Jamjareegulgarn, Punyawi

Preferred name

Alternative Name

Jamjareegulgarn, P.

Main Affiliation

KMITL Prince of Chumphon Campus

punyawi.ja@kmitl.ac.th

Now showing 1 - 10 of 44

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Satellite-derived Spatio-temporal Dynamics of Sea Surface Temperature in the Indonesian and Halmahera Seas During ENSO Events
(2025-03-01)
Lubis, Muhammad Zainuddin
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Purwanto, Budi
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Sobaruddin, Dyan Primana
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Adrianto, Dian
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Dwinovantyo, Angga
Our study investigates the satellite-derived spatio-temporal dynamics of sea surface temperature (SST) in the Indonesian and Halmahera Seas from 2019 to 2021, highlighting its implications for climate change and marine resource management. SST values range from 21.95ºC to 33.50ºC, with pronounced peaks during the East Season (June to October) and lower temperatures in the West Season (January to March). These variations are closely associated with the El Niño-Southern Oscillation (ENSO) and seasonal wind and rainfall patterns. During the East Season, we observed notable upwelling events that indicate significant ecological impacts on fish distribution and fisheries productivity. Our study employed Conductivity-Temperature-Depth (CTD) data to validate satellite observations from the Copernicus Marine Environment Monitoring Service (CMEMS). The results revealed a strong correlation between satellite and observation data (coefficients of 0.91 and 0.93), confirming the reliability of satellite data for monitoring SST in remote marine areas. Our findings underscore the critical importance of continuous SST monitoring for sustainable marine resource management and the integration of satellite data in oceanographic studies. Our study is vital for developing adaptive strategies to address climate variability, particularly El Niño and La Niña events, which significantly influence regional weather patterns and ocean dynamics and ultimately impact global climate systems. Future research should explore the long-term trends of SST toward ongoing climate change and the resilience of marine ecosystems in the face of such variability.
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Variations in Ionospheric Total Electron Content and Scintillation at GPS stations in Uzbekistan and China during the Annular Solar Eclipse on June 21, 2020
(2025-05-01)
Eshkuvatov, H. E.
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Jamjareegulgarn, Punyawi
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Ahmedov, B. J.
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Tillayev, Y. A.
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Ruziev, Z. J.
This study presents a novel investigation into the distinct ionospheric variations observed over China and Uzbekistan during the annular solar eclipse on June 21, 2020. For the first time, we demonstrate the influence of this celestial event on Total Electron Content (TEC) measurements obtained from GPS satellites. We analyzed fluctuations in TEC and the Ionospheric Scintillation Index (S4) across six strategically selected sites—three in Uzbekistan (MTAL, KIT3, MADK) and three in China (JFNG, LHAZ, BJFS) located near the eclipse path, with obscuration levels of 52%, 57%, 58%, in Uzbekistan and 92%, 94% and 95% in China. Our study involved continuous monitoring of ionospheric parameters over three days, from June 20 to June 22, 2020. Results indicated a significant TEC depletion ranging from 10% to 30% on the day of the eclipse. The analysis reveals that both TEC levels and the S4 scintillation index experienced notable reductions during the event, attributed to the decreased ionizing radiation. These findings enhance our understanding of ionospheric dynamics in response to solar eclipses and have important implications for satellite communication and navigation systems.
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Drought vulnerability assessment using morphometric features and extreme precipitation indicators to prioritize sub-basins: AI-based Fuzzy Logic approach
(2026-03-01)
Nigam, Utkarsh
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Patel, Vinodkumar M.
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Patel, Dhruvesh P.
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Jodhani, Keval H.
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Gupta, Nitesh
The identification of watersheds and extraction of drainage networks are essential for effective hydrological and geomorphological modelling. This study investigates the influence of morphometric factors and extreme precipitation events on the hydrological responses of the Sabarmati River Basin (SRB), India, to identify the drought-vulnerable sub-basins. Watershed prioritization was carried out using satellite remote sensing, GIS, and secondary data, including topographic sheets and ASTER DEM with a spatial resolution of 90 m. The SRB was divided into nine sub-watersheds, and 28 morphometric parameters were evaluated, comprising 07 linear, 15 areal, and 06 relief parameters. A compound factor (CF) was derived using multi-criteria decision-making techniques such as Weighted Sum Analysis (WSA), Principal Component Analysis (PCA), Analytic Hierarchy Process (AHP), Fuzzy-AHP (FAHP), and TOPSIS. Sub-watersheds were ranked based on CF value, where a lower CF indicated higher priority for runoff management strategies. Additionally, 42 years of precipitation data were analysed using the Standardized Precipitation Index (SPI) at timescales ranging from 3 to 24 months to assess trends in drought and extreme precipitation events. The analysis indicate decline in runoff potential in several sub-basins, however others (e.g., SB2, SB3, SB4, SB5) exhibit positive precipitation trends, making them suitable for runoff enhancement. This integrated methodology offers a comprehensive framework for managing sub-basins, optimizing runoff potential, and supporting sustainable water conservation. The results provide actionable insights for policymakers and planners to better utilize the SRB water resources based on its geomorphological and climatic characteristics.
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Climate thresholds and yield elasticity of durian, mangosteen, and coffee under hydroclimatic variability in Thailand
(2026-08-01)
Ansari, Kutubuddin
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Tanır Kayıkçı, Emine
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Jamjareegulgarn, Punyawi
This study examines the empirical relationships between hydroclimatic variability and the yields of durian, mangosteen, and coffee across Thailand using meteorological observations from 56 stations and provincial level yield statistics for 2008 to 2024. An integrated statistical framework was applied, including exploratory correlation analysis, nonlinear quadratic additive modelling, lagged climate response analysis, elasticity estimation, model comparison, mangosteen regional sensitivity analysis, and a Climate Risk Index (CRI). The results show clear spatial gradients in temperature, humidity, and precipitation across the six agroclimatic regions of Thailand, broadly corresponding to regional crop productivity patterns. Annual anomaly analysis indicates that warm and humid years are generally associated with higher durian and mangosteen yields, whereas excessive rainfall and warming are associated with reduced coffee productivity. Pairwise linear correlations between annual climate variables and crop yields are generally weak, suggesting that simple linear models may not fully capture crop climate relationships. Nonlinear modelling indicates approximate empirical temperature turning points near 28.0°C for durian, 27.3°C for mangosteen, and 26.6°C for coffee, with humidity related turning points around 76–78%. Lagged climate response models suggest that multi-year hydroclimatic conditions may influence perennial crop productivity, particularly humidity for durian, precipitation for coffee, and temperature and precipitation for mangosteen. The mangosteen sensitivity analysis shows that humidity and precipitation thresholds are affected by regional composition, especially when marginal production regions are included. The CRI formulation under the equal weight, mangosteen shows the highest rainfall related climate risk signal, while coffee is more sensitive to temperature related risk and durian shows moderate vulnerability to prolonged humid and wet conditions.
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Development of a Global Climate Model for Atmospheric Temperature Using Machine Learning
(2026-01-01)
Okoh, Daniel
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Awuor, Adero
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Ochieng, George
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Baki, Paul
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Habarulema, John Bosco
This article presents a novel three-dimensional global model of atmospheric temperature developed using Artificial Neural Networks (ANNs) trained on radio occultation (RO) data from the COSMIC I and COSMIC II satellite missions. Over 14.7 million quality-controlled profiles were used, providing approximately 9.5 billion data points that capture temperature variability across latitude, longitude, altitude (0-60 km), and time (2006-2025). The global domain was divided into 1296 spatial grid cells (10° × 5°) to enable localized ANN training and ensure efficient handling of regional atmospheric dynamics. Model performance was evaluated through cross-validation and independent testing against radiosonde measurements from 684 stations worldwide. Results show mean absolute errors of 1.5 °C-4.5 °C and root-mean-square errors of 2.5 °C-6.5 °C, with best performance in the tropical troposphere and increasing errors toward high latitudes. The model successfully reproduces key climatological structures (including the tropospheric lapse rate, stratospheric inversion, and seasonal hemispheric asymmetries), and accurately captures diurnal and annual thermal cycles. Long-term simulations (2006-2025) reveal a distinct tropospheric warming trend (∼+0.07 °C per year at 11 km) and a corresponding stratospheric cooling (∼-0.03 °C per year near 32 km), consistent with established satellite and reanalysis records. These results demonstrate that ANN-based frameworks can effectively model global atmospheric thermal structure and evolution, providing a scalable approach for future climate monitoring and forecasting applications.
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Sustainable groundwater management through water quality index and geochemical insights in Valsad India
(2025-12-01)
Jodhani, Keval H.
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Gupta, Nitesh
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Dadia, Sanidhya
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Patel, Harsh
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Patel, Dhruvesh
Groundwater quality assessment is crucial for sustainable water resource management and public health protection. This study evaluated the Water Quality Index (WQI) of groundwater in the southern part of Gujarat focusing on the Valsad District. Groundwater in this region occurs in porous, unconsolidated formations and fracture formations, both under groundwater table conditions and confined aquifers. Various parameters including Nitrate (NO<inf>3</inf>¯), pH, Calcium (Ca2+), Electrical Conductivity (EC), Total Hardness (TH), Magnesium (Mg2+), Total Dissolved Solids (TDS), Potassium (K+), Sodium (Na+), Sulphate (SO<inf>4</inf>2−), Chloride (Cl¯), Bicarbonate (HCO<inf>3</inf>¯), Silicate (SiO<inf>4</inf>4−), and Fluoride (F¯) were analyzed to assess groundwater quality. Results indicate that most of the parameters fell within acceptable permissible limits for drinking water, except for Muli and Nanaponda villages with the parameters Cl¯, EC, and TDS exceeding the permissible limit. The WQI analysis revealed that 31.25% of water samples from different villages were found in the excellent category (WQI < 25). About 68.75% of samples from 16 villages were classified as good quality category (WQI ∼ 25–50). Overall, the WQI ranged from 14.20 to 41.98, suggesting that groundwater in the Valsad district is suitable for drinking. The Piper diagram analysis of water samples collected from the field indicated unique geochemical compositions and good water. The diagram revealed that the Ca2+ was the predominant cation, followed by K+, Na+, and Mg2+. Among the anions, the HCO<inf>3</inf>− showed the highest concentrations, followed by SO<inf>4</inf>2−, NO<inf>3</inf>−, and Cl−. This dominance pattern demonstrated that the weathering of minerals significantly influenced the groundwater. This study recommends remediation for areas with reduced water quality to address geogenic and anthropogenic contamination.
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Ionospheric gradients in multi-constellation global navigation satellite system signals onboard UAV using GIM and Klobuchar model over Thailand region
(2026-07-01)
Ansari, Kutubuddin
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Panda, Sampad Kumar
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Venkatesh, Kavutarapu
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Jamjareegulgarn, Punyawi
The effects of the ionosphere on Global Navigation Satellite System (GNSS) signals have been a focal point of research nowadays. During adverse ionospheric conditions, ionospheric gradients become more pronounced and disruptive compared to quiet days, potentially leading to increased positioning errors or loss of satellite signal lock. We introduce an ionospheric spatial gradient estimation method to detect the anomalous gradients from multi-constellation GNSS signals (i.e., GPS, GLONASS, and Galileo) signals recorded by the onboard sensor of flying real-time kinematic unmanned aerial vehicle (RTK UAV) over the Thailand region. We employ the Klobuchar model and global ionospheric maps (GIMs) for estimating the slant total electron contents (STECs) and the corresponding ionospheric spatial gradients between base station and rover (RTK UAV) receivers among the studied multi-constellation systems. The results show that the STEC values estimated from IGS-GIM are larger than those computed by Klobuchar model. Such kind of gradient variation cannot show a perfect correlation due to limited accuracy of Klobuchar model parameters. As for our analysis, the ionospheric spatial gradients estimated from GPS satellites are higher than those calculated from GLONASS and Galileo satellites due to the smallest differences between the two successive positions of flying rover estimated from GPS satellites. The outcomes from this study complement the multi-GNSS cooperative strategy for monitoring ionospheric gradients, thereby mitigating the adverse effects in dynamic positioning and navigation solutions over low-latitude regions.
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Multi-Instrument Analysis of Ionospheric Equatorial Plasma Bubbles over the Indian and Southeast Asian Longitudes During the 19–20 April 2024 Geomagnetic Storm
(2025-03-01)
Panda, Sampad Kumar
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Rajana, Siva Sai Kumar
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Vivek, Chiranjeevi G.
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Dabbakuti, Jyothi Ravi Kiran Kumar
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Jamir, Wangshimenla
In this study, we explored the occurrence of near-sunrise equatorial plasma bubbles (EPBs) and inhibition of dusk-time EPBs during the geomagnetic storm (SYM-Hmin= −139 nT) of 19–20 April 2024 using multi-instrument observations over the Indian and Southeast Asian longitude sectors. The initial phase of this storm commenced around 0530 UT on 19 April 2024 and did not manifest any visible alterations in the ionospheric electric fields during the main phase of the storm, which corresponded to a period between post-sunset to midnight over the study region. However, during the recovery phase of the storm, the IMF Bz suddenly flipped northward and was associated with an overshielding of the penetrating electric fields, which triggered the formation of near-sunrise EPBs. Interestingly, the persistence of EPBs was also noticed for more than three hours after the sunrise terminator. Initially, sunrise EPBs were developed in the Southeast Asian region and later drifted toward the Indian longitude region, along with the sunrise terminator. Moreover, this study suggested that the occurrence of EPBs was suppressed due to the altered storm time electric fields at the dip equatorial region across the 70–90°E longitude sector in the recovery period. This study highlighted that even moderate geomagnetic storms can generate near-sunrise EPBs in a broader longitude sector due to penetrating electric fields in overshielding conditions, which can significantly affect trans-ionospheric signals.
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Development of Geomatics Technology Curriculum for Associate Degree Programs within Project-Based Learning (PBL)
(2025-01-01)
Lubis, Muhammad Zainuddin
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Sari, Luthfiya Ratna
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Chayati, Siti Noor
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Rassarandi, Farouki Dinda
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Irawan, Sudra
Geomatics technology program has strategically implemented project-based learning (PBL) in its curriculum to improve the quality of learning and prepare competent graduates in the field of geomatics. Student learning outcomes have been aligned with the Indonesian National Qualifications Framework (KKNI) Level 5, which includes capabilities in terrestrial surveying, hydrography, remote sensing, geographic information systems, and cartography. Through the PBL approach, the learning process is designed to develop students' abilities in identifying and solving real problems in the field of geomatics, as well as communicating these solutions effectively. This method encourages the development of student creativity, critical thinking, and collaboration. Alignment of Program Educational Objectives (PEOs) with the institutional mission and industry needs reflects the study program's commitment to providing superior and relevant learning experiences, as well as preparing professional and ethical graduates. The percentage of achievement of PEO and PLOs (Program Learning Outcomes) from 60% in 2019 to almost 80% in 2023, and the increase in the number of students during the period, indicate the success of the educational program in geomatics technology programs. The difference in academic achievement and behavior between the fields of hydrographic surveying (75% achievement, 17% plagiarism, 172 submissions) and oceanography (72.40% achievement, 17.40% plagiarism, 160 submissions) during 2019-2023. Through the implementation of comprehensive and integrated PBL, the geomatics technology program can effectively equip students with the technical competencies, problem-solving skills, and understanding of professional ethics needed to face challenges in the field of geomatics.
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Was the Unseasonal Development of Post-Sunset Equatorial Plasma Bubbles in Southeast Asia Driven by Quasi-2-Day Planetary Waves?
(2025-03-01)
Dai, Guofeng
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Li, Guozhu
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Otsuka, Yuichi
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Hu, Lianhuan
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Sun, Wenjie
Previous studies suggest that the planetary waves in mesosphere and low thermosphere (MLT) could modulate the occurrence of equatorial plasma bubbles (EPBs) via altering post-sunset F layer height. Using simultaneous observations by Global Navigation Satellite System receiver networks, two ionosondes separated by about 10° in longitude, high frequency and very high frequency radars, we investigated the day-to-day variations of post-sunset F layer height and EPB occurrence in southeast Asia during the quasi-2-day planetary wave (QTDW) event in July 2023. The results showed that the post-sunset F layer height over Bac Lieu (9.3°N, 105.7°E) and EPB occurrence had a quasi-2-day (QTD) variation. However, such a 2 day variation of F layer height was confined in a very limited longitude, that is contradictory to the planetary scale characteristics of QTDW. We suggest that the QTD variations of post-sunset F layer height and EPB occurrence over the specific location were not necessarily due to the QTDW in MLT. The local seeding source, as characterized by satellite traces in ionosonde ionograms, could drive the small-scale longitudinal structure of F layer height and play an important role in shaping the QTD variation of EPB. The results implicate that the connection between planetary waves and the EPB occurrence over a specific location should be interpreted carefully, even if the day-to-day variation of post-sunset F layer height shows periodic behavior with planetary wave scale.

Jamjareegulgarn, Punyawi

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