Susan Macmillan

Current Workplace
Geomagnetism Team, British Geological Survey
Current Role
Geophysicist
My Mathematics Success Story is...

I am a mathematical modeller for the geomagnetism team in the British Geological Survey and this is my mathematical journey. I got a maths degree from Glasgow University in 1984. After completing that I had no ambition for the world of work and did a post-graduate diploma in land surveying. I remember the head of the topographical sciences department, Professor Petrie, was particularly keen to have a maths graduate as he said a lot of students with other degrees struggled with the survey computations and geodesy. I loved that course, particularly the more mathematically demanding parts and the possibilities it presented for working outside, but after finishing it I still wasn’t ready for the world of work. I then went to Aberdeen and being a “greeny” did a PhD in looking at the viability of wind energy. Unfortunately the turbines I was studying were at energy-intensive chicken and pig farms and in response I turned vegan (I am still a veggie)! The wind turbines at that time were all prototypes and my task was to develop a model that would predict their energy output from Met Office data, monitor actual energy output and energy usage and do some cost modelling work. Another fascinating world but when I finished there weren’t any jobs I could apply for as it was still early days for wind energy in the UK. After doing a lucrative summer of land survey work for the oil industry to get the job that I still have, I fell back on the maths degree. I was taken on by the BGS in Edinburgh in 1989 to develop Fourier transformation techniques to obtain directional information from scalar magnetic data collected over extensive areas by planes and ships. These data map out the crustal magnetic field particularly well. This work was to support drilling and survey companies in the oil industry who were drilling long wells towards small targets using the Earth’s magnetic field as a directional reference. The local crustal magnetic field can present a significant bias to estimates from global models. I also got involved in producing global and local models of the Earth’s magnetic field, in particular the International Geomagnetic Reference Field, the World Magnetic Model, the BGS Global Geomagnetic Model and a UK model. These models are very widely used, with the IGRF being the traditional model for reducing magnetic surveys and for magnetic coordinate systems, the WMM being used for compass rose information on nautical charts and embedded in a wide range of navigation systems including smart phones, the BGGM being a standard model for directional drilling and the UK model being used for the magnetic north information depicted on Ordnance Survey maps. Over the years I have helped develop the data selection and modelling techniques in order to separate out the various sources of the Earth’s magnetic field and to take advantage of the plethora of magnetic data from satellites to which we now have access. The job is an excellent blend of strategic, commerical and academic work and I have a publication record that would not be entirely shameful if I were in a university geophysics department. In my spare time I have done maths tutoring and for the past 20 years, adult basic numeracy volunteering. The pursuit of the outdoor life is done in my spare time rather than work time. Despite preferring pure nerdy maths at university the most rewarding part of my mathematical career has been the applied nature of my work.

Categories
Women in mathematics