Global Electric Circuit research at Graciosa Island (ENA-ARM facility): First year of measurements and ENSO influences

Around 100 years after Carnegie expeditions discovered the Global Electric Circuit, a measuring campaign started at ARM, Eastern North Atlantic facility (Graciosa Island, Azores), meant for the first time to resemble the conditions in which those took place. Here, the first year of measurements (starting April 2015) are analysed and initial results are discussed. The Potential Gradient findings show a deviation from the Carnegie Curves towards inland measurements as a consequence of local aerosol and ion load. The Potential Gradient maxima evolves from 18 UTC (spring/autumn) to 20 UTC (summer), being consistent with the strong 2015 El Niño.