To start off, say a little about yourself, your interests, undergraduate degree and what you are doing now. “I did my Undergraduate degree (Hons. Physics, Minor Mathematics) at UNB (2007-2011), my Masters in Atmospheric and Oceanic Science at McGill University (2011-2013), and my Ph.D. in Physics at UNB (2013-2018), focusing on Space Plasma and Radio Physics. Following the completion of my Ph.D., I took up a postdoctoral fellowship at UNB to build and lead the Canadian High Arctic Ionospheric Models research team, which received a contract with Defence Research and Development Canada to turn a model I developed in my Ph.D. research into an operational product for use by the Canadian Department of National Defence. I will be leaving UNB in the Fall for a faculty position at the University of Birmingham. I conduct research on a layer of plasma in the upper atmosphere, called the ionosphere, between 80km and 2000km altitude and examine how radio signals interact with that plasma. The ionosphere complicates the use of satellite-based navigations systems, such as the Global Positioning System (GPS). As GPS signals pass through the ionosphere, they are slowed down and bent. GPS uses the time it takes these signals to get to you as a measure of the distance between you and the satellite. If the signal is delayed or bent, your GPS will wrongly think that the satellite is further away than it really is and produce a bad positioning estimate. To combat this, your GPS uses a model of the ionosphere to correct for this ionospheric delay. Other technologies, such as Over-the-Horizon-Radars (OTHRs), actually benefit from existence of the ionosphere. Since the Earth is curved, traditional radars have maximum ranges of one to two hundred kilometers because the horizon curves away from the original propagation direction of the signal as you move away from the radar. To signals used by OTHR systems, the ionosphere acts as a giant mirror that will reflect these back toward the Earth. OTHRs use the mirror properties of the ionosphere to bounce signals past the horizon, allowing for these radars to see ranges of up to ~4000km. The problem is that the ionosphere is not a perfect mirror, it’s cloudy and warped, so these OTHR systems need very accurate models of the ionosphere in order to function. For these reasons, as part of my Ph.D. and Postdoctoral research, I built a model of the ionosphere, called the Empirical Canadian High Arctic Ionospheric Model (E-CHAIM). This model outperforms all previous models of the ionosphere at high latitudes and could enable the use of OTHR systems to surveil the Canadian Arctic, which would require dozens of traditional radars to properly monitor, but only a handful of OTHR systems. With increasing interest in the Arctic due to deglaciation, monitoring this region is becoming increasingly important.”
Was it always your goal to pursue graduate school or was there an event or organization that helped determine this for you? ”I originally came to UNB to study Math and Chemistry and had no intention of getting a degree in Physics. I just happened to take the Advanced Intro to Physics class in first year, which was taught by two excellent professors (Dr. Dennis Tokaryk and Dr. Stephen Ross), and it was enough to get me interested to pursue Physics as my major. In my second year, Jay approached me to apply with him for a National Science and Engineering Research Council (NSERC) Undergraduate Student Research Award (USRA) to do research with him over the summer. I ended up getting that award and, despite a steep learning curve in my first summer, managed to catch my bearings in my second summer with the lab. Without Jay taking a chance on me and allowing to work with him, I would never have even considered that I would have my current career.”
What do you love the most about your job with C.H.A.I.N.? “Honestly, just having the freedom to pursue whatever research interests me. Jay has always been very good at judging his students’ learning style, being more hands-off with independent students and more hands-on with students that need more direction.”
What would your best advice be to incoming students interested in research? “Don’t get caught up on an idea of where you expected your life to go. Obstacles are just as common as opportunities and both rarely come at a convenient time.”
David can be reached at david.themens@unb.ca for further questions.