Brent McBride, Physics
“Monte Carlo Simulation (MCS) of Photon Transport in Three-Dimensional Clouds”
Radiative transfer contributes to the growing influence of heat pollution, weather patterns, and the energy balance of our planet on human activity via the permeability and reflectivity of Earth’s thin atmospheric layers. Using Monte Carlo pseudo-random number generation simulation, this research inspected the presence, uniformity, and unpredictability of Sun-based photon “packets” entering and travelling through one, two, and three-dimensional isotropic and anisotropic cloud systems. By likening the model to a “pinball game” and the Earth as a virtual blackbody, MCS was used to visualize the bounce-like scattering behavior of particle-like photons on their way to extinction. Factors including single-scattering albedo, directional scattering modeled by the Henyey-Greenstein phase function, cloud depth, the angle of solar incidence, and azimuthal scattering angle contributed to the determination of chaos and homogeneity in photon samples sent through ideal cloud structures. This modeling was supported by previous observations of planetary surface and atmospheric reflectivity at pre-determined photon incidence angles. This research provides a foundation for future investigations into atmospheric intensity and temperature patterns as a factor of planetary latitude, longitude, or solar strength.
What was your specific research proposal?
With this research, I postulated that atmospheric radiative transfer, though uniform on the macro scale, would yield chaotic and ergodic behavior on the level of individual photons. When light particles enter the atmosphere, there is a chance they will pass straight through to the surface of the Earth, hit a molecule and jump back to space, or bounce around in an atmospheric layer like a "pinball" until they run out of energy. This last event is called scattering, and the probability photons will scatter is based on the thickness/density of the atmospheric layer, the angle at which the photons approach the atmosphere, and the reflectivity of the layer (albedo), among other factors.
Which faculty member did you work with on this project?
Dr. Zhibo Zhang, Assistant Professor in the Physics Department, served as my faculty mentor for this research.
How did you find the research opportunity?
Dr. Zhang received an Undergraduate Research Assistantship Support Award (URAS) in 2011 for a student willing to accompany him in his approved research proposal. He presented his need to the UMBC Honors College. I responded to the email inquiry and after meeting with Dr. Zhang in September 2011, I was brought aboard!
Was this your first independent research project?
Yes, but it was not my only research experience. In April 2011, I worked alongside a diverse team from Howard Community College studying 21cm hydrogen spectral lines at the National Radio Astronomy Observatory in Greenbank, West Virginia. We were able to determine the relative speed of and distance to a particular “spiral arm” of the Milky Way galaxy by integrating the deviations of each spectral pattern we received as we scanned the radio telescope across the sky. Earlier in 2011, I took on political science research as a legislative intern at the Maryland House of Delegates. The majority of my work focused on collaboration with Delegate Elizabeth Bobo (D,12B) on environmental sustainability issues.
How much time do you put into your research?
I met with Dr. Zhang to gauge my progress once a week, but typically put in four hours a week outside of the meeting into research. The time flexibility was great because I was able to throw in research time whenever my busy schedule permitted. The internship was also paid, which was a nice bonus!
How did your background contribute to your perception of the project?
I am a senior Physics major, with a love of weather and the atmosphere since childhood. I had never looked at the atmosphere in such a mathematical way before this research, so the entire process gave me a new understanding of the system I had read about and admired from my living room window as a kid.
What was the hardest part about your research?
The programming expectations were daunting at first, but MATLAB, the software we used to create the model, was easy to pick up and understand. Dr. Zhang also had a very specific, unique way of looking at the atmosphere as a constantly moving, planar system that took some time to grasp.
What is your advice to other students about getting involved in research?
Start early and stick with it. The experience is invaluable, and it looks great to have already contributed to your field when applying for internships, jobs, and related opportunities.
What are your career goals?
I plan to become a research professor at a research university, after some time in the lab, with a focus on atmospheric science. I’m inspired every day by the faculty members in the Physics department who can balance the heavy load of designing, executing, and finalizing research proposals while teaching classes.
What are you doing next for research?
I’ve spoken with a few professors about continuing research on campus in the coming year in fields from atmospheric physics to physics education. I’ve also applied for several summer internships, including the program at the nearby Johns Hopkins Applied Physics Lab.
What else are you involved in on campus?
I am an RA in Patapsco Hall with a great floor! I’m also involved with the Tau Sigma Transfer Honor Society and the Honors College.