Andrew Williams

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Andrew Williams

Graduate Student (DTP)

Twitter page.
Github account.

I am a second year DPhil (PhD) student in the Atmospheric, Oceanic, and Planetary Physics Department at the University of Oxford, working with Prof. Philip Stier.

I completed my Masters in Physics last year and during my undergraduate I was lucky enough to be able to do two summers of research in the USA:

In 2018, courtesy of the S.U.R.F. programme, I spent my summer at Caltech working with Tapio Schneider and Yair Cohen in the climate dynamics group. During the summer I worked on a problem in parametrizing moist convection in atmospheric models, specifically, I used high-resolution large-eddy simulations to estimate the number of dynamically distinct plumes that are necessary to represent a field of convective clouds in a new parameterization scheme. EGU poster here!

In 2019, as part of the Laidlaw Scholarship, I spent a summer at MIT working with Paul O'Gorman. The focus of this summer was to study the impact of climate change on seasonal precipitation extremes in the Northern Hemisphere using observations and large ensembles of coupled climate models, and to investigate to what extent we can already see a climatic signal in the observational record. Outreach poster here!

Example_plumeworld_10sig_grey_stockimg.jpg

In my PhD work I'm interested in understanding the sensitivity of the Earth's climate to spatially heterogeneous forcing such as aerosol emissions or anomalous SST patterns. To do this I am employing large ensembles of climate model simulations such as in the "PlumeWorld" set-up (see above figure) to help quantify the impacts of identical aerosol emissions in different locations on regional precipitation changes and global radiative forcing.

Outside of my PhD work, I'm interested in using simple models to understand the state-dependence of climate sensitivity (à la Seeley and Jeevanjee, 2020) and I also continue to work on projects from my undergraduate studies, mainly using observations and CMIP models to investigate changes in extreme precipitation.

In prep:

Watson-Parris, D., Williams, A., Deaconu, L., Stier, P.: GCEm v1.0.0 An open, scalable General Climate Emulator., in prep.

Williams, A., O'Gorman, P.A.: Contrasting Seasonal Response of Northern Hemisphere Precipitation Extremes to Climate Change, in prep.

Williams, A., Watson-Parris, D., Dagan, G., Stier, P.: Strong radiative forcing from absorbing aerosols over the West Pacific driven by cloud-circulation adjustments, in prep.

Teaching:

- TA in 'Atmospheric, Oceanic and Planetary Physics' Masters Course (C5)

- TA, Advanced Quantitative Methods (DTP, 2020)

- Workshop lead: "Exploring the global mean climate response using the Finite Amplitude Impulse Response (FaIR) model" (iMIRACLI Summer School, 2020; NERC Doctoral Training Programme, 2021)

Outreach:
- Oxford Sparks 'Lockdown Walks' video (www.youtube.com/watch?v=VlhBdp5OWhk, 2020)
- Co-author on "Climate change and COVID-19" briefing paper (Scientists for Labour, 2020)