li-etal_2023_SA

Persistent Urban Heat

Dan Li^1*, Linying Wang¹, Weilin Liao², Ting Sun³, Gabriel Katul⁴, Elie Bou-Zeid⁵, and Björn Maronga^6,7

¹ Department of Earth and Environment, Boston University, Boston, USA

² Guangdong Key Laboratory for Urbanization and Geo-simulation, School of Geography and Planning, Sun Yat-sen University, Guangzhou, China

³ Institute for Risk and Disaster Reduction, University of College London, London, UK

⁴ Department of Civil and Environmental Engineering, Duke University, Durham, USA

⁵ Department of Civil and Environmental Engineering, Princeton University, Princeton, USA

⁶ Institute of Meteorology and Climatology, Leibniz University Hannover, Hannover, Germany

⁷ Geophysical Institute, University of Bergen, Bergen, Norway

* corresponding author: [email protected]

Abstract

Urban surface and near-surface air temperatures are known to be often higher than their rural counterparts, a phenomenon now labeled as the urban heat island (UHI) effect. However, whether the elevated urban temperatures are more persistent than rural temperatures at time scales commensurate to heat waves has not been addressed despite its importance for human health. Combining numerical simulations by a global climate model with a surface energy balance theory, it is demonstrated here that urban surface and near-surface air temperatures are significantly more persistent than their rural counterparts in cities dominated by impervious materials with large thermal inertia. Further use of these materials will result in even stronger urban temperature persistence, especially for tropical cities. The present findings help pinpoint mitigation strategies that can simultaneously ameliorate the larger magnitude and stronger persistence of urban temperatures.

Journal reference

Li, D., L. Wang, W. Liao, T. Sun, G. Katul, E. Bou-Zeid, & B. Maronga (2023). Persistent Urban Heat. Science Advances.

Code reference

https://github.com/IMMM-SFA/urban_clm5/tree/greenroof_version2.3.3

Data reference

Input data

https://svn-ccsm-inputdata.cgd.ucar.edu/trunk/inputdata/

Output data

NERSC Perlmutter:

/global/cfs/cdirs/m2702/wangly/li-etal_2023_SA/urban_I2000Clm50Sp_f09_g17_regular_roof/ /global/cfs/cdirs/m2702/wangly/li-etal_2023_SA/urban_I2000Clm50Sp_f09_g17_regular_roof_urbuniform/ /global/cfs/cdirs/m2702/wangly/li-etal_2023_SA/urban_I2000Clm50Sp_f09_g17_regular_roof_urbuniform2/ /global/cfs/cdirs/m2702/wangly/li-etal_2023_SA/urban_I2000Clm50Sp_f09_g17_regular_roof_urbuniform3/ /global/cfs/cdirs/m2702/wangly/li-etal_2023_SA/urban_I2000Clm50Sp_f09_g17_regular_roof_urbuniform4/ /global/cfs/cdirs/m2702/wangly/li-etal_2023_SA/urban_I2000Clm50Sp_f09_g17_regular_roof_urbuniform5/ /global/cfs/cdirs/m2702/wangly/li-etal_2023_SA/urban_I2000Clm50Sp_f09_g17_regular_roof_urbuniform6/

Contributing modeling software

Model	Version	Repository Link	DOI
CESM2	release-cesm2.0.1	https://github.com/ESCOMP/CESM/releases/tag/release-cesm2.0.1	10.1029/2019MS001916

Reproduce my experiment

1. Install the software components required to conduct the experiment from Contributing modeling software. The detailed download instructions are also available online https://www.cesm.ucar.edu/models/cesm2/release_download.html
2. Download and install the supporting input data required to conduct the experiement from Input data
3. Create the surface data input for the uniform city simulations

Script Name	Description	How to Run
surfdata_uniform_urban1.ncl	Script to generate the uniform city surfdata	ncl surfdata_uniform_urban1.ncl
surfdata_uniform_urban2.ncl	Script to generate the uniform city surfdata by multiplying the heat capacity and thermal conductivity by factors of 2, 5, 10, 20 and 50	ncl surfdata_uniform_urban2.ncl

4. Run the following scripts in the workflow directory to re-create this experiment:

Script Name	Description	How to Run
create_spinup_case.sh	Script to run the first part of my experiment (spinup)	./create_spinup_case.sh
create_exp_case.sh	Script to run the last part of my experiment (control run and six sensitivity runs with increased thermal inertia of the imperious urban land)	./create_exp_case.sh

Reproduce my figures

Use the scripts found in the figures directory to post-process my outputs and reproduce the figures used in this publication. See details in the Readme_Persistent_Urban_Heat.docx document in the figures directory.