NASA Logo in the header
Sciences and Exploration Directorate

Alexa J Halford

(Chief)

Alexa J Halford's Contact Card & Information.
Email: alexa.j.halford@nasa.gov
Phone: 301.286.7794
Org Code: 675
Address:
NASA/GSFC
 Mail Code 675
 Greenbelt, MD 20771
Employer:
NASA

Missions & Projects

Brief Bio

I am currently the Lab chief for the ITM lab and a space physics researcher at NASA Goddard Space Flight Center, working with the LAMP, petitSat, Artemis, and AIMFAHR missions and projects. As an undergraduate at Augsburg College with Mark Engebretson, I started researching waves in Earth's magnetosphere using ground-based magnetometers in the Arctic and Antarctic. I moved away from waves to focus on geomagnetic storms and substorms during my masters at the University of Colorado Boulder with Dan Baker. Still, I returned to waves with my Ph.D. at the University of Newcastle NSW, Australia, working under Brian Fraser and Steve Morley. My Ph.D. thesis was on Electromagnetic Ion Cyclotron (EMIC) waves during the CRRES mission and their relationship to the plasmasphere and radiation belts. During my postdoc at Dartmouth College, I worked on the BARREL mission. I have moved down the field line (from a space perspective) and looked at the population of particles lost due to these interactions and their impact on the ionosphere and upper atmosphere. Ultimately, this research will help inform how we live and work in space. Some of my research looks at understanding the radiation environment in space which impacts humans and technology. Other aspects of my research look at predicting the neutral density in low Earth orbit - impacting the lifetime of satellites and orbital debris.


Today, I continue to bounce around the heliosphere and work to connect these regions, processes, and analysis techniques across boundaries. Much of my research is cross-disciplinary and focused on space weather - two of the Goddard vectors

Research Interests

Space Precipitation Impacts (SPI)

Heliophysics: Space Weather

SPI is an interdisciplinary and cross-institutional research group focused on studying the drivers and dynamics of low (<10 keV), medium (10-100 keV), and high energy (>100 keV) precipitation and their subsequent impacts on the ionosphere and upper atmosphere. SPI uses a unique combination of data analysis, theory and model development, and simulations within our team of experts to address three topics. Still, interconnected science questions investigating (A) the drivers of, (B) the variation in, and (C) the impacts of precipitation. SPI's three high-level science objectives are:


(A) How do the drivers of and pathways to energetic particle precipitation change under varying geomagnetic and solar wind conditions?

(B) How does the amount of low, medium, and high energy ion and electron precipitation change with varying physical drivers under different solar wind and geomagnetic conditions?

(C) What effect does precipitation have on satellite drag, and how does this vary with the dynamics of solar wind driving and geomagnetic activity?


Papers related to and from this work:


  • Murphy, K., Halford, A. J., Liu, V., Klenzing, J., Smith, J., Garcia-Sage, K., et al. (2025). Understanding and modeling the dynamics of storm-time atmospheric neutral density using random forests. Space Weather, 23, e2024SW003928. https://doi.org/10.1029/2024SW003928
  • Halford, A. J., Garcia-Sage, K., Mann, I. R., Turner, D. L., & Breneman, A. W. (2023). The effect of compression-induced chorus waves on 10–100 s eV electron precipitation. Geophysical Research Letters, 50, e2022GL098842. https://doi.org/10.1029/2022GL098842
  • Murphy, K. R., Sandhu, J., Rae, I. J., Daggitt, T., Glauert, S., Horne, R. B., et al. (2023). A new four-component L*-dependent model for radial diffusion based on solar wind and magnetospheric drivers of ULF waves. Space Weather, 21, e2023SW003440. https://doi.org/10.1029/2023SW003440
  • Pettit J, Elliott S, Randall C, Halford A, Jaynes A and Garcia-Sage K (2023) Investigation of the drivers and atmospheric impacts of energetic electron precipitation. Front. Astron. Space Sci. 10:1162564. doi: 10.3389/fspas.2023.1162564
  • Remya, B., Halford, A. J., Sibeck, D. G., Murphy, K. R., & Fok, M.-C. (2023). Understanding quiet and storm time EMIC waves—Van Allen Probes results. Journal of Geophysical Research: Space Physics, 128, e2023JA031712. https://doi.org/10.1029/2023JA031712
  •  Halford AJ, Chen TY, and Rastaetter L (2022) Data needs to be a priority. Front. Phys. 10:1061681. doi: 10.3389/fphy.2022.1061681
  • Elliott SS, Breneman A, Colpitts C, Bortnik J, Jaynes A, Halford A, Shumko M, Blum L, Chen L, Greeley A and Turner D (2022) Understanding the properties, wave drivers, and impacts of electron microburst precipitation: Current understanding and critical knowledge gaps. Front. Astron. Space Sci. 9:1062422. doi: 10.3389/fspas.2022.1062422
  • Shumko M, Chaddock D, Gallardo-Lacourt B, Donovan E, Spanswick EL, Halford AJ, Thompson I and Murphy KR (2022) AuroraX, PyAuroraX, and aurora-asi-lib: A user-friendly auroral all-sky imager analysis framework. Front. Astron. Space Sci. 9:1009450. doi: 10.3389/fspas.2022.1009450
  • Klenzing J, Smith JM, Halford AJ, Huba JD and Burrell AG (2022) sami2py—Overview and applications. Front. Astron. Space Sci. 9:1066480. doi: 10.3389/fspas.2022.1066480
  • Elliott, S. S., Breneman, A. W., Colpitts, C., Pettit, J. M., Cattell, C. A., Halford, A. J., et al. (2022). Quantifying the size and duration of a microburst-producing chorus region on 5 December 2017. Geophysical Research Letters, 49, e2022GL099655. https://doi.org/10.1029/2022GL099655
  • Klenzing J, Halford AJ, Kellerman A and Thompson B (2023) Using Application Usability Levels to support tracking the health of Heliophysics. Front. Astron. Space Sci. 10:1144053. doi: 10.3389/fspas.2023.1144053
  • Bain HM, Onsager TG, Mertens CJ, Copeland K, Benton ER, Clem J, Mangeard P-S, Green JC, Guild TB, Tobiska WK, Shelton-Mur K, Zheng Y, Halford AJ, Carlson S and Pulkkinen A (2023) Improved space weather observations and modeling for aviation radiation. Front. Astron. Space Sci. 10:1149014. doi: 10.3389/fspas.2023.1149014
  • Pettit J, Elliott S, Randall C, Halford A, Jaynes A and Garcia-Sage K (2023) Investigation of the drivers and atmospheric impacts of energetic electron precipitation. Front. Astron. Space Sci. 10:1162564. doi: 10.3389/fspas.2023.1162564
  •  Klenzing J, Halford AJ, Liu G, Smith JM, Zhang Y, Zawdie K, Maruyama N, Pfaff R and Bishop RL (2023) A system science perspective of the drivers of equatorial plasma bubbles. Front. Astron. Space Sci. 9:1064150. doi: 10.3389/fspas.2022.1064150
  • Schonfeld SJ, Pesnell WD, Verniero JL, Rivera YJ, Halford AJ, Vines SK and Spitzer SA (2023) Expanding the deep space network to support the heliophysics system observatory. Front. Astron. Space Sci. 9:1051527. doi: 10.3389/fspas.2022.1051527
  • Garcia-Sage K, Farrish AO, Airapetian VS, Alexander D, Cohen O, Domagal-Goldman S, Dong C, Gronoff G, Halford AJ, Lazio J, Luhmann JG, Schwieterman E, Sciola A, Segura A, Toffoletto F, Vievering J, Ahmed MR, Bali K and Rau G (2023) Star-exoplanet interactions: A growing interdisciplinary field in heliophysics. Front. Astron. Space Sci. 10:1064076. doi: 10.3389/fspas.2023.1064076
  • Shumko, M., Gallardo-Lacourt, B., Halford, A. J., Liang, J., Blum, L. W., Donovan, E., et al. (2021). A strong correlation between relativistic electron microbursts and patchy aurora. Geophysical Research Letters, 48, e2021GL094696. https://doi.org/10.1029/2021GL094696
  • Breneman, A. W., Halford, A. J., Millan, R. M., Woodger, L. A., Zhang, X.-J., Sandhu, J. K., et al. (2020). Driving of outer belt electron loss by solar wind dynamic pressure structures: Analysis of balloon and satellite data. Journal of Geophysical Research: Space Physics, 125, e2020JA028097. https://doi.org/10.1029/2020JA028097
  • Shumko, M., Johnson, A. T., O'Brien, T. P., Turner, D. L., Greeley, A. D., Sample, J. G., et al. (2020). Statistical properties of electron curtain precipitation estimated with AeroCube-6. Journal of Geophysical Research: Space Physics, 125, e2020JA028462. https://doi.org/10.1029/2020JA028462

The Balloon Array for Relativistic Radiation Belt Electron Loss (BARREL)

Heliophysics: Earth's Magnetosphere

During my postdoc, I worked with the Balloon Array for Relativistic Radiation belt Electron Losses (BARREL) mission. While the mission has ended, the research has not. We continue to use this unique data set to continue to explore the spatial and temporal dynamics of particle loss from the Sun and Magnetosphere into the ionosphere and upper atmosphere.


Papers from this work: 

  • Millan R.M. et al. (2013) The Balloon Array for RBSP Relativistic Electron Losses (BARREL). In: Fox N., Burch J.L. (eds) The Van Allen Probes Mission. Springer, Boston, MA
  • Manweiler, J.W., Breneman, A., Niehof, J. et al. Science of the Van Allen Probes Science Operations Centers. Space Sci Rev 218, 66 (2022). https://doi.org/10.1007/s11214-022-00919-x
  • Breneman, A.W., Wygant, J.R., Tian, S. et al. The Van Allen Probes Electric Field and Waves Instrument: Science Results, Measurements, and Access to Data. Space Sci Rev 218, 69 (2022). https://doi.org/10.1007/s11214-022-00934-y
  • Halford, A. J., McGregor, S. L., Murphy, K. R., Millan, R. M., Hudson, M. K., Woodger, L. A., Cattel, C. A., Breneman, A. W., Mann, I. R., Kurth, W. S., Hospodarsky, G. B., Gkioulidou, M., and Fennell, J. F. ( 2015), BARREL observations of an ICME‐shock impact with the magnetosphere and the resultant radiation belt electron loss. J. Geophys. Res. Space Physics, 120, 2557– 2570, doi: 10.1002/2014JA020873.
  • Halford, A. J., McGregor, S. L., Hudson, M. K., Millan, R. M., and Kress, B. T. ( 2016), BARREL observations of a solar energetic electron and solar energetic proton event, J. Geophys. Res. Space Physics, 121, 4205– 4216, doi:10.1002/2016JA022462.
  • Blum, L. W., Halford, A., Millan, R., Bonnell, J. W., Goldstein, J., Usanova, M., Engebretson, M., Ohnsted, M., Reeves, G., Singer, H., et al. ( 2015), Observations of coincident EMIC wave activity and duskside energetic electron precipitation on 18–19 January 2013, Geophys. Res. Lett., 42, 5727– 5735, doi:10.1002/2015GL065245.
  • Breneman, A., Halford, A., Millan, R. et al. Global-scale coherence modulation of radiation-belt electron loss from plasmaspheric hiss. Nature 523, 193–195 (2015) doi:10.1038/nature14515
  • Blum, L. W., Schiller, Q., Li, X., Millan, R., Halford, A., and Woodger, L. ( 2013), New conjunctive CubeSat and balloon measurements to quantify rapid energetic electron precipitation, Geophys. Res. Lett., 40, 5833– 5837, doi:10.1002/2013GL058546.
  • Woodger, L. A., Halford, A. J., Millan, R. M., McCarthy, M. P., Smith, D. M., Bowers, G. S., Sample, J. G., Anderson, B. R., and Liang, X. ( 2015), A summary of the BARREL campaigns: Technique for studying electron precipitation. J. Geophys. Res. Space Physics, 120, 4922– 4935. doi: 10.1002/2014JA020874.
  • Angelopoulos, V., Cruce, P., Drozdov, A. et al. The Space Physics Environment Data Analysis System (SPEDAS). Space Sci Rev 215, 9 (2019) doi:10.1007/s11214-018-0576-4
  • Zhang, J., et al. ( 2016), EMIC waves and associated relativistic electron precipitation on 25–26 January 2013, J. Geophys. Res. Space Physics, 121, 11,086– 11,100, doi:10.1002/2016JA022918.
  • Brito, T., Hudson, M. K., Kress, B., Paral, J., Halford, A., Millan, R., and Usanova, M. ( 2015), Simulation of ULF wave‐modulated radiation belt electron precipitation during the 17 March 2013 storm. J. Geophys. Res. Space Physics, 120, 3444– 3461. doi: 10.1002/2014JA020838.
  • Clilverd, M. A., Rodger, C. J., McCarthy, M., Millan, R., Blum, L. W., Cobbett, N., Brundell, J. B., Danskin, D., and Halford, A. J. ( 2017), Investigating energetic electron precipitation through combining ground‐based and balloon observations, J. Geophys. Res. Space Physics, 122, 534– 546, doi:10.1002/2016JA022812.
  • Rae, I. J., Murphy, K. R., Watt, C. E. J., Halford, A. J., Mann, I. R., Ozeke, L. G., … Singer, H. J. ( 2018). The role of localized compressional ultra‐low frequency waves in energetic electron precipitation. Journal of Geophysical Research: Space Physics, 123, 1900– 1914. https://doi.org/10.1002/2017JA024674
  • Chaston, C. C., Bonnell, J. W., Halford, A. J., Reeves, G. D., Baker, D. N., Kletzing, C. A., & Wygant, J. R. ( 2018). Pitch angle scattering and loss of radiation belt electrons in broadband electromagnetic waves. Geophysical Research Letters, 45, 9344– 9352. https://doi.org/10.1029/2018GL079527






 

Current Projects

petitSat

Earth's Ionosphere

petitSat is a 6U CubeSat designed to look at plasmaspheric bubbles and blobs. We are hoping to launch in 2021 from the international space station. 


Selected Publications:

J. Klenzing, R.L. Davidson, S.L. Jones, C. Martinis, K.A. Zawdie, G.D. Earle, J.M. Smith, A.J. Halford, S. Noel, N. Paschalidis, R.F. Pfaff, E. Robertson, The petitSat mission – Science goals and instrumentation, Advances in Space Research, Volume 66, Issue 1, 2020, Pages 107-115, ISSN 0273-1177, https://doi.org/10.1016/j.asr.2019.12.013.

Community for the Unified Study of Interhemispheric Asymmetries

Earth's Magnetosphere

From the CUSIA Website https://cusia.uta.edu/about/:


"CUSIA is leading in the next generation of theory and models that account for asymmetries imposed onto the geospace system

Understanding the effects of interhemispheric asymmetries is a grand challenge that crosses all boundaries in geospace. It is a critical area for understanding solar wind-magnetosphere coupling, magnetosphere-ionosphere coupling, thermospheric dynamics, and outflow into the magnetosphere. It remains one of the most glaring deficiencies of our numerical modeling capabilities.


"At present, no global model or combination of coupled models incorporates all or even most of the existing asymmetries found in nature. This issue is compounded by the interconnected nature of these asymmetries: it is not sufficient to include one or some; all processes must be considered to understand how interhemispheric asymmetries change the fundamental nature of the M-I-T system. This capability void represents a significant impediment to modeling, understanding, and forecasting space and upper atmosphere environment.


A large-scale center approach is necessary to bring together the scientists and resources to update and validate models and theory to properly account for interhemispheric asymmetries. "

LAMP Loss through Auroral Microburst Precipitation

Earth's Ionosphere

From the LAMP website https://lamp-mission.sites.uiowa.edu/


LAMP is a sounding rocket mission designed to explore the energy of a certain type of aurora called pulsating aurora. The aurora, or Northern Lights, comes in many forms. Pulsating aurora looks like large patches or splotches of light across the sky and is typically much fainter than the bright arcs and curtains shown in most photography. It gets its name from the periodic pulsations it exhibits – from several to 10’s of seconds between on and off phases. 


Relevant Publications:


Simultaneous Precipitation of Sub-Relativistic Electron Microburst and Pulsating Aurora Electrons Taku Namekawa, Takefumi Mitani, Kazushi Asamura, Yoshizumi Mioshi, Keisuke Hosokawa, Marc R Lessard, Chrystal Moser, Alexa J. Halford, Takeshi Sakanoi, Miki Kawamura, Masahito Nosé, Reiko Nomura, Mariko Teramoto, Mykhaylo Shumko, Kristina A Lynch, Allison N Jaynes, Matthew G McHarg DOI: 10.22541/essoar.168167378.83120518/v1


Variation of the altitude of auroral emission during a substorm cycle: Stereoscopic optical observations during the LAMP rocket experiment. Hosokawa, K., Miyoshi, Y., Mcharg, M., Ledvina, V., Hampton, D., Lessard, M., et al. (2024). Journal of Geophysical Research: Space Physics, 129, e2024JA033036. https://doi.org/10.1029/2024JA033036


Field-aligned currents associated with pulsating auroral patches: Observation with magneto-impedance magnetometer (MIM) onboard loss through auroral microburst pulsations (LAMP) sounding rocket. Nosé, M., Hosokawa, K., Nomura, R., Teramoto, M., Asamura, K., Miyoshi, Y., et al. (2024). Journal of Geophysical Research: Space Physics, 129, e2023JA032232. https://doi.org/10.1029/2023JA032232


Positions/Employment

PostDoc/Space Grant Visiting Scientist

Dartmouth College - Hanover NH

July 2012 - October 2017

During my postdoc I worked with the BARREL mission.

 

Papers from this work: 

 

 

 

Research Staff Member

The Aerospace Corporation - Chantilly VA

November 2017 - October 2019

I worked on space weather impacts from magnetospheric radiation populations with the REACH satellite constellation. 


Selected Publications:

  • Burrell, A. G., Halford, A., Klenzing, J., Stoneback, R. A., Morley, S. K., Annex, A. M., et al. (2018). Snakes on a spaceship—An overview of Python in heliophysics. Journal of Geophysical Research: Space Physics, 123, 10,384– 10,402. https://doi.org/10.1029/2018JA025877
  • Rae, I. J., Murphy, K. R., Watt, C. E. J., Halford, A. J., Mann, I. R., Ozeke, L. G., et al, (2018). The role of localized compressional ultra‐low frequency waves in energetic electron precipitation. Journal of Geophysical Research: Space Physics, 123, 1900– 1914. https://doi.org/10.1002/2017JA024674
  • J.T. Rudd, D.M. Oliveira, A. Bhaskar, A.J. Halford, How do interplanetary shock impact angles control the size of the geoeffective magnetosphere?, Advances in Space Research, Volume 63, Issue 1, 2019, Pages 317-326, ISSN 0273-1177, https://doi.org/10.1016/j.asr.2018.09.013.
  • Chaston, C. C., Bonnell, J. W., Halford, A. J., Reeves, G. D., Baker, D. N., Kletzing, C. A., & Wygant, J. R. (2018). Pitch angle scattering and loss of radiation belt electrons in broadband electromagnetic waves. Geophysical Research Letters, 45, 9344– 9352. https://doi.org/10.1029/2018GL079527
  • Bingley, L., Angelopoulos, V., Sibeck, D., Zhang, X., & Halford, A. (2019). The evolution of a pitch‐angle “bite‐out” scattering signature caused by EMIC wave activity: A case study. Journal of Geophysical Research: Space Physics, 124, 5042– 5055. https://doi.org/10.1029/2018JA026292
  • A. J. Halford, Adam C. Kellerman, Katherine Garcia-Sage, Jeffrey Klenzing, Brett A. Carter, Ryan M. McGranaghan, Timothy Guild, Consuelo Cid, Carl J. Henney, Natalia Yu. Ganushkina, Angeline G. Burrell, Mike Terkildsen, Daniel T. Welling, Sophie A. Murray, K. D. Leka, James P. McCollough, Barbara J. Thompson, Antti Pulkkinen, Shing F. Fung, Suzy Bingham, Mario M. Bisi, Michael W. Liemohn, Brian M. Walsh, Steven K. Morley, Application usability levels: a framework for tracking project product progress, J. Space Weather Space Clim. 9 A34 (2019) DOI: 10.1051/swsc/2019030
  • Claudia Medeiros, V. M. Souza, L. E. A. Vieira, D. G. Sibeck, A. J. Halford, S.-B. Kang, L. A. Da Silva, L. R. Alves, J. P. Marchezi, R. S. Dallaqua, P. R. Jauer, M. Rockenbach, O. Mendes, M. V. Alves, A. Dal Lago, M.-C. Fok, S. G. Kanekal, D. N. Baker, C. A. Kletzing, On the Contribution of EMIC Waves to the Reconfiguration of the Relativistic Electron Butterfly Pitch Angle Distribution Shape on 2014 September 12: A Case Study, The Astrophysical Journal, vol 872, p. 36, American Astronomical Society, Feb. 2019

Research Scientist

Goddard Space Flight Center NASA Code 675 - Greenbelt

November 2019 - Present

I am within the Ionosphere-Thermosphere-Mesosphere lab. I am currently the deputy PI of petitSat which will launch hopefully in 2021 from the international space station. 


Selected publications:

  • Remya, B., Sibeck, D. G., Ruohoniemi, J. M., Kunduri, B., Halford, A. J., Reeves, G. D., & Reddy, V. (2020). Association between EMIC wave occurrence and enhanced convection periods during ion injections. Geophysical Research Letters, 47, e2019GL085676. https://doi.org/10.1029/2019GL085676
  • Cid, C., Guerrero, A., Saiz, E., Halford, A. J., & Kellerman, A. C. (2020). Developing the LDi and LCi geomagnetic indices, an example of application of the AULs framework. Space Weather, 18, e2019SW002171. https://doi.org/10.1029/2019SW002171
  • Shumko, Mykhaylo and Johnson, Arlo and O’Brien, Thomas Paul and Turner, Drew L. and Greeley, Ashley D and Sample, John and Blake, J Bernard and Blum, Lauren W and Halford, Alexa J., Statistical Properties of Electron Curtain Precipitation Estimated with AeroCube-6, Earth and Space Science Open Archive, 17, 2020, 10.1002/essoar.10503661.1
  • Thiago V. Brito, Alexa J. Halford, Scot R. Elkington, Chapter 2 - Ultralow frequency-wave induced losses, Editor(s): Allison N. Jaynes, Maria E. Usanova, The Dynamic Loss of Earth's Radiation Belts, Elsevier, 2020, Pages 29-48, ISBN 9780128133712, https://doi.org/10.1016/B978-0-12-813371-2.00002-0.
  • J. Klenzing, R.L. Davidson, S.L. Jones, C. Martinis, K.A. Zawdie, G.D. Earle, J.M. Smith, A.J. Halford, S. Noel, N. Paschalidis, R.F. Pfaff, E. Robertson, The petitSat mission – Science goals and instrumentation, Advances in Space Research, Volume 66, Issue 1, 2020, Pages 107-115, ISSN 0273-1177, https://doi.org/10.1016/j.asr.2019.12.013.


Education

PhD 2012, The University of Newcastle Australia - Thesis can be found here

Masters 2007 CU Boulder 

BA double major in Math/Physics graduated from honors & McNair program Augsburg University

Professional Societies

The American Geophysical Union

2002 - Present

The American Meteorological Society

2019 - Present

Professional Service

 

Examples of Service to Mission Coordination and Mission leadership

  • Led BARREL collaborations and contact to multiple missions (both US-based and international), including NASA’s Van Allen Probes (US-NASA), Cluster (EU), ABOVE2 (CA), Firebird (US-UNH and MSU ), AC6 (US-Aerospace Corporation), and CSSWE (US-LASP CU Boulder) as well as with the larger scientific community. I was the BARREL lead for the daily meetings between BARREL and the Van Allen Probe’s instruments teams to determine data collection and retrieval during the BARREL campaigns. Other satellite, ground, and CubeSat missions also attended these meetings to determine when to collect and download data to ensure the correct data type for answering critical science questions for the 2012-2013, 2013-2014, and the August 2015 and 2016 campaigns.
  • Helped organize and plan the EFW/BARREL workshop and follow-up science meetings, 2013- 2014
  • Successfully conceived, planned, and developed experimental investigations and proposed for EISCAT radar time with strong international collaborations for experimental investigations, taking advantage of conjugate observations with FIREBIRD, Van Allen Probes, and BARREL for both the 2015 and 2016 campaigns. This work addressed and attempted to resolve scientific problems by identifying the in situ source and scale size of microbursts and other radiation belt electron precipitation events.
  • Stepped into the PI position for LAMP when the original PI stepped down - then led the team to a successful launch ultimately resulting in sharing our results through multiple presentations and papers.


Sample of Organisation of conferences/workshops and sessions/seminars

  • Co-convener for over 25 AGU sessions
  • Co-convener for multiple AGU and CEDAR sessions
  • Co-convener of multiple Chapman conferences
  • On the organizing committee for the Inner Magnetosphere Coupling III meeting held in March 2015 at the University of California Los Angeles.
  • Co-organizer for multiple BARREL/Van Allen Probes workshops


Professional Organization Membership and Committees

  • Serving on the GEM Metrics and Validation Standing Resource Group 2020 - present
  • Serving on the Space Weather Council
  • Heliophysics Liason to the Lunar Exploration Analysis Group, 2024 - present
  • Served on NASA LWS TR&T steering committee 2016
  • Served on the SWORM
  • Member of the American Geophysical Union 2002 - present
  • Serving on the AGU SPA Fellows Committee 2017, 2018,
  • Chair of the AGU SPA Fellows Committee 2019, 2020
  • Serving on the AGU SPA Advocacy Committee. 2017 - 2019


Service to Community/institute

  • Topic Editor for Annales Geophysicae
  • Guest editor for multiple special issues in Frontiers and JGR
  • Panelist on the GEM student night panel about Ethics 2017
  • Goddard point of contact/organizer for the United States Naval Academy- Goddard Summer Student Research Program 2017
  • Code 674 point of contact for nugget slides for codes 600, 100, and headquarters, working with Dr. Alex Young 2016 - 2017
  • Served on NASA and NSF grant review panels as a write-in reviewer, panelist, and chair.
  • Active referee for several journals, including Geophysical Reviews, the Journal of Geophysical Research, Geophysical Research Letters, Annales Geophysicae, Physics of Plasmas, EOS, and Nature Communications.

Awards

Selection of awards:

  • NASA Peer Award for setting up Science Fridays, a new networking event to enable cross-pollination of ideas and innovative thinking throughout Goddard, September 2020
  • NASA Special Act Award For serving in a critical leadership role as the ARTEMIS Point of Contact in 670, and connecting Heliophysics to the larger efforts at the Center in support of human exploration of the Moon and Moon to Mars.August 2020
  • 2018 Editor’s Citation for Excellence in Refereeing for Reviews of Geophysics
  • The Aerospace Corporation ”Strategic Imperative Hero pin” for growth 2018
  • Goddard Heliophysics Science Division Peer Award 2017
  • Augsburg First Decade Award 2013 “The First Decade Award is presented to Augsburg graduates of the past 10 years who have made significant progress in their professional achievements and contributions to the community, and in so doing exemplify the mission of the College: to prepare future leaders in service to the world.” - Augsburg College (now Augsburg University)
  • Dartmouth Young Visiting Scientist 2012 - 2013.
  • Best Science Story at the 10th annual New Year’s Poster Party at NASA Goddard 2017
  • Finalist in the Three min. thesis competition, Newcastle University, Callaghan Australia June 2010
  • Winner of the Three min. thesis competition in the College round Newcastle University, Callaghan Australia, June 2010
  • Voted Best Poster by participating students at Science Research Expo, Newcastle University, Callaghan Australia June 2008
  • BA Graduation with honors and from the McNair program, Augsburg College Minneapolis MN May 2003
  • Received Outstanding Student Paper Award for poster at Spring 2002 AGU conference

Publications

Refereed

2025. "Understanding and Modeling the Dynamics of Storm‐Time Atmospheric Neutral Density Using Random Forests.", Space Weather, 23 (1): [10.1029/2024sw003928] [Journal Article/Letter]

2024. "Additions to Space Physics Data Facility and pysatNASA: Increasing Mars Global Surveyor and Mars Atmosphere and Volatile EvolutioN Dataset Utility.", Data, 9 (11): 133 [10.3390/data9110133] [Journal Article/Letter]

2023. "Will we find Martian lightning via Schumann resonances?.", Frontiers in Astronomy and Space Sciences, 10 [10.3389/fspas.2023.1162624] [Journal Article/Letter]

2023. "How Open Data and Interdisciplinary Collaboration Improve Our Understanding of Space Weather: A Risk & Resiliency Perspective.", Bulletin of the AAS, [10.3847/25c2cfeb.165ff6b0] [Journal Article/Letter]

2023. "Cross-Scale and Cross-Regime Coupling in the ITM: Studying Weather, not just Climate, in the Middle and Upper Atmosphere.", Bulletin of the AAS, 55 (3): [10.3847/25c2cfeb.041166a2] [Journal Article/Letter]

2023. "Using Application Usability Levels to support tracking the health of Heliophysics.", Frontiers in Astronomy and Space Sciences, 10 [10.3389/fspas.2023.1144053] [Journal Article/Letter]

2023. "Expanding the deep space network to support the heliophysics system observatory.", Frontiers in Astronomy and Space Sciences, 9 [10.3389/fspas.2022.1051527] [Journal Article/Letter]

2023. "A system science perspective of the drivers of equatorial plasma bubbles.", Frontiers in Astronomy and Space Sciences, 9 [10.3389/fspas.2022.1064150] [Journal Article/Letter]

2022. "Supporting responsible machine learning in heliophysics.", Frontiers in Astronomy and Space Sciences, 9 [10.3389/fspas.2022.1064233] [Journal Article/Letter]

2022. "Data needs to be a priority.", Frontiers in Physics, 10 [10.3389/fphy.2022.1061681] [Journal Article/Letter]

2022. "sami2py—Overview and applications.", Frontiers in Astronomy and Space Sciences, 9 [10.3389/fspas.2022.1066480] [Journal Article/Letter]

2022. "The Van Allen Probes Electric Field and Waves Instrument: Science Results, Measurements, and Access to Data.", Space Science Reviews, 218 (8): 69 [10.1007/s11214-022-00934-y] [Journal Article/Letter]

2022. "Science of the Van Allen Probes Science Operations Centers.", Space Science Reviews, 218 (8): 66 [10.1007/s11214-022-00919-x] [Journal Article/Letter]

2022. "Impacts of acoustic and gravity waves on the ionosphere.", Frontiers in Astronomy and Space Sciences, 9 [10.3389/fspas.2022.1064152] [Journal Article/Letter]

2022. "GMAG: An open-source python package for ground-based magnetometers.", Frontiers in Astronomy and Space Sciences, 9 [10.3389/fspas.2022.1005061] [Journal Article/Letter]

2022. "AuroraX, PyAuroraX, and aurora-asi-lib: A user-friendly auroral all-sky imager analysis framework.", Frontiers in Astronomy and Space Sciences, 9 [10.3389/fspas.2022.1009450] [Journal Article/Letter]

2022. "The Effect of Compression Induced Chorus Waves on 10s to 100s eV Electron Precipitation.", Geophysical Research Letters, [10.1029/2022gl098842] [Journal Article/Letter]

2022. "Proton aurora and relativistic electron microbursts scattered by electromagnetic ion cyclotron waves.", Frontiers in Astronomy and Space Sciences, 9 [10.3389/fspas.2022.975123] [Journal Article/Letter]

2022. "Quantifying the Size and Duration of a Microburst‐Producing Chorus Region on 5 December 2017.", Geophysical Research Letters, 49 (15): [10.1029/2022gl099655] [Journal Article/Letter]

2022. "Drift Phase Structure Implications for Radiation Belt Transport.", Journal of Geophysical Research: Space Physics, 127 (8): [10.1029/2022ja030331] [Journal Article/Letter]

2021. "A Strong Correlation Between Relativistic Electron Microbursts and Patchy Aurora.", Geophysical Research Letters, 48 (18): [10.1029/2021gl094696] [Journal Article/Letter]

2020. "Driving of Outer Belt Electron Loss by Solar Wind Dynamic Pressure Structures: Analysis of Balloon and Satellite Data.", Journal of Geophysical Research: Space Physics, 125 (12): [10.1029/2020ja028097] [Journal Article/Letter]

2020. "Statistical Properties of Electron Curtain Precipitation Estimated With AeroCube‐6.", Journal of Geophysical Research: Space Physics, 125 (12): [10.1029/2020ja028462] [Journal Article/Letter]

2020. "The petitSat Mission – Science Goals and Instrumentation.", Advances in Space Research, 66 (1): 107-115 [10.1016/j.asr.2019.12.013] [Journal Article/Letter]

2020. "Association between EMIC wave occurrence and enhanced convection periods during ion injections.", Geophysical Research Letters, 2019GL085676 [10.1029/2019gl085676] [Journal Article/Letter]

2020. "Ultralow frequency-wave induced losses.", The Dynamic Loss of Earth's Radiation Belts, 29-48 [10.1016/b978-0-12-813371-2.00002-0] [Article in Book]

2019. "Developing the LDi and LCi geomagnetic indices, an example of application of the AULs framework.", Space Weather, 2019SW002171 [10.1029/2019sw002171] [Journal Article/Letter]

2019. "Application Usability Levels: A Framework for Tracking Project Product Progress.", J. Space Weather Space Clim. , 9 A34 [https://doi.org/10.1051/swsc/2019030] [Journal Article/Letter]

2019. "The Evolution of a Pitch‐Angle “Bite‐Out” Scattering Signature Caused by EMIC Wave Activity: A Case Study.", Journal of Geophysical Research: Space Physics, 124 (7): 5042-5055 [10.1029/2018ja026292] [Journal Article/Letter]

2019. "Generation of EMIC Waves and Effects on Particle Precipitation During a Solar Wind Pressure Intensification with B z > 0.", Journal of Geophysical Research: Space Physics, 2019JA026477 [10.1029/2019ja026477] [Journal Article/Letter]

2019. "On the Contribution of EMIC Waves to the Reconfiguration of the Relativistic Electron Butterfly Pitch Angle Distribution Shape on 2014 September 12—A Case Study.", The Astrophysical Journal, 872 (1): 36 [10.3847/1538-4357/aaf970] [Journal Article/Letter]

2019. "The Space Physics Environment Data Analysis System (SPEDAS).", Space Science Reviews, 215 (1): 9 [10.1007/s11214-018-0576-4] [Journal Article/Letter]

2019. "How do interplanetary shock impact angles control the size of the geoeffective magnetosphere?.", Advances in Space Research, 61 (1): 317-326 [10.1016/j.asr.2018.09.013] [Journal Article/Letter]

2018. "Snakes on a Spaceship—An Overview of Python in Heliophysics.", Journal of Geophysical Research: Space Physics, 123 (12): 2018JA025877 [10.1029/2018ja025877] [Journal Article/Letter]

2018. "Pitch Angle Scattering and Loss of Radiation Belt Electrons in Broadband Electromagnetic Waves.", Geophysical Research Letters, 45 (18): 9344-9352 [10.1029/2018gl079527] [Journal Article/Letter]

2018. "Ion Injection Triggered EMIC Waves in the Earth's Magnetosphere.", Journal of Geophysical Research: Space Physics, 123 (6): 4921-4938 [10.1029/2018ja025354] [Journal Article/Letter]

2018. "Geomagnetically induced currents caused by interplanetary shocks with different impact angles and speeds.", Space Weather, 16 (6): 636-647 [10.1029/2018sw001880] [Journal Article/Letter]

2018. "The Role of Localized Compressional Ultra-low Frequency Waves in Energetic Electron Precipitation.", Journal of Geophysical Research: Space Physics, [10.1002/2017ja024674] [Journal Article/Letter]

2017. "Investigating energetic electron precipitation through combining ground‐based and balloon observations.", Journal of Geophysical Research: Space Physics, 122 (1): 534-546 [10.1002/2016ja022812] [Journal Article/Letter]

2016. "EMIC waves and associated relativistic electron precipitation on 25-26 January 2013.", Journal of Geophysical Research: Space Physics, 121 (11): 11,086-11,100 [10.1002/2016ja022918] [Journal Article/Letter]

2016. "Dependence of EMIC wave parameters during quiet, geomagnetic storm, and geomagnetic storm phase times.", Journal of Geophysical Research: Space Physics, 121 (7): 6277–6291 [10.1002/2016ja022694] [Journal Article/Letter]

2016. "BARREL observations of a solar energetic electron and solar energetic proton event.", Journal of Geophysical Research: Space Physics, 121 (5): 4205-4216 [10.1002/2016ja022462] [Journal Article/Letter]

2015. "Interplanetary shocks and the resulting geomagnetically induced currents at the equator.", Geophysical Research Letters, 42 (16): 6554-6559 [10.1002/2015gl065060] [Journal Article/Letter]

2015. "Observations of coincident EMIC wave activity and duskside energetic electron precipitation on 18-19 January 2013.", Geophysical Research Letters, 42 (14): 5727-5735 [10.1002/2015gl065245] [Journal Article/Letter]

2015. "Global-scale coherence modulation of radiation-belt electron loss from plasmaspheric hiss.", Nature, 523 (7559): 193-195 [10.1038/nature14515] [Journal Article/Letter]

2015. "A summary of the BARREL campaigns: Technique for studying electron precipitation.", Journal of Geophysical Research: Space Physics, 120 (6): 4922-4935 [10.1002/2014ja020874] [Journal Article/Letter]

2015. "Simulation of ULF wave-modulated radiation belt electron precipitation during the 17 March 2013 storm.", Journal of Geophysical Research: Space Physics, 120 (5): 3444-3461 [10.1002/2014ja020838] [Journal Article/Letter]

2015. "BARREL observations of an ICME-shock impact with the magnetosphere and the resultant radiation belt electron loss.", Journal of Geophysical Research: Space Physics, 120 (4): 2557-2570 [10.1002/2014ja020873] [Journal Article/Letter]

2015. "EMIC waves and plasmaspheric and plume density: CRRES results.", Journal of Geophysical Research: Space Physics, 120 (3): 1974-1992 [10.1002/2014ja020338] [Journal Article/Letter]

2013. "New conjunctive CubeSat and balloon measurements to quantify rapid energetic electron precipitation.", Geophysical Research Letters, 40 (22): 5833-5837 [10.1002/2013gl058546] [Journal Article/Letter]

2013. "The Balloon Array for RBSP Relativistic Electron Losses (BARREL).", Space Science Reviews, 179 (1-4): 503-530 [10.1007/s11214-013-9971-z] [Journal Article/Letter]

2010. "EMIC wave activity during geomagnetic storm and nonstorm periods: CRRES results.", Journal of Geophysical Research: Space Physics, 115 (A12): [10.1029/2010ja015716] [Journal Article/Letter]

2004. "Latitudinal and seasonal variations of quasiperiodic and periodic VLF emissions in the outer magnetosphere.", Journal of Geophysical Research, 109 (A5): A05216 [10.1029/2003ja010335] [Journal Article/Letter]

Talks, Presentations and Posters

Invited

The Effect of Compression Induced Chorus Waves on 10s eV to 100s keV Electron Precipitation

August 2020

CU Boulder LASP FoM Seminar series

Space Weather: Killer Electron Edition, USIP: Balloon-borne System Data Sensors Seminar Class

May 2020

University Houston

The Assessment of Understanding and Quantifying Progress Working Group, Tracking Space Weather Application Progress Towards Usability: Application Usability Levels

June 2019

A.J. Halford A. Kellerman,B. Thompson, A. Pulkkinen, K. Garcia-Sage, B. Carter, S. A. Murray, S. Bingham, D. Welling, The Assessment of Understanding and Quantifying Progress Working Group, Tracking Space Weather Application Progress Towards Usability: Application Usability Levels, JPGU, May 2019, Chiba, Japan

Panelist on "And Beyond… the Next 60 Years of NASA" 

April 2019

The panel was recorded can be watched at http://www.ustream.tv/recorded/120752782

 Application Usability Levels, European Space Weather Week, Nov. 2018

December 2018

European Space Weather Week

The storm that wasn't: A look at multiple loss processes occurring simultaneously and how they interact with each other

August 2018

Exploring Systems-Science Techniques for the Earth's Magnetosphere-Ionosphere-Thermosphere, Los Alamos NM

Coincident Compression Generated EMIC Chorus and Hiss waves

June 2017

JpGU-AUG Joint meeting May 2017, Chiba, Japan

Taking up Space

April 2017

Maryland Institute College of Art, March 2017

Observations of a solar storm from the stratosphere: The BARREL Mission

2016

Dec. 2016, Google Hangout University of Houston Physics Seminar series

A Sun to mud view of a heliospheric storm: The little mission that could

February 2016

Plasma Physics seminar, January 2016 Dartmouth College Hanover NH

Precipitation events as observed with BARREL

April 2015

the BARREL team, Precipitation events as observed with BARREL, Inner Magnetosphere Coupling III, March 2015, UCLA

Space Balloons and Killer Electrons

November 2014

Space Balloons and Killer Electrons, Google Hangout about Space physics directed for STEM majors at Alabama universities. I was asked to give this talk based on my twitter activities and participation through EPSCORE workshops. October 21 2014

Early Results from the BARREL 2013 Balloon Campaign and a look to the 2014 Campaign

October 2013

A.J. Halford, R. Millan, BARREL Team, Early Results from the BARREL 2013 Balloon Campaign and a look to the 2014 Campaign, Cluster workshop, Tromso, Norway, September 2013

Early Results from the BARREL 2013 Balloon Campaign

September 2013

A.J. Halford, R. Millan, BARREL Team, Early Results from the BARREL 2013 Balloon Campaign, IAGA, Merida, Mexico, August 2013

EMIC waves and the radiation belts

July 2012

EMIC waves and the radiation belts, Dartmouth, New Hampshire, invited talk 2012

EMIC waves and the plasmasphere

2011

EMIC waves and the plasmasphere, UNH, New Hampshire, invited talk 2011

Other

Selected Public Outreach

Panelist on Astrobiology, at Awesome Con Washington DC

May 2019 - May 2019

Massive sunspots and huge solar flares mean unexpected space weather for Earth, originally posted in TheConversation.com

October 2017 - October 2017

Halford, A. J., B. A. Carter, J. Currie, editor Maggie Villiger, Massive sunspots and huge solar flares mean unexpected space weather for Earth, originally posted in TheConversation.com at https://theconversation.com/massive-sunspots-and-huge-solar-flares-mean-unexpected-space-weather-for-earth-83677, picked up by other newsoutlets e.g. NewsWeek

Participated in the June 22nd and August 20th 2017 Reddit Ask Me Anything through NASA about the August 21st 2017 Solar Eclipse

September 2017 - September 2017

Damaging electric currents in space affect Earth’s equatorial region, not just the pole

September 2015 - September 2015

Scientists at work: space balloons and charged particles above the Arctic Circle

October 2015 - October 2015

We are scientists from NASA and The Washington Post talking about today's eclipse. AMA!

September 2017 - September 2017

What's the science behind the eclipse?

September 2017 - September 2017

Ask the Expert: How to Savour the Heavens

October 2016 - October 2016

FaceBook Live event with the SciTech Discovery Center.

August 2020 - August 2020

Contact Us

For general inquiries about the Sciences and Exploration Directorate.

Jocelyn Lynch

Project Support Specialist

301-286-6066 jocelyn.m.lynch@nasa.gov
Ellie Jeffries

Project Support Specialist

301-286-6066 ellie.jeffries@nasa.gov
Technical issues with this website may be reported to ben.pelletier@nasa.gov.
General inquiries about the scientific programs at NASA's Goddard Space Flight Center may be directed to the Center Office of Communications at 1.301.286.8955.