关键词: 峡口城市, 乌鲁木齐, 污染物, 时空变化规律, 低空型东南风

Abstract: monitoring stations increased in urban area while the air pollutants such as PM_2.5，O₃ and CO began to list on daily operation besides the previous pollutants（PM₁₀，SO₂ and NO₂）. It is should be noted that large-scale coal-gas heating engineering came into effect in urban area since last October，which implied that the amount of air pollution emission could remarkably go down as well as urban air quality could improve to a certain degree during the last winter. In order to better understand the general public concern，the tempo-spatial distribution disciplines of air pollutants were analyzed in the light of hourly pollutants data including PM10，SO₂，NO₂，PM_2.5，CO and O₃ in combination with homochronous meteorological data during January 6-March 13，2013. The results show that the models of pollutants’spatial distribution can be broken down into two types，namely urban center-suburb model and south-north model. The concentration of PM10 increases from suburb to urban center but the ones of SO₂ and CO decrease from suburb to center. The concentrations of PM_2.5 and O₂ go up from the south to the north area while NO₂ exhibits the inverse model. Judging by the new Ambient Air Quality Standard（GB3095-2012），the air quality indices of six air pollutants（O₃，SO₂，NO₂，CO，PM₁₀ and PM_2.5）ranking from low to high are Ⅰ，Ⅱ，Ⅱ-Ⅲ，Ⅲ，Ⅳ and Ⅴ，respectively. The diurnal variations shapes of air pollutants display two classes including the double-peak structure（PM₁₀、PM_2.5 and SO₂） and the single-peak structure（NO₂、CO and O₃）. The air qualities during two periods of 13∶00-16∶00 and 7∶00-8∶00 are the poorest and the best all day，respectively. It is noteworthy that the over standard rate caused by PM_2.5 is relatively high with value of 88.7%. There are positive relationships between the concentration of PM_2.5 and relative humidity，visibility，wind speeds and rainfall，as well as significant inverse relationship between the frequency and the inverse temperature difference. In addition，the occurrence frequency of the elevated southeasterly gale，inversion depth and the temperature difference between top and bottom of inversion all tend to increase with the AQI rising corresponding to PM_2.5 concentration，which indicate that the elevated  southeasterly gale has great impacts on the local air quality.

Key words: mountain gap town, Urumqi, air pollutants, temporal-spatial variation features, the elevated southeasterly gale