عنوان مقاله [English]
نویسندگان [English]چکیده [English]
Pollution in themetropolitansurfaceseverelythreatensthe quality of citizens life. Thisphenomenon inrecent yearshas createdamajorenvironmentalproblem.To study thecharacteristics ofsynopticpatternsondustpollution daysincity, the present research has used environmentalapproachto circulation. Todoso,first using particulate pollutants, the data and Standard Index Pollution (PSI>100) were extracted for pollutant days during 7 years (2005-2011).Then, for recognition of circulation patterns in pollutant days, sea level pressure data, geopotential height 500hpa, 850hpa levels and Temperature of soilmoistureat1000hpalevel with applying cluster analysis were employed. The resultsof70days ofpollutant, the mostpolluteddayswith24daysdustoccurredin 2005,based oncluster analysisby calculating theEuclideandistanceand linkage of ‘ward’, so, fourcirculation patterns were extracted and a key day was devoted to each cluster. As a result, Synopticanalysisshowed thatathermallow pressuresystemat sea level, a cyclone form at850hpa level and a stronganticycloneoverthe 500hPalevel form inthewarm period whereas ahigh pressuresystemat thesealevel, anticyclonicsystemat850hpa level and barotropic atmosphericat500hpa levelform in cold period that it is the most important circulation patterns atdustpollutantdays in shiraz.