Senior Thesis: Part One

Note: This is a living document and will be revised until the data collection period ends (which is still to be determined).

This article discusses the first part of my senior thesis, namely the simulation and analysis-related components. When I move into the second phase of the thesis, I will split this.

I’ve tried to write this as a mostly-plain language introduction to the problem that my senior thesis is trying to solve (both for myself to keep my eyes on the higher-level goals at hand and for those unfamiliar with this area of research). For a more technical explanation, stay tuned for the inevitable final paper, which you will find along with simulator code at this page.

The Melt-Freeze Problem

Warming global climate will lead to a warming Arctic, which will result in longer ice-free summers. This will have negative effects on the yearly sea ice cycle: higher summer ocean temperatures will result in delayed freeze-up, which will result in shorter winter ice growth, which leads to thinner sea ice in the spring, completing the loop. Existing work has found a strong correlation between the dates of melt-out to freeze-up, which suggests this cycle is correct, but the link between freeze-up dates to melt-out is not as well understood¹. The extent to which this feedback impacts future ice formation and the spatial patterns of drifting ice along this cycle will ultimately determine the impacts of climate change on Arctic sea ice loss.

Our lab’s previous work on this research investigated the specific timing in dates over general areas. I seek to extend this research in my thesis by looking at how sea ice moves, so we can look into the spatial trends relating freeze-up and melt-out dates to see how those are related. It would also be nice to have a general Lagrangian buoy simulator program for sea-ice related work; once that is done, we can track any number of variables with realistic movement (based off of existing sea ice reanalysis vector movement data).

Current Work

I am currently building the aforementioned simulator from scratch, following some failed attempts to modify CICE’s motion logic to fit the task. So far, it has the following features:

• BuoyTrajectory (IABP data) is implemented
• IceTrajectory (sea ice motion vectors) is implemented
• Reasonably fast parallel simulator runner
• Arbitrary simulation date range and tick length
• Object-oriented design makes swapping parts easy
• Export to CSV, JSON, and eventually GeoJSON
• Quality running, logging, and debugging experience with a good CLI
• Relatively low memory overhead per simulation

It is still missing the following features:

• Re-implementation of the core loops into a faster language (Fortran or Rust)
• Data collection of arbitrary climate variables (tracers)
• End-to-end testing of scientifically important components for accuracy
• Property-based testing of some components to ensure invariants hold
• Better plotting system with Python-to-R FFI
• MATLAB FFI interface (for MATLAB users)

The current goal of development is to create a simulator where it should be possible to examine the melt-freeze question in a Monte Carlo-esque way, by creating buoys in freeze locations and observing their final state at freeze-time. At present, I am still quite a ways off from this, but good progress is being made almost daily during the summer research period.