Dr. David Themens PhD

School of Engineering

Lecturer in Space Weather & Space Systems

Address
Engineering Building
University of Birmingham
Birmingham
B15 2TT, UK

David Themens is a Lecturer in Space Weather and Space Systems in SERENE group at the University of Birmingham.

David primarily undertakes research in modelling and mitigating the impacts of space weather on radio communications and navigation systems. More specifically, David explores the effects of changes in the ionosphere, a layer of plasma in the earth’s upper atmosphere, on these systems. His work includes exploring the synergistic properties of different earth observation instruments, measurement technique development, data assimilation, empirical modelling, ionospheric physics, and HF/UHF raytracing.

David is the principal developer of the Empirical Canadian High Arctic Ionospheric Model (E-CHAIM).

Lecturer in Space Weather & Space Systems:

  • PhD in Physics University of New Brunswick, 2018

  • MSc in Atmospheric and Oceanic Science, McGill University, 2013

  • BSc (Hons) in Physics, University of New Brunswick, 2011

Dr. David R. Themens earned his B.Sc. (Hon. Phys.) from the University of New Brunswick in 2011, under the supervision of Prof. P.T. Jayachandran, where his research focused on the development of Global Navigation Satellite System (GNSS) receiver calibration and the validation of ionospheric models.

David completed his M.Sc. in Atmospheric and Oceanic Science at McGill University in 2013, under the supervision of Prof. Frédéric Fabry. At McGill, David participated in the development of a scanning microwave radiometer system, designed to make large-scale volumetric measurements of atmospheric water vapour and temperature, which are vitally important to weather forecasting and severely under-observed. David’s research focused on instrument simulation and information theory, attempting to determine the optimal operating frequencies of the instrument and assessing the distribution of information measured by the system. His work demonstrated that traditional use of these instruments discarded large quantities of information, such that simple modifications to traditional measurement inversion methods could produce a more than 10,000% increase in the information provided by scanning microwave radiometers.

David completed his Ph.D. in Physics at the University of New Brunswick in 2018. His Ph.D. research focused on the development of the Empirical Canadian High Arctic Ionospheric Model (E-CHAIM), a high-latitude alternative to the use of the International Reference Ionosphere (IRI) in modelling ionospheric electron density, necessary for HF/UHF signal propagation modelling. During his Ph.D., David acquired a pair of contracts with Defence Research and Development Canada (DRDC) to expand his E-CHAIM model and develop an operational near-real-time data assimilation system for use with Over-The-Horizon-Radar. This continued into David’s postdoctoral research, where he served as Project Lead for the Canadian High Arctic Ionospheric Models (CHAIMs) contracts. For access or information about E-CHAIM and its related systems, check the system website here: https://e-chaim.chain-project.net/

David has a passion for data science and a, perhaps unhealthy, fascination with ionosondes.

David is always looking for new Ph.D. students interested in the ionosphere, data assimilation, and radio propagation.

Interested students should send David a complete CV and a one-page (single sided) statement on their research interests.

David’s research focuses on four main topics: ionospheric modelling, physics, measurement techniques, and radio propagation.

David’s main physics research focuses on the interaction between the ionosphere and the atmosphere. His interests concern the degree to which lower atmospheric forcing drives variability within the ionosphere and the interactions between the ionosphere and thermosphere.

David is also actively expanding and improving upon his E-CHAIM ionospheric electron density model, having recently lead the development of a near-real-time and reanalysis data assimilation system, based on E-CHAIM, and having developed an auroral particle precipitation module and a quiet D-Region for the model.

David’s modelling research is applications-oriented, focusing on the mitigation of ionospheric impacts on radio communications, Over-The-Horizon-Radar (OTHR), and navigation systems. To this end, David conducts ionospheric raytracing for HF and UHF signals to assess the impacts of the ionosphere on these systems and develop mitigation strategies.

David is also highly interested in exploring novel ways to extract new information from existing instruments and infrastructure using non-linear data assimilation techniques.

  • Engineering Institute of Canada Strategic Conference Planning Committee – Member: 2020 – Present
  • International Union of Radio Science (URSI): Canadian National Committee (CNC) Chair for Commissions G (Ionospheric radio and propagation) and H (Waves in plasmas): Jan, 2020 – 2023 (3-year term)
  • COSPAR International Space Weather Action Teams (ISWAT) G2b-04, G2b-05, G2b-06, and S03-03 – Member: December 2019 – Present
  • Canadian Association of Physicists (CAP) Division of Atmospheric and Space Physics (DASP) – Vice Chair: Feb, 2019 – Present (2-year term)
  • International Association of Geodesy (IAG) – Global Geodetic Observing System (GGOS) Joint Working Group on Ionospheric Electron Density Modelling – Member: 2019 – Present
  • Abdus Salam International Centre for Theoretical Physics (ICTP) NeQuick Model Working Group – Inaugural Member: Oct, 2019 – Present
  • International Association of Geomagnetism and Aeronomy (IAGA) – Canadian National Representative: Sept, 2018 – Present (2-year term)
  • International Reference Ionosphere (IRI) Working Group – Member/Canadian National Representative: July, 2018 – Present

Swarnalingam, N., D. Wu, and D.R. Themens (2020), Comparison and Evaluation of a Bottom-Up GPS-RO Electron Density Retrieval for D and E regions using Radar Observations and Models, Journal of Atmospheric and Solar-Terrestrial Physics, doi: 10.1016/j.jastp.2020.105333

Prikryl, P., J. M. Weygand, R. Ghoddousi-Fard, P. T. Jayachandran, D. R Themens, A. M. McCaffrey, B. S. R. Kunduri, L. Nikitina (2020), Temporal and spatial variations of GPS TEC and phase during auroral substorms and breakups, Polar Science, Submitted March 25th, 2020 (Manuscript # POLAR-D-20-00037).

Themens, D.R., P.T. Jayachandran, A.M. McCaffrey, and B. Reid (2020), The limits of empirical electron density modeling: Examining the capacity of E-CHAIM and the IRI for modeling intermediate (1- to 30-day) timescales at high latitudes, Radio Science, doi: 10.1029/2018RS006763

Pignalberi, A., M. Pezzopane, D.R. Themens, H. Haralambous, B. Nava, and P.Coisson (2020). On the Analytical Description of the Topside Ionosphere made by NeQuick: Modeling the Scale Height through COSMIC/FORMOSAT-3 Selected Data, IEEE Journal of Selected Topics in Applied Earth Observations and Remote Sensing, vol. 13, pp. 1867-1878, 2020, doi:10.1109/JSTARS.2020.2986683.

Yamazaki, Y., V. Matthias, Y. Miyoshi, C. Stolle, T. Siddiqui, G. Kervalishvili, J. Lastovicka, M. Kozubek, W. Ward, D. R. Themens, S. Kristoffersen, and P. Alken (2020) September 2019 Antarctic sudden stratospheric warming: quasi-6-day wave burst and ionospheric effects, Geophys. Res. Let., 47, doi:10.1029/2019GL086577

Koustov, A.V., S. Ullrich, P.V. Ponomarenko, R.G. Gillies, D.R. Themens, and N. Nishitani (2020) Comparison of SuperDARN peak electron density estimates based on elevation angle measurements to ionosonde and incoherent scatter radar measurements, Earth, Planets, and Space, 72, 43. doi:10.1186/s40623-020-01170-w

Perry, G., C. Watson, A. Howarth, D.R. Themens, V. Foss, R.B. Langley, and A.W. Yau (2019). Topside ionospheric disturbances detected using radio occultation measurements during the August 2017 solar eclipse, Geophys. Res. Let., doi: 10.1029/2019GL083195

Themens, D.R., P.T. Jayachandran, A.M. McCaffrey, B. Reid, and R.H. Varney (2019). A bottomside parameterization for the Empirical Canadian High Artic Ionospheric Model (E-CHAIM), Radio Sci., doi: 10.1029/2018RS006748

Themens, D.R., P.T. Jayachandran, and A.M. McCaffrey (2019), Validating the performance of the Empirical Canadian High Arctic Ionospheric Model (E-CHAIM) with in situ observations from DMSP and CHAMP, J. Space Weather and Space Clim., doi: 10.1051/swsc/2019021

Prol, F. dos S., D.R. Themens, M. Hernández-Pajares, P. de O. Camargo, and M.T. de A.H. Muella (2018). Linear Vary-Chap Topside Electron Density Model with Topside Sounder and Radio-Occultation Data, Surveys in Geophys, doi: 10.1007/s10712-019-09521-3

Koustov, A. V., P.V. Ponomarenko, C.J. Graf, R.G. Gillies, and D.R. Themens (2018). Optimal F region electron density for the PolarDARN radar echo detection near the Resolute Bay zenith. Radio Science, 53, 1002–1013. doi: 10.1029/2018RS006566

Themens, D.R., et al. (2018). Topside Electron Density Representations for Middle and High Latitudes: A Topside Parameterization for E-CHAIM based on the NeQuick, J. Geophys. Res. Space Physics, 123, doi: 10.1002/2017JA024817

Watson, C., R.B. Langley, D.R. Themens, A.W. Yau, A. Howarth, and P.T. Jayachandran (2017). Receiver bias estimates and validation of e-POP GAP-O ionospheric radio occultation measurements, Radio Sci., doi: 10.1002/2017RS006453

Themens, D.R., P.T. Jayachandran, and R.H. Varney (2017), Examining the use of the NeQuick bottomside and topside parameterizations at high latitudes, Advances in Space Research, 61(1), 287-294, doi: 10.1016/j.asr.2017.09.037

Themens, D.R., P.T. Jayachandran, I. Galkin, and C. Hall (2017). The Empirical Canadian High Arctic Ionospheric Model (E-CHAIM): NmF2 and hmF2, J. Geophys. Res. Space Physics, doi: 10.1002/2017JA024398

Zhang, Q.-H., Y.-Z. Ma, P.T. Jayachandran, J. Moen, M. Lockwood, Y.-L. Zhang, J.C. Foster, S.-R. Zhang, Y. Wang, D.R. Themens, B.-C. Zhang, and Z.Y. Xing (2017), Polar cap hot patches: enhanced density structures different from the classical patches in the ionosphere. Geophysical Research Letters, doi:10.1002/2017GL073439

Athieno, R., P.T. Jayachandran, and D.R. Themens (2017). A Neural Network based foF2 model for a single station in the polar cap, Radio Sci., doi: 10.1002/2016RS006192

McCaffrey, A. M., P.T. Jayachandran, D.R. Themens, and R.B. Langley (2017). GPS Code Bias Estimation: A Comparisons of Two Methods, Advances in Space Research, 59(8), doi: 10.1016/j.asr.2017.01.047

Yamazaki, Y., M. J. Kosch, Y. Ogawa, and D. R. Themens (2016), High-latitude Ion Temperature Climatology during the International Polar Year 2007–2008, Journal of Space Weather and Space Climate, 6, doi:10.1051/swsc/2016029

Themens, D.R., and P.T. Jayachandran (2016), Solar Activity Variability in the IRI at high latitudes: Comparisons with GPS Total Electron Content, J. Geophys. Res. Space Physics, 121, 3793–3807, doi:10.1002/2016JA022664.

Themens, D. R., P. T. Jayachandran, and R. B. Langley (2015), The nature of GPS differential receiver bias variability: An examination in the polar cap region, J. Geophys. Res. Space Physics, 120, 8155–8175, doi:10.1002/2015JA021639.

Athieno, R., P.T. Jayachandran, D.R. Themens, and D.W. Danskin (2015), Comparison of observed and predicted MUF(3000)F2 in the Polar cap region , Radio Sci., 50, 509–517. doi:10.1002/2015RS005725.

Koustov, A.V., P. V. Ponomarenko, M. Ghezelbash, D. R. Themens, and P. T. Jayachandran (2014), Electron density and electric field over Resolute Bay and F region ionospheric echo detection with the Rankin Inlet and Inuvik SuperDARN radars, Radio Sci., 49,1194–1205, doi:10.1002/2014RS005579.

Ghezelbash, M., A.V. Koustov, D.R. Themens, and P.T. Jayachandran (2014). Seasonal and diurnal variations of PolarDARN F region echo occurrence in the polar cap and their causes, J. Geophys. Res. Space Physics, 119, 10,426–10,439, doi:10.1002/2014JA020726.

Themens, D. R., P.T. Jayachandran, M.J. Nicolls, and J.W. MacDougall (2014), A top to bottom evaluation of IRI 2007 within the polar cap, J. Geophys. Res. Space Physics, 119, 6689–6703, doi:10.1002/2014JA020052.

Themens, D.R., and F. Fabry (2014). Why scanning instruments are a necessity for constraining temperature and humidity fields in the lower atmosphere. J. Atmos. Oceanic Technol., 31, 2462–2481

Themens, D.R., P.T. Jayachandran, R.B. Langley, J.W. MacDougall, and M.J. Nicolls (2013). Determining Receiver Biases in GPS-derived Total Electron Content in Auroral Oval and Polar Cap Region Using Ionosonde Measurements. GPS Solutions, 17(3), pp. 357-369.



OTHER PUBLICATIONS (non-refereed articles, technical reports, etc.)



Themens, D.R., B. Reid, A.M. McCaffrey, Joey Bernard, Chris Watson, and P.T. Jayachandran (2020), The Reanalysis Canadian High Arctic Ionospheric Model (R-CHAIM): A sophisticated reanalysis data assimilation system for high latitudes. Report submitted to Defence Research and Development Canada for contract #W7714-186507/001/SS (public release TBD)

Themens, D.R., Chris Watson, A.M. McCaffrey, B. Reid, and P.T. Jayachandran (2020), The Development and Implementation of a Precipitation Enhanced E-Region for E-CHAIM. Report submitted to Defence Research and Development Canada for contract #W7714-186507/001/SS (public release TBD)

Themens, D.R., B. Reid, A.M. McCaffrey, and P.T. Jayachandran (2019), The Assimilation Canadian High Arctic Ionospheric Model (A-CHAIM): Implementation, Workflow, and Performance. Report submitted to Defence Research and Development Canada for contract #W7714-186507/001/SS (public release TBD)

Young, G., J.W. Kim, G. Fotopoulos, P.J.A. McCausland, D.R. Themens, R. Petrone, G. Ali, P. Kushner, T. Merlis, J. Klymak, P. Galbraith, F. Darbyshire, S. Molnar, G. Wiliams-Jones, N.Vigouroux, R. Kelly, and R. Scharien (2019). Geodesy and Geophysics in Canada 2015-2019 Quadrennial Report of the Canadian National Committee for the International Union of Geodesy and Geophysics, Prepared on the Occasion of the 27th General Assembly of the IUGG Montreal, Canada, July 2019 (http://cgu-ugc.ca/cguwp/wp-content/media/CNC-IUGG-2019-Quad-Report-complete.pdf)

Themens, D.R., P.T. Jayachandran, A.M. McCaffrey, and B. Reid (2019), The Empirical Canadian High Arctic Ionospheric Model (E-CHAIM): NmF2 and hmF2. Report submitted to Defence Research and Development Canada, Report Number: DRDC-RDDC-2018-C195 (http://cradpdf.drdc-rddc.gc.ca/PDFS/unc332/p809273_A1b.pdf)

Themens, D.R., P.T. Jayachandran, A.M. McCaffrey, and B. Reid (2018), The Empirical Canadian High Arctic Ionospheric Model (E-CHAIM): Validation and Release. Report submitted to Defence Research and Development Canada, Report Number: DRDC-RDDC-2018-C185 (http://cradpdf.drdc-rddc.gc.ca/PDFS/unc327/p808067_A1b.pdf)

Themens, D.R., P.T. Jayachandran, A.M. McCaffrey, and B. Reid (2018), The Empirical Canadian High Arctic Ionospheric Model (E-CHAIM): Bottomside. Report submitted to Defence Research and Development Canada, Report Number: DRDC-RDDC-2018-C184 (http://cradpdf.drdc-rddc.gc.ca/PDFS/unc330/p808078_A1b.pdf)

Themens, D.R., P.T. Jayachandran, A.M. McCaffrey, and B. Reid (2018), The Empirical Canadian High Arctic Ionospheric Model (E-CHAIM): Topside. Report submitted to Defence Research and Development Canada, Report Number: DRDC-RDDC-2018-C202 (http://cradpdf.drdc-rddc.gc.ca/PDFS/unc330/p808500_A1b.pdf)