Hisao Takahashi's research while affiliated with National Institute for Space Research, Brazil and other places

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Publications (2)

Geographic distributions of the Digisonde (red asterisk) and GPS...
Examples of data used in the model building process. (a and b) S4 and...
Construction process of the prediction model.
The confusion matrix showing correct (TP and TN) and incorrect (FN and...
+4 The accuracy, area under the curve and F1 of prediction models using...
The Prediction of Day‐to‐Day Occurrence of Low Latitude Ionospheric Strong Scintillation Using Gradient Boosting Algorithm
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  • Dec 2021
Ionospheric scintillations caused by equatorial plasma bubbles (EPBs) can seriously affect various high technology systems based on Global Navigation Satellite System (GNSS) signals at equatorial and low latitudes. A reliable prediction of ionospheric scintillation occurrence is critical to relieve the effect. Using the long‐term ground‐based GNSS...
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Climatology of equatorial and low-latitude F region kilometer-scale irregularities over the meridian circle around 120°E/60°W
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  • Jan 2021
The occurrences of equatorial plasma bubble (EPB) irregularities over Asian and American sectors often show a different behavior due to significantly different geometries of the geomagnetic field. By using the GPS total electron content observations over equatorial and low latitudes sectors of Asian (about 120°E) and American (about 60°W) during 19...
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Citations

... A four layers neural network is trained using a database of 13 parameters to predict the level of the S 4 index, which is discretized in two levels of not strong and strong with lead time of hours (de Lima et al., 2015). A prediction model of low-latitude ionospheric strong scintillation has been built based on the gradient boosting algorithms using long-term ground-based GPS receiver and ionosonde data over the Brazilian longitude sector (Zhao et al., 2021). However, most of these studies are limited to L-band ionospheric scintillation events and the data size employed are limited. ...
Reference: Precursors Identification for Forecasting UHF‐Band Ionospheric Scintillation Events Over Chinese Low‐Latitude Region by Deep Learning
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... In Equinox (Figures 4c and 4f), the irregularities at nighttime, in general, had low occurrence rates (and mainly occurred in American and African sectors). For the nighttime irregularities under different seasons and solar activities, their distributions have been well studied in previous studies (e.g., Li et al., 2007;Su et al., 2006;Xiong et al., 2010;Yizengaw et al., 2013;Zhao et al., 2021) and will not be discussed here. ...
Reference: The occurrence characteristics of daytime irregularities in the low latitude F region topside at solar minimum revealed by ICON
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