Traveling Ionospheric Disturbances Characteristics during the 2018 Typhoon Maria from GPS Observations

Abstract

Typhoons often occur and may cause huge loss of life and damage of infrastructures, but they are still difficult to precisely monitor and predict by traditional in-situ measurements. Nowadays, ionospheric disturbances at a large-scale following typhoons can be monitored using ground-based dual-frequency Global Positioning System (GPS) observations. In this paper the responses of ionospheric total electron content (TEC) to Typhoon Maria on 10 July 2018 are studied by using about 150 stations of the GPS network in Taiwan. The results show that two significant ionospheric disturbances on the southwest side of the typhoon eye were found between 10:00 and 12:00 UTC. This was the stage of severe typhoon and the ionospheric disturbances propagated at speeds of 118.09 and 186.17 m/s, respectively. Both traveling ionospheric disturbances reached up to 0.2 TECU and the amplitudes were slightly different. The change in the filtered TEC time series during the typhoon was further analyzed with the azimuth. It can be seen that the TEC disturbance anomalies were primarily concentrated in a range of between −0.2 and 0.2 TECU and mainly located at 135–300° in the azimuth, namely the southwest side of the typhoon eye. The corresponding frequency spectrum of the two TEC time series was about 1.6 mHz, which is consistent with the frequency of gravity waves. Therefore, the upward propagating gravity wave was the main cause of the traveling ionospheric disturbance during Typhoon Maria.

Detecting Total Electron Content Precursors Before Earthquakes by Examining Total Electron Content Images Based on Butterworth Filter in Convolutional Neural Networks

“…In these split images used as inputs, a low pass filter called a Butterworth filter (Bianchi and Sorrentino, 2007) is applied to reduce wedge effects for the split images in vertical and horizontal directions before the convolutional layers in the first hidden layer as described. The Butterworth filter has been identified as a suitable filter for TEC data (Jayachandran et al, 2012;Chandrasekhar et al, 2016;Wen and Jin, 2020). (4) For both CNN models, the training epoch is set as 2000 (Omatu et al, 2018), and the learning rate is adaptive at 0 to 1, with an increment of 0.01.…”

Statistical Study of F‐Region Short Period Ionospheric Disturbances Related to Convection in the Lower Atmosphere Over Wuhan, China

“…Internal atmospheric dynamics have been identified as one of the main causes of ionospheric disturbances, especially convective activity. The study of the relationship between convective activity and the ionosphere can provide a unique perspective on ionosphere‐atmosphere coupling (Azeem et al., 2015; Bauer, 1958; Chen et al., 2020; Chou et al., 2017; Georges, 1973; Lay, 2018; Nishioka et al., 2013; Peng et al., 2021; Wen & Jin, 2020). The ionospheric disturbances caused by convective activity are generally traveling ionospheric disturbances (TIDs).…”

Characterization of Ionospheric Disturbances Following Multiple Typhoons Using GPS‐Derived TEC

“…(2019) reported the horizontal propagation velocities of the TIDs were 268 and 143 m/s using the GPS network data of China combined with observations of an ionosonde chain. Interestingly, there was no significant disturbance at the eye of the typhoon, and the disturbance at several stations became greater with the increasing distance to the eye (Wen & Jin, 2020). The typhoon‐induced ionospheric disturbances are reaching a maximum at a distance of 1,300 km from the typhoon eye, and are reduced progressively to zero at more than 2100 km (Chen et al., 2020).…”

“…There are obvious differences among the results of the characteristics of typhoon‐induced ionospheric disturbances caused by the different chosen typhoons and the coupling relations between typhoons and ionospheric disturbances (Chou et al., 2017; Wen & Jin, 2020). To answer how typhoons trigger gravity waves and how they propagate through the atmosphere, the ionospheric disturbance characteristics triggered by several typhoons with different intensities and paths should be investigated and analyzed for the relationship between typhoons and ionospheric disturbance.…”