Article
Environmental Sciences
Miguel Morata, Bastian Siegmann, Pablo Morcillo-Pallares, Juan Pablo Rivera-Caicedo, Jochem Verrelst
Summary: This study aims to approximate SFM-based SIF retrieval using statistical learning, specifically emulation, to reduce computational loads. By implementing double PCA dimensionality reduction and evaluating different machine learning regression algorithms, the emulated SIF maps showed good agreement with reference SFM maps, suggesting that emulation can efficiently reduce computational burdens in SIF retrieval methods.
Article
Chemistry, Analytical
Shilei Li, Maofang Gao, Zhao-Liang Li
Summary: A method based on SVD technique was proposed for detecting SIF from remotely sensed data with ultra-high spectral resolution and in a broad spectral window without assuming that SIF remains constant. The method combines singular vectors, atmospheric contributions, and a linear combination of remaining singular vectors to express non-fluorescence spectra, showing good consistency and rationality in comparison with existing SIF data.
Article
Environmental Sciences
Yelu Zeng, Dalei Hao, Grayson Badgley, Alexander Damm, Uwe Rascher, Youngryel Ryu, Jennifer Johnson, Vera Krieger, Shengbiao Wu, Han Qiu, Yaling Liu, Joseph A. Berry, Min Chen
Summary: Disentangling the individual contributions from vegetation and soil in measured canopy reflectance is difficult. Solar Induced chlorophyll Fluorescence (SIF) can help separate vegetation and soil components, with NIRvH showing the smallest offset compared to NIRv and DVI in isolating true NIR reflectance of vegetation. This study highlights the potential of NIRvH in retrieving canopy structure parameters and estimating fluorescence yield using hyperspectral measurements.
REMOTE SENSING OF ENVIRONMENT
(2021)
Article
Environmental Sciences
Jidai Chen, Xinjie Liu, Guijun Yang, Shaoyu Han, Yan Ma, Liangyun Liu
Summary: This study explores the relationship between solar-induced chlorophyll fluorescence (SIF) and gross primary productivity (GPP) in winter wheat. The results show that GPP, red canopy SIF, and far-red canopy SIF all decrease during overwintering periods. GPP and red canopy SIF are more responsive to air temperature compared to far-red canopy SIF. Additionally, the study finds that the light use efficiency (LUEp) and certain chlorophyll fluorescence yield parameters are positively correlated with air temperature. Accounting for temperature improves the estimation of GPP based on total SIF emitted at the photosystem level.
Article
Forestry
Siyuan Chen, Liangyun Liu, Lichun Sui, Xinjie Liu
Summary: Partitioning non-photosynthetic components is important for accurate estimation of gross primary production in deciduous forests. The use of vegetation indices and radiation absorption observations can effectively separate the radiation absorbed by photosynthetic components. The results of this study demonstrate that the APAR(green)-based method significantly improves daily GPP estimation.
JOURNAL OF FORESTRY RESEARCH
(2023)
Article
Geochemistry & Geophysics
Lisheng Song, Zhonghao Ding, William P. Kustas, Wei Hua, Xinjie Liu, Liangyun Liu, Shaomin Liu, Mingguo Ma, Yan Bai, Ziwei Xu
Summary: Quantifying and monitoring land surface evapotranspiration (ET) is crucial for understanding the earth's water, energy, and carbon cycles. This study developed an empirical relationship between sun-induced chlorophyll fluorescence (SIF) and plant transpiration (T) at ecosystem scale, and coupled it with the two-source energy balance model (TSEB-SIF) to estimate ET components. The TSEB-SIF model outperformed the TSEB model in estimating ET, particularly under water deficit conditions, and provided more accurate partitioning of T from ET.
IEEE GEOSCIENCE AND REMOTE SENSING LETTERS
(2023)
Article
Environmental Sciences
Xiao-Xiao Zhang, Jia-Qiang Lei, Shi-Xin Wu, Sheng-Yu Li, Lian-You Liu, Zi-Fa Wang, Shuang-Yan Huang, Yu-Hong Guo, Yong-Dong Wang, Xiao Tang, Jie Zhou
Summary: Aeolian dust in China has been decreasing gradually since 1984, with the frequency of dust storms declining significantly by 97.7%. The main dust sources influencing China are the Mongolian Gobi Desert, the Taklimakan Desert, the Hexi Corridor, the Alxa Plateau Desert, the Qaidam basin Desert, and the northeast-southwest stretching semiarid farming-pasture ecotone. The Atlantic multidecadal oscillation (AMO) and Pacific decadal oscillation (PDO) may play important roles in the occurrence of aeolian dust events in China.
LAND DEGRADATION & DEVELOPMENT
(2023)
Article
Environmental Sciences
Xiaojin Qian, Liangyun Liu, Xidong Chen, Xiao Zhang, Siyuan Chen, Qi Sun
Summary: In this study, a global 500 m leaf chlorophyll content (LCC) weekly dataset (GLCC) was generated using satellite data and a physical radiative transfer modeling approach. The GLCC dataset facilitates vegetation growth monitoring and terrestrial carbon cycle modeling. The dataset was validated using field measurements and showed good consistency with the existing MERIS LCC dataset.
Article
Endocrinology & Metabolism
Yuxia Zhou, Lu Liu, Bangming Jin, Yixuan Wu, Lifen Xu, Xuebing Chang, Laying Hu, Guifang Wang, Yali Huang, Lingyu Song, Tian Zhang, Yuanyuan Wang, Ying Xiao, Fan Zhang, Mingjun Shi, Lingling Liu, Tuanlao Wang, Rui Yan, Bing Guo
Summary: Ectopic lipid accumulation in renal tubules is closely related to the pathogenesis of diabetic kidney disease, and mitochondrial dysfunction is thought to play a key role. This study shows that the Metrnl gene product mediates lipid accumulation in the kidney and has therapeutic potential for DKD.
Article
Environmental Sciences
Shanshan Du, Xinjie Liu, Jidai Chen, Weina Duan, Liangyun Liu
Summary: In recent years, several satellite-based solar-induced chlorophyll fluorescence (SIF) products have emerged, but direct validation of these products has not been conducted. This study validated two groups of TROPOMI SIF products using tower-based SIF measurements at seven sites. Challenges such as spatial scale mismatch were addressed using a near-infrared reflectance of vegetation (NIRv)-scaled approach. The validation results showed differences in the performance of the SIF datasets and highlighted unresolved issues in SIF product quality.
REMOTE SENSING OF ENVIRONMENT
(2023)
Article
Environmental Sciences
Tingting Zhao, Xiao Zhang, Yuan Gao, Jun Mi, Wendi Liu, Jinqing Wang, Mihang Jiang, Liangyun Liu
Summary: In the past decades, several fine-resolution global land cover (GLC) products have been developed with the development of computing capacity and free access to imagery. However, there is a lack of consistency analysis or comprehensive accuracy assessment using a common validation dataset for these GLC products. In this study, a novel stratified random sampling GLC validation dataset (SRS_Val) was developed, and the accuracy of six GLC products was quantitatively assessed. The results revealed variations in accuracy and consistency among the GLC products.
Article
Environmental Sciences
Tiewei Li, Lanlan Guo, Bin He, Lianyou Liu, Wenping Yuan, Xiuzhi Chen, Xingming Hao, Xuebang Liu, Hao Zheng, Huan Zheng, Rui Wang
Summary: More frequent droughts are changing the European forest ecosystem, impacting the global carbon cycle. Tree height plays a role in forests' resistance to drought, with taller forests showing higher resistance and shorter forests experiencing larger negative effects. The capacity for water absorption and regulation differs between forests of different heights, contributing to these resistance differences. This research provides insight into tree-level function and its implications for future droughts.
JOURNAL OF GEOPHYSICAL RESEARCH-BIOGEOSCIENCES
(2023)
Article
Environmental Studies
Hong Jia, Rui Wang, Hang Li, Baijian Diao, Hao Zheng, Lanlan Guo, Lianyou Liu, Jifu Liu
Summary: Desertification in the Gonghe Basin has been effectively controlled through remote sensing monitoring and the Albedo-NDVI feature space method. From 2010 to 2020, the desertification situation improved, especially in the western part of the basin where desertification land area decreased by 827.46 km(2) and desertification intensity decreased. The changes in desertification were influenced by both natural and human factors, with human activities gradually playing a larger role in desertification reversal.
Article
Agronomy
Peiqi Yang, Xinjie Liu, Zhigang Liu, Christiaan van der Tol, Liangyun Liu
Summary: This study examines the relationship between sun-induced chlorophyll fluorescence (SIF) and gross primary productivity (GPP) and the factors influencing this relationship. The results show that the radiative and structural components of SIF have a positive impact on the linearity of the SIF-GPP relationship, while the physiological component has a negative impact. The controls of the relationship also vary with temporal scale.
AGRICULTURAL AND FOREST METEOROLOGY
(2023)
Article
Environmental Sciences
Mengjia Qi, Xinjie Liu, Shanshan Du, Linlin Guan, Ruonan Chen, Liangyun Liu
Summary: This study emphasizes the importance of considering soil reflectance in estimating fluorescence escape probability (fesc) for downscaling solar-induced chlorophyll fluorescence (SIF) from canopy level to leaf level. The proposed fesc_GPR-SR model, accounting for soil reflectance, outperforms the traditional NIRv/FAPAR model in estimating fesc, especially for sparse vegetation. The evaluation results indicate that the leaf-level SIF calculated by the fesc_GPR-SR model tracks better with absorbed photosynthetic active radiation by green components (APARgreen). Therefore, accounting for soil reflectance can contribute to a better understanding of the physiological mechanism between SIF and gross primary productivity (GPP).
Article
Geosciences, Multidisciplinary
Xiao Zhang, Liangyun Liu, Tingting Zhao, Xidong Chen, Shangrong Lin, Jinqing Wang, Jun Mi, Wendi Liu
Summary: This study proposes a novel method for wetland mapping by combining multiple data sources and satellite images. The method successfully generated a global 30 m wetland map with a fine classification system, including inland and coastal wetland sub-categories. The resulting dataset showed significant advantages in capturing spatial patterns and diversity of wetland sub-categories compared to other global wetland products.
EARTH SYSTEM SCIENCE DATA
(2023)
Article
Chemistry, Analytical
Lieshen Yan, Xinjie Liu, Xia Jing, Liying Geng, Tao Che, Liangyun Liu
Summary: This study proposes a multi-angular NDVI (MAVI) method to enhance the estimation of leaf area index (LAI) by reducing interference from soil background and saturation effects. The MAVI is evaluated against other vegetation indices and shown to have improved performance in LAI retrieval. The findings demonstrate the utility of tower-based multi-angular spectral observations in LAI estimation and expand the potential applications of multi-angular observations.
Article
Environmental Sciences
Xiao Zhang, Liangyun Liu, Jinqing Wang, Tingting Zhao, Wendi Liu, Xidong Chen
Summary: A novel method for automated global tidal flat mapping was proposed using Google Earth Engine, resulting in the first global tidal flat dataset covering high latitudes. The method achieved high mapping accuracy and covered the entire global coastline. The dataset provides valuable information for coastal ecosystem protection and supports coastal development. The study also compared the dataset with existing ones, demonstrating significant improvement in mapping accuracy.
JOURNAL OF REMOTE SENSING
(2023)