Interannual variation of persistent organic pollutants over the Great Lakes induced by tropical Pacific sea surface temperature anomalies (Formerly Paper Number 10.8)

A correlation analysis using decadal monitored air concentrations of persistent organic pollutants (POPs) around the Great Lakes from 1992-2002 was carried out to investigate influences of the sea surface temperature anomalies (SSTA) in the tropical Pacific on the year-to-year changes in POPs air concentrations in the spring and summer seasons. It is shown that interannual fluctuations of air concentrations of a-hexachlorocyclohexanes (a-HCH), hexachlorobenzene (HCB), and polychlorinated biphenyls (PCBs) measured in the Great Lakes basin in the spring and summer seasons are correlated fairly well with the tropical Pacific SSTA. Spatial correlation pattern between the POPs and SSTA exhibits a feature of the characteristic SST signature associated with the occurrence of an El Niño event. The relations between the Great Lakes POPs air concentration and the tropical Pacific SSTA are consistent with the response of midlatitude atmospheric circulation to the Pacific SSTA, showing that POPs air concentration in the spring and summer seasons is related to tropical Pacific sea surface temperature anomalies in the preceding winter and spring months. The responses of the POPs fluctuations to the western tropical Pacific SSTA are stronger than to the equatorial central and eastern Pacific SSTA. The up to six month lag relationship between the POPs air concentration and SSTA provides a basis for forecasting the temporal trend of POPs in the atmosphere over the Great Lakes basin. The connection of the SSTA and the changes in the POPs air concentration was shown to be a response to the changes in the atmospheric circulation associated with the tropical Pacific SST forcing which plays a major role in the reemissions of the POPs from sources and their long-range transport in the atmosphere.