Article
Environmental Sciences
Xiaojun Li, Jean-Pierre Wigneron, Frederic Frappart, Gabrielle De Lannoy, Lei Fan, Tianjie Zhao, Lun Gao, Shengli Tao, Hongliang Ma, Zhiqing Peng, Xiangzhuo Liu, Huan Wang, Mengjia Wang, Christophe Moisy, Philippe Ciais
Summary: ESA's SMOS and NASA's SMAP are two L-band radiometer missions providing key information on global surface soil moisture and vegetation water content. This study presents the first global long-term and continuous dataset of soil moisture and L-band vegetation optical depth (VOD) retrieved by merging SMOS and SMAP observations. The results show that the inter-calibration approach effectively removes bias and the merged dataset performs well in terms of detection metrics.
REMOTE SENSING OF ENVIRONMENT
(2022)
Article
Environmental Sciences
Victoria A. Walker, Vivian Wallace, Enes Yildirim, William E. Eichinger, Michael H. Cosh, Brian K. Hornbuckle
Summary: Soil surface roughness in the U.S. Corn Belt varies due to rainfall and soil management activities. The assumption of static roughness in the SMAP soil moisture retrieval algorithm is not consistent with the actual changes. Through field measurements and simulations, it was found that the actual roughness coefficient is significantly higher than the assumed value. Retrievals of roughness using satellite measurements can provide information on tillage and other soil management activities.
REMOTE SENSING OF ENVIRONMENT
(2023)
Review
Environmental Sciences
Jean-Pierre Wigneron, Xiaojun Li, Frederic Frappart, Lei Fan, Amen Al-Yaari, Gabrielle De Lannoy, Xiangzhuo Liu, Mengjia Wang, Erwan Le Masson, Christophe Moisy
Summary: This study provides an overview of the SMOS-IC retrieval data set, discussing its importance in research and applications, introducing the latest version of the product and its improvements. It also outlines the plan to merge the SMOS and SMAP L-VOD data sets for data continuity in the future.
REMOTE SENSING OF ENVIRONMENT
(2021)
Article
Environmental Sciences
Yu Bai, Tianjie Zhao, Li Jia, Michael H. Cosh, Jiancheng Shi, Zhiqing Peng, Xiaojun Li, Jean -Pierre Wigneron
Summary: A multi-temporal and multi-angular approach using SMOS satellite data was proposed to retrieve vegetation optical depth, effective scattering albedo, soil surface roughness, and soil moisture. The results showed that the method had a reasonable spatial distribution and high correlation with in-situ measurements, making it suitable for systematic retrieval of soil moisture and other parameters.
REMOTE SENSING OF ENVIRONMENT
(2022)
Article
Geochemistry & Geophysics
David Chaparro, Andrew F. Feldman, Mario Julian Chaubell, Simon H. Yueh, Dara Entekhabi
Summary: Microwave vegetation optical depth (VOD) and soil moisture (SM) can be retrieved simultaneously using L-band radiometry with polarization information, providing new perspectives on ecosystem science. Correlations between brightness temperatures (TBs) introduce uncertainty in VOD retrievals, which can be assessed using degrees-of-information and signal-to-noise ratio metrics. Regularization products can reduce noise in VOD retrievals, but result in differences in seasonal amplitude and coupling to SM.
IEEE TRANSACTIONS ON GEOSCIENCE AND REMOTE SENSING
(2022)
Article
Remote Sensing
M. Barree, A. Mialon, T. Pellarin, M. Parrens, R. Biron, F. Lemaitre, S. Gascoin, Y. H. Kerr
Summary: The SMOS satellite has been providing global data for over 11 years, allowing the study of soil moisture and vegetation optical depth. The evolution of radiative transfer modeling is based on ground measurements done on experimental sites. Placing an L-band radiometer on an 800-meter-high cliff enables coverage of larger and varied scenes, improving the performance of SM/VOD retrievals.
INTERNATIONAL JOURNAL OF APPLIED EARTH OBSERVATION AND GEOINFORMATION
(2021)
Article
Geochemistry & Geophysics
Kaitlin Togliatti, Colin Lewis-Beck, Victoria A. Walker, Theodore Hartman, Andy VanLoocke, Michael H. Cosh, Brian K. Hornbuckle
Summary: Satellite L-band vegetation optical depth (L-VOD) provides new information about terrestrial ecosystems. We quantitatively assessed three L-VOD products at a validation site in Iowa and found that the satellite products underestimated crop plant water, suggesting the need to consider the effect of dynamic soil surface roughness on crop plant water observations.
IEEE GEOSCIENCE AND REMOTE SENSING LETTERS
(2022)
Article
Engineering, Electrical & Electronic
Andrew F. Feldman, David Chaparro, Dara Entekhabi
Summary: Satellite soil moisture and vegetation optical depth are important for studying soil-plant water relations, but errors in estimation can affect their relationship. Regularizing VOD can reduce errors and improve accuracy in large scale studies.
IEEE JOURNAL OF SELECTED TOPICS IN APPLIED EARTH OBSERVATIONS AND REMOTE SENSING
(2021)
Article
Geochemistry & Geophysics
Chuen Siang Kang, Tianjie Zhao, Jiancheng Shi, Michael H. Cosh, Yingying Chen, Patrick J. Starks, Chandra Holifield Collins, Shengli Wu, Ruijing Sun, Jingyao Zheng
Summary: A global soil moisture retrieval algorithm was developed using FY-3D satellite data, incorporating vegetation effects correction and a Q(p) model for addressing soil surface roughness effects, resulting in encouraging accuracy.
IEEE TRANSACTIONS ON GEOSCIENCE AND REMOTE SENSING
(2021)
Article
Environmental Sciences
Bonan Li, Stephen P. Good, Dawn R. URycki
Summary: The research demonstrates that utilizing soil moisture and vegetation optical depth data from NASA's SMAP mission can improve the prediction accuracy of leaf area index, with a more significant impact on grasslands. Soil moisture is more important in arid regions, while vegetation optical depth has a lesser influence.
Article
Agriculture, Multidisciplinary
Mina Moradizadeh, Prashant K. Srivastava
Summary: This study evaluates the potential of AMSR2 data for VSM estimation in bare and agricultural areas. A new retrieval model called MMLPRM is proposed and calibrated using in situ observations from 50 monitoring stations. The analysis demonstrates the potential and usefulness of the model for soil moisture retrieval.
COMPUTERS AND ELECTRONICS IN AGRICULTURE
(2021)
Article
Environmental Sciences
Lun Gao, Ardeshir Ebtehaj, Mario Julian Chaubell, Morteza Sadeghi, Xiaojun Li, Jean-Pierre Wigneron
Summary: NASA's SMAP satellite mission has been providing global estimates of soil moisture and vegetation optical depth since 2015 using L-band radiometry. Various retrieval algorithms have been developed, and this study evaluates their performance across different biomes, climates, and terrain slopes. The study found that some algorithms, such as SCA-V and RDCA, outperform others in terms of temporal correlation with in-situ measurements.
REMOTE SENSING OF ENVIRONMENT
(2021)
Article
Geochemistry & Geophysics
Xiaoji Shen, Jeffrey P. Walker, Nan Ye, Xiaoling Wu, Foad Brakhasi, Liujun Zhu, Edward Kim, Yann Kerr, Thomas Jackson
Summary: This study compared the performance of soil moisture remote sensing at P-band and L-band, and found that P-band showed a clear reduction in vegetation impact compared to L-band. Although P-band did not achieve the target accuracy, it can still be considered acceptable considering the high vegetation water content. Additionally, the calibrated vegetation parameters at P-band were found to apply to broader conditions.
IEEE GEOSCIENCE AND REMOTE SENSING LETTERS
(2023)
Article
Environmental Sciences
Tianjie Zhao, Jiancheng Shi, Dara Entekhabi, Thomas J. Jackson, Lu Hu, Zhiqing Peng, Panpan Yao, Shangnan Li, Chuen Siang Kang
Summary: This study investigates the use of multi-angular and multi-frequency approaches for soil moisture and vegetation optical depth retrieval. A multi-channel collaborative algorithm is developed based on ground observations, improving the accuracy and stability of soil moisture detection.
REMOTE SENSING OF ENVIRONMENT
(2021)
Article
Environmental Sciences
Robin van der Schalie, Mendy van der Vliet, Nemesio Rodriguez-Fernandez, Wouter A. Dorigo, Tracy Scanlon, Wolfgang Preimesberger, Remi Madelon, Richard A. M. de Jeu
Summary: The study evaluates the impact of using passive microwave observations for temperature and filtering in soil moisture climate data records. The results show an increase in coverage in boreal regions, changes in overall dynamic range, and decreased humidity in tropical regions. Skill evaluation indicates that using microwave-based data is a preferable alternative to land surface models for passive microwave sensors in soil moisture climate data records.
Article
Geosciences, Multidisciplinary
Lun Gao, Ardeshir Ebtehaj, Judah Cohen, Jean-Pierre Wigneron
Summary: This study utilizes four reanalysis data sets and ground-based observations to reveal that approximately 30% of the snow cover in the Northern Hemisphere experiences unfrozen bottom soil. The occurrence of unfrozen soil is found to be correlated with different types of snow, with the highest probability observed under ephemeral snow, followed by maritime and prairie snow. The seasonal evolution of unfrozen soil areas does not align with snow cover extent, displaying two peaks in April and October. The analysis of interannual trends suggests that the decrease in spring snow has led to an increase in the proportion of unfrozen bottom soils, particularly in polar climate regimes dominated by tundra and taiga snow.
GEOPHYSICAL RESEARCH LETTERS
(2022)
Article
Biodiversity Conservation
Liyang Liu, Xiuzhi Chen, Philippe Ciais, Wenping Yuan, Fabienne Maignan, Jin Wu, Shilong Piao, Ying-Ping Wang, Jean-Pierre Wigneron, Lei Fan, Pierre Gentine, Xueqin Yang, Fanxi Gong, Hui Liu, Chen Wang, Xuli Tang, Hui Yang, Qing Ye, Bin He, Jiali Shang, Yongxian Su
Summary: Research shows that the impact of drought on forest canopies varies with canopy height, with taller tropical forests experiencing greater reductions in Ku-VOD during drought and larger increases in non-drought periods. Taller forests are more vulnerable to drought stress due to smaller xylem-transport safety margins. The variation in hydraulic transport based on canopy height should be considered in ecosystem models to improve predictions of tropical forest responses to drought.
GLOBAL CHANGE BIOLOGY
(2022)
Article
Environmental Sciences
Michaela Hegglin, Ana Bastos, Heinrich Bovensmann, Michael Buchwitz, Dominic Fawcett, Darren Ghent, Gemma Kulk, Shubha Sathyendranath, Theodore G. Shepherd, Shaun Quegan, Regine Roethlisberger, Stephen Briggs, Carlo Buontempo, Anny Cazenave, Emilio Chuvieco, Philippe Ciais, David Crisp, Richard Engelen, Suvarna Fadnavis, Martin Herold, Martin Horwath, Oskar Jonsson, Gabriel Kpaka, Christopher J. Merchant, Christian Mielke, Thomas Nagler, Frank Paul, Thomas Popp, Tristan Quaife, Nick A. Rayner, Colas Robert, Marc Schroder, Stephen Sitch, Sara Venturini, Robin van der Schalie, Mendy van der Vliet, Jean-Pierre Wigneron, R. Iestyn Woolway
Summary: Space-based Earth observation plays a crucial role in monitoring and quantifying climate system changes, and is essential for effective policy making and measuring progress towards the goals of the Paris Agreement. However, the best approach for translating observation data into actionable information is still unclear.
FRONTIERS IN ENVIRONMENTAL SCIENCE
(2022)
Article
Biodiversity Conservation
Dominic Fawcett, Stephen Sitch, Philippe Ciais, Jean Pierre Wigneron, Celso H. L. Silva-Junior, Viola Heinrich, Christelle Vancutsem, Frederic Achard, Ana Bastos, Hui Yang, Xiaojun Li, Clement Albergel, Pierre Friedlingstein, Luiz E. O. C. Aragao
Summary: Deforestation and degradation in the Amazon have led to significant losses in biomass carbon, outweighing the gains from regrowing forests. This study provides a pessimistic assessment of the Amazon's carbon balance and highlights the urgent need to address the rising deforestation and degradation, especially in the Brazilian Amazon.
GLOBAL CHANGE BIOLOGY
(2022)
Article
Geochemistry & Geophysics
Dileep Kumar Gupta, Prashant K. Srivastava, Dharmendra Kumar Pandey, Sumit Kumar Chaudhary, Rajendra Prasad, Peggy E. O'Neill
Summary: The present study aims to parameterize the single channel soil moisture active passive (SMAP) passive soil moisture (SM) retrieval algorithm for Indian conditions. MODIS data products and soil texture data were used to improve the parameterization of the algorithm. The algorithm was calibrated using vegetation and roughness parameters to minimize the error between the model retrieved and ground measured SM. The performance of the new parameterized model was evaluated and compared with other SM products, showing significant improvements.
IEEE TRANSACTIONS ON GEOSCIENCE AND REMOTE SENSING
(2023)
Article
Geosciences, Multidisciplinary
Lei Fan, Jean-Pierre Wigneron, Philippe Ciais, Jerome Chave, Martin Brandt, Stephen Sitch, Chao Yue, Ana Bastos, Xin Li, Yuanwei Qin, Wenping Yuan, Dmitry Schepaschenko, Liudmila Mukhortova, Xiaojun Li, Xiangzhuo Liu, Mengjia Wang, Frederic Frappart, Xiangming Xiao, Jingming Chen, Mingguo Ma, Jianguang Wen, Xiuzhi Chen, Hui Yang, Dave van Wees, Rasmus Fensholt
Summary: Siberian forests have been considered an important carbon sink, but severe droughts and fire disturbances may have affected their carbon dynamics. Limited forest inventories have led to uncertainties in the carbon balance. This study analyzed microwave observations from 2010 to 2019 and found that the carbon balance of Siberian forests was close to neutral, with a small carbon sink. Fire and drought caused significant losses of live above-ground carbon, contrasting with the greening trends in leaf area index. This highlights the vulnerability of large forest carbon stores in Siberia to climate-induced disturbances.
Article
Environmental Sciences
Lei Fan, Zanpin Xing, Gabrielle De Lannoy, Frederic Frappart, Jian Peng, Jiangyuan Zeng, Xiaojun Li, Kun Yang, Tianjie Zhao, Jiancheng Shi, Hongliang Ma, Mengjia Wang, Xiangzhuo Liu, Chuanxiang Yi, Mingguo Ma, Xuguang Tang, Jianguang Wen, Xiuzhi Chen, Chong Wang, Lingxiao Wang, Guojie Wang, Jean-Pierre Wigneron
Summary: This study evaluated the accuracy of SSM and RZSM datasets in croplands of Jiangsu province and found that model-based and combined SSM products performed better, while RZSM products from ESA CCI, GLDAS-Noah, and ERA5-Land generally showed higher accuracy compared to GLDAS-Noah. The study also compared time-invariant and time-variant Triple Collocation Analysis (TCA)-based R with in situ-based R and found that TCA-R values were higher, indicating potential bias in in situ-based R due to representativeness errors.
REMOTE SENSING OF ENVIRONMENT
(2022)
Article
Environmental Sciences
Yujie Dou, Feng Tian, Jean-Pierre Wigneron, Torbern Tagesson, Jinyang Du, Martin Brandt, Yi Liu, Linqing Zou, John S. Kimball, Rasmus Fensholt
Summary: Vegetation optical depth (VOD) from satellite passive microwave sensors has been used to monitor aboveground biomass carbon dynamics. However, uncertainty in the relationship between VOD and biomass carbon arises from changes in water stress and moisture content. This study evaluated the reliability of using VOD from different frequencies and temporal aggregation methods for estimating decadal biomass carbon dynamics at the global scale.
REMOTE SENSING OF ENVIRONMENT
(2023)
Article
Environmental Sciences
Huan Wang, Jean-Pierre Wigneron, Philippe Ciais, Yitong Yao, Lei Fan, Xiangzhuo Liu, Xiaojun Li, Julia K. Green, Feng Tian, Shengli Tao, Wei Li, Frederic Frappart, Clement Albergel, Mengjia Wang, Shuangcheng Li
Summary: Vegetation optical depth (VOD) is sensitive to plant water content and aboveground biomass. It has strong penetrability within the vegetation canopy and is less impacted by atmosphere aerosol contamination effects, clouds and sun illumination. However, VOD retrieval over dense forests is subject to uncertainties and a comprehensive evaluation of VOD products is needed for accurate applications.
REMOTE SENSING OF ENVIRONMENT
(2023)
Article
Environmental Sciences
Hongliang Ma, Xiaojun Li, Jiangyuan Zeng, Xiang Zhang, Jianzhi Dong, Nengcheng Chen, Lei Fan, Morteza Sadeghi, Frederic Frappart, Xiangzhuo Liu, Mengjia Wang, Huan Wang, Zheng Fu, Zanpin Xing, Philippe Ciais, Jean-Pierre Wigneron
Summary: A comprehensive evaluation of five L-band SSM products in tropical areas revealed that they have good performance in estimating soil moisture, but exhibit some uncertainties in dense vegetation areas such as rainforests.
REMOTE SENSING OF ENVIRONMENT
(2023)
Review
Environmental Sciences
Anne C. Richer-de-Forges, Qianqian Chen, Nicolas Baghdadi, Songchao Chen, Cecile Gomez, Stephane Jacquemoud, Guillaume Martelet, Vera L. Mulder, Diego Urbina-Salazar, Emmanuelle Vaudour, Marie Weiss, Jean-Pierre Wigneron, Dominique Arrouays
Summary: Soils are a finite resource facing threats due to human activities, making it necessary to map and monitor them to prevent degradation. The development of digital soil mapping (DSM) approaches, supported by remote sensing (RS) data, has allowed for high-resolution mapping of soils and assessing changes over time. French (inter)national research has played a significant role in pioneering the use of RS imagery in DSM.
Article
Environmental Sciences
A. Al-Yaari, Y. Zhao, F. Cheruy, W. Thiery
Summary: This study analyzes the representation of heatwaves in CMIP6 models and evaluates their performance against global reanalysis and observations. It investigates how heatwaves are projected to change at different global warming levels. The results show that the models perform reasonably well in representing time-related criteria but have larger uncertainty in capturing the magnitude of heatwaves. The projections indicate that heatwave occurrence, spatial extension, and duration will increase globally at different global warming levels, but with strong regional variability and model dependency.
Article
Environmental Sciences
Amen Al-Yaari, Thomas Condom, Clementine Junquas, Antoine Rabatel, Victor Ramseyer, Jean-Emmanuel Sicart, Mariano Masiokas, Sophie Cauvy-Fraunie, Olivier Dangles
Summary: This study focuses on 25 glaciers in different climates and latitudes and investigates their recent and projected trends in precipitation, temperatures, ice mass loss, and their relationships with cloud properties. The findings show that almost half of the studied glaciers are likely to vanish by 2050, with widespread warming and drying trends. These results highlight the serious consequences for future water availability.
Article
Geosciences, Multidisciplinary
Shengli Tao, Zurui Ao, Jean-Pierre Wigneron, Sassan Saatchi, Philippe Ciais, Jerome Chave, Thuy Le Toan, Pierre-Louis Frison, Xiaomei Hu, Chi Chen, Lei Fan, Mengjia Wang, Jiangling Zhu, Xia Zhao, Xiaojun Li, Xiangzhuo Liu, Yanjun Su, Tianyu Hu, Qinghua Guo, Zhiheng Wang, Zhiyao Tang, Yi Y. Liu, Jingyun Fang
Summary: Satellite radar backscatter provides unique information on land surface properties and has been widely used in Earth science. However, there is currently no long-term global radar dataset with suitable characteristics. In this study, we present the first long-term, high-resolution radar backscatter dataset over global land areas, called LHScat, by merging data from different sensors. We assessed the quality of the merged data and validated it against the ESA ERS-2 dataset. The results showed high accuracy and consistency of the merged radar signals, demonstrating the potential of LHScat to advance our understanding of long-term changes in global vegetation and soil moisture.
EARTH SYSTEM SCIENCE DATA
(2023)
Article
Engineering, Electrical & Electronic
Lei Fan, Amen Al-Yaari, Frederic Frappart, Jian Peng, Jianguang Wen, Qing Xiao, Rui Jin, Xiaojun Li, Xiangzhuo Liu, Mengjia Wang, Xiuzhi Chen, Lin Zhao, Mingguo Ma, Jean-Pierre Wigneron
Summary: This study uses a random forest method to merge multiple data sources and provide accurate soil moisture estimates in mountainous regions through high-resolution SM mapping.
IEEE JOURNAL OF SELECTED TOPICS IN APPLIED EARTH OBSERVATIONS AND REMOTE SENSING
(2022)