Greg Cooke

Employment

Research Associate in Exoplanetary Atmospheres, Institute of Astronomy, University of Cambridge; August 2023 – present.

PI: Nikku Madhusudhan

• My work centres on simulations of exoplanets in the sub-Neptune regime using one-dimensional (1D) and 3D photochemical models.
• I am exploring the chemical nature of habitable exoplanet atmospheres, assuming different stellar hosts, and various initial conditions.
• I am examining how biologically-produced molecules influence the spectroscopic signature of exoplanet atmospheres.
• I am a supervisor for the Stellar Structure and Evolution 3\textsuperscript{rd} year undergraduate course.

Education

Astrophysics PhD student, University of Leeds, UK. October 2019 – present.

Thesis title: 3D simulations of rocky exoplanets and future observations; Advisors: Professor Dan Marsh, Dr Catherine Walsh

• My thesis focuses on simulating rocky worlds and understanding their climates, chemistry, and habitability. I use and modify the Community Earth System Model (CESM2), mostly the Whole Atmosphere Community Climate Model (WACCM6) configuration, to simulate paleoclimates and exoplanets.
• I simulated early Earth with a younger Sun and with varied atmospheric oxygen (O₂) concentrations.
• I used the Planetary Spectrum Generator (PSG) to determine how detectable specific planetary properties (e.g. chemical species such as ozone and oxygen; temporal variability) are using the next generation of telescopes (e.g. LUVOIR).
• I am performing simulations for tidally‑locked M dwarf exoplanets (Proxima Centauri and TRAPPIST‑1 systems) and will predict observations of these exoplanets.
• I was selected competitively as a Priestley Climate Scholar.

MPhys integrated masters student, University of Manchester, UK. October 2015 – June 2019

Two MPhys projects:

1. Investigating and defining habitability metrics for all known exoplanets.
2. Designing an optimized telescope search for habitable exoplanets using the Besançon galactic model. Most optional courses taken were related to astrophysics (e.g. Astrophysical plasmas, General relativity, Exoplanets).

Funding

STFC studentship. October 2019 – April 2023.

• A 3.5-year STFC studentship (approximately worth £75,000).
• Funding for travel and funding for the conference fee to attend the 3rd Eddy Cross Disciplinary Symposium: Sun, Earth, Planet, Space, Atmosphere and Ocean, in Vail, Colorado, USA (total $2,800).

Publications

• Cooke GJ, Marsh DR, Walsh C, Black B, Lamarque J-F. 2022 A revised lower estimate of ozone columns during Earth’s oxygenated history. R. Soc. Open Sci. 9: 211165. https://doi.org/10.1098/rsos.211165
• Cooke GJ, Marsh DR, Walsh C, Rugheimer S, Villanueva GL, Variability due to climate and chemistry in observations of oxygenated Earth‑analogue exoplanets, Monthly Notices of the Royal Astronomical Society, 2022;, stac2604, https://doi.org/10.1093/mnras/stac2604
• Cooke GJ et al., The O₃‑O₂ relationship on M dwarf terrestrial atmospheres: critical dependence on the stellar UV flux.
• Ji A, Cooke GJ, et al., Comparison between ozone column depths and methane lifetimes computed by 1‑D and 3‑D Models at different atmospheric O₂ levels.

Contributed talks

• UK Exoplanet Meeting, Oxygen’s 2.4 billion year control on Earth’s atmosphere with consequences for exoplanet biosignatures (April 2021, virtual).
• CESM Workshop, Viewing the Earth and its exoplanet analogues through time (June 2021, virtual).
• 3^rd Eddy Cross Disciplinary Symposium, 3D whole‑atmosphere modelling of rocky exoplanet systems and synthetic telescope observations (June 2022, Vail, CO, USA).
• ResCompLeedsCon2022, Simulations of tidally locked exoplanet atmospheres in 3D. (July 2022, Leeds, UK).
• Rocky Worlds II, A revised lower estimate of ozone columns during Earth’s oxygenated history.. (July 2022, Oxford, UK).

Invited and internal seminars

• Invited, National Center for Atmospheric Research, Oxygen as a control over 2.4 billion years of atmospheric evolution (October 2020, virtual).
• Invited, University of Cambridge, Oxygen’s 2.4 billion year control on Earth’s atmosphere with consequences for exoplanet biosignatures (May 2021, virtual).
• Internal, University of Leeds, A revised lower estimate of ozone columns during Earth’s oxygenated history (March 2022, Leeds, UK).
• Invited, National Center for Atmospheric Research, A revised lower estimate of ozone columns during Earth’s oxygenated history (May 2022, Boulder, CO, USA).
• Internal, University of Leeds, Variability due to climate and chemistry in observations of oxygenated Earth‑analogue exoplanets. (October 2022, Leeds, UK).
• Invited, University of Exeter, A revised lower estimate of ozone columns during Earth’s oxygenated history (TBC, Exeter, UK).

Posters

• Exoplanets III, Variable detectability of biosignatures on inhabited worlds. (October 2020, virtual).
• The Coupling, Energetics, and Dynamics of Atmospheric Regions workshop, Atmospheric escape on oxygenated Earth‑like exoplanet atmospheres. (October 2020, virtual).
• European Astronomical Society Annual Meeting,, Oxygen’s 2.4 billion year control on Earth’s atmosphere with consequences for exoplanet bisoignatures (June-July 2021, virtual).
• Exoplanets IV, , Variability due to climate in observations of oxygenated Earth‑analogue exoplanets. (May 2022, Las Vegas, Nevada, USA).
• UK Exoplanet Meeting,, Accurate UV stellar spectra measurements required to use O3 as an indicator for O2 abundance (September 2022, virtual poster).

Software experience

• I have used and developed an open‑source model (CESM2‑WACCM6). I have read Fortran‑90 code to understand how certain calculations in WACCM6 are made. I modified the Fortran‑90 code to set up different planetary conditions (e.g. altered upper boundary conditions, tidally locked the model).
• Advanced user of Python for atmospheric data analysis, e.g., matplotlib, pandas, numpy, and xarray.
• Developing open‑source Python code in Jupyter Notebook to analyse vast amounts of climate data that can switch between different types of plots and datasets. I developed the Stellar Wind and Irradiance Module (SWIM), a flexible notebook for multi‑model use that downloads Mega‑MUSCLES stellar spectra and scales the exoplanet to any exoplanet chosen by the user.
• I used and developed a pipeline to interact with the Planetary Spectrum Generator (PSG). I used new methods (where I swapped particular atmo‑ spheric components) to analyse the results for the WACCM6 oxygenated scenarios.
• Coding experience in C++ during my master’s degree.

Teaching

Lab demonstrating, University of Leeds, UK. October 2019 – May 2022.

I have taught experiments in the Phys 10001 undergraduate laboratory to 1st year students including: the determination of Planck’s constant; measurement of Earth’s magnetic field, spectrometer measurement of sodium lines; viscosity of glycerine using Stokes Law; electrical circuits; the understanding of random Gaussian measurements using a dartboard experiment. I have also marked lab workbooks and formal reports on several of these experiments.

Informal MPhys student supervision, University of Leeds, UK. October 2021 – March 2022.

I aided B. Butcher to produce and analyse transmission spectra of Jupiter‑sized exoplanets. I helped I. Willis analyse WACCM data and produce figures using Python.

Introductory python course, University of Leeds, UK. September 2022.

Introduction to Python lesson during a Community Earth System Model (CESM) tutorial. I demonstrated data visualisation using Xarray, Matplotlib, and Cartopy in functions combined with IPyWidgets in a Jupyter notebook

Organisation and citizenship

Priestley scholar, University of Leeds, UK. January 2020 – December 2021.

I attended multiple seminars on interdisciplinary topics relating to climate change, including transport, climate finance, climate modelling, and climate justice. I co-organised a seminar on climate finance, as well as a monthly journal club focussed on climate science topics.

Internal seminars chair, University of Leeds, UK. January 2020 – present.

I have arranged and chaired internal seminars for the University of Leeds Astrophysics group. Additionally, I have organised and led weekly informal science sessions where members of the group get together to discuss their current work. During this time, I have included a journal club for astronomy session which has run once every three weeks.

Treasurer for University of Manchester Men’s Hockey Club, UK. May 2017 – May 2018.

I was elected out from a club of approximately 80 members. I managed up to £20,000 in financial transactions between the club, club members, the university’s Athletic Union, and between several different organisations.

Public engagement

• Priestley Scholar Twitter spotlight, 2021. I was retweeted by the Priestley Scholar Twitter account for a whole day as I tweeted about my research and scientific interests.
• Live YouTube talk for the University of Leeds Be Curious festival 2021 on planet habitability (https://www.youtube.com/watch?v=Ei_Tte-BvWo).
• TikTok Video summarizing my research for COP 26 and how it is important for understanding our planet.
• I have written a number of astronomy news articles for the astronomy magazine Popular Astronomy.
• Everything Astronomy virtual session for Xavier Space Solutions, February 2022.
• Invited talk at Bradford Astronomical Society (April 2023).

Press interest

University of Leeds press release: Study reveals hostile conditions on earth as life evolved.