Relationship between Amazon biomass burning aerosols and rainfall over the La Plata Basin

High aerosol loads are discharged into the atmosphere\ud by biomass burning in the Amazon and central\ud Brazil during the dry season. These particles can interact with\ud clouds as cloud condensation nuclei (CCN) changing cloud\ud microphysics and radiative properties and, thereby, affecting\ud the radiative budget of the region. Furthermore, the biomass\ud burning aerosols can be transported by the low-level jet (LLJ)\ud to the La Plata Basin, where many mesoscale convective\ud systems (MCS) are observed during spring and summer.\ud This work proposes to investigate whether the aerosols from\ud biomass burning may affect the MCS in terms of rainfall over\ud the La Plata Basin during spring. Aerosol effects are very difficult\ud to isolate because convective clouds are very sensitive\ud to small environment disturbances; for that reason, detailed\ud analyses using different techniques are used. The binplot,\ud 2-D histograms and combined empirical orthogonal function\ud (EOF) methods are used to identify certain environmental\ud conditions with the possible effects of aerosol loading. Reanalysis\ud 2, TRMM-3B42 and AERONET data are used from\ud 1999 up to 2012 during September–December. The results\ud show that there are two patterns associated with rainfall–\ud aerosol interaction in the La Plata Basin: one in which the\ud dynamic conditions are more important than aerosols to generation\ud of rain; and a second one where the aerosol particles\ud have a more important role in rain formation, acting mainly\ud to suppress rainfall over the La Plata Basin. However, these\ud results need further investigation to strengthen conclusions,\ud especially because there are limitations and uncertainties in\ud the methodology and data set usedCAPESFAPESP - 2012/08115-