Caitlin Semmens

Faculty of Arts
Andreas Christen

Research Topic

Characterizing Turbulent Exchange Over a Heterogeneous Urban Landscape

Research Description

The aim of my research is to investigate how the spatial heterogeneity or "patchiness" of urban surfaces affects turbulent exchange in cities. Much of our understanding of land-atmosphere interactions is rooted in direct flux measurements by the eddy covariance (EC) method. This stationary, tower-based approach has become the standard tool for monitoring the terrestrial carbon cycle, trace gas emissions, and the water balance. However, despite its use in many cities globally, the EC method was initially developed for ecosystems like croplands and forests, where the source area has a uniform or homogeneous distribution of sources and sinks. This is not the case in urban ecosystems, where emission sources of heat, water, and trace gases vary both spatially and temporally. To date, few studies have addressed source heterogeneity on the ability to measure fluxes in urban settings. And there have been no studies that analyze long-term urban flux data seasonally, and relate it to remotely-sense geospatial information. Properly describing the unique surface-atmosphere exchanges of heat, momentum, water vapour, and trace gases in cities is critical for urban-scale weather and air pollution forecasting.

Why did you decide to study at UBC?

Logistically, it made sense because my home is Vancouver. But more importantly, I wanted to test myself and get as much as I could out of my education, and I felt UBC was really the best place to do this.


Why did you decide to pursue a graduate degree?

My favourite thing to do is learn. Near the end of my undergrad degree (at UBC) I began working in Prof. Andreas Christen's micrometeorology lab, continuing past research on isotope analysis of vehicle emissions and undertaking a directed studies which more broadly focused on urban air. I participated in MURC, took some great courses, met some incredible people, and became very excited about the work I was doing. I decided I really wasn't ready to leave UBC.

What do you like to do for fun or relaxation?

Whenever I can catch a break, my favourite thing to do is hunker down with a good video game. I also read a lot and spend a good deal of time out in nature!

What advice do you have for new graduate students?

Be excited about your work. Be ambitious and learn new (sometimes scary) things. Most importantly, don't get "lost" in your work – try to keep in mind what comes next and where you want to go from here.