Published Papers

• DISCOVER SUSTAINABILITY, Mangrove forest food products as alternative livelihood measures: mangrove conservation by community in Muara Gembong, Bekasi Regency, Indonesia, Kevin Muhamad Lukman; Jay Mar D. Quevedo; Husen Rifai; La Ode Alifatri; Yaya Ihya Ulumuddin; Yuki Sofue; Yuta Uchiyama; Ryo Kohsaka, 03 Apr. 2025, 6, 1, Scientific journal, 10.1007/s43621-025-01049-4

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• Regional Studies in Marine Science, Elsevier BV, Identifying changes in mangrove landscapes in the Philippines and Indonesia using remote sensing and community perceptions: Towards ecosystem services management, Yuki Sofue; Jay Mar D. Quevedo; Kevin Muhamad Lukman; Ryo Kohsaka, Feb. 2025, 82, 104023, 104023, Scientific journal, 10.1016/j.rsma.2025.104023

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• Environmental and Sustainability Indicators, Elsevier BV, Vegetation cover survey methods at cross-roads: Choice of aerial photography or satellite imagery by Japanese municipalities, Yuki Sofue; Ryo Kohsaka, Dec. 2024, 24, 100471, 100471, Scientific journal, 10.1016/j.indic.2024.100471

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• Refereed, Environmental and Sustainability Indicators, Elsevier BV, Conversion patterns of agricultural lands in plains and mountains: An analysis of underpinning factors by temporal comparison with geographically weighted regression in depopulating rural Japan, Yuki Sofue; Ryo Kohsaka, Jun. 2024, 22, 100346, 100346, Scientific journal, 10.1016/j.indic.2024.100346

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• Journal of Agricultural Science, Canadian Center of Science and Education, Estimation of Rice Yield Considering Heading Stage Using Satellite Imagery and Ground-Based Data in Indonesia, Yuki Sofue; Chiharu Hongo; Naohiro Manago; Gunardi Sigit; Koki Homma; Budi Utoyo, Understanding the temporal and spatial variability in crop yield is considered as one of the key steps in agricultural risk assessment. Therefore, a study of an irrigated area in Cihea, West Java, Indonesia, was conducted to assess rice yield per field using SENTINEL-2 imagery and yield observation data in 2018 and 2019. The study area is located in the Citarum River basin. SENTINEL-2 images were used to derive paddy rice’s growth curve and estimate rice growth stages based on the normalized difference vegetation index. Using these results, the regression model formula using Band 4 (665 nm) and the normalized difference water index in the ripening stage was created (R2 = 0.40, RMSE = 1.21 t/ha). The results from this model were used to generate yield maps, which illustrated a distinct spatial variation in rice yield, such as the average rice productivity in the study area was relatively high, however, the difference between years tended to be small in the upper stream area. The results of this study show that this method is effective in this area to monitor rice yield condition and distribution.Understanding the temporal and spatial variability in crop yield is considered as one of the key steps in agricultural risk assessment. Therefore, a study of an irrigated area in Cihea, West Java, Indonesia, was conducted to assess rice yield per field using SENTINEL-2 imagery and yield observation data in 2018 and 2019. The study area is located in the Citarum River basin. SENTINEL-2 images were used to derive paddy rice’s growth curve and estimate rice growth stages based on the normalized difference vegetation index. Using these results, the regression model formula using Band 4 (665 nm) and the normalized difference water index in the ripening stage was created (R2 = 0.40, RMSE = 1.21 t/ha). The results from this model were used to generate yield maps, which illustrated a distinct spatial variation in rice yield, such as the average rice productivity in the study area was relatively high, however, the difference between years tended to be small in the upper stream area. The results of this study show that this method is effective in this area to monitor rice yield condition and distribution., 15 Jul. 2022, 14, 8, 1, 1, Scientific journal, 10.5539/jas.v14n8p1

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• Refereed, 2021 IEEE International Geoscience and Remote Sensing Symposium IGARSS, IEEE, Estimation of Normal Rice Yield Considering Heading Stage Based on Observation Data and Satellite Imagery, Yuki Sofue; Chiharu Hongo; Naohiro Manago; Gunardi Sigit; Koki Homma; Baba Barus, 11 Jul. 2021, International conference proceedings, True, 10.1109/igarss47720.2021.9554679

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• Refereed, Agriculture, MDPI AG, Transplanting Date Estimation Using Sentinel-1 Satellite Data for Paddy Rice Damage Assessment in Indonesia, Naohiro Manago; Chiharu Hongo; Yuki Sofue; Gunardi Sigit; Budi Utoyo, In Indonesia, there is a need to improve the efficiency of damage assessments of the agricultural insurance system for paddy rice producers affected by floods, droughts, pests, and diseases. In this study, we develop a method to estimate the transplanting date required for damage assessments of paddy rice fields. The study area is the Cihea irrigation district in West Java, Republic of Indonesia. Backscattering coefficients of VH polarization measured by a synthetic aperture radar onboard the Sentinel-1 satellite were used for the estimations. We investigated the accuracy of the estimations of the proposed method by smoothing out the time-series data, applying a speckle filter, and by signal synthesis of the surrounding fields. It was found that these variations effectively improved the estimation accuracy. To further improve the estimation accuracy, the data for all incident angles were used after correcting the incident angle dependence of the backscattering coefficients for three types of data with different incident angles (32°, 41°, and 45°) obtained in the study area. The estimated transplanting date for each field in the test site was compared with the transplanting date obtained through interviews. The standard deviations of the estimation errors for the four cropping periods from March 2018 to February 2020 were found to be ~5–6 days, and the percentages of estimation errors in transplanting dates within 5, 10, and 15 days were estimated to be 69%, 92%, and 97%, respectively. It was confirmed that a sufficiently reliable transplanting date estimation can be obtained ~10–15 days after transplantation., 11 Dec. 2020, 10, 12, 625, 625, Scientific journal, 10.3390/agriculture10120625

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• Refereed, Remote Sensing, MDPI AG, Cropland Mapping Using Fusion of Multi-Sensor Data in a Complex Urban/Peri-Urban Area, Eunice Nduati; Yuki Sofue; Akbar Matniyaz; Jong Park; Wei Yang; Akihiko Kondoh, Urban and Peri-urban Agriculture (UPA) has recently come into sharp focus as a valuable source of food for urban populations. High population density and competing land use demands lend a spatiotemporally dynamic and heterogeneous nature to urban and peri-urban croplands. For the provision of information to stakeholders in agriculture and urban planning and management, it is necessary to characterize UPA by means of regular mapping. In this study, partially cloudy, intermittent moderate resolution Landsat images were acquired for an area adjacent to the Tokyo Metropolis, and their Normalized Difference Vegetation Index (NDVI) was computed. Daily MODIS 250 m NDVI and intermittent Landsat NDVI images were then fused, to generate a high temporal frequency synthetic NDVI data set. The identification and distinction of upland croplands from other classes (including paddy rice fields), within the year, was evaluated on the temporally dense synthetic NDVI image time-series, using Random Forest classification. An overall classification accuracy of 91.7% was achieved, with user’s and producer’s accuracies of 86.4% and 79.8%, respectively, for the cropland class. Cropping patterns were also estimated, and classification of peanut cultivation based on post-harvest practices was assessed. Image spatiotemporal fusion provides a means for frequent mapping and continuous monitoring of complex UPA in a dynamic landscape., 21 Jan. 2019, 11, 2, 207, 207, Scientific journal, 10.3390/rs11020207

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• Refereed, E3S Web of Conferences, EDP Sciences, Imaging of micro-organisms on topsoil particles collected from different landscape in the Gobi Desert, Morine Kuribayashi; Keiichi Kawano; Yuta Demura; Kenji Baba; Yuki Sofue; Purevsuren Tsedendamba; Tamaki Matsumoto; Katsuro Hagiwara; Olaf Karthaus; Kenji Kai; Buho Hoshino, This study shows the results of field experiments of soil particles saltation and laboratory experiments of imaging of the surface structure of dust particles. In the Gobi area, dust occurs when the wind speed at ground level exceeds 7 m/s. It has been reported that bacteria are attached to dust, but the details of its attachment are unknown. It is also expected that these bacteria will fly at the time of occurrence of dust, and fundamental research is important to clarify the relationship between dust components and bacteria., 2019, 99, 01011, 01011, International conference proceedings, 10.1051/e3sconf/20199901011

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• Refereed, Land, MDPI AG, Satellite Monitoring of Vegetation Response to Precipitation and Dust Storm Outbreaks in Gobi Desert Regions, Yuki Sofue; Buho Hoshino; Yuta Demura; Kenji Kai; Kenji Baba; Eunice Nduati; Akihiko Kondoh; Troy Sternberg, 01 Feb. 2018, 7, 1, 19, 19, Scientific journal, True, 10.3390/land7010019

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• Refereed, Journal of Arid Land Studies, Detection of dry lake beds formation and estimate of environmental regime shift in semi-arid region, Buho HOSHINO; Yuki SOFUE; Yuta DEMURA; Tsedendamba PUREVSUREN; Morine KURIBAYASHI; Kenji BABA; Enkhtuvshin ZOLJARGAL; Katsuro HAGIWARA; Jun NODA; Keiichi KAWANO; Olaf KARTHAUS; Kenji KAI, 2018, 28, 109, 113, Scientific journal
• Refereed, Land, MDPI AG, Determining the Frequency of Dry Lake Bed Formation in Semi-Arid Mongolia From Satellite Data, Yuta Demura; Buho Hoshino; Kenji Baba; Christopher McCarthy; Yuki Sofue; Kenji Kai; Tsedendamba Purevsuren; Katsuro Hagiwara; Jun Noda, 08 Dec. 2017, 6, 4, 88, 88, Scientific journal, 10.3390/land6040088

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• Refereed, 2017 IEEE International Geoscience and Remote Sensing Symposium (IGARSS), IEEE, Remote sensing methodology for detection of environmental regime shifts in semi-arid region, Yuki Sofue; Buho Hoshino; Eunice Nduati; Akihiko Kondoh; Kenji Kai; Ts. Purevsuren; Kenji Baba, Jul. 2017, International conference proceedings, 10.1109/igarss.2017.8128153

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• Refereed, Copernicus GmbH, The Interactions Between Precipitation, Vegetation and Dust Emission Over Semi-Arid Mongolia, Yuki Sofue; Buho Hoshino; Yuta Demura; Eunice Nduati; Akihiko Kondoh, Abstract. Recently, droughts have become widespread in the Northern Hemisphere, including in Mongolia. The ground surface condition, particularly vegetation coverage affects the occurrence of dust storms. The main sources of dust storms in the Asian region are Taklimakan and Gobi deserts. The purpose of this study is to examine the relationship between the trend of vegetation variation and the effects of precipitation in the Gobi region. In the Gobi region, precipitation is confined to the period from May to September. We compared the patterns of interactions between precipitation and normalized difference vegetation index (NDVI) for a period of 29 years. The precipitation and vegetation datasets were examined to investigate the trends between 1985–2013. Cross correlation analysis between the precipitation and the NDVI anomalies was performed. Data analysis showed a decreasing trend in precipitation amount and its spatial shift from the east to west part of the region investigated. The vegetation in the area with the lowest precipitation was more sensitive to the precipitation dynamics than those parts with relatively higher values. The most degraded area was the southwest region of Gobi with the least precipitation., 09 Mar. 2017, True, 10.5194/acp-2017-83

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• Refereed, ProScience, Estimates of ground surface characteristics for outbreaks of the Asian Dust Storms in the sources region, Yuta Demura; Buho Hoshino; Yuki Sofue; Kenji Kai; Ts. Purevsuren; Kenji Baba; Jun Noda, source region in the world. However, in recent years the dust storms were found to have out-broken from the pastureland around the dry lakes, dry river channels and degraded pasturelands. Surrounding of dry lake beds, dry river channels and degraded pastures are the main new sources of Asian Dust Storms (ADS). In this study, based on satellite data, we measured of the Critical Ground Surface Condition (CGSC) (such as vegetation index (NDVI), soil moisture index (SMI), terrain roughness index (TRI), and soil particles) in ASD source region, to establish their influence on ADS and
  
  evaluate the mechanism of their occurrence., Dec. 2016, 3, 1, 21, 30, International conference proceedings, 10.14644/dust.2016.004

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• 2015 IEEE INTERNATIONAL GEOSCIENCE AND REMOTE SENSING SYMPOSIUM (IGARSS), ESTIMATES OF CRITICAL GROUND SURFACE CONDITION FOR ASIAN DUST STORM OUTBREAK IN GOBI DESERT REGION BASED ON REMOTELY SENSED DATA, Yuta Demura; Buho Hoshino; Yuki Sofue; Kenji Kai; Ts Purevsuren; Kenji Baba; Jan-Chang Chen; Kaori Mori, 2015, 870, 873, International conference proceedings