Kenpankho, Prasert

Preferred name

Kenpankho, Prasert

Alternative Name

Kenpankho, P.

Main Affiliation

School of Industrial Education and Technology

prasert.ke@kmitl.ac.th

Now showing 1 - 10 of 20

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On improvement in representation of foE in IRI
(2017-07-15)
Yang, Zhe
;
Ssessanga, Nicholas
;
Tran, Lan Thi
;
Bilitza, Dieter
;
Kenpankho, Prasert
Improvements in representation of foE for use in the International Reference Ionosphere (IRI) model are investigated. The IRI model currently depends on the 12-month running mean of sunspot number to estimate the foE. Using the F10.7 daily and F10.7_81 indices as the new model drivers, results are compared to ionosonde measurements at low, mid and high latitudes during solar minimum and solar maximum. Results show that the IRI model estimates the foE parameter better at low-mid latitudes than at high latitudes, specifically during solar maximum. Using the F10.7 indices to derive the IRI model improves estimates of foE, specifically at low-mid latitudes. The F10.7_81 index was found to perform better than the daily F10.7 index. Improvements during solar maximum and during solar minimum were on average 3.5% and 1%, respectively. Therefore, the F10.7_81 index is recommended as IRI model driver for foE estimates.
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Variation of ionospheric slab thickness observations at Chumphon equatorial magnetic location
(2011-01-01)
Kenpankho, P.
;
Supnithi, P.
;
Tsugawa, T.
;
Maruyama, T.
This study presents the diurnal and seasonal variations of slab thickness at the equatorial magnetic latitudes in Thailand during 2004-2006, corresponding to the declining part of low solar activity. The GPS-derived total electron content (TEC) and the maximum electron density of the F-region (N <inf>m</inf>F<inf>2</inf>) are used to compute the slab thickness (&tau) at the Chumphon station (10.72°N, 99.37°E), located near the magnetic equator. The results show that large peaks of slab thickness exist during the pre-sunrise hours in all three seasons at Chumphon when compared with other latitudes. The maximum value of slab thickness occurs when the peak electron density in the F<inf>2</inf> region is at the lowest level. During daytime, the slab thickness ranges from 200 kilometers to 580 kilometers for all seasons. During nighttime, the maximum value of slab thickness is 1250 kilometers in the summer of 2004. Moreover, the diurnal variation shows two minima that appear around 0900 LT and 1900 LT, during the post-sunrise and sunset hours. The seasonal variations show that the average slab thickness daily value is greater during summer and winter than those during equinox. Our study finds that the slab thickness at Chumphon located near the equatorial latitude is much larger than those found at low, mid, and high latitudes. The difference in slab thickness between the equatorial latitude and other zones is explained by the lack of plasma flow from the plasmasphere to the F<inf>2</inf> region at the magnetic equator. Copyright © The Society of Geomagnetism and Earth.
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A Novel Short-Term Prediction Model for Regional Equatorial Plasma Bubble Irregularities in East and Southeast Asia
(2025-02-01)
Zhao, Xiukuan
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Li, Guozhu
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Xie, Haiyong
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Hu, Lianhuan
;
Sun, Wenjie
Equatorial plasma bubble (EPB) irregularities can significantly impact satellite-based communication and navigation systems. Accurate prediction of EPB occurrence is essential for mitigating these impacts. Using the GNSS receiver network and ionosonde data from East and Southeast Asia during 2010–2021, and the rate of TEC change index to characterize the occurrence of EPB irregularities, we developed a novel Spatio-Temporal deep learning model for regional EPB irregularities short-term Prediction (STEP). The model integrates the convolutional neural network and long short-term memory (LSTM) network, together with attention mechanisms, to capture both spatial and temporal features of regional ionospheric irregularities. The results show that for 5-min forecast, the STEP model achieves a root mean square error (RMSE) of 0.062 TECU/min and an R2 of 0.818, reducing RMSE by 19.48% compared to LSTM and 27.06% compared to gated recurrent unit model. For 60-min prediction, the STEP model can still achieve reasonable accuracy with an RMSE of 0.110 TECU/min and an R2 of 0.482, showing significant improvement over traditional models. The equatorial F layer height and regional TEC fluctuations were identified as the most critical factors for predicting the generation and duration of EPB irregularities, respectively. The spatial and temporal distributions of EPB irregularities, including their latitudinal variation and delayed onset after sunset, and the occurrence across different days in East and Southeast Asia, were well predicted by the STEP. It is expected that the STEP model would provide a valuable tool for improving the resilience of GNSS against ionospheric scintillations induced by EPB irregularities.
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Improving the modeling of bottomside thickness parameters over midlatitudes and high latitudes
(2020-02-01)
Jamjareegulgarn, Punyawi
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Supnithi, Pornchai
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Kenpankho, Prasert
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Wichaipanich, Noraset
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Nayak, Chinmaya
This paper investigates bottomside thickness parameters at Digisonde stations over midlatitude and high latitude regions, and compares the diurnal, seasonal, and solar activity variations in 2014 and 2009. The geographic latitudes of high latitude considered in this work are located beyond ±60° and those of midlatitude are located between ±40° and ±60°. The IRI-modeled B0 with ABT-2009 option (B0_IRI) are also examined and compared with four kinds of the B0 values, i.e., the observed B0 (B0_obs) from GIRO, the computed B0 following to Jamjareegulgarn et al. (2017a) (B0_old), the calculated B0 with a correction factor regarding to Jamjareegulgarn et al. (2017b) (B0_new), and the B0 with an average correction factor (B0_new_c_av). The average correction factors are proposed additionally in this work so as to assist occasionally the experimental B0 nonexistence of Digisonde which are equal to 0.2658 and 0.2058 for midlatitudes and high latitudes, respectively. Results show that the diurnal variations of B0_new and B0_new_c_av are in a good agreement with those of B0_obs evidently compared with those of B0_IRI and B0_old at every station during the three seasons over high and middle latitudes. During the three seasons, the diurnal variations of B0_new_c_av show similar trends and are close to one another with the B0_obs and the B0_new with small deviations. The differences between the B0obs and the B0_new_c_av also show similar trends and are close to one another with those between the B0obs and the B0_new. In contrast, the B0_IRI with ABT-2009 option seems to predict the B0 values poorly during the three seasons at high latitudes and some seasons at midlatitudes. The proposed B0_new is useful for computing approximately the observed B0 and the ionogram-based total electron content (ITEC) of Digisonde, and the plasma scale height over midlatitudes and high latitudes.
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Comparison of e layer critical frequency over the Thai station Chumphon with IRI
(2015-04-15)
Wongcharoen, P.
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Kenpankho, P.
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Supnithi, P.
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Ishii, M.
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Tsugawa, T.
In this research, as a part of working towards improving the IRI over magnetic equatorial region, the critical frequency of E layer in the ionosphere (foE) derived from the ionogram at Chumphon station (10.72°N, 99.37°E), Thailand, during 2005-2008 is analyzed. The Chumphon station is located in the magnetic equatorial region at the magnetic latitude of 3.22°N. The seasonal variation of the foE measurements is compared to the IRI foE predictions with the optional input in the sunspot number (Rz12) and the solar radio noise flux (F10.7). For a declining phase of the solar cycle 23 during the year 2005-2008, the study shows that the IRI foE prediction is similar to the foE observation during the period of 2005-2008. The maximum differences between the IRI foE prediction and foE observation are about 500 kHz during daytime period of 2007.
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Ionospheric disturbances as precursor signals of the March 28, 2025, Myanmar earthquake
(2026-03-15)
Pansong, C.
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Ruttanaburee, S.
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Pornsopin, P.
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Kenpankho, P.
This study examined the ionospheric response associated with the Mw 7.7 Myanmar earthquake on March 28, 2025, using GPS-derived Total Electron Content (TEC) data from seven GNSS stations across Thailand. TEC variations were analyzed alongside Dst and Kp indices, as well as ionosonde-derived parameters, namely the critical frequency of the F2 layer (foF2), the peak height of the F2 layer (hmF2), the disturbances in NmF2, and the slab thickness (τ), which were obtained from three IGS-supported stations. We detected abnormal variations in TEC approximately 15 days before the earthquake (13–27 March 2025), characterized by alternating positive and negative deviations. The TEC exhibited alternating positive and negative deviations throughout the analysis period, reflecting ionospheric variability prior to the earthquake. During the early period (13–18 March), the deviations remained within approximately ±6 TECU. However, from 19 to 21 and 23–24 March, moderate fluctuations were observed, particularly at mid- and low-latitude stations (UTHG, THBK, THCP, and THPK), where ΔTEC ranged from ±6 to 10 TECU. The TEC decrease occurred on 25 March under weak geomagnetic conditions (Dst > −30 nT) at the northern stations MAEH (−18.40 TECU), THCM (−15.65 TECU), and NANN (−15.73 TECU), marking the most pronounced negative anomaly observed during the study period. Subsequently, on 26–27 March, TEC values recovered to positive anomalies of +4 to +10 TECU, indicating a return to normal ionospheric conditions. To objectively identify pre-seismic ionospheric anomalies, a Median Absolute Deviation (MAD) approach was applied using a ±1.34MAD threshold. This statistical technique effectively detects subtle deviations while minimizing transient noise. The results reveal coherent TEC depletions across multiple stations on 25 March, suggesting the presence of localized ionospheric disturbances potentially related to seismo-ionospheric processes rather than geomagnetic effects. Furthermore, concurrent anomalous increases in foF2 and hmF2, along with a reduction in slab thickness near the epicentral region, indicate vertical uplift of the F2 layer, consistent with possible Lithosphere–Atmosphere–Ionosphere Coupling (LAIC) mechanisms.
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Galileo-E6 Bandwidth Frequency Filter Design for Galileo Receiver
(2021-09-01)
Chinnapark, Surachet
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Onanong, Narumol
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Pattameak, Julongkorn
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Mekpradab, Teerachet
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Kenpankho, Prasert
This research discusses about the combination of the LPF and HPF to perform band reject filter. Therefore, there are two combination also in designing band reject filter. The aim of this combination to get know is there have an influence on the performance of band reject filter was designed by using the frequency of the GalileoE6 with bandwidth 40 MHz. This filter is used a Butterworth filter which is presented in this study. These filter circuit is composed 4rd order. In addition to, the combination between LPF and HPF forming to a band reject filter is designed. As a result, the filter design on the frequency of Galileo-E6 is successfully used in band reject filter.
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GNSS Receiver Bias Model for Near Real Time TEC Monitoring at Low Latitude, Thailand
(2026-01-01)
Kenpankho, Prasert
;
Maichuen, Samatchaya
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Phothila, Prarinya
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Zhang, Jianfeng
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Keokhumcheng, Thanapon
This research proposes and investigates GNSS receiver bias modeling for near real time total electron content (TEC) monitoring across 16 multi-frequency GNSS stations in low latitude, Thailand, from 2022-2024. By applying a refined methodology based on Kenpankho et al. (2021) and integrating IONOLAB-BIAS for single station bias estimation, the research corrects for satellite and receiver inter-frequency biases to enhance TEC accuracy. Results show a consistent upward trend in TEC values, reflecting increased latitudes, seasonal ionospheric activity, and geomagnetic storms. Comparative analysis with the IRI 2020 model using correlation coefficients and RMSE reveals spatial and temporal variation, with near equatorial latitude stations showing strong alignment than upper low latitude stations. The results highlight the importance of localized GNSS-based TEC models for improving satellite positioning accuracy in equatorial regions and highlight the limitations of global models under dynamic ionospheric conditions.
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Comparison of GPS TEC measurements with IRI TEC prediction at the equatorial latitude station, Chumphon, Thailand
(2011-01-01)
Kenpankho, P.
;
Watthanasangmechai, K.
;
Supnithi, P.
;
Tsugawa, T.
;
Maruyama, T.
We have analyzed the total electron content (TEC) derived from dual-frequency GPS receivers (GPS TEC) at the Chumpon station, Thailand, during the period 2004-2006. The diurnal, monthly, and seasonal variation in the measured TEC is compared with the TEC derived from the IRI-2007 model as well as the TEC obtained from the International GNSS service (IGS). To date, TEC data at equatorial latitudes are limited. The Chumphon station (10.72 °N, 99.37°E) is located at the equatorial latitude and the dip latitude of 3°N. The TEC from the IRI-2007 model is based on the actual F<inf>2</inf> plasma frequency (f<inf>o</inf>F<inf>2</inf>) measurement. The results of our study show that the TEC derived from the IRI-2007 model agrees with the GPS TEC data mostly in the morning hours, but that it generally underestimates the GPS TEC. The maximum differences are about 15 TECU during the daytime and 5 TECU during the nighttime. The underestimation is more evident at daytime than at nighttime. The noon-bite out phenomena are clearly seen for the IRI-2007 TEC, but not on the IGS TEC and GPS TEC. The general underestimation of the IRI-2007 model can be explained from the exclusion of the plasmasphere, whereas the large difference during noon bite-outs is caused by the difference in the slab thickness in the ionosphere between the IRI-2007 model and the actual measurement. When compared with the TEC from the IGS model, the TEC measurements at Chumpon appear to be quite similar. Copyright © The Society of Geomagnetism and Earth.
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Galileo-E5a Bandwidth Frequency Filter Design for Galileo-E5a Receiver
(2022-09-01)
Mekpradab, Teerachet
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Onanong, Narumol
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Chinnapark, Surachet
;
Pattameak, Julongkorn
;
Kenpankho, Prasert
This study focused on the design of the band-reject filter on the frequency of the Galileo satellite by providing bandwidth at the cut-off frequency equal to the bandwidth of the Galileo-E5a. The selecting of response characteristic is Butterworth's maximally flat, amplitude-frequency response of the band-reject filter. This poster shows the combination of the LPF and HPF to perform a band-reject filter. Therefore, there are two combinations also in designing for the band-reject filter. This combination aims to influence the performance of the band-reject filter. Band rejects filter design using the frequency of the Galileo-E5a with bandwidth is 25 MHz.using a Butterworth filter which is presented in this poster. The circuit is composed 3rd.order.Moreover, the combination between LPF and HPF is designed to act as a band-reject filter. As a result, we can filter the frequency of Galileo-E5a by using the band-reject filter.

Kenpankho, Prasert

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