Rainwater samples are collected using a semi-automatic precipitation collector designed for the INDAAF network. The first rain droplets order the rain detector to open the lid of the collector. To collect rainwater, polyethylene single-use bags are used. In order to avoid any contamination by aerosols and insects, the rain collector remains closed before and after the rain. Rain samples are immediately collected by a local observer after the rain event. Samples are stored in Greiner tubes of 50 ml in a freezer -18°C (WMO-GAW report n°160, 2004). After collection, samples are sent for analysis to the Laboratoire d’Aérologie (Laero) in Toulouse in the strict respect of the cold chain, where they are stored in a freezer (-18°C) until analysis. Rainfall samples are analyzed for pH, conductivity, major inorganic and organic ion concentrations (in μeq.L-1) with analytical precision estimated to be 5% or better for all the ions.
