---
DOAJ_listed: '1'
OA_place: publisher
OA_type: gold
_id: '22537'
abstract:
- lang: eng
  text: "Urban heat islands (UHIs) are a widely studied phenomenon, while research
    on urban-rural differences in humidity, the 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 is still lacking. However, 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 metrics, respectively.\r\n\r\nResults 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 (RH) decrease and vapor pressure deficit
    (VPD) increase occurs in the late evening hours with values of around −10% to
    −11% for RH and 2.9–3.6 hPa for VPD between 20–00 local time during summer. Relative
    and absolute UDIs are largest during the warm season, except for daytime RH 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."
article_number: '054044'
article_processing_charge: No
article_type: letter_note
author:
- first_name: Naika
  full_name: Meili, Naika
  last_name: Meili
- first_name: Athanasios
  full_name: Paschalis, Athanasios
  last_name: Paschalis
- first_name: Gabriele
  full_name: Manoli, Gabriele
  last_name: Manoli
- first_name: Simone
  full_name: Fatichi, Simone
  id: cf8e546b-a9b0-11f0-a43b-aa89ed1b56d6
  last_name: Fatichi
citation:
  ama: Meili N, Paschalis A, Manoli G, Fatichi S. Diurnal and seasonal patterns of
    global urban dry islands. <i>Environmental Research Letters</i>. 2022;17(5). doi:<a
    href="https://doi.org/10.1088/1748-9326/ac68f8">10.1088/1748-9326/ac68f8</a>
  apa: Meili, N., Paschalis, A., Manoli, G., &#38; Fatichi, S. (2022). Diurnal and
    seasonal patterns of global urban dry islands. <i>Environmental Research Letters</i>.
    IOP Publishing. <a href="https://doi.org/10.1088/1748-9326/ac68f8">https://doi.org/10.1088/1748-9326/ac68f8</a>
  chicago: Meili, Naika, Athanasios Paschalis, Gabriele Manoli, and Simone Fatichi.
    “Diurnal and Seasonal Patterns of Global Urban Dry Islands.” <i>Environmental
    Research Letters</i>. IOP Publishing, 2022. <a href="https://doi.org/10.1088/1748-9326/ac68f8">https://doi.org/10.1088/1748-9326/ac68f8</a>.
  ieee: N. Meili, A. Paschalis, G. Manoli, and S. Fatichi, “Diurnal and seasonal patterns
    of global urban dry islands,” <i>Environmental Research Letters</i>, vol. 17,
    no. 5. IOP Publishing, 2022.
  ista: Meili N, Paschalis A, Manoli G, Fatichi S. 2022. Diurnal and seasonal patterns
    of global urban dry islands. Environmental Research Letters. 17(5), 054044.
  mla: Meili, Naika, et al. “Diurnal and Seasonal Patterns of Global Urban Dry Islands.”
    <i>Environmental Research Letters</i>, vol. 17, no. 5, 054044, IOP Publishing,
    2022, doi:<a href="https://doi.org/10.1088/1748-9326/ac68f8">10.1088/1748-9326/ac68f8</a>.
  short: N. Meili, A. Paschalis, G. Manoli, S. Fatichi, Environmental Research Letters
    17 (2022).
das_tickbox: '1'
date_created: 2026-07-27T12:30:24Z
date_published: 2022-05-09T00:00:00Z
date_updated: 2026-08-06T11:57:54Z
day: '09'
doi: 10.1088/1748-9326/ac68f8
extern: '1'
intvolume: '        17'
issue: '5'
keyword:
- Urban dry island
- Urban moisture island
- Urban heat island
- Urban climate
- Urbanization effects
- Humidity
language:
- iso: eng
main_file_link:
- open_access: '1'
  url: https://doi.org/10.1088/1748-9326/ac68f8
month: '05'
oa: 1
oa_version: Published Version
publication: Environmental Research Letters
publication_identifier:
  eissn:
  - 1748-9326
publication_status: published
publisher: IOP Publishing
quality_controlled: '1'
scopus_import: '1'
status: public
title: Diurnal and seasonal patterns of global urban dry islands
tmp:
  image: /images/cc_by.png
  legal_code_url: https://creativecommons.org/licenses/by/4.0/legalcode
  name: Creative Commons Attribution 4.0 International Public License (CC-BY 4.0)
  short: CC BY (4.0)
type: journal_article
user_id: ba8df636-2132-11f1-aed0-ed93e2281fdd
volume: 17
year: '2022'
...