Air　pollution　in　urban　cites　is　caused　not　only　by　local　emission　sources　but　also　significantly　by　regional　atmospheric　pollutant　transport　from　surrounding　areas.　This　study　is　to　identify　regional　atmospheric　PM10　transport　pathways　through　an　integrated　modeling　and　synoptic　pressure　pattern　analysis　approach　with　a　case　study　in　Beijing,　northern　China.　Beijing　is　a　city　sensitive　to　trans-boundary　transport　of　aerosols　from　its　surrounding　provinces.　The　pathway　identification　was　conducted　through　tracking　air　masses　and　analyzing　dominant　transport　patterns　leading　to　air　pollution　episode　in　Beijing.　Trajectories　were　calculated　using　NOAA-HYSPLIT　model　based　on　the　meteorological　field　of　MM5　outputs　in　October　2002.　A　k-means　clustering　algorithm　was　applied　to　group　these　trajectories　into　different　transport　patterns.　Monitored　PM10　levels　during　each　transport　pattern　were　then　examined　to　evaluate　its　influence　on　atmospheric　PM10　in　Beijing.　The　southwest　transport　pathway　was　identified　to　be　closely　associated　with　the　increasing　phase　of　PM10.　An　integrated　MM5-CMAQ　modeling　system　was　then　applied　to　simulate　PM10　concentrations　in　Beijing　and　its　surrounding　provinces　for　the　southwest　transport　period.　It　was　found　that　a　convergence　flow　field　with　high　PM10　concentrations　frequently　appeared　between　northwest　mountain　breeze　and　southwest　plain　breeze　on　the　lee　of　the　Taihang　Mountains.　Further　analysis　indicated　that　high-pressure　systems　accompanied　with　thermal　inversion　in　the　boundary　layer　were　the　governing　synoptic　patterns　in　southwest　transport　period.　Trans-boundary　transport　along　with　the　convergence　zone　induced　by　mesoscale　low　pressure　system　in　front　of　the　Taihang　Mountains,　which　was　generated　by　topographical　dynamics　and　thermal　effects,　proved　to　be　the　main　cause　of　high　PM10　levels　in　Beijing.　(C)　2010　Elsevier　Ltd.　All　rights　reserved.