Impacts of ionospheric electric fields on the GPS tropospheric delays during geomagnetic storms in Antarctica Impacts of ionospheric electric fields on the GPS tropospheric delays during geomagnetic storms in Antarctica (original) (raw)

This paper aimed to overview the interaction of the thunderstorm with the ionospheric electric fields during major geomagnetic storms in Antarctica through the GPS tropospheric delays. For the purpose of study, geomagnetic activity and electric fields data for the period from 13 to 21 March 2015 representing the St. Patrick's Day storm is analyzed. To strengthen the analysis, data for the period of 27 October to 1 st November 2003 representing for the Halloween storm is also compared. Our analysis showed that both geomagnetic storms were severe (Ap ≥ 100 nT), where the intensity of Halloween storm is double compared to St. Patrick's Day storm. For the ionospheric electric field, the peaks were dropped to-1.63 mV/m and-2.564 mV/m for St. Patrick and Halloween storms, respectively. At this time, the interplanetary magnetic field Bz component was significantly dropped to-17.31 nT with Ap > 150 nT (17 March 2015 at 19:20 UT) and-26.51 nT with Ap = 300 nT (29 October 2003 at 19:40 UT). For both geomagnetic storms, the electric field was correlated well with the ionospheric activity where tropospheric delays show a different characteristic. 1. Introduction Characterization the cause-effect mechanisms driving the formation and evolution of middle and the coupling between the upper and the lower levels of the atmosphere is challenging task. The physical mechanism on how the ionospheric activities interact directly or indirectly to troposphere is still not clear. It is well known theoretically that the high latitude ionosphere-troposphere contains the footprints of processes that have their origin in the planetary space. Many different techniques are now available for probing the ionosphere-troposphere, from radar measurements to the analysis of radio propagation noise. Among them the use of Global Navigation Satellite System (GNSS) measurements allows to describe the 3D plus time evolution of the ionospheric plasma and water vapor over restricted regions [1,2]. Mathematical techniques combined with experimental observations provide the ability to study the ionosphere from high in the F-region to the lower atmosphere. Thus the coupling processes between the magnetosphere and the neutral atmosphere can be approximated. Therefore, the possible linkages between solar phenomena, solar-induced interplanetary disturbances, the magnetospheric state and the chemistry of the middle and lower terrestrial atmosphere have been explored over the years with intent to separate natural variations from the anthropogenic forcing [3]. However, a solar influence on water vapor over Antarctica during the intense magnetospheric disturbance [2] found that the coupling between the upper and lower levels of the atmosphere is less sensitive enough to sense the coupling process. In fact, there are many phenomena occurs from the ionosphere to the lower atmosphere such as precipitation events, including water vapor distribution, formation of clouds and aerosols and the chemistry of the lower atmosphere [3], formation of polar stratospheric clouds, lightning and atmospheric electricity [4], and a long-lived trace gas in the mesosphere provides a possibility atmospheric motion and drags as well as hazard material detection during active weather. In this sense, global electric circuit is identified as a possible physical mechanism for the coupling process. Lightning and thunderstorm activity, as related to global electric circuit plays an important role in the coupling between Earth's lower atmosphere and the ionosphere [5]. Thunderstorm activity has an effect on the E-sporadic layer and the global electric circuits are shown to be organized by lightning phenomena over the geomagnetic equator. Global thunderstorm charge ionosphere and current returns