Impact Of Synoptic System On The Urban Atmospheric Particles And Urban Heat Island

Abstract:Research shows that meteorological factors have a major impact on urban air pollution and the heat island effect.However, meteorological factors are not alone, but accompanied by specific synoptic system appear. At present only few Research on to study the depth of increased to the extent of synoptic system on urban atmospheric particulate matter and the heat island effect, and atmospheric dynamics and urban heat island effect relationship between air pollution and different weather systems have not yet systematically analyzed. Therefore, it is great significance of study the influence of weather types on urban heat island effect and air pollutant concentrations.This research is taking Changsha as example. The data of meteorological for weather system classification is from2005to2009of Changsha, including air temperature, atmospheric pressure, dew point temperature, wind speed and direction, and visibility. The data of the temperature for the heat island effect for Changsha7meteorological stations hourly temperature data for the five years.PM10concentration data are average concentration day data from2005to2009, and average hour concentration data from January4,2008to January21.Statistics of principal component analysis, cluster analysis method is used to analyze the characteristics of weather systems. Mesoscale numerical model (MM5)is used to simulate the mixing layer height, potential temperature and other characteristics of the atmospheric dynamics.The results show that:(1) There are mainly five synoptic system in summer, such as Tibetan high,Westerly trough, Indian suit low cyclones, Cyclones, Subtropical high, the number of days is152,59,80,54,97. The UHI is strongest under the influence of the Tibetan high and Subtropical high; Indian low pressure cyclone and Low pressure cyclone are times; West wind trough is weakest.(2) There are mainly5synoptic system in winter, such as Cold front, Siberian high, High-pressure front, Past frontal, Low cyclone, the number of days are66,193,60,40,39. concentration are the highest under the influence of Siberian high and High-pressure front; Past frontal and Low cyclone are times; Cold front is lowest.(3) Urban atmospheric dynamic characteristics (mixing layer height, height of the entrainment zone, potential temperature) and meteorological factors (atmospheric pressure, temperature, wind speed, wind direction) have an important influence on typical synoptic system day in summer and atmosphere particulate matter concentrations on episode period/clear days in winter.Synoptic system have an important impact on urban atmospheric particulate matter and the heat island effect:Atmospheric particulate matter concentration is highest, heat island effect is strongest under high pressure synoptic system; Meteorological factors and dynamics of the atmosphere is the fundamental reasons for the significant differences about urban heat island intensity and atmospheric particulate matter pollution levels under different synoptic system.