---
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. Environmental Research Letters. 2022;17(5). doi:10.1088/1748-9326/ac68f8
apa: Meili, N., Paschalis, A., Manoli, G., & Fatichi, S. (2022). Diurnal and
seasonal patterns of global urban dry islands. Environmental Research Letters.
IOP Publishing. https://doi.org/10.1088/1748-9326/ac68f8
chicago: Meili, Naika, Athanasios Paschalis, Gabriele Manoli, and Simone Fatichi.
“Diurnal and Seasonal Patterns of Global Urban Dry Islands.” Environmental
Research Letters. IOP Publishing, 2022. https://doi.org/10.1088/1748-9326/ac68f8.
ieee: N. Meili, A. Paschalis, G. Manoli, and S. Fatichi, “Diurnal and seasonal patterns
of global urban dry islands,” Environmental Research Letters, 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.”
Environmental Research Letters, vol. 17, no. 5, 054044, IOP Publishing,
2022, doi:10.1088/1748-9326/ac68f8.
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'
fulldoi: https://doi.org/10.1088/1748-9326/ac68f8
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'
...
---
OA_place: publisher
OA_type: hybrid
_id: '22564'
abstract:
- lang: eng
text: "It is well known that cities increase air and surface temperatures compared
to their rural surroundings, the so-called urban heat island (UHI) effect. However,
the associated changes in atmospheric humidity (also known as urban dry island,
UDI) and convection triggering remain largely unexplored and it is still unclear
how urban modifications of the surface energy budget Influence the diurnal evolution
of temperature and humidity in the Atmospheric Boundary Layer\r\n(ABL) and ultimately
control the initiation of convective clouds.\r\nHere we quantify the impact of
different urban settings and free atmospheric conditions on\r\nUHI, UDI, and convection
triggers by means of a zero-order model of the ABL. Specifically, we\r\nderive
an approximate solution for urban-rural changes in surface energy fluxes and ABL
potential\r\ntemperature and humidity and we investigate the crossing between
the ABL height and the lifting\r\ncondensation level (LCL) which is a proxy for
the triggering of convective clouds. We show that\r\nurban areas are generally
warmer and drier, thus causing an increase in both ABL and LCL\r\nheights. However,
the response of the ABL-LCL crossing to surface conditions is non-linear and\r\nthere
exists a range of free atmosphere conditions for which changes in imperviousness
can\r\nimpact convective clouds."
article_number: '101346'
article_processing_charge: No
article_type: original
author:
- first_name: Clinton T.F.
full_name: Chiu, Clinton T.F.
last_name: Chiu
- first_name: Kai
full_name: Wang, Kai
last_name: Wang
- first_name: Athanasios
full_name: Paschalis, Athanasios
last_name: Paschalis
- first_name: Tohid
full_name: Erfani, Tohid
last_name: Erfani
- first_name: Nadav
full_name: Peleg, Nadav
last_name: Peleg
- first_name: Simone
full_name: Fatichi, Simone
id: cf8e546b-a9b0-11f0-a43b-aa89ed1b56d6
last_name: Fatichi
- first_name: Natalie
full_name: Theeuwes, Natalie
last_name: Theeuwes
- first_name: Gabriele
full_name: Manoli, Gabriele
last_name: Manoli
citation:
ama: Chiu CTF, Wang K, Paschalis A, et al. An analytical approximation of urban
heat and dry islands and their impact on convection triggering. Urban Climate.
2022;46. doi:10.1016/j.uclim.2022.101346
apa: Chiu, C. T. F., Wang, K., Paschalis, A., Erfani, T., Peleg, N., Fatichi, S.,
… Manoli, G. (2022). An analytical approximation of urban heat and dry islands
and their impact on convection triggering. Urban Climate. Elsevier. https://doi.org/10.1016/j.uclim.2022.101346
chicago: Chiu, Clinton T.F., Kai Wang, Athanasios Paschalis, Tohid Erfani, Nadav
Peleg, Simone Fatichi, Natalie Theeuwes, and Gabriele Manoli. “An Analytical Approximation
of Urban Heat and Dry Islands and Their Impact on Convection Triggering.” Urban
Climate. Elsevier, 2022. https://doi.org/10.1016/j.uclim.2022.101346.
ieee: C. T. F. Chiu et al., “An analytical approximation of urban heat and
dry islands and their impact on convection triggering,” Urban Climate,
vol. 46. Elsevier, 2022.
ista: Chiu CTF, Wang K, Paschalis A, Erfani T, Peleg N, Fatichi S, Theeuwes N, Manoli
G. 2022. An analytical approximation of urban heat and dry islands and their impact
on convection triggering. Urban Climate. 46, 101346.
mla: Chiu, Clinton T. F., et al. “An Analytical Approximation of Urban Heat and
Dry Islands and Their Impact on Convection Triggering.” Urban Climate,
vol. 46, 101346, Elsevier, 2022, doi:10.1016/j.uclim.2022.101346.
short: C.T.F. Chiu, K. Wang, A. Paschalis, T. Erfani, N. Peleg, S. Fatichi, N. Theeuwes,
G. Manoli, Urban Climate 46 (2022).
das_tickbox: '1'
date_created: 2026-07-27T12:30:24Z
date_published: 2022-12-01T00:00:00Z
date_updated: 2026-08-06T14:03:31Z
day: '01'
doi: 10.1016/j.uclim.2022.101346
extern: '1'
fulldoi: https://doi.org/10.1016/j.uclim.2022.101346
intvolume: ' 46'
keyword:
- Urban heat island
- Urban dry island
- Boundary layer
- Convective clouds
- Analytical model
language:
- iso: eng
main_file_link:
- open_access: '1'
url: https://doi.org/10.1016/j.uclim.2022.101346
month: '12'
oa: 1
oa_version: Published Version
publication: Urban Climate
publication_identifier:
eissn:
- 2212-0955
publication_status: published
publisher: Elsevier
quality_controlled: '1'
scopus_import: '1'
status: public
title: An analytical approximation of urban heat and dry islands and their impact
on convection triggering
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: 46
year: '2022'
...
---
OA_place: publisher
OA_type: free access
_id: '22542'
abstract:
- lang: eng
text: Temporal dynamics of urban warming have been extensivelystudied at the diurnal
scale, but the impact of background cli-mate on the observed seasonality of surface
urban heat islands(SUHIs) remains largely unexplored. On seasonal time scales,
theintensity of urban–rural surface temperature differences (∆Ts)exhibits distinctive
hysteretic cycles whose shape and loopingdirection vary across climatic zones.
These observations high-light possible delays underlying the dynamics of the coupledurban–biosphere
system. However, a general argument explain-ing the observed hysteretic patterns
remains elusive. A coarse-grained model of SUHI coupled with a stochastic soil
waterbalance is developed to demonstrate that the time lags betweenradiation forcing,
air temperature, and rainfall generate a rate-dependent hysteresis, explaining
the observed seasonal varia-tions of ∆Ts. If solar radiation is in phase with
water availability,summer conditions cause strong SUHI intensities due to highrural
evaporative cooling. Conversely, cities in seasonally dryregions where evapotranspiration
is out of phase with radia-tion show a summertime oasis effect controlled by backgroundclimate
and vegetation properties. These seasonal patterns ofwarming and cooling have
significant implications for heat mit-igation strategies as urban green spaces
can reduce ∆Ts duringsummertime, while potentially negative effects of albedo
man-agement during winter are mitigated by the seasonality of solarradiation.
article_processing_charge: No
article_type: original
author:
- 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
- first_name: Elie
full_name: Bou-Zeid, Elie
last_name: Bou-Zeid
- first_name: Gabriel G.
full_name: Katul, Gabriel G.
last_name: Katul
citation:
ama: Manoli G, Fatichi S, Bou-Zeid E, Katul GG. Seasonal hysteresis of surface urban
heat islands. Proceedings of the National Academy of Sciences. 2020;117(13):7082-7089.
doi:10.1073/pnas.1917554117
apa: Manoli, G., Fatichi, S., Bou-Zeid, E., & Katul, G. G. (2020). Seasonal
hysteresis of surface urban heat islands. Proceedings of the National Academy
of Sciences. National Academy of Sciences. https://doi.org/10.1073/pnas.1917554117
chicago: Manoli, Gabriele, Simone Fatichi, Elie Bou-Zeid, and Gabriel G. Katul.
“Seasonal Hysteresis of Surface Urban Heat Islands.” Proceedings of the National
Academy of Sciences. National Academy of Sciences, 2020. https://doi.org/10.1073/pnas.1917554117.
ieee: G. Manoli, S. Fatichi, E. Bou-Zeid, and G. G. Katul, “Seasonal hysteresis
of surface urban heat islands,” Proceedings of the National Academy of Sciences,
vol. 117, no. 13. National Academy of Sciences, pp. 7082–7089, 2020.
ista: Manoli G, Fatichi S, Bou-Zeid E, Katul GG. 2020. Seasonal hysteresis of surface
urban heat islands. Proceedings of the National Academy of Sciences. 117(13),
7082–7089.
mla: Manoli, Gabriele, et al. “Seasonal Hysteresis of Surface Urban Heat Islands.”
Proceedings of the National Academy of Sciences, vol. 117, no. 13, National
Academy of Sciences, 2020, pp. 7082–89, doi:10.1073/pnas.1917554117.
short: G. Manoli, S. Fatichi, E. Bou-Zeid, G.G. Katul, Proceedings of the National
Academy of Sciences 117 (2020) 7082–7089.
das_tickbox: '1'
date_created: 2026-07-27T12:30:24Z
date_published: 2020-03-31T00:00:00Z
date_updated: 2026-08-07T09:21:58Z
day: '31'
doi: 10.1073/pnas.1917554117
extern: '1'
external_id:
pmid:
- '32184330 '
fulldoi: https://doi.org/10.1073/pnas.1917554117
intvolume: ' 117'
issue: '13'
keyword:
- Cities
- Hysteresis
- Seasonality
- Surface temperature
- Urban heat island
language:
- iso: eng
main_file_link:
- open_access: '1'
url: https://doi.org/10.1073/pnas.1917554117
month: '03'
oa: 1
oa_version: Published Version
page: 7082-7089
pmid: 1
publication: Proceedings of the National Academy of Sciences
publication_identifier:
eissn:
- 1091-6490
issn:
- 0027-8424
publication_status: published
publisher: National Academy of Sciences
quality_controlled: '1'
scopus_import: '1'
status: public
title: Seasonal hysteresis of surface urban heat islands
type: journal_article
user_id: ba8df636-2132-11f1-aed0-ed93e2281fdd
volume: 117
year: '2020'
...