Meili, Naika;
Paschalis, Athanasios;
Manoli, Gabriele;
Fatichi, Simone;
(2022)
Diurnal and seasonal patterns of global urban dry islands.
Environmental Research Letters
10.1088/1748-9326/ac68f8.
(In press).
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Abstract
Urban heat islands (UHIs) are a widely studied phenomenon, however, research on urban-rural differences in humidity, so called urban dry or moisture islands (UDIs, UMIs), is less common and a large-scale quantification of the seasonal and diurnal patterns of the UDI effect is still lacking. Quantification of the UDI/UMI effect is essential to understand the impacts of humidity on outdoor thermal comfort, building energy consumption, and urban ecology in cities worldwide. Here, we use a set of globally distributed air temperature and humidity measurements (1089 stations) to quantify diurnal and seasonal patterns of UHI and UDI resulting from rapid urbanization over many regions of the world. The terms "absolute UDI" and "relative UDI" are defined, which quantify urban-rural differences in actual and relative humidity measurements, respectively. Results show that absolute UDI is largest during daytime with the peak humidity decrease in urban areas occurring during late afternoon hours. In contrast, relative UDI is largest during night and the peak urban relative humidity decrease occurs in the late evening hours with values around -10 to -11% for relative humidity and 2.9 to 3.6 hPa for vapor pressure deficit between 20 – 00 local time during summer. Relative and absolute UDIs are largest during the warm season, except for daytime relative humidity UDI, which does not show any seasonal pattern. In agreement with literature, canopy air UHI is shown to be a nighttime phenomenon, which is larger during summer than winter. Relative UDI is predominantly caused by changes in actual humidity during day and UHI during nighttime.
| Type: | Article |
|---|---|
| Title: | Diurnal and seasonal patterns of global urban dry islands |
| Open access status: | An open access version is available from UCL Discovery |
| DOI: | 10.1088/1748-9326/ac68f8 |
| Publisher version: | https://doi.org/10.1088/1748-9326/ac68f8 |
| Language: | English |
| Additional information: | As the Version of Record of this article is going to be/has been published on a gold open access basis under a CC BY 3.0 licence, this Accepted Manuscript is available for reuse under a CC BY 3.0 licence immediately. |
| UCL classification: | UCL > Provost and Vice Provost Offices > UCL BEAMS > Faculty of Engineering Science UCL > Provost and Vice Provost Offices > UCL BEAMS > Faculty of Engineering Science > Dept of Civil, Environ and Geomatic Eng UCL > Provost and Vice Provost Offices > UCL BEAMS UCL |
| URI: | https://discovery.ucl.ac.uk/id/eprint/10147792 |
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