Origin of the intense positive and moderate negative atmospheric electric field variations measured during and after Antarctic blizzards

• Published in: Atmospheric Research
• Main Authors: Minamoto, Yasuhiro, Kamogawa, Masashi, Kadokura, Akira, Omiya, Satoshi, Hirasawa, Naohiko, Sato, Mitsuteru
• Format: Article in Journal/Newspaper
• Language: English
• Published: Elsevier
• Subjects: Atmospheric electric field; Potential gradient; Electric field mill; Blizzard; Antarctica; Charged snow particles; 451; Antarctic; Syowa Station; Antarc*
• Online Access: http://hdl.handle.net/2115/90848; https://doi.org/10.1016/j.atmosres.2021.105812

There is an atmospheric electric field (AEF) or an electric potential gradient (PG) in fair weather between the Earth's surface and the mesosphere/ionosphere, which is positive. During blizzards/snowstorms in the polar regions, an intense positive AEF/PG in the order of 10(3)V/m of the same polarity in fair weather was observed using an electric field mill at 1.4 m in height. In contrast, a moderately negative AEF/PG variation after a blizzard was observed in 2015 at Syowa Station, Antarctica. The negative variation, where the magnitude ranged from tens to hundreds of V/m, gradually recovered into the positive AEF/PG for more than 40 min. According to various studies on blowing/drifting snow dynamics and electricity in laboratory experiments and field observations, snow particles colliding with the snow surface are charged, and the charge of suspended and saltating particles during the snowstorm is negative on average. To verify the AEF/PG observed during and after the blizzards, we numerically estimated the electric field surrounding the conductive sensor unit of the electric field mill using a three-dimensional Poisson equation. Under blizzard conditions, the polarity of the estimated AEF/PG was the opposite of that of the observed AEF/PG. From the noise study of the field mill, we deduced that the positive AEF/PG variations were caused by the collision of negatively charged snow particles with the electric probe on the sensor unit. Just after the blizzard, the number of snow particles measured at 4.4 m in height clearly decreased, and the camera image showed clear visibility. From this evidence, we modeled the suspended and saltating negatively charged snow particles that had fallen onto the ground surface and then constructed a charge layer of the snow particles softly attaching to the ground, which slowly discharged following the study on the electrical resistance of the powders. The three-dimensional Poisson calculation based on the model reproduced a moderately negative AEF/PG. Thus, we elucidated that ...