The urban heat island effect in Malta and Gozo

Abstract

This dissertation analyses the Urban Heat Island Effect over the Maltese islands. The analysation of this study focused on two seasons (summer and winter). In-situ measurements took place on the 23/07/19, 08/02/20 in Malta, and 24/08/19, 07/02/20 in Gozo. LANDSAT 7 and 8 remotely sensed data were used to investigate this study. This study found the Land Surface Temperature (LST) using the Mono-Window Algorithm (MWA) with SAGAGIS being the main raster processor for this investigation. Operational Land Imager (OLI) and Thermal Infrared Sensor (TIR) in LANDSAT 8 and the Enhanced Thematic Mapper (ETM+) in LANDSAT 7, allowed the generation of meaningful thermal heat maps. The use of the Normalised Difference Vegetation Index (NDVI) was also used to investigate any correlations between the urban-rural Land Surface Temperature. The In-situ parameters included dry bulb temperatures, wet bulb temperatures - both calculated at ground level and 2metres above ground, relative humidity, and the wind force. Results have shown the severity of the LST across the Maltese islands during the summer period pointing out areas with excessive LST known as hotspots e.g. Paola. The use of contouring in QGIS allowed this investigation to identify various hotspots in Malta and Gozo which granted further analysation. On the contrary, the level of the UHI effect in winter was less significant and this could be dependent on many factors, especially the type of season, weather, the elevation of the sun and so on. Terrain analyses such as the aspect and slopes had also a significant impact on the surface land temperature especially those slopes facing the direct sunlight for a constant amount of time. Moreover, this investigation focused on the importance of open green areas. As this dissertation shows, open green areas had a significant impact both on the ambient air temperature but also on the LST. Green pockets are an ideal approach in mitigating the UHI effect. San Anton Gardens (Malta), Villa Rundle (Gozo), Marsa golf course and also some spots in Mellieħa are cases which support this argument.