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Seasonal hysteresis of surface urban heat islands.

Publication ,  Journal Article
Manoli, G; Fatichi, S; Bou-Zeid, E; Katul, GG
Published in: Proceedings of the National Academy of Sciences of the United States of America
March 2020

Temporal dynamics of urban warming have been extensively studied at the diurnal scale, but the impact of background climate on the observed seasonality of surface urban heat islands (SUHIs) remains largely unexplored. On seasonal time scales, the intensity of urban-rural surface temperature differences ([Formula: see text]) exhibits distinctive hysteretic cycles whose shape and looping direction vary across climatic zones. These observations highlight possible delays underlying the dynamics of the coupled urban-biosphere system. However, a general argument explaining the observed hysteretic patterns remains elusive. A coarse-grained model of SUHI coupled with a stochastic soil water balance is developed to demonstrate that the time lags between radiation forcing, air temperature, and rainfall generate a rate-dependent hysteresis, explaining the observed seasonal variations of [Formula: see text] If solar radiation is in phase with water availability, summer conditions cause strong SUHI intensities due to high rural evaporative cooling. Conversely, cities in seasonally dry regions where evapotranspiration is out of phase with radiation show a summertime oasis effect controlled by background climate and vegetation properties. These seasonal patterns of warming and cooling have significant implications for heat mitigation strategies as urban green spaces can reduce [Formula: see text] during summertime, while potentially negative effects of albedo management during winter are mitigated by the seasonality of solar radiation.

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Published In

Proceedings of the National Academy of Sciences of the United States of America

DOI

EISSN

1091-6490

ISSN

0027-8424

Publication Date

March 2020

Volume

117

Issue

13

Start / End Page

7082 / 7089
 

Citation

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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 of the United States of America, 117(13), 7082–7089. https://doi.org/10.1073/pnas.1917554117
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 of the United States of America 117, no. 13 (March 2020): 7082–89. https://doi.org/10.1073/pnas.1917554117.
Manoli G, Fatichi S, Bou-Zeid E, Katul GG. Seasonal hysteresis of surface urban heat islands. Proceedings of the National Academy of Sciences of the United States of America. 2020 Mar;117(13):7082–9.
Manoli, Gabriele, et al. “Seasonal hysteresis of surface urban heat islands.Proceedings of the National Academy of Sciences of the United States of America, vol. 117, no. 13, Mar. 2020, pp. 7082–89. Epmc, doi:10.1073/pnas.1917554117.
Manoli G, Fatichi S, Bou-Zeid E, Katul GG. Seasonal hysteresis of surface urban heat islands. Proceedings of the National Academy of Sciences of the United States of America. 2020 Mar;117(13):7082–7089.
Journal cover image

Published In

Proceedings of the National Academy of Sciences of the United States of America

DOI

EISSN

1091-6490

ISSN

0027-8424

Publication Date

March 2020

Volume

117

Issue

13

Start / End Page

7082 / 7089