METEOROLOGICAL SIMULATIONS TO INVESTIGATE THE STRATEGIES IN MITIGATING URBAN HEAT ISLAND (UHI) EFFECT IN A NEIGHBORHOOD IN BEIRUT CITY: A MODEL BASED APPROACH

Abstract

The Urban heat island (UHI) effect is a threatening event expected to be as alarming as global warming. Given the aforementioned, several mitigation strategies were investigated in order to detect which has the most impact on alleviating the UHI effect in a neighborhood in Beirut city, the capital of Lebanon. These include changing the ground surface albedo, replacing old buildings with new ones, and last but not least adding vegetation. This was simulated through the use of ENVI-met V4.4 software. The simulations were conducted on the 20th of January and August to exploit two main seasons in the country, which are winter and summer seasons, respectively. The simulations were carried on a 200 x 200 x 46-meter domain at a resolution of 2 meters, which enables the study of small-scale interfaces between buildings, surfaces, and vegetation. The present study will allow urban planners to determine the precise policies needed to meliorate the urban living environment in cities in parallel with Beirut. Furthermore, the simulation which exhibited the most impact in reducing the UHI effect is the including of vegetation. It demonstrated to be the most effective mitigation strategy given its ability to improve the thermal comfort conditions at the pedestrian’s pathway sidewalks. The maximum decrease in air temperature was 2.4 oC at 17:00 on August 20th, while the maximum decrease in the mean radiant temperature was 10.5 oC at 12 noon. Besides, the optimum cooling regarding the outdoor thermal comfort (PET) was recorded in street S2 with an average reduction by 3.8 oC. In addition, another study was conducted to examine the effects of climate change on Beirut for more accurate forecasts and unerring precautions.