Contents lists available at ScienceDirect Urban Climate journal homepage: www.elsevier.com/locate/uclim Interconnections of the urban heat island with the spatial and temporal micrometeorological variability in Rome Virginia Ciardini a, ⁎ ,1 , Luca Caporaso b , Roberto Sozzi c , Igor Petenko a , Andrea Bolignano c , Matteo Morelli c , Dimitris Melas d , Stefania Argentini a a Institute of Atmospheric Sciences and Climate, CNR - Via Fosso del Cavaliere, 100, 00133 Rome, Italy b Institute of Marine Sciences, CNR - Via Fosso del Cavaliere, 100, 00133 Rome, Italy c Regional Environmental Protection Agency of Lazio, Via Boncompagni, 101, 00187 Rome, Italy d Laboratory of Atmospheric Physics, Physics Department, Aristotle University of Thessaloniki, 54124 Thessaloniki, Greece ARTICLE INFO Keywords: Urban heat island Rome Ultrasonic anemometer Micrometeorological parameters Sea-breeze ABSTRACT The annual and diurnal behavior of the temperature differences in urban areas is important to predict the possible impacts of the future land-use development on climate change and air pol- lution in heavily populated areas. The behavior of the temperature as well as wind spatio-tem- poral differences in turn is strongly interconnected with the turbulent and radiative fluxes variability. A 3-year dataset from three automated micrometeorological stations run by the Regional Agency for Environment Protection of Lazio and located in and around the city of Rome is used. The distribution of the urban heat island intensity for the whole period of measurements peaks at 1 °C, but higher values are frequently registered especially referring to differences with the coastal site also due to the sea-breeze cooling effects. The city is generally drier and char- acterized by winds of lower intensity reaching their maximum 1 h later with the respect to the sub-urban/coastal sites during the afternoon. The micrometeorological data are also analyzed to estimate some key parameter characteristic of the terrain, which represents the main forcing in the numerical models for UHI estimates, such as the albedo, aerodynamics and atmospheric turbulence parameters. 1. Introduction In highly developed urban areas the surfaces, impervious and dry concrete, are characterized by a less moisture availability for evapotranspiration than natural ground, involving higher surface and air temperatures and leading to the formation of an urban heat island (U.S. EPA, 2008); phenomenon that primarily results from different cooling rates between urban areas and their surrounding (rural or suburban areas) (e.g. Steeneveld et al., 2011). Hence, the intensity of the urban heat island is a quantitative indicator of the thermal modification, imposed by the city upon the territory (Martin-Vide et al., 2015) and expressed as the difference between background rural and highest urban temperatures (Oke, 1973). https://doi.org/10.1016/j.uclim.2019.100493 Received 29 January 2019; Received in revised form 20 June 2019; Accepted 24 June 2019 ⁎ Corresponding author at: Institute of Atmospheric Sciences and Climate, CNR - Via Fosso del Cavaliere, 100, 00133 Rome, Italy. E-mail addresses: virginia.ciardini@enea.it (V. Ciardini), luca.caporaso@artov.ismar.cnr.it (L. Caporaso), roberto.sozzi@arpalazio.it (R. Sozzi), i.petenko@isac.cnr.it (I. Petenko), andrea.bolignano@arpalazio.gov.it (A. Bolignano), matteo.morelli@arpalazio.gov.it (M. Morelli), melas@auth.gr (D. Melas), s.argentini@isac.cnr.it (S. Argentini). 1 Current affiliation: Laboratory for Observations and Analyses of the Earth and Climate, ENEA - Via Anguillarese, 301, 00123 Rome, Italy. Urban Climate 29 (2019) 100493 2212-0955/ © 2019 Published by Elsevier B.V. T