A framework to assess the contribution of bioaerosols to the outcome of meteorological contexts favorable for rainfall

Rainfall feedback results from the sensitivity of atmospheric processes to environmental conditions that are generated by a preceding rainfall event. Feedback that is persistent over several weeks is most likely due to environmental phenomena that involve growth and therefore most probably involves aerosols of biological origin. Based on a tool developed to quantify feedback at specific sites from historical daily rainfall data and maps of the feedback trends (http://w3.avignon.inra.fr/rainfallfeedback/index.html) we have generated a series of site-specific and season-specific hypotheses about the extent to which aerosols, from biological sources in particular, influence the outcome of meteorological conditions that are favorable for rainfall. We illustrate how the tools we report here and elsewhere can be applied in a framework of rationale for the design of field experiments finely tuned to site-specific hypotheses and thereby to a more refined understanding of the contexts of geography, season and land use that underlie the extent to which aerosols influence the fate of cloud processes.