Effect of land use changes on local meteorological conditions in Jakarta, Indonesia: toward the evaluation of the thermal environment of megacities in Asia

In the past few decades, the surroundings of the initially urbanised area (the old city) of Jakarta, Indonesia, was rapidly urbanised and the daily mean air temperature increased by approximately 1 K. Accordingly, the effect of the land use change in the area of Jakarta on the local climate was investigated using a mesoscale meteorological model. After model performance was validated against observational data, the model was run to simulate the meteorological field over the city for the dry season. In the simulations, three cases were considered: (1) the land use in the present day, (2) the land use in the 1970s, and (3) land use with no urban areas. The simulations led to the following findings. First, the sea breeze developed at an earlier time of day in the present day than in the 1970s. Second, in the present-day case, a converging flow developed over the old city in association with the low pressure which formed over the same location. Third, the daytime average and maximum air temperature in the old city were higher in the present day than in the 1970s by 0.6 and 0.9 K, respectively, due to the advection of heat from the new urban area. Finally, the amount of heat advected into the old city was estimated to be -0.7 Wm(-2) in the 1970s and 77 Wm(-2) in the 2000s. The estimated value in the 2000s case was 44% of the magnitude of the sensible heat flux from the ground surface into the atmosphere. Copyright (C) 2010 Royal Meteorological Society