Article
Environmental Sciences
Sang-Eun Park, Yoon Taek Jung, Hyun-Cheol Kim
Summary: This study explores the possibility of using combined interpretation of optical and SAR data to identify and understand the spatiotemporal changes in the permafrost active layer. The results show a significant correlation between winter changes observed in SAR data and summer land cover changes observed in optical data. Additional data from independent sources also support this relationship.
REMOTE SENSING OF ENVIRONMENT
(2022)
Article
Environmental Sciences
Maurizio Santoro, Oliver Cartus, Johan E. S. Fransson
Summary: This article presents a study on the estimation and tracking of carbon density in Swedish forests using satellite L-band observations. The study found that while there were substantial uncertainties at the pixel level, the average values at landscape and county scale were consistent with existing data, and Swedish forests acted as a carbon sink between 2010 and 2015.
REMOTE SENSING OF ENVIRONMENT
(2022)
Article
Environmental Sciences
Mark L. Williams, Anthea L. Mitchell, Anthony K. Milne, Tim Danaher, Geoff Horn
Summary: This study utilizes L-band synthetic aperture radar (SAR) data to estimate vegetation indicators. It proposes a method to reduce the influence of external factors by correcting terrain slope and cross-track tendencies, and normalizing backscatter differences using linear least squares difference minimization. The method is applied in New South Wales, Australia, and demonstrates improved estimation of vegetation and provides spatially explicit forest structural information.
REMOTE SENSING OF ENVIRONMENT
(2022)
Article
Forestry
Igor da Silva Narvaes, Joao Roberto dos Santos, Polyanna da Conceicao Bispo, Paulo Mauricio de Alencastro Graca, Ulisses Silva Guimaraes, Fabio Furlan Gama
Summary: We developed a method for estimating above-ground biomass (AGB) from polarimetric SAR images. The model used power and phase-radar attributes, as well as attributes from Touzi decomposition. The proposed model showed good predictive capacity and a positive correlation with the validation results.
Article
Environmental Sciences
Maurizio Santoro, Oliver Cartus, Johan E. S. Fransson
Summary: This study revisited the Water Cloud Model (WCM) for estimating forest biomass-related variables, aiming to reduce systematic retrieval errors associated with empirical assumptions in the model by exploring physically-based, Light Detection and Ranging (LiDAR)-aided, model parameterization at a larger scale. The integration of allometries in the WCM effectively reduced estimation errors, demonstrating the potential for providing large-scale estimates of biomass-related variables using L-band backscatter observations.
REMOTE SENSING OF ENVIRONMENT
(2021)
Article
Engineering, Electrical & Electronic
Soni Darmawan, Ita Carolita, Rika Hernawati, Dede Dirgahayu, Agustan, Didin Agustian Permadi, Dewi Kania Sari, Widya Suryadini, Dhimas Wiratmoko, Yohanes Kunto
Summary: This study explores the scattering model of oil palm phenology using spaceborne X-, C-, and L-band polarimetric Synthetic Aperture Radar (SAR) imaging. Different scattering characteristics were observed for X-, C-, and L-band polarimetric SAR, with the potential of C-band on TV polarization. The results suggest that the scattering model has potential for identifying oil palm phenology in Indonesia, with future improvements needed for accuracy.
JOURNAL OF SENSORS
(2021)
Article
Ecology
Rakesh Fararoda, R. Suraj Reddy, G. Rajashekar, T. R. Kiran Chand, C. S. Jha, V. K. Dadhwal
Summary: Accurate estimation of spatial above ground biomass in tropical forests is crucial for understanding the global carbon cycle. This study combines field inventory data with optical and microwave images to spatially estimate biomass over Indian forests using a random forest approach. The inclusion of multisource data significantly increases the saturation range and reduces estimation error.
ECOLOGICAL INFORMATICS
(2021)
Article
Ecology
Unmesh Khati, Gulab Singh
Summary: This study explores the potential of combining backscatter with polarimetric SAR interferometry (PolInSAR) estimated forest stand height for improved above-ground biomass (AGB) estimation. The results demonstrate the potential of this synergistic combination for AGB mapping over a tropical forest range in India.
FRONTIERS IN FORESTS AND GLOBAL CHANGE
(2022)
Article
Environmental Sciences
Wei Chen, Qihui Zheng, Haibing Xiang, Xu Chen, Tetsuro Sakai
Summary: This study utilized PolInSAR technology to estimate forest canopy height based on full-polarized ALOS/PALSAR data, proposing multiple algorithms such as differential DEM, coherent amplitude, coherent phase-amplitude, and RVoG_3 for comparison. By introducing change rate and slope, the estimation model was optimized to improve accuracy in forest canopy height estimation.
Article
Environmental Sciences
Konrad Wessels, Xiaoxuan Li, Alexandre Bouvet, Renaud Mathieu, Russell Main, Laven Naidoo, Barend Erasmus, Gregory P. Asner
Summary: Global savannas, as the third largest carbon sink, are facing rapid changes. This study tested the ability of L-band SAR to track changes in savanna vegetation structure and found that it has a higher sensitivity than previous studies suggested.
REMOTE SENSING OF ENVIRONMENT
(2023)
Article
Environmental Sciences
Helen Blue Parache, Timothy Mayer, Kelsey E. Herndon, Africa Ixmucane Flores-Anderson, Yang Lei, Quyen Nguyen, Thannarot Kunlamai, Robert Griffin
Summary: A study using ALOS PALSAR satellite data for forest height estimation showed comparable results to previous research. Despite limitations in data quality and quantity, the use case in Savannakhet, Lao demonstrated the applicability of these techniques for estimating FSH in tropical forests.
Article
Environmental Sciences
Hiroto Nagai, Takahiro Abe, Masato Ohki
Summary: The study proposes a method called NoBADI to exclude water surfaces during floods, reducing uncertainty in flood mapping results and enabling quicker decision-making in crisis management.
Article
Geochemistry & Geophysics
Punithraj Gururaj, Pruthviraj Umesh, Amba Shetty
Summary: This study focused on using ALOS PALSAR-2 and polarization decomposition techniques to retrieve surface soil moisture, with Van Zyl decomposition showing the best results. A semi-empirical model was developed with high accuracy compared to existing models, demonstrating the applicability and effectiveness of ALOS PALSAR-2 in soil moisture retrieval.
Article
Engineering, Geological
Xiaojie Liu, Chaoying Zhao, Qin Zhang, Zhong Lu, Zhenhong Li, Chengsheng Yang, Wu Zhu, Jing Liu-Zeng, Liquan Chen, Chuanjin Liu
Summary: Active landslides along the Jinsha River corridor pose serious threats and attract widespread attention due to their large scale, number, and potential disaster chain characteristics. Conventional InSAR-based methods face challenges in mapping landslides efficiently in this region, leading to the development of a new procedure integrating surface deformation and geomorphological features for large-area landslide mapping.
ENGINEERING GEOLOGY
(2021)
Article
Computer Science, Information Systems
Saeid Gharechelou, Ryutaro Tateishi, Josaphat Tetuko Sri Sumantyo, Brian Alan Johnson
Summary: The study focuses on using polarimetric SAR data and decompositions, along with field and laboratory measurements, to detect soil moisture and introduce a better model for soil moisture retrieval over bare land and sparse vegetation. Results show that the Oh model has more reliable accuracy for soil moisture mapping, but the selection of the best model is difficult due to different characteristics in land cover.
ISPRS INTERNATIONAL JOURNAL OF GEO-INFORMATION
(2021)
Article
Geosciences, Multidisciplinary
Yoshiharu Omura
Summary: This paper summarizes the nonlinear processes associated with the generation of whistler-mode chorus emissions, including the interaction between energetic electrons and coherent whistler-mode waves to form electromagnetic electron holes or hills, and the conditions for resonant electrons to be free from anomalous trapping. It also discusses how resonant currents are generated leading to rising-tone or falling-tone emissions due to inhomogeneity in the frequency and magnetic field gradient. The triggering of nonlinear wave growth is described, as well as the formation of subpackets forming chorus elements and discrete hiss elements with varying frequencies in higher plasma density environments.
EARTH PLANETS AND SPACE
(2021)
Article
Geosciences, Multidisciplinary
S. Nakamura, Y. Miyoshi, K. Shiokawa, Y. Omura, T. Mitani, T. Takashima, N. Higashio, I Shinohara, T. Hori, S. Imajo, A. Matsuoka, F. Tsuchiya, A. Kumamoto, Y. Kasahara, M. Shoji, H. Spence, V Angelopoulos
Summary: The study observed rapid flux depressions in relativistic electrons, known as EMIC-induced drifting electron holes (EDEHs), caused by electromagnetic ion cyclotron waves on a short timescale in a limited region. These flux depressions occur in the relativistic energy range and small pitch angles, potentially leading to significant depression of the radiation belt.
GEOPHYSICAL RESEARCH LETTERS
(2022)
Article
Astronomy & Astrophysics
Takeshi Nogi, Yoshiharu Omura
Summary: We conducted a particle-in-cell simulation to reproduce the triggering process of whistler-mode rising-tone emissions. We found that the rising-tone elements with increasing frequencies are generated through the self-sustaining formation of a long subpacket in the upstream region, which then splits into smaller subpackets during propagation.
JOURNAL OF GEOPHYSICAL RESEARCH-SPACE PHYSICS
(2022)
Article
Astronomy & Astrophysics
Yi-Kai Hsieh, Yoshiharu Omura, Yuko Kubota
Summary: The study investigates the interaction between electrons and whistler mode chorus waves of different amplitudes and directions in the outer radiation belt. It finds that oblique chorus emissions lead to greater electron precipitation and proposes a two-step precipitation process involving Landau resonance and cyclotron resonance, resulting in higher precipitation rates.
JOURNAL OF GEOPHYSICAL RESEARCH-SPACE PHYSICS
(2022)
Article
Geosciences, Multidisciplinary
Li Li, Yoshiharu Omura, Xu-Zhi Zhou, Qiu-Gang Zong, Robert Rankin, Chao Yue, Sui-Yan Fu
Summary: This study presents observations of periodic chorus wave emissions in the troughs of compressional ultralow frequency (ULF) waves using Van Allen Probes. The spectral gap of chorus waves was found to widen as the spacecraft moved towards higher latitudes, and the intensity and frequency range of chorus waves increased after a substorm injection. The periodic occurrence of chorus waves was attributed to the modulation of threshold amplitude for nonlinear growth of chorus waves by the second spatial derivative of ULF compressional magnetic field. The findings also supported the applicability of the nonlinear theory in describing the chorus wave generation and damping, together with their modulations by ULF waves.
GEOPHYSICAL RESEARCH LETTERS
(2022)
Article
Astronomy & Astrophysics
Yin Liu, Yoshiharu Omura
Summary: The study investigates the nonlinear wave growth process of plasmaspheric hiss in the equatorial plasmasphere through electromagnetic particle simulations in a uniform magnetic environment. The analysis of wavenumber-time evolution reveals the coherence and nonlinear growth of wave packets within a specific range of the inhomogeneity factor S.
JOURNAL OF GEOPHYSICAL RESEARCH-SPACE PHYSICS
(2022)
Article
Multidisciplinary Sciences
N. Kitamura, T. Amano, Y. Omura, S. A. Boardsen, D. J. Gershman, Y. Miyoshi, M. Kitahara, Y. Katoh, H. Kojima, S. Nakamura, M. Shoji, Y. Saito, S. Yokota, B. L. Giles, W. R. Paterson, C. J. Pollock, A. C. Barrie, D. G. Skeberdis, S. Kreisler, O. Le Contel, C. T. Russell, R. J. Strangeway, P-A Lindqvist, R. E. Ergun, R. B. Torbert, J. L. Burch
Summary: This article provides direct observational evidence for the locally ongoing secular energy transfer from the resonant electrons to the whistler-mode waves in Earth's magnetosheath, and demonstrates that the energy source of the wave is carried by the nongyrotropic electrons with resonant current.
NATURE COMMUNICATIONS
(2022)
Article
Physics, Fluids & Plasmas
Miwa Tobita, Yoshiharu Omura
Summary: This study explores the nonlinear wave-particle interaction between electrons and plasmaspheric hiss through test particle simulations. The modeling of hiss elements with varying frequencies and amplitudes allows for a more realistic simulation of electron scattering.
PHYSICS OF PLASMAS
(2022)
Article
Physics, Multidisciplinary
Jing-Huan Li, Zhi-Yang Liu, Xu-Zhi Zhou, Li Li, Yoshiharu Omura, Chao Yue, Qiu-Gang Zong, Zu-Yin Pu, Sui-Yan Fu, Lun Xie, Christopher T. Russell, Craig J. Pollock, Guan Le, James L. Burch
Summary: The classical picture fails to describe the interaction between large-amplitude plasma waves and low-energy particles. The authors identify anomalous resonance and validate it with experimental measurements.
COMMUNICATIONS PHYSICS
(2022)
Article
Physics, Fluids & Plasmas
Peter H. Yoon, Yoshiharu Omura
Summary: The dynamics of the upper-hybrid mode instability driven by an initial ring electron distribution function, which is a form of loss-cone distribution, is investigated using a one-dimensional electrostatic particle-in-cell simulation and a reduced quasilinear kinetic theoretical analysis. A favorable comparison is found between the two approaches, indicating that the reduced quasilinear theory can be an effective tool in the study of plasma instabilities.
PHYSICS OF PLASMAS
(2023)
Article
Environmental Sciences
Shoko Kobayashi, Motoko S. Fujita, Yoshiharu Omura, Dendy S. Haryadi, Ahmad Muhammad, Mohammad Irham, Satomi Shiodera
Summary: The biodiversity loss in Southeast Asia is urgent for long-term monitoring, but lacking. Attention has been focused on bird diversity monitoring using remote sensing, based on relation to forest structure. However, few studies have utilized space-borne active microwave remote sensing. This study evaluates threatened bird occurrence from L-band satellite data explaining forest structure in Sumatra, Indonesia.
Article
Astronomy & Astrophysics
Takeshi Nogi, Yoshiharu Omura
Summary: We conducted simulation runs of whistler-mode wave-particle interaction in a parabolic magnetic field, considering 12 different frequencies of triggering waves and 3 different plasma frequencies. The triggering wave can generate rising-tone emissions within a specific frequency range under certain plasma conditions. The velocity of the wave generation region depends on the duration of the subpacket, determined by the resonant current formation.
JOURNAL OF GEOPHYSICAL RESEARCH-SPACE PHYSICS
(2023)
Review
Materials Science, Paper & Wood
Sari Delviana Marbun, Wahyu Dwianto, Susan Barbara Patricia Sembiring Meliala, Ragil Widyorini, Sarah Augustina, Salim Hiziroglu
Summary: Binderless composite panels have advantages such as being eco-friendly and low production cost. However, challenges of low dimensional stability and internal bond strength exist. Various techniques, such as hot-pressing and steam treatment, have been explored to improve dimensional stability. This study aims to clarify the self-bonding mechanisms of binderless boards to enhance their performance and promote industrialization.
Article
Geosciences, Multidisciplinary
Huayue Chen, Xueyi Wang, Lunjin Chen, Yoshiharu Omura, Bruce T. Tsurutani, Yu Lin, Zhiyang Xia
Summary: Chorus subpackets are wave packets that play a crucial role in the formation of substructures within pulsating aurora. The frequency of these subpackets increases in the upstream region but remains unchanged in the downstream region. Simulation results indicate that both resonant electrons and wave amplitude influence the frequency chirping. This study provides insight into the nonlinear wave-particle interactions involved in the evolution of chorus subpackets.
GEOPHYSICAL RESEARCH LETTERS
(2023)
Article
Environmental Sciences
Shoko Kobayashi, Hiyuto Ide
Summary: This study used C-band microwave images taken by the Sentinel-1 satellites to monitor rice crop growth and found that decreases in panicle water content affect C-band backscatter. Multivariate regression analysis combined with field observations showed that VV and VH with shallow incidence angles were significantly negatively correlated with panicle water content, indicating an increase in backscatter with plant senescence. Additionally, backscatter behaviors were consistent with changes in crop phenology and surface condition. Therefore, C-band SAR data has the potential to estimate grain filling conditions for proper harvesting time.
