Impacts of future urbanization and rooftop photovoltaics on the surface meteorology and energy balance of Lhasa, China

Abstract

Little attention has been given to possible future urban expansion and its potential impacts in high-altitude cities of the Tibetan Plateau. This study predicts the future urban expansion of Lhasa using a metacellular automata method and investigates the change in the surface thermal environment under projected urbanization and rooftop photovoltaic (RPV) scenarios using numerical simulations. Until 2035, Lhasa will further expand along the Lhasa River Basin to the east, west, and south, most prominently to the south. Such urban expansion contributes to an increase in daily average surface air temperature of 0.63 ± 0.16 °C and a decrease in relative humidity of 1.89 ± 0.43% under cloudless weather conditions, with more significant nighttime impacts. An increase of 34.89 ± 7.69 W•m−2 in sensible heat flux and a decrease of 40.92 ± 8.02 W•m−2 in latent heat flux are shown to coincide with the urban expansion areas. In addition, it is found that the city-scale RPV scenario results in a decrease in surface sensible heat flux of 3.02 ± 1.54 W•m−2 but has little influence on latent heat and surface meteorological elements, especially in the daytime.