus GmbH

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Archer M, 2020, Further reply to RC1, Publisher: Copernicus GmbH

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Archer M, 2020, Reply to RC3, Publisher: Copernicus GmbH

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Archer M, 2020, Thank you, Publisher: Copernicus GmbH

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Archer M, 2020, Reply to RC3, Publisher: Copernicus GmbH

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Archer M, 2020, Reply to RC4, Publisher: Copernicus GmbH

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Archer M, 2020, Reply to RC2, Publisher: Copernicus GmbH

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Archer M, 2020, Reply to RC2, Publisher: Copernicus GmbH

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Archer M, 2020, Reply to RC2, Publisher: Copernicus GmbH

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Archer M, 2020, Reply to RC1, Publisher: Copernicus GmbH

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Archer M, 2020, Reply to abstract review, Publisher: Copernicus GmbH

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, 2020, Reply to RC1, Publisher: Copernicus GmbH

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Archer M, 2020, Teacher development strategy in PRiSE, Publisher: Copernicus GmbH

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Archer M, 2020, Response to RC1, Publisher: Copernicus GmbH

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Archer M, 2020, Comment on citizen science, Publisher: Copernicus GmbH

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Archer MO, 2020, Space Sound Effects Short Film Festival: using the film festival model to inspire creative art–science and reach new audiences, Geoscience Communication, Vol: 3, Pages: 147-166, ISSN: 2569-7110

The ultra-low frequency analogues of sound waves in Earth'smagnetosphere play a crucial role in space weather; however, the publicis largely unaware of this risk to our everyday lives and technology.As a way of potentially reaching new audiences, SSFX (Space Sound Effects) made 8 yearsof satellite wave recordings audible to the human ear with the aimof using it to create art. Partnering with film industry professionals,the standard processes of international film festivals were adoptedby the project in order to challenge independent filmmakers to incorporatethese sounds into short films in creative ways. Seven films coveringa wide array of topics and genres (despite coming from the same sounds)were selected for screening at a special film festival out of 22 submissions.The works have subsequently been shown at numerous established filmfestivals and screenings internationally. These events have attracteddiverse non-science audiences resulting in several unanticipated impacts on them, thereby demonstrating how working with the art world canopen up dialogues with both artists and audiences who would not ordinarily engage with science.

Journal article

Turc L, Roberts OW, Archer MO, Palmroth M, Battarbee M, Brito T, Ganse U, Grandin M, Pfau-Kempf Y, Escoubet CP, Dandouras Iet al., 2019, First observations of the disruption of the Earth's foreshock wave field During magnetic clouds, Geophysical Research Letters, Vol: 46, Pages: 12644-12653, ISSN: 0094-8276

The foreshock, extending upstream of Earth's bow shock, is a region of intense electromagnetic wave activity and nonlinear phenomena, which can have global effects on geospace. It is also the first geophysical region encountered by solar wind disturbances journeying toward Earth. Here, we present the first observations of considerable modifications of the foreshock wave field during extreme events of solar origin called magnetic clouds. Cluster's multispacecraft data reveal that the typical quasi‐monochromatic foreshock waves can be completely replaced by a superposition of waves each with shorter correlation lengths. Global numerical simulations further confirm that the foreshock wave field is more intricate and organized at smaller scales. Ion measurements suggest that changes in shock‐reflected particle properties may cause these modifications of the wave field. This state of the foreshock is encountered only during extreme events at Earth, but intense magnetic fields are typical close to the Sun or other stars.

Journal article

Archer MO, Hietala H, Hartinger MD, Plaschke F, Angelopoulos Vet al., 2019, Direct observations of a surface eigenmode of the dayside magnetopause, Nature Communications, Vol: 10, ISSN: 2041-1723

The abrupt boundary between a magnetosphere and the surrounding plasma, the magnetopause, has long been known to support surface waves. It was proposed that impulses acting on the boundary might lead to a trapping of these waves on the dayside by the ionosphere, resulting in a standing wave or eigenmode of the magnetopause surface. No direct observational evidence of this has been found to date and searches for indirect evidence have proved inconclusive, leading to speculation that this mechanism might not occur. By using fortuitous multipoint spacecraft observations during a rare isolated fast plasma jet impinging on the boundary, here we show that the resulting magnetopause motion and magnetospheric ultra-low frequency waves at well-defined frequencies are in agreement with and can only be explained by the magnetopause surface eigenmode. We therefore show through direct observations that this mechanism, which should impact upon the magnetospheric system globally, does in fact occur.

Journal article

Archer MO, Hartinger MD, Redmon R, Angelopoulos V, Walsh BMet al., 2018, First results from sonification and exploratory cttizen science of magnetospheric ULF waves: long-lasting decreasing-frequency poloidal Field line resonance following geomagnetic storms, Space Weather, Vol: 16, Pages: 1753-1769, ISSN: 1539-4956

Magnetospheric ultralow‐frequency (ULF) waves contribute to space weather in the solar wind‐magnetosphere‐ionosphere system. The monitoring of these waves by space‐ and ground‐based instruments, however, produces big data, which are difficult to navigate, mine, and analyze effectively. We present sonification, the process of converting an oscillatory time series into audible sound, and citizen science, where members of the public contribute to scientific investigations, as a means to potentially help tackle these issues. Magnetometer data in the ULF range at geostationary orbit have been sonified and released to London high schools as part of exploratory projects. While this approach reduces the overall likelihood of useful results from any particular group of citizen scientists compared to typical citizen science projects, it promotes independent learning and problem solving by all participants and can result in a small number of unexpected research outcomes. We present one such example, a case study identified by a group of students of decreasing‐frequency poloidal field line resonances over multiple days found to occur during the recovery phase of a coronal mass ejection‐driven geomagnetic storm. Simultaneous plasma density measurements show that the decreasing frequencies were due to the refilling of the plasmasphere following the storm. The waves were likely generated by internal plasma processes. Further exploration of the audio revealed many similar events following other major storms; thus, they are much more common than previously thought. We therefore highlight the potential of sonification and exploratory citizen science in addressing some of the challenges facing ULF wave research.

Journal article

Palmroth M, Hietala H, Plaschke F, Archer M, Karlsson T, Blanco-Cano X, Sibeck D, Kajdič P, Ganse U, Pfau-Kempf Y, Battarbee M, Turc Let al., 2018, Magnetosheath jet properties and evolution as determined by a global hybrid-Vlasov simulation, Annales Geophysicae: atmospheres, hydrospheres and space sciences, Vol: 36, Pages: 1171-1182, ISSN: 0992-7689

Abstract. We use a global hybrid-Vlasov simulation for the magnetosphere, Vlasiator, to investigate magnetosheath high-speed jets. Unlike many other hybrid-kinetic simulations, Vlasiator includes an unscaled geomagnetic dipole, indicating that the simulation spatial and temporal dimensions can be given without scaling. Thus, for the first time, this allows investigating the magnetosheath jet properties and comparing them directly with the observed jets within the Earth's magnetosheath. In the run shown in this paper, the interplanetary magnetic field (IMF) cone angle is 30°, and a foreshock develops upstream of the quasi-parallel magnetosheath. We visually detect a structure with high dynamic pressure propagating from the bow shock towards the magnetopause. The structure is confirmed as a jet using three different criteria, which have been adopted in previous observational studies. We compare these criteria against the simulation results. We find that the magnetosheath jet is an elongated structure extending Earthward of the bow shock by ~ 2.3 RE, while its size perpendicular to the direction of propagation is ~ 0.5 RE. We also investigate the jet evolution, and find that the jet originates due to the interaction of the foreshock Ultra Low Frequency (ULF) waves with the bow shock surface. The simulation shows that magnetosheath jets can develop also under steady IMF, as inferred by observational studies.

Journal article

Plaschke F, Hietala H, Archer M, Blanco-Cano X, Kajdic P, Karlsson T, Lee SH, Omidi N, Palmroth M, Roytershteyn V, Schmid D, Sergeev V, Sibeck Det al., 2018, Jets downstream of collisionless shocks, Space Science Reviews, Vol: 214, ISSN: 0038-6308

The magnetosheath flow may take the form of large amplitude, yet spatially localized, transient increases in dynamic pressure, known as “magnetosheath jets” or “plasmoids” among other denominations. Here, we describe the present state of knowledge with respect to such jets, which are a very common phenomenon downstream of the quasi-parallel bow shock. We discuss their properties as determined by satellite observations (based on both case and statistical studies), their occurrence, their relation to solar wind and foreshock conditions, and their interaction with and impact on the magnetosphere. As carriers of plasma and corresponding momentum, energy, and magnetic flux, jets bear some similarities to bursty bulk flows, which they are compared to. Based on our knowledge of jets in the near Earth environment, we discuss the expectations for jets occurring in other planetary and astrophysical environments. We conclude with an outlook, in which a number of open questions are posed and future challenges in jet research are discussed.

Journal article

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