EXAMINING THE EFFECT OF URBANISATION ON LONG-TERM TEMPERATURE DATA IN SINGAPORE

Abstract

Inhomogeneities in observed climatic data can prevent the accurate estimation of the long-term climate signals. A large source of inhomogeneities is increased urbanisation, which can lead to station relocation and influence observed climatic data through the urban heat island (UHI) effect. As such, it is important to analyse the impact of urbanisation on observed climatic data. First, land use and land cover (LULC) changes surrounding official Meteorological Society Singapore (MSS) weather stations from 1960 to 2016 is examined and classified using the Local Climate Zone system developed by Stewart and Oke. Second, the long-term temperature trends are identified through graphs. Last, statistical tests are used to derive an estimate of the urban influence on temperature cycles through difference testing of derived cooling rates and diurnal temperature ranges (DTR) at each MSS station. By separating the impact of urbanisation from climatic effects, it contributes to potential improvements in depiction of large-scale natural occurrences of variability (e.g. ENSO and other tropical phenomenon) on Singapore temperature, and expose underlying long-term climatic changes due to anthropogenic global warming. The results of this thesis show that the urban signal in Singapore’s temperatures is strong. Stations that underwent huge changes to their land cover and had intensified land use and human activity showed increase in mean temperatures, maximum and minimum temperatures, and showed statistically significant decreases in their mean nocturnal cooling rates and DTR as compared to stations that remained largely rural. The results from this research indicate that inhomogeneities contribute to significant warming biases in the Singapore temperature record. With increasing urbanisation and development in Singapore, it will be hard to acquire sites that can accurately reflect solely the climatic effects on Singapore’s temperature.