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The local climate impact of an African city during clear‐sky conditions—Implications of the recent urbanization in Kampala (Uganda)
Author(s) -
Brousse Oscar,
Wouters Hendrik,
Demuzere Matthias,
Thiery Wim,
Van de Walle Jonas,
Lipzig Nicole P. M.
Publication year - 2020
Publication title -
international journal of climatology
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 1.58
H-Index - 166
eISSN - 1097-0088
pISSN - 0899-8418
DOI - 10.1002/joc.6477
Subject(s) - urbanization , urban heat island , climatology , environmental science , urban climate , relative humidity , climate model , climate change , geography , sky , daytime , meteorology , atmospheric sciences , geology , oceanography , economic growth , economics
This study aims at assessing and understanding the impact of recent urbanization on the (surface) urban heat island ((S)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 SUHI during clear sky conditions is found to be about 4°C on average over the capital city of Kampala, Uganda. The UCM, consisting of TERRA_URB embedded in COSMO‐CLM, represents the SUHI well during night but overestimates it by about 3°C in the mean during day. Moreover, a systematic warm land surface temperature bias of about 4°C 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.