Investigations of Light Absorbing Aerosols in the Central Amazon During the Wet Season

We use a global chemical transport (GEOS-Chem) model to interpret observed light absorbing aerosols in Amazon during the wet season. Observed BC (black carbon) concentrations and absorption at ATTO site in Amazon have a relatively low background, but frequently show high peaks during Jan-Apr 2014. Our simulation successfully captured the observed variation of both BC concentrations and total absorption. The source attribution in the model indicates the importance of fire influence originated from regional sources and the long transport of Northern Africa fire plumes during the wet season. Correlations between BC and CO as well as correlations between absorption and CO provide further information for sources and optical properties. The analysis shows different enhancement ratios for BC versus CO, with higher/lower values for regional/long-transport fire plumes. Estimated time for transporting Northern Africa fire plumes to ATTO is around 10 days. In addition to the major contribution of fire aerosols, we found occasional dust influence on total absorption, which occurred mainly between February and April. We will discuss the vertical distribution of absorbing aerosols and the implications for the transport path for different aerosols layers over the Amazon.