Arctic Haze: Meteorological Aspects Of Long-Range Transport

Abstract

A time series of concentrations of pollution aerosols collected over a period of four years in the near-surface air at Barrow, Alaska, was used to investigate tropospheric long-range transport of anthropogenic pollution from mid-latitudes into the Arctic. This transport takes place when the mid-latitudinal and arctic atmospheric circulations remain in a quasi-persistent mode. Sudden changes in the circulation pattern explain the episodic character of the arctic pollution aerosol. Transport of aerosols is accomplished by quasi-stationary anticyclones and takes place along their peripheries where pressure gradients are relatively strong. The seasonal variation in concentration of the arctic pollution aerosol is explained by the seasonal variation in the occurrence and position of mid-latitude blocking anticyclones, of the arctic anticyclone, and of the Asiatic anticyclone. The positions of the major anticyclonic centers are responsible for the fact that Soviet industrial sources contribute to the arctic pollution aerosol predominantly during winter, European sources during spring, and that North American and Far Eastern industrial sources contribute little to the arctic pollution aerosols. Air masses carrying pollutants can be traced by their chemical characteristics obtained over the source regions, however, the original meteorological characteristics are lost during the transport which lasts for about 8-9 days. A second data set, collected during the "Ptarmigan" weather reconnaissance flights, was investigated for observations of Arctic Haze over the Alaskan Arctic. A connection between Arctic Haze and the arctic pollution aerosols is suggested, for the occurrence of Arctic Haze undergoes a similar seasonal variation as that of the pollution aerosols, and similar circulation modes leading to the Soviet Union and Europe can be found during the presence of Arctic Haze. In addition, the data seem to suggest that besides a probable pollution-derived component during winter/spring Arctic Haze might be desert dust-derived during summer.