Study On Guangzhou's Local Climate Zone And Its Surface Energy,Microclimate

In recent years,with the continuous acceleration of urbanization,the scope of cities is gradually expanding,and the ensuing problems of urban heat island effect have become increasingly prominent.The rapid rise in urban temperature has caused the deterioration of the urban thermal environment.At the same time,it has been accompanied by frequent occurrence of extreme weather and climate events such as rainstorms,which has exacerbated the spread of diseases and threatened social and economic development and the health of urban residents.In recent years,the Chinese government has attached great importance to the issue of climate change adaptation,and combined with the national economic and social development plans,has issued a series of policies and regulations related to climate change adaptation,indicating that it is of great significance to carry out urban thermal environment research.Local Climate Zone(LCZ) is currently the most commonly used urban climate zone method to study the urban heat island effect.It divides 17 LCZs based on different urban forms.Comparing the air temperature of different zones can refine the study of urban heat island problems.In addition,LCZ is also used to study urban planning,building energy consumption,outdoor thermal comfort,etc.Based on the free Landsat8 remote sensing image combined with image supervised classification and hierarchical classification,this paper draws a map of Guangzhou LCZ.A study of Guangzhou‘s LCZ reveals that there are 13 LCZ zones in Guangzhou and Guangzhou,including 8 built types and 5 natural types.The largest ratio is the dense forest area LCZ A,which is mainly distributed in the northern forest area,and the city center is dominated by high-density built-up areas(LCZ1?3).The urban energy exchange and hydrological movement have a greater impact on the urban microclimate,which is the basis for studying the urban heat island and waterlogging disasters.The SUEWS(Surface Urban Energy and Water Balance Scheme)model integrates the study of urban surface energy and water balance.Only a small number of input items are needed to simulate the local size of urban surface energy sub-items,microclimate parameters and hydrological characteristics.Although the model has been validated in many cities such as Europe,America and China since it was proposed,it has not yet been validated in subtropical cities in China.In this paper,the SUEWS model is verified by using test data in Guangzhou,and it is found that the simulation can better simulate the radiant flux(R~2 is in the range of 0.5?0.98),and the simulation of the latent heat flux in the turbulent flux is poor(R~2=0.25),but the comparison In other cities,the simulation results are within a reasonable range.The shape of urban space is closely related to the formation of urban microclimate.Therefore,based on the typical LCZ in Guangzhou,this paper uses the SUEWS model to simulate the surface energy and microclimate performance of each LCZ.The built-up type has more heat storage during the day than the natural type LCZ,and the near-surface temperature is higher.Among them,near the ground temperature of the high-density low-rise building areas(LCZ 3 and LCZ 8)is higher than other high-rise building areas.