Can local fieldwork help to represent intra-urban variability of canopy parameters relevant for tropical African climate studies?

Jonas Van de Walle*, Oscar Brousse, Lien Arnalsteen, Disan Byarugaba, Daniel S. Ddumba, Matthias Demuzere, Shuaib Lwasa, Gloria Nsangi, Hakimu Sseviiri, Wim Thiery, Roxanne Vanhaeren, Hendrik Wouters, Nicole P.M. van Lipzig

*Corresponding author for this work

Research output: Contribution to journalArticleAcademicpeer-review

9 Citations (Scopus)
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Abstract

Rapid and uncontrolled urbanization in tropical Africa is increasingly leading to unprecedented socio-economical and environmental challenges in cities, particularly urban heat and climate change. The latter calls for a better representation of tropical African cities’ properties relevant for urban climate studies. Here, we demonstrate the possibility of collecting urban canopy parameters during a field campaign in the boreal summer months of 2018 for deriving a Local Climate Zone (LCZ) map and for improving the physical representation of climate-relevant urban morphological, thermal and radiative characteristics. The comparison of the resulting field-derived LCZ map with an existing map obtained from the World Urban Data and Access Portal Tool framework shows large differences. In particular, our map results in more vegetated open low-rise classes. In addition, site-specific fieldwork-derived urban characteristics are compared against the LCZ universal parameters. The latter shows that our fieldwork adds important information to the universal parameters by more specifically considering the presence of corrugated metal in the city of Kampala. This material is a typical roofing material found in densely built environments and informal settlements. It leads to lower thermal emissivity but higher thermal conductivity and capacity of buildings. To illustrate the importance of site-specific urban parameters, the newly derived site-specific urban characteristics are used as input fields to an urban parametrization scheme embedded in the regional climate model COSMO-CLM. This implementations decreases the surface temperature bias from 5.34 to 3.97 K. Based on our results, we recommend future research on tropical African cities to focus on a detailed representation of cities, with particular attention to impervious surface fraction and building materials.

Original languageEnglish
Pages (from-to)457-474
Number of pages18
JournalTheoretical and Applied Climatology
Volume146
Issue number1-2
Early online date13 Aug 2021
DOIs
Publication statusPublished - Oct 2021
Externally publishedYes

Bibliographical note

Funding Information:
This work was financially supported by the KU Leuven Internal Special Research Fund (BOF-C1 project C14/17/053) and BELSPO (Belgian Federal Science Policy Office) in the frame of the STEREO III program, as part of the REACT (SR/00/337) project ( http://react.ulb.be/ ).

Publisher Copyright:
© 2021, The Author(s).

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