BACCHUS is a collaborative project of 21 international partner institutes from 13 different European countries. The project ran from 2013 to 2017 and was funded by the European Union. The acronym BACCHUS stands for Impact of Biogenic versus Anthropogenic emissions on Clouds and Climate: towards a Holistic UnderStanding. The project focuses on aerosols and clouds, and their interaction to one another. The radiative forcing of these two climate-relevant factors is not well understood, especially when compared to greenhouse gases or other forcing agents. The main objective of the project is to identify and quantify the key processes and feedbacks that control aerosol-cloud-interactions. The primary focus is on regions that are either largely unaffected by human activities, or are heavily affected by climate change. By studying these unperturbed regions through field observations and numerical modelling it is hoped to gain knowledge on the pre-industrial state of cloud active aerosols. As a partner of BACCHUS we analyzed several hundreds of aerosol samples from three measurement sites (Figure 1) by FRIDGE for their ice nucleation activity. The stations were located in the Amazon (ATTO site in Brazil), in the Arctic (Ny-Alesund in Svalbard) and in the Caribbean (Martinique). These long-term measurements of ice nucleating particles are one of a kind in terms of timespan and regions of high interest.

Figure 1: Abundance and composition of INP were monitored at three remote sites spanning the range of global climates from the high Arctic to the equator.