ABSTRACT
Climate represents the average pattern of variation in temperature, precipitation, atmospheric pressure, wind, and other meteorological variables in a given region over long periods of time. The climate of a region generated by the climate system has five components: atmosphere, hydrosphere, cryosphere, land surface, and biosphere. The change of land surface can modify local or regional climate by alternating transition of energy fluxes from surface to atmosphere. The transition is completed through both air dynamic and thermal processes. The terrain feature of urban surface can change airflow and creates interacting wakes and plumes (of heat, humidity, and pollutants) introduced by individual roughness elements (Arnfield 2003). The urban atmosphere usually is divided into two layers: mixing layer and surface layer. The mixing layer is from the top of urban construction to the top of atmospheric boundary. The surface layer is from land surface to the top of urban construction. Urban structures and features such as buildings, streets, and parks significantly shape weather patterns by altering atmospheric flows, turbulence, humidity, precipitation, and temperature, and influence the transport, dispersion, and deposition of atmospheric pollutants (Cotton and Pielke 1995; Taha et al. 1997). Beyond the air dynamic effects introduced by urban landscape, urban areas also implement surface radiative and thermodynamic impacts on atmospheric system (Voogt and Oke 2003; Xian 2008). Urban development changes natural landscape feature into anthropogenic impervious surface that usually is a poor storage system for water and is a heat source. The resultant surface temperature in urban area affects thermal admittance and surface emissivity, the radiative input at the surface from the sun and atmosphere, and the near surface atmosphere condition and turbulent transfer from the surface.
