Daniel A. Williams

North Park Road,

University of Exeter

Exeter, Devon

I am a Postdoctoral Research Associate working with Cyril Morcrette and Jim Haywood as part of the project Quantifying and Reducing aviation Contrail radiative forcing (QR-CODE). QR-CODE forms part of a larger tranche of projects funded by NERC’s Jet Zero programme, a series of projects investigating different ways of reducing the climate impacts of non-CO2 effects (those not directly from fuel burning) by the aviation industry.

As part of my research I will be aiming to better understand the environmental conditions that lead to contrail formation (the white clouds that come out the back of a plane), with the ambition that by doing so we can reduce the impact they have on the environment through possible schemes for rerouting flights. Contrails are important to research since they contribute a net-warming to the climate system in cool, moist conditions where the contrail persists for a long time after formation.

Previously I was a PhD student investigating the climates and atmospheres of moist terrestrial (Earth-like) planets, under the supervision of Prof. Geoffrey Vallis, Dr. William Seviour and Dr. Stephen Thomson. My research involved using 3D climate models such as Isca to understand cloudy aquaplanets along with the hydrological cycle and greenhouse effect of tidally locked planets.

selected publications

ApJ
Clouds and Seasonality on Terrestrial Planets with Varying Rotation Rates

Daniel A. Williams, Xuan Ji, Paul Corlies, and 1 more author

The Astrophysical Journal, Feb 2024

Abs DOI Bib PDF

Using an idealized climate model incorporating seasonal forcing, we investigate the impact of rotation rate on the abundance of clouds on an Earth-like aquaplanet, and the resulting impacts upon albedo and seasonality. We show that the cloud distribution varies significantly with season, depending strongly on the rotation rate, and is well explained by the large-scale circulation and atmospheric state. Planetary albedo displays nonmonotonic behavior with rotation rate, peaking at around 1/2\textohmE. Clouds reduce the surface temperature and total precipitation relative to simulations without clouds at all rotation rates, and reduce the dependence of total precipitation on rotation rate, causing nonmonotonic behavior and a local maximum around 1/8\textohmE; these effects are related to the impacts of clouds on the net atmospheric and surface radiative energy budgets. Clouds also affect the seasonality. The influence of clouds on the extent of the winter Hadley cell and the intertropical convergence zone is relatively minor at slow rotation rates (<1/8\textohmE), but becomes more pronounced at intermediate rotation rates, where clouds decrease their maximum latitudes. The timing of seasonal transitions varies with rotation rate, and the addition of clouds reduces the seasonal phase lag.
@article{williams2024-Clouds, title = {Clouds and {{Seasonality}} on {{Terrestrial Planets}} with {{Varying Rotation Rates}}}, author = {Williams, Daniel A. and Ji, Xuan and Corlies, Paul and Lora, Juan M.}, year = {2024}, month = feb, journal = {The Astrophysical Journal}, volume = {963}, number = {1}, pages = {36}, publisher = {The American Astronomical Society}, issn = {0004-637X}, doi = {10.3847/1538-4357/ad192f}, urldate = {2024-02-27}, langid = {english}, keywords = {Isca}, file = {/home/daniel/Documents/exeter/zotero/Williams_et_al._2024-clouds_and_seasonality_on_terres.pdf}, }