Monitoring Urban Underlying Surface Characteristics Temporal And Spatial Evolution And Its Influence On Wind Field By Remote Sensing

Cities and towns are the most profound and concentrated areas of human impacts on climate change.With the rapid development of urbanization,there have been a series of meteorological disasters and ecological problems,such as climate warming,frequent meteorological disasters,ecological imbalance,air pollution and so on.By using multiple remote sensing data to observe spatial and temporal characteristics of surface evolution and its impact on climate under the rapid urbanization process,therefore,in this paper we use the synthetic aperture radar data,night light data and the scatterometer data.The paper analyzes the expansion of the urban underlying surface in the horizontal and vertical dimension in two levels.The relationship between the urban underlying surface expansion and the wind field is analyzed based on the meteorological station data and WRF weather forecast model.Furthermore,we specific the influence of urbanization on regional climate and environment change and spatial differentiation.It is very useful for the urban development and urban plan,improve the atmospheric quality and the mitigation of urban meteorological disasters.This paper mainly studies the following three aspects:(1)Using QuikSCAT scatterometer data and OLS/DMSP data to extract 2000-2009 the urban underlying surface change information and backscattering coefficient of China,analyzed the change of underlying surface city,discusses the city expansion characteristics of different regions.In general,the scope of China's urban expansion in 2000-2009 was significant,and the urban area increased by about 4 times.However,the city expansion in different regions showed significant differences,the eastern region has the largest expansion,central region expansion of medium,western expansion of the smallest,expanding the area and regional economic levels showed a strong positive correlation between different groups;in addition the city expansion mode is also very different,mainly in the area(urban area)and vertical(height)differences in two aspects.(2)Due to the spillover effect of light,the underlying surface area extracted by the night light data always larger than real.the underlying surface area extracted by ALOS PALSAR data always facing with the false alarm.This article combines ALOS PALSAR data and night light data to proposes a method of comprehensive utilization of the city under the pad extraction of multi-source remote sensing data,effectively removing the existing false alarm of SAR data in the built-up area extraction,and apply this method to Beijing Tianjin Hebei region.According to the data of meteorological stations in the same period,the influence of the urban underlying surface expansion on wind field is discussed.The results show that the increase of the area and height of the built-up area changes the roughness of the underlying surface.For the Beijing area,the blocking effect caused by urban expansion is especially significant for the Northwest wind.(3)In order to verify the phenomenon that the wind speed is reduced in the process of urbanization,this paper introduces the WRF weather forecast model.Two groups of contrast experiments are designed for the WRF model,and the influence of the change of the underlying surface on the wind field is verified from the point of view of the model.The test under the control of surface types as input variables,compared with two groups of experimental results can be found: the remote sensing data as auxiliary information to get real surface coverage information as WRF surface update input helps to improve the simulation accuracy of meteorological elements;wind field on surface type sensitive to changes in surface wind speed the expansion of regional city is obviously reduced.