Spatial-Temporal Variation of Surface Roughness and Its Effect on the Wind Fields in the Beijing-Tianjin-Hebei Region during 2007–2011

Abstract

ABSTRACTUrbanization has greatly changed the underlying surface roughness characteristics to a great extent and has great influence on the environment and climate. The Beijing-Tianjin-Hebei region is an important political and economic center in China and also one of the regions with the most rapid urbanization speed in the world. However, in recent years, haze contamination with extremely high Particulate Matter 2.5 concentration has occurred very frequently in this region. In this article, the extraction method for urban built-up area was proposed jointly using ALOS PALSAR data and nighttime light data, and then urbanization expansion in the study area from 2007 to 2011 was analyzed. At the same time, the wind velocity variation in the region was analyzed using observation data from meteorological stations. Using these two kinds of data, the effect of the roughness variation on wind velocity was investigated. The results showed that average wind velocities in the northern and western parts of the Beijing-Tianjin-Hebei region have been increasing, but the average wind velocity, the wind velocity in the prevailing wind direction, and the average north wind velocity in the southern cities, have all declined significantly except the seaside city, which is induced by the rapid expansion of built-up areas in this region.