The local climate impact of an African city during clear‐sky conditions ‐ implications of the recent urbanization in Kampala (Uganda)

This study is set up in collaboration with the REACT5 project (Remote sensing for Epidemiology in sub-saharan African CiTies) led by ULB. The work aims at assessing and understanding the impact of recent urbanization on the urban heat island (UHI) under clear-sky conditions in a tropical African city using different sources of remotely sensed data sets together with an urban climate model (UCM). The observed UHI during clear sky conditions is found to be about 4⁰C on average over the capital city of Kampala, Uganda. The UCM, consisting of TERRA_URB embedded in COSMO-CLM, represents the UHI well during night but overestimates it by about 3⁰C in the mean during day. Moreover, a systematic warm land surface temperature bias of about 4⁰C is identified by night. Improved urban input parameters - derived from Local Climate Zones following the World Urban Database and Access Portal Tool (WUDAPT) framework - lead to a more realistic representation of spatial land surface temperatures patterns. In addition, this parameterization of the UCM can properly represent atmospheric variables such as air temperature, specific and relative humidity, as observed by the automated weather stations. A model sensitivity study furthermore demonstrates that the stronger urban heat island induced by the recent urbanization of Kampala over the past 15 years strongly interacts with the lake-land breeze circulation. Stronger daytime convection over the hotter city leads to areas of convergence that amplify the afternoon lake breeze in the southern parts of the metropolis. Overall, this study demonstrates that the city of Kampala has a tangible effect on the regional climate that needs to be considered when studying present and future climate impacts.

Jaar van publicatie:2020

BOF-keylabel:ja

IOF-keylabel:ja

BOF-publication weight:1

CSS-citation score:3

Auteurs:International

Authors from:Higher Education

Toegankelijkheid:Open