The Global Representativeness of Fair-Weather Atmospheric Electricity Parameters From the Coastal Station Maitri, Antarctica

Atmospheric electricity parameters (AEP) measurements from Antarctica predominantly feature either the potential gradient (PG) and/or air-Earth current (AEC) density. We report for the first time simultaneous measurements of the bipolar ions concentration/conductivity, PG, and AEC density. AEP measurements were carried out at Maitri (70.8 degrees S, 11.8 degrees E) from December 2018 to November 2019. We formulated a few criteria, irrespective of the weather conditions, to select the electrically quiet days and some additional criteria based on the conductivity measurements to discern globally representative data (GRD) from such days. The measurements of the PG and AEC density over the Antarctic plateau demonstrated the diurnal curves similar to the Carnegie pattern, which represents the global thunderstorms and electrified shower clouds (ESCs) occurring on different continents and oceans, we regard the data having such trend as GRD. We found significant variability in the concentration of small bipolar ions/conductivity in the austral summer which in turn affects GRD. However, the concentration of bipolar ions is nearly consistent at similar to 250 negative ions cm(-3) and similar to 300 positive ions cm(-3) in winter and enhances the probability of GRD. Such differences can arise out of the prevalent planetary boundary layer processes in the two seasons. When the PG varied between similar to 50 Vm(-1) and similar to 150 Vm(-1) and the maximum range of conductivity variations was similar to 0.2 x 10(-14). m(-1), the AEPs represented the signatures of the global thunderstorm and ESC activities. Plain Language Summary Monitoring of the atmospheric electricity parameters is a simple technique to monitor global thunderstorm activity and electrified shower clouds. For this, the data need to be free from local disturbances. Obtaining such data in Antarctic Plateau was found to be successful. On the other hand, the coastal Antarctic stations, experience local or regional contributions in it. This paper attempts to provide some techniques to obtain globally representative data (GRD). This paper suggests that the diurnal variation of the concentration of bipolar small ions strongly impacts the GRD. Therefore a day free from the diurnal variation of the concentration of bipolar ions is essential to discern the global signals. The winter season appears to be a better season for this as the summer season experiences mild convection activity that causes local and regional electrical signals that contaminate the data.

Automated summary

This study reports simultaneous measurements of bipolar ions concentration/conductivity, potential gradient (PG), and air-Earth current (AEC) density in Antarctica. The measurements of PG and AEC density show diurnal curves similar to global thunderstorm and electrified shower cloud activities. The concentration of bipolar ions varies significantly in the austral summer, affecting the interpretation of global signals.