Urban heat island

Energy flux parametrization as an opportunity to get Urban Heat Island insights: The case of Athens, Greece (Thermopolis 2009 Campaign)

 Science of The Total Environment, Vol.  542(Pt A) , 136-143,  (2016).
doi:10.1016/j.scitotenv.2015.10.056
 
 
Energy flux parametrization as an opportunity to get Urban Heat Island insights: The case of Athens, Greece (Thermopolis 2009 Campaign).
 
                                    G. Loupa, S. Rapsomanikis, A. Trepekli, K. Kourtidis

 
 

Abstract.Energy flux parameterization was effected for the city of Athens, Greece, by utilizing two approaches, the Local- Scale UrbanMeteorological Parameterization Scheme(LUMPS) and the Bulk Approach (BA). In situ acquired data are used to validate the algorithms of these schemes and derive coefficients applicable to the study area. Model results from these corrected algorithms are compared with literature results for coefficients applicable to other cities and their varying construction materials. Asphalt and concrete surfaces, canyons and anthropogenic heat releases were found to be the key characteristics of the city center that sustain the elevated surface and air temperatures, under hot, sunny and dryweather, during theMediterranean summer. A relationship between storage heat flux plus anthropogenic energy flux and temperatures (surface and lower atmosphere) is presented, that results in understanding of the interplay between temperatures, anthropogenic energy releases and the city characteristics under the Urban Heat Island conditions.

 
 
 
 

Numerical study of the urban heat island over Athens (Greece) with the WRF model

Atmospheric Environment,Volume 73, 103-111, (2013).

doi:10.1016/j.atmosenv.2013.02.055

Numerical study of the urban heat island over Athens (Greece) with the WRF model

T.M. Giannaros, D. Melas, I.A. Daglis, I. Keramitsoglou, K. Kourtidis.

Abstract. In this study, the Weather Research and Forecasting (WRF) model coupled with the Noah land surface model was tested over the city of Athens, Greece, during two selected days. Model results were compared against observations, revealing a satisfactory performance of the modeling system. According to the numerical simulation, the city of Athens exhibits higher air temperatures than its surroundings during the night (>4 °C), whereas the temperature contrast is less evident in early morning and mid-day hours. The minimum and maximum intensity of the canopy-layer heat island were found to occur in early morning and during the night, respectively. The simulations, in agreement with concurrent observations, showed that the intensity of the canopy-layer heat island has a typical diurnal cycle, characterized by high nighttime values, an abrupt decrease following sunrise, and an increase following sunset. The examination of the spatial patterns of the land surface temperature revealed the existence of a surface urban heat sink during the day. In the nighttime, the city surface temperature was found to be higher than its surroundings. Finally, a simple data assimilation algorithm for satellite-retrieved land surface temperature was evaluated. The ingestion of the land surface temperature data into the model resulted to a small reduction in the temperature bias, generally less than 0.2 °C, which was only evident during the first 4–5 h following the assimilation.