Characteristics of Anomalous Radio Propagation before and after the 2011 Tohoku-Oki Earthquake as Seen by Oblique Ionograms

The characteristics of anomalous radio propagation in the frequency 1 - 30 MHz before and after the 2011 Tohoku-Oki earthquake are firstly revealed by using oblique ionograms for the pass from Wakkanai to Kokubunji which is closest to the epicenter. An oblique ionogram with a wavy-shape-trace was observed at 06:30 UTC on 11 March 2011 after the 2011 Tohoku-Oki earthquake. The velocity of northward-propagating disturbance caused this wavy-shape-trace is estimated to be 130 m/s. This wave-shape-trace shows very clear signature appearing in the oblique ionograms as the characteristic of strong ionospheric disturbances triggered by the earthquake. An oblique ionogram with a steep slopy-shape-trace was observed at 04:45 UTC on 11 March 2011 one hour before the 2011 Tohoku-Oki earthquake. This slopy-shape-trace is investigated as the signatures of preseismic ionospheric anomaly. This anomalous oblique ionogram with a slopy-shape-trace is examined with the slope ratio of virtual height to sweep-frequency, and the difference between monthly median foF2 and hourly value foF2 at Wakkanai and Kokubunji. These features appearing in oblique ionograms suggest that it is useful for studying the signatures of preseismic ionospheric anomaly.

Numerical simulation of the propagation of electromagnetic waves in ionospheric irregularities

The characteristics of high-frequency(HF)electromagnetic(EM)wave propagation can be affected when EM waves propagate in the ionosphere.When ionospheric irregularities appear in the ionosphere,they can have a serious impact on the propagation of HF EM waves.In this study,the propagation of HF EM waves in ionospheric irregularities was investigated by numerical simulation.First,a twodimensional model of plasma bubbles was used to produce ionospheric irregularities in the ionosphere.A ray-tracing method was then utilized to simulate the propagation of HF radio waves in these ionospheric irregularities.Results showed that the propagation of HF radio waves in the ionosphere was more complex in ionospheric irregularities than without ionospheric irregularities.In addition,corresponding ionograms were synthesized by radio rays propagated in the ionosphere with these irregularities.The synthesized ionograms were then compared with the experimental ionograms recorded by an ionosonde.Results showed that spread F could be simulated on the ionograms when ionospheric irregularities occurred in the ionosphere.This result was consistent with the ionosonde observations.

The high-latitude ionospheric phenomena observed by DPS-4 at Zhongshan Station, Antarctica

Ionograms, which were obtained from February 1995 to January 1999 by a Digisonde Portable Sounder-4 (DPS-4) at Zhongshan Station in Antarctica, have been scaled. The ionograms interpretation has shown various ionosphcric phcnomena occurred in the cusp region. They are particle precipitation effects in the E region. F region magnetic noon phenomena, slant Es phenomena and lacuna. F layer irregularity zone (FLIZ) phenomena, and auroral oval identification. Typical examples of ionograms and ionogram sequences observed at Zhongshan Station are displayed in this paper.

Obtaining the Real Height Profile of Ionospheric Electron Density with Back Propagation Network

A new method to obtain the real height profile of ionospheric electron density is described, which is called 'approximation with network'. Also it has been demonstrated how to solve the group path integral equation with Back Propagation(BP) neural network, and given the computation results with this method for a parabolic model.Simulation results show that the proposed method is effective.

Ionic Disorders Observed in Infants with Severe Wasting at the Yalgado Ouedraogo Teaching Hospital and the Charles de Gaulle Pediatric Teaching Hospital in Ouagadougou, Burkina Faso

Introduction: A higher risk of death is associated with wasting in children if it is not treated properly. The objective of this study was to investigate the ionic disorders observed in infants suffering from severe wasting at Yalgado Ouedraogo Teaching Hospital (YO-TH) and at Charles de Gaulle Pediatric Teaching Hospital (CDG-PTH) in Ouagadougou (Burkina Faso). Methods: This was a retrospective study with a descriptive and analytical aim over the period from January 1, 2016 to December 31, 2020. Results: It concerned infants aged 6 to 24 months hospitalized at YO-TH and at CDG-PTH from Ouagadougou. We included 271 infants. The mean age of the infants was 14.48 ± 5.44 months with 42.07% which was in the age range of [12 - 18] months. On admission to the hospital, the children had an average weight, height and BMI of 6.22 ± 1.32 kg, 0.73 ± 0.07 m and 11.67 ± 1.53 kg/m2. In urban areas 56.46% of children and the main reasons for consultation were fever (88.19%), vomiting (52.80%) and diarrhea (50.20%). Electrolyte disturbances in emaciated infants affected all 8 parameters of the blood ionogram. However, the major disorders were 65.68% hyponatremia, 55.35% hypobicarbonatemia, 41.33% hypoprotidemia and 32.47% hypokalemia in infants aged 6 to 24 months. We found an association between diarrhea and residence with hypokalemia (p = 0.0000) and hypochloremia (p = 0.010), respectively. Conclusion: Severe acute wasting in infants 6 to 24 months of age remains a concern in the hospital setting. The frequency of biochemical disturbances is also high.

Application of the oblique ionogram as vertical ionogram

The vertical ionogram can provide the important ionospheric parameters, such as critical frequency, virtual height and electron density, for ionospheric research. The oblique ionosonde has the ability to detect the ionosphere over sea and other terrain where it is not practical to deploy vertical sounder and provide more ionograms with less transmitting and receiving devices. Therefore, the conversion of the oblique ionogram to vertical ionogram for obtaining the important ionospheric parameters is a very useful inversion technology. The experimental comparison between oblique and vertical detections was carried out in the equatorial ionospheric anomaly (EIA) region of south China on 25 and 26 August 2010. The oblique detecting path was from Wuhan to Shenzhen and the VI ionosonde was located in the midpoint of the oblique path. The oblique ionogram reversion results showed a small deviation of the critical frequency, minimum virtual height as well as the electron density profile of the ionospheric F layer, as compared with the real vertical observations.

Martian ionogram scaling by the Object Tracking Method

The Mars Advanced Radar for Subsurface and Ionosphere Sounding(MARSIS) onboard the Mars Express(MEX) spacecraft started to collect data of the Martian topside ionosphere from May,2005.By now a large amount of ionograms has been obtained.It is important to extract vertical ionospheric information effectively from the ionograms for further study.In this paper a new method,Object Tracking Method(OTM),is proposed to automatically extract the ionospheric electron density profiles by computer.This method is based on three algorithms,namely the Hough transform,region growing segmentation algorithm and moving objects detection method from video sequences.In processing ionosphere echoes are treated as moving objects.The identification ratio of OTM for the MARSIS ionograms is estimated to be around 90%.

Real-Time Automatic Scaling Method of Oblique Ionogram Parameters Based on Morphological Operator and Inversion Technique

Automatic scaling ionogram can get the parameters of ionogram which are vital to ionosphere detecting. In this paper, a new method is proposed to scale F2 layer trace automatically from oblique ionogram based on morphological operator and inversion technique. This method is verified through the comparison of actual detecting data with statistical analysis. The results show that the proposed automatic scaling method has high acceptable rate and is suitable for scaling oblique ionogram with different high angle wave states. It is fast and precise to fit O-mode echoes in F2 layer without the influence from F1 layer. This method could be applied in real-time ionospheric oblique sounding research with high reliability and versatility.