In the Spring of 2019, I began research work alongside one of my professors Dr. Brian Thomas. He has been interested in possible effects from supernovas on earth, especially in regards to past or future mass extinctions. He suggested I downloaded and began using PlaSim, an intermediate complexity climate model to help find out effects on Earth's climate from ozone depletion resulting from supernova radiation. He helped be familiarize myself with how scientific models function. I learned how to pre-process data into a valid input format, set up model parameters by changing namelist text files and navigating with a command line, and eventually post-processing, plotting, and making sense of all the data.
Our first project was running two sets of ten models, each with a randomized initial seed and one of two ozone profiles, for one hundred years. The control had ozone profiles based on modern earth recordings and the other is the output from a chemistry model representing a depleted ozone with radiation from a supernova that had occurred about 50pc (163 light years) away. The results showed no short-term effects at the surface that would have significant impacts for life on earth, only about 0.3 C warmer in the supernova case. However, there were some regions that would have changes in their climate and effects on the upper atmosphere may have a more significant impact over time.
The second project changed the scripting for our run procedure, the surface files to replicate the Silurian period and made the code reusable for future tests. The Silurian period took place 415 - 445 Mya and had a known mass extinction involving about 85% of life on Earth.
This time instead of running 10 control runs and 10 supernova runs, we did 10 long runs simulating that contained both cases. Each one started with a randomized seed with prescribed orography, control ozone profile, temperatures and ice-cover profiles. This is shown as a flat line on the line graph below. After 50 years, the temperature and ice were set to calculated. At year 100 the ozone profile was switched from control to the supernova case. The results were similar to the modern day scenario. The difference in surface temperatures between the supernova and control sections were statistically significant, but only half a degree on average. Now that I used PlaSim for multiple tests, I created a directory environment and run scripts to make automation for running the model and making plots much easier for Dr. Thomas, future student-researchers and I.
Below is the original paper publishing findings from the modern day tests, a presentation poster of the modern day and Silurian case studies, my PlaSim directory and scripting code and the original PlaSim model.
Published Research Paper
Presentation Poster With Summary
PlasSim Ensemble Code
PlaSim Model
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