Numerical analysis of the impact of anthropogenic emissions on the urban environment of Singapore.

Increased urbanization and anthropogenic activities in tropical cities lead to the temperature gradient between the urban and rural environments, causing the urban heat island (UHI) phenomenon. This study is a pioneering attempt that examines the changes in the temporal evolution of the surface energy budget induced by urbanization known as the Anthropogenic Influence (AI) in modifying the urban climate of a tropical city using Weather Research and Forecasting (WRF) numerical modeling system. The AI from buildings, traffic and power plants is determined in five different scenarios and the model is validated with high temporal resolution in-situ data. These increased AIs provide improved WRF capability with root mean square error (RMSE) less than 2 °C and mean bias error (MBE) less than 0.5 °C between different performance indicators. Building envelopes (without indoor activity/equipment) are found to be a major contributor in exacerbating the island wide urban heat ∆TaAI, max to 3.7 °C compared to baseline all green scenario. This is followed by the air-conditioner (AC) systems that contribute up to 1.4 °C. The maximum local contribution of traffic and power plants to urban heat is 0.9 °C and 0.4 °C, respectively.

Standing wave spectrometer.

A standing wave Fourier transform spectrometer is realized. The spectrometer consists of an ultra thin and partially transparent photodetector and a tunable mirror. The incident light forms a standing wave in front of the mirror, which is sampled by the ultra thin optical detector. The thickness of the photodetector is significantly smaller than the wavelength of the incident light. The spectral information of the incident light is determined by the Fourier transform of the detector signal. The linear arrangement of the optical detector and the mirror enables the realization of spectrometer arrays and optical cameras with high spectral resolution. For the first time a complete optical model of the standing wave spectrometer is presented and compared with experimental results. The influence of the design of the optical detector on the performance of the spectrometer is discussed.