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Ice albedo feedback amplifies climate change signals and thus affects the global climate. Global long-term records on sea-ice albedo are important to characterize the regional or global energy budget. As the successor of MODIS (Moderate Resolution Imaging Spectroradiometer), VIIRS (Visible Infrared Imaging Radiometer Suite) started its observation from October 2011 on S-NPP (Suomi National Polar-orbiting Partnership). It has improved upon the capabilities of the operational Advanced Very High Resolution Radiometer (AVHRR) and provides observation continuity with MODIS. We used a direct estimation algorithm to produce a VIIRS sea-ice albedo (VSIA) product, which will be operational in the National Oceanic and Atmospheric Administration’s (NOAA) S-NPP Data Exploration (NDE) version of the VIIRS albedo product. The algorithm is developed from the angular bin regression method to simulate the sea-ice surface bidirectional reflectance distribution function (BRDF) from physical models, which can represent different sea-ice types and vary mixing fractions among snow, ice, and seawater. We compared the VSIA with six years of ground measurements at 30 automatic weather stations from the Programme for Monitoring of the Greenland Ice Sheet (PROMICE) and the Greenland Climate Network (GC-NET) as a proxy for sea-ice albedo. The results show that the VSIA product highly agreed with the station measurements with low bias (about 0.03) and low root mean square error (RMSE) (about 0.07) considering the Joint Polar Satellite System (JPSS) requirement is 0.05 and 0.08 at 4 km scale, respectively. We also evaluated the VSIA using two datasets of field measured sea-ice albedo from previous field campaigns. The comparisons suggest that VSIA generally matches the magnitude of the ground measurements, with a bias of 0.09 between the instantaneous albedos in the central Arctic and a bias of 0.077 between the daily mean albedos near Alaska. The discrepancy is mainly due to the scale difference at both spatial and temporal dimensions and the limited sample size. The VSIA data will serve for weather prediction applications and climate model calibrations. Combined with the historical observations from MODIS, current S-NPP VIIRS, and NOAA-20 VIIRS observations, VSIA will dramatically contribute to providing high-accuracy routine sea-ice albedo products and irreplaceable records for monitoring the long-term sea-ice albedo for climate research.
Jingjing Peng; Yunyue Yu; Peng Yu; Shunlin Liang. The VIIRS Sea-Ice Albedo Product Generation and Preliminary Validation. Remote Sensing 2018, 10, 1826 .
AMA StyleJingjing Peng, Yunyue Yu, Peng Yu, Shunlin Liang. The VIIRS Sea-Ice Albedo Product Generation and Preliminary Validation. Remote Sensing. 2018; 10 (11):1826.
Chicago/Turabian StyleJingjing Peng; Yunyue Yu; Peng Yu; Shunlin Liang. 2018. "The VIIRS Sea-Ice Albedo Product Generation and Preliminary Validation." Remote Sensing 10, no. 11: 1826.
The Clumping Index (Ω) was introduced to quantify the spatial distribution pattern of vegetation elements. It is crucial to improve the estimation accuracy of vital vegetation parameters, such as Leaf Area Index (LAI) and Gross Primary Production (GPP). Meanwhile, the parameterization of Ω is challenging partly due to the varying observations of canopy gaps from different view angles. Many previous studies have shown the increase of Ω with view zenith angle through samples of gap size distribution from in situ measurements. In contrast, remote sensing retrieval algorithms only assign a constant value for each biome type to roughly correct the clumping effect as a compromise between the accuracy and efficiency. In this paper, analytical models are proposed that estimate the directional clumping index (Ω(θ)) of crop and forest at canopy level. The angular variation trend and magnitude of crop Ω(θ) was analyzed within row structure where vegetation elements are randomly spaced along rows. The forest model predicts Ω(θ) with tree density, distribution pattern, crown shape, trunk size, and leaf area and angle distribution function. The models take into account the main directional characteristics of clumping index using easy-to-measure parameters. Test cases showed that Ω(θ) magnitude variation for black spruce forest was 102.3% of the hemispherical average clumping index ( Ω ˜ ), whereas the Larch forest had 48.7% variation, and row crop variation reached 32.4%. This study provided tools to assess Ω(θ) of discontinuous canopies.
Jingjing Peng; Wenjie Fan; Lizhao Wang; Xiru Xu; Jvcai Li; Beitong Zhang; Dingfang Tian. Modeling the Directional Clumping Index of Crop and Forest. Remote Sensing 2018, 10, 1576 .
AMA StyleJingjing Peng, Wenjie Fan, Lizhao Wang, Xiru Xu, Jvcai Li, Beitong Zhang, Dingfang Tian. Modeling the Directional Clumping Index of Crop and Forest. Remote Sensing. 2018; 10 (10):1576.
Chicago/Turabian StyleJingjing Peng; Wenjie Fan; Lizhao Wang; Xiru Xu; Jvcai Li; Beitong Zhang; Dingfang Tian. 2018. "Modeling the Directional Clumping Index of Crop and Forest." Remote Sensing 10, no. 10: 1576.
The leaf area index (LAI) is one of the most important parameters of vegetation canopy structure, which can represent the growth conditions of vegetation effectively. The accuracy, availability, and timeliness of LAI data can be improved greatly, which is of great importance to vegetation‐related research. There are various types of vegetation and terrain conditions in the Heihe River Basin, the second largest inland river basin in northwest China. It is not only helpful to evaluate the accuracy of LAI retrieval algorithms for the complex land surface but also useful to understand the fragile ecological status of the Heihe River Basin. In contrast to previous LAI inversion models, the bidirectional reflectance distribution function unified model can be applied for both continuous and discrete vegetation, and it is appropriate for analyzing heterogeneous vegetation distributions. In this work, we produced 30‐m LAI products once a month in the growing season of 2012. Results show that the algorithm can effectively retrieve LAIs. We verified the LAI product using field measurement data. The mean absolute errors in forest, farmland, and sparse grassland are 0.44, 0.56, and 0.38 respectively, and the R2 is 0.8736. Further analysis shows that main errors come from three parts: errors in the parameters, mistakes in the vegetation classification, and interval of the look‐up table. Mixed pixel is also a problem for this model. Despite this, high resolution and applicability means this algorithm can be a good approach for LAI retrieval.
Bo Ma; Jucai Li; Wenjie Fan; Huazhong Ren; Xiru Xu; Yaokui Cui; Jingjing Peng. Application of an LAI Inversion Algorithm Based on the Unified Model of Canopy Bidirectional Reflectance Distribution Function to the Heihe River Basin. Journal of Geophysical Research: Atmospheres 2018, 123, 10,671 -10,687.
AMA StyleBo Ma, Jucai Li, Wenjie Fan, Huazhong Ren, Xiru Xu, Yaokui Cui, Jingjing Peng. Application of an LAI Inversion Algorithm Based on the Unified Model of Canopy Bidirectional Reflectance Distribution Function to the Heihe River Basin. Journal of Geophysical Research: Atmospheres. 2018; 123 (18):10,671-10,687.
Chicago/Turabian StyleBo Ma; Jucai Li; Wenjie Fan; Huazhong Ren; Xiru Xu; Yaokui Cui; Jingjing Peng. 2018. "Application of an LAI Inversion Algorithm Based on the Unified Model of Canopy Bidirectional Reflectance Distribution Function to the Heihe River Basin." Journal of Geophysical Research: Atmospheres 123, no. 18: 10,671-10,687.
A new directional canopy emissivity model (CE-P) based on spectral invariants is proposed in this paper. First, we prove the existence of the spectral invariant properties in the thermal infrared (TIR) band using a Monte Carlo model. Based on it, the equation of the new model is derived from the perspective of absorption. In this expression, single-scattering and multiscattering effects are separated analytically in the TIR band. We find that the overall contribution of multiple scatterings is less than 0.005 when the component emissivities are over 0.90, and the overall contribution decreases with increasing leaf or soil emissivity. Furthermore, the new model can avoid the logical difficulty encountered when using the traditional cavity effect factor to simulate the emissivity of a sparse vegetation canopy. The results of 4SAIL and Discrete Anisotropic Radiative Transfer (DART) are selected to do cross validation. The CE-P can achieve a high accuracy compared with 4SAIL and DART, with an absolute bias less than 0.002 when the leaf (soil) emissivity is equal to 0.98 (0.94). Four widely used analytical models are selected for comparison. The resulting accuracies of these models are ordered from CE-P to REN15, FR97, FR02, and VALOR96 with the most serious error up to 0.002, 0.002, 0.007, 0.013, and 0.014, respectively. Three main conclusions are obtained through the sensitivity analysis: the multiscattering between vegetation and the background can be ignored when the leaf (soil) emissivity is no less than 0.94 (0.90), the second and higher order scattering within the vegetation can also be ignored when the leaf (soil) emissivity is no less than 0.94 (0.90), and the single-scattering effect within the canopy should be considered which can be calculated using three view factors.
Biao Cao; Mingzhu Guo; Wenjie Fan; Xiru Xu; Jingjing Peng; Huazhong Ren; Yongming Du; Hua Li; Zunjian Bian; Tian Hu; Qing Xiao; Qinhuo Liu. A New Directional Canopy Emissivity Model Based on Spectral Invariants. IEEE Transactions on Geoscience and Remote Sensing 2018, 56, 6911 -6926.
AMA StyleBiao Cao, Mingzhu Guo, Wenjie Fan, Xiru Xu, Jingjing Peng, Huazhong Ren, Yongming Du, Hua Li, Zunjian Bian, Tian Hu, Qing Xiao, Qinhuo Liu. A New Directional Canopy Emissivity Model Based on Spectral Invariants. IEEE Transactions on Geoscience and Remote Sensing. 2018; 56 (12):6911-6926.
Chicago/Turabian StyleBiao Cao; Mingzhu Guo; Wenjie Fan; Xiru Xu; Jingjing Peng; Huazhong Ren; Yongming Du; Hua Li; Zunjian Bian; Tian Hu; Qing Xiao; Qinhuo Liu. 2018. "A New Directional Canopy Emissivity Model Based on Spectral Invariants." IEEE Transactions on Geoscience and Remote Sensing 56, no. 12: 6911-6926.
In contrast to herbaceous canopies and forests, savannas are grassland ecosystems with sparsely distributed individual trees, so the canopy is spatially heterogeneous and open, whereas the woody cover in savannas, e.g., tree cover, adversely affects ecosystem structures and functions. Studies have shown that the dynamics of canopy structure are related to available water, climate, and human activities in the form of porosity, leaf area index (LAI), and clumping index (CI). Therefore, it is important to identify the biophysical parameters of savanna ecosystems, and undertake practical actions for savanna conservation and management. The canopy openness presents a challenge for evaluating canopy LAI and other biophysical parameters, as most remotely sensed methods were developed for homogeneous and closed canopies. Clumping index is a key variable that can represent the clumping effect from spatial distribution patterns of components within a canopy. However, it is a difficult task to measure the clumping index of the moderate resolution savanna pixels directly using optical instruments, such as the Tracing Radiation and Architecture of Canopies, LAI-2000 Canopy Analyzer, or digital hemispherical photography. This paper proposed a new method using hemispherical photographs combined with high resolution remote sensing images to estimate the clumping index of savanna canopies. The effects of single tree LAI, crown density, and herbaceous layer on the clumping index of savanna pixels were also evaluated. The proposed method effectively calculated the clumping index of moderate resolution pixels. The clumping indices of two study regions located in Ejina Banner and Weichang were compared with the clumping index product over China’s landmass.
Jucai Li; Wenjie Fan; Yuan Liu; Gaolong Zhu; Jingjing Peng; Xiru Xu. Estimating Savanna Clumping Index Using Hemispherical Photographs Integrated with High Resolution Remote Sensing Images. Remote Sensing 2017, 9, 52 .
AMA StyleJucai Li, Wenjie Fan, Yuan Liu, Gaolong Zhu, Jingjing Peng, Xiru Xu. Estimating Savanna Clumping Index Using Hemispherical Photographs Integrated with High Resolution Remote Sensing Images. Remote Sensing. 2017; 9 (1):52.
Chicago/Turabian StyleJucai Li; Wenjie Fan; Yuan Liu; Gaolong Zhu; Jingjing Peng; Xiru Xu. 2017. "Estimating Savanna Clumping Index Using Hemispherical Photographs Integrated with High Resolution Remote Sensing Images." Remote Sensing 9, no. 1: 52.
To evaluate and improve the quality of coarse-pixel land surface albedo products, validation with ground measurements of albedo is crucial over the spatially and temporally heterogeneous land surface. The performance of albedo validation depends on the quality of ground-based albedo measurements at a corresponding coarse-pixel scale, which can be conceptualized as the “truth” value of albedo at coarse-pixel scale. In this paper, a sampling strategy based on multiple nodes using wireless sensor network (WSN) technology, WSN-based albedo observation, is proposed. The WSN nodes are distributed in an optimal layout determined by a sequential selection method based on the representativeness of each sensor. The WSN dataset in this study includes 6 nodes. A method of weighting is used to upscale WSN node albedo to a coarse-pixel scale. The weights for each node are calculated with the ordinary least squares (OLS) linear regression method. Compared with the multiple scale validation strategy, the dataset of WSN albedo “truth” at the coarse-pixel scale reveals a good quality both in stability and continuity. Application of this strategy is exemplified by validation of the MODIS 1 km albedo product.
Xiaodan Wu; Jianguang Wen; Qing Xiao; Qiang Liu; Jingjing Peng; Baocheng Dou; Xiuhong Li; DongQin You; Yong Tang; Qinhuo Liu. Coarse scale in situ albedo observations over heterogeneous snow-free land surfaces and validation strategy: A case of MODIS albedo products preliminary validation over northern China. Remote Sensing of Environment 2016, 184, 25 -39.
AMA StyleXiaodan Wu, Jianguang Wen, Qing Xiao, Qiang Liu, Jingjing Peng, Baocheng Dou, Xiuhong Li, DongQin You, Yong Tang, Qinhuo Liu. Coarse scale in situ albedo observations over heterogeneous snow-free land surfaces and validation strategy: A case of MODIS albedo products preliminary validation over northern China. Remote Sensing of Environment. 2016; 184 ():25-39.
Chicago/Turabian StyleXiaodan Wu; Jianguang Wen; Qing Xiao; Qiang Liu; Jingjing Peng; Baocheng Dou; Xiuhong Li; DongQin You; Yong Tang; Qinhuo Liu. 2016. "Coarse scale in situ albedo observations over heterogeneous snow-free land surfaces and validation strategy: A case of MODIS albedo products preliminary validation over northern China." Remote Sensing of Environment 184, no. : 25-39.
Mountainous areas with rugged terrains are widely distributed around the world. Remotely sensed values of the fraction of absorbed photosynthetically active radiation (FAPAR) suffer from the effect of rugged terrain. In this study, the effect of rugged terrain was incorporated into the FAPAR model based on recollision probability (FAPAR-P), which was improved in two aspects: calculating the sky viewing factor to correct for the fraction of diffuse sky radiation to the total radiation, and correcting the interception probability according to the slope and aspect of each pixel. The newly developed model is called FAPAR-PR (FAPAR-P Model for Rugged Terrain Area). Two study areas were chosen to validate the proposed model: the Dayekou watershed in Gansu Province, and Weichang in Hebei Province, China. The FAPAR values derived from the models were compared with FAPAR values measured in situ using photon flux sensors and the SunScan canopy analysis system (Delta-T Devices Ltd., Cambridge, UK). The validation results show that the FAPAR-PR model is applicable to rugged terrain areas, and it achieves a high level of accuracy. The FAPAR retrieval at different scales was also conducted to estimate the effect of terrain on the FAPAR-P and FAPAR-PR models. In our chosen study area, the effect of rugged terrain was significant in fine resolution pixels, but it was not obvious at larger scales, as the effects of slope and aspect were partly eliminated by the upscaling of the digital elevation model.
Peng Zhao; Wenjie Fan; Yuan Liu; Xihan Mu; Xiru Xu; Jingjing Peng. Study of the Remote Sensing Model of FAPAR over Rugged Terrains. Remote Sensing 2016, 8, 309 .
AMA StylePeng Zhao, Wenjie Fan, Yuan Liu, Xihan Mu, Xiru Xu, Jingjing Peng. Study of the Remote Sensing Model of FAPAR over Rugged Terrains. Remote Sensing. 2016; 8 (4):309.
Chicago/Turabian StylePeng Zhao; Wenjie Fan; Yuan Liu; Xihan Mu; Xiru Xu; Jingjing Peng. 2016. "Study of the Remote Sensing Model of FAPAR over Rugged Terrains." Remote Sensing 8, no. 4: 309.
How to obtain the “truth” of land surface parameter as reference value to validate the remote sensing retrieved parameter in heterogeneous scene and coarse-resolution pixel is one of the most challenging topics in environmental studies. In this paper, a distributed sensor network system named CPP-WSN was established to capture the spatial and temporal variation of land surface parameters at coarse-resolution satellite pixel scale around the Huailai Remote Sensing Station, which locates in the North China Plain. The system consists of three subnetworks that are RadNet, SoilNet, and VegeNet. Time series observations of typical land surface parameters, including UVR, PAR, SWR, LWR, albedo, and land surface temperature (LST) from RadNet, multilayer soil moisture and soil temperature from SoilNet, and fraction of vegetation cover (FVC), clumping index (CI), and leaf area index (LAI) from VegeNet, have been obtained and shared on the web. Compared with traditional single-point measurement, the “true” reference value of coarse pixel is obtained by averaging or representativeness-weighted averaging the multipoint measurements acquired using the sensor network. The preliminary applications, which validate several remote sensing products with CPP-WSN data, demonstrate that a high quality ground “truth” dataset has been available for remote sensing as well as other applications.
Baocheng Dou; Jianguang Wen; Xiuhong Li; Qiang Liu; Jingjing Peng; Qing Xiao; Zhigang Zhang; Yong Tang; Xiaodan Wu; Xingwen Lin; DongQin You; Hua Li; Li Li; Yelu Zeng; Erli Cai; Jialin Zhang. Wireless Sensor Network of Typical Land Surface Parameters and Its Preliminary Applications for Coarse-Resolution Remote Sensing Pixel. International Journal of Distributed Sensor Networks 2016, 12, 9639021:1 -9639021:11.
AMA StyleBaocheng Dou, Jianguang Wen, Xiuhong Li, Qiang Liu, Jingjing Peng, Qing Xiao, Zhigang Zhang, Yong Tang, Xiaodan Wu, Xingwen Lin, DongQin You, Hua Li, Li Li, Yelu Zeng, Erli Cai, Jialin Zhang. Wireless Sensor Network of Typical Land Surface Parameters and Its Preliminary Applications for Coarse-Resolution Remote Sensing Pixel. International Journal of Distributed Sensor Networks. 2016; 12 (4):9639021:1-9639021:11.
Chicago/Turabian StyleBaocheng Dou; Jianguang Wen; Xiuhong Li; Qiang Liu; Jingjing Peng; Qing Xiao; Zhigang Zhang; Yong Tang; Xiaodan Wu; Xingwen Lin; DongQin You; Hua Li; Li Li; Yelu Zeng; Erli Cai; Jialin Zhang. 2016. "Wireless Sensor Network of Typical Land Surface Parameters and Its Preliminary Applications for Coarse-Resolution Remote Sensing Pixel." International Journal of Distributed Sensor Networks 12, no. 4: 9639021:1-9639021:11.
Baocheng Dou; Jianguang Wen; Xiuhong Li; Qiang Liu; Qing Xiao; Junhua Bai; Jingjing Peng; Xingwen Lin; Zhigang Zhang; Xiaodan Wu; Erli Cai; Jialin Zhang; Chongyan Chang. Sensor intercomparison of distributed surface radiation measurement system. International Conference on Intelligent Earth Observing and Applications 2015, 98081F -98081F-6.
AMA StyleBaocheng Dou, Jianguang Wen, Xiuhong Li, Qiang Liu, Qing Xiao, Junhua Bai, Jingjing Peng, Xingwen Lin, Zhigang Zhang, Xiaodan Wu, Erli Cai, Jialin Zhang, Chongyan Chang. Sensor intercomparison of distributed surface radiation measurement system. International Conference on Intelligent Earth Observing and Applications. 2015; ():98081F-98081F-6.
Chicago/Turabian StyleBaocheng Dou; Jianguang Wen; Xiuhong Li; Qiang Liu; Qing Xiao; Junhua Bai; Jingjing Peng; Xingwen Lin; Zhigang Zhang; Xiaodan Wu; Erli Cai; Jialin Zhang; Chongyan Chang. 2015. "Sensor intercomparison of distributed surface radiation measurement system." International Conference on Intelligent Earth Observing and Applications , no. : 98081F-98081F-6.
Albedo characterizes the radiometric interface of land surfaces, especially vegetation, and the atmosphere. Albedo is a critical input to many models, such as crop growth models, hydrological models and climate models. For the extensive attention to crop monitoring, a physical albedo model for crops is developed based on the law of energy conservation and spectral invariants, which is derived from a prior forest albedo model. The model inputs have been efficiently and physically parameterized, including the dependency of albedo on the solar zenith/azimuth angle, the fraction of diffuse skylight in the incident radiance, the canopy structure, the leaf reflectance/transmittance and the soil reflectance characteristics. Both the anisotropy of soil reflectance and the clumping effect of crop leaves at the canopy scale are considered, which contribute to the improvement of the model accuracy. The comparison between the model results and Monte Carlo simulation results indicates that the canopy albedo has high accuracy with an RMSE < 0.005. The validation using ground measurements has also demonstrated the reliability of the model and that it can reflect the interaction mechanism between radiation and the canopy-soil system.
Jingjing Peng; Wenjie Fan; Xiru Xu; Lizhao Wang; Qinhuo Liu; Jvcai Li; Peng Zhao. Estimating Crop Albedo in the Application of a Physical Model Based on the Law of Energy Conservation and Spectral Invariants. Remote Sensing 2015, 7, 15536 -15560.
AMA StyleJingjing Peng, Wenjie Fan, Xiru Xu, Lizhao Wang, Qinhuo Liu, Jvcai Li, Peng Zhao. Estimating Crop Albedo in the Application of a Physical Model Based on the Law of Energy Conservation and Spectral Invariants. Remote Sensing. 2015; 7 (11):15536-15560.
Chicago/Turabian StyleJingjing Peng; Wenjie Fan; Xiru Xu; Lizhao Wang; Qinhuo Liu; Jvcai Li; Peng Zhao. 2015. "Estimating Crop Albedo in the Application of a Physical Model Based on the Law of Energy Conservation and Spectral Invariants." Remote Sensing 7, no. 11: 15536-15560.
A physical model for simulating crop albedo based on the law of energy conservation and spectral invariants was developed. The idea referred to the primary PARAS albedo model for forest. The developed model concerned two key problems for crop monitoring, one is the anisotropy of soil reflectance and the other is the clumping effect of crop leaves at canopy scale, which contributed to the improvement of the model accuracy. The comparison between the model results and those simulated using a Monte Carlo method shows that the calculated clumping index, soil absorptance and canopy albedo all have high accuracy, indicating that the model is able to reflect the interaction mechanism between radiation and the canopy-soil system.
Jingjing Peng; Wenjie Fan; Xiru Xu; Yuan Liu; Lizhao Wang. Crop specified albedo model based on the law of energy conservation and spectral invariants. 2015 IEEE International Geoscience and Remote Sensing Symposium (IGARSS) 2015, 653 -656.
AMA StyleJingjing Peng, Wenjie Fan, Xiru Xu, Yuan Liu, Lizhao Wang. Crop specified albedo model based on the law of energy conservation and spectral invariants. 2015 IEEE International Geoscience and Remote Sensing Symposium (IGARSS). 2015; ():653-656.
Chicago/Turabian StyleJingjing Peng; Wenjie Fan; Xiru Xu; Yuan Liu; Lizhao Wang. 2015. "Crop specified albedo model based on the law of energy conservation and spectral invariants." 2015 IEEE International Geoscience and Remote Sensing Symposium (IGARSS) , no. : 653-656.
The adjacency effect and non-uniform responses complicate the precise delimitation of the surface support of remote sensing data and their derived products. Thus, modeling spatial response characteristics (SRCs) prior to using remote sensing information has become important. A point spread function (PSF) is typically used to describe the SRCs of the observation cells from remote sensors and is always estimated in a laboratory before the sensor is launched. However, research on the SRCs of high-order remote sensing products derived from the observations remains insufficient, which is an obstacle to converting between multi-scale remote sensing products and validating coarse-resolution products. This study proposed a method that combines simulation and validation to establish SRC models of coarse-resolution albedo products. Two series of commonly used 500-m/1-km resolution albedo products, which are derived from Moderate Resolution Imaging Spectroradiometer (MODIS) reflectance data, were investigated using 30-m albedo products that provide the required sub-pixel information. The analysis proves that the size of the surface support of each albedo pixel is larger than the nominal resolution of the pixel and that the response weight is non-uniformly distributed, with an elliptical Gaussian shape. The proposed methodology is generic and applicable for analyzing the SRCs of other advanced remote sensing products.
Jingjing Peng; Qiang Liu; Lizhao Wang; Qinhuo Liu; Wenjie Fan; Meng Lu; Jianguang Wen. Characterizing the Pixel Footprint of Satellite Albedo Products Derived from MODIS Reflectance in the Heihe River Basin, China. Remote Sensing 2015, 7, 6886 -6907.
AMA StyleJingjing Peng, Qiang Liu, Lizhao Wang, Qinhuo Liu, Wenjie Fan, Meng Lu, Jianguang Wen. Characterizing the Pixel Footprint of Satellite Albedo Products Derived from MODIS Reflectance in the Heihe River Basin, China. Remote Sensing. 2015; 7 (6):6886-6907.
Chicago/Turabian StyleJingjing Peng; Qiang Liu; Lizhao Wang; Qinhuo Liu; Wenjie Fan; Meng Lu; Jianguang Wen. 2015. "Characterizing the Pixel Footprint of Satellite Albedo Products Derived from MODIS Reflectance in the Heihe River Basin, China." Remote Sensing 7, no. 6: 6886-6907.
A land-cover-based linear BRDF (bi-directional reflectance distribution function) unmixing (LLBU) algorithm based on the kernel-driven model is proposed to combine the compact airborne spectrographic imager (CASI) reflectance with the moderate resolution imaging spectroradiometer (MODIS) daily reflectance product to derive the BRDF/albedo of the two sensors simultaneously in the foci experimental area (FEA) of the Heihe Watershed Allied Telemetry Experimental Research (HiWATER), which was carried out in the Heihe River basin, China. For each land cover type, an archetypal BRDF, which characterizes the shape of its anisotropic reflectance, is extracted by linearly unmixing from the MODIS reflectance with the assistance of a high-resolution classification map. The isotropic coefficients accounting for the differences within a class are derived from the CASI reflectance. The BRDF is finally determined by the archetypal BRDF and the corresponding isotropic coefficients. Direct comparisons of the cropland archetypal BRDF and CASI albedo with in situ measurements show good agreement. An indirect validation which compares retrieved BRDF/albedo with that of the MCD43A1 standard product issued by NASA and aggregated CASI albedo also suggests reasonable reliability. LLBU has potential to retrieve the high spatial resolution BRDF/albedo product for airborne and spaceborne sensors which have inadequate angular samplings. In addition, it can shorten the timescale for coarse spatial resolution product like MODIS.
DongQin You; Jianguang Wen; Qing Xiao; Qiang Liu; Qinhuo Liu; Yong Tang; Baocheng Dou; Jingjing Peng. Development of a High Resolution BRDF/Albedo Product by Fusing Airborne CASI Reflectance with MODIS Daily Reflectance in the Oasis Area of the Heihe River Basin, China. Remote Sensing 2015, 7, 6784 -6807.
AMA StyleDongQin You, Jianguang Wen, Qing Xiao, Qiang Liu, Qinhuo Liu, Yong Tang, Baocheng Dou, Jingjing Peng. Development of a High Resolution BRDF/Albedo Product by Fusing Airborne CASI Reflectance with MODIS Daily Reflectance in the Oasis Area of the Heihe River Basin, China. Remote Sensing. 2015; 7 (6):6784-6807.
Chicago/Turabian StyleDongQin You; Jianguang Wen; Qing Xiao; Qiang Liu; Qinhuo Liu; Yong Tang; Baocheng Dou; Jingjing Peng. 2015. "Development of a High Resolution BRDF/Albedo Product by Fusing Airborne CASI Reflectance with MODIS Daily Reflectance in the Oasis Area of the Heihe River Basin, China." Remote Sensing 7, no. 6: 6784-6807.
Coarse-resolution satellite albedo products are important for climate change and energy balance research because of their capability to characterize the spatiotemporal patterns of land surface parameters at both the regional and global scales. The accuracy of coarse-resolution products is usually assessed via comparison with in situ measurements. The key issue in the comparison of remote sensing observations with in situ measurements is scaling and uncertainty. This paper presents a strategy for validating 1-km-resolution remote sensing albedo products using field measurements and high-resolution remote sensing observations. Field measurements were collected to calibrate the high-resolution (30 m) albedo products derived from HJ-1a/b images. Then, the calibrated high-resolution albedo maps were resampled (i.e., upscaled) to assess the accuracy of the coarse-resolution albedo products. The samples of field measurements and high-resolution pixels are based on an uncertainty analysis. Two types of coarse-resolution albedo datasets, from global land surface satellite (GLASS) and moderate-resolution imaging spectroradiometer (MODIS), are validated over the middle reaches of the Heihe River in China. The results indicate that the upscaled HJ (Huan Jing means environment in Chinese and this refers to a satellite constellation designed for environment and disaster monitoring by China) albedo, which was calibrated using field measurements, can provide accurate reference values for validating coarse-resolution satellite albedo products. However, the uncertainties in the upscaled HJ albedo should be estimated, and pixels with large uncertainties should be excluded from the validation process.
Jingjing Peng; Qiang Liu; Jianguang Wen; Qinhuo Liu; Yong Tang; Lizhao Wang; Baocheng Dou; DongQin You; Changkui Sun; Xiaojie Zhao; Youbin Feng; Jian Shi. Multi-scale validation strategy for satellite albedo products and its uncertainty analysis. Science China Earth Sciences 2014, 58, 573 -588.
AMA StyleJingjing Peng, Qiang Liu, Jianguang Wen, Qinhuo Liu, Yong Tang, Lizhao Wang, Baocheng Dou, DongQin You, Changkui Sun, Xiaojie Zhao, Youbin Feng, Jian Shi. Multi-scale validation strategy for satellite albedo products and its uncertainty analysis. Science China Earth Sciences. 2014; 58 (4):573-588.
Chicago/Turabian StyleJingjing Peng; Qiang Liu; Jianguang Wen; Qinhuo Liu; Yong Tang; Lizhao Wang; Baocheng Dou; DongQin You; Changkui Sun; Xiaojie Zhao; Youbin Feng; Jian Shi. 2014. "Multi-scale validation strategy for satellite albedo products and its uncertainty analysis." Science China Earth Sciences 58, no. 4: 573-588.
The evaluation of uncertainty in satellite-derived albedo products is critical to ensure their accuracy, stability and consistency for studying climate change. In this study, we assess the Moderate-resolution Imaging Spectroradiometer(MODIS) albedo 8 day standard product MOD43B3 using the ground-based albedometer measurement based on the wireless sensor network (WSN) technology. The experiment have been performed in Huailai, Hubei province. A 1.5 km*2 km area are selected as study region, which locates between 115.78° E-115.80° E and 40.35° N-40.37° N. This area is characterized by its distinct landscapes: bare ground between January and April, corn from May to Octorber. That is, this area is relatively homegeneous from January to Octorber, but in Novermber and December, the surface is very heterogeneous because of straw burning, as well as snow fall and snow melting. It is a big challenge to validate the MODIS albedo products because of the vast difference in spatial resolution between ground measurement and satellite measurement. Here, we use the HJ albedo products as the bridge that link the ground measurement with satellite data. Firstly, we analyses the spatial representativeness of the WSN site under green-up, dormant and snow covered situations to decide whether direct comparison between ground-based measurement and MODIS albedo can be made. The semivariogram is used here to describe the ground hetergeneity around the WSN site. In addition, the bias between the average albedo of the certain neighborhood centered at the WSN site and the center pixel albedo is also calculated.Then we compare the MOD43B3 value with the ground-based value. Result shows that MOD43B3 agree with in situ well during the growing season, however, there are relatively large difference between ground albedos and MCD43B3 albedos during dormant and snow-coverd periods.
Xiaodan Wu; Jianguang Wen; Qing Xiao; Jingjing Peng; Qiang Liu; Baocheng Dou; Yong Tang; Xiuhong Li. Remote sensing albedo product validation over heterogenicity surface based on WSN: preliminary results and its uncertainty. SPIE Asia-Pacific Remote Sensing 2014, 9260, 92603P .
AMA StyleXiaodan Wu, Jianguang Wen, Qing Xiao, Jingjing Peng, Qiang Liu, Baocheng Dou, Yong Tang, Xiuhong Li. Remote sensing albedo product validation over heterogenicity surface based on WSN: preliminary results and its uncertainty. SPIE Asia-Pacific Remote Sensing. 2014; 9260 ():92603P.
Chicago/Turabian StyleXiaodan Wu; Jianguang Wen; Qing Xiao; Jingjing Peng; Qiang Liu; Baocheng Dou; Yong Tang; Xiuhong Li. 2014. "Remote sensing albedo product validation over heterogenicity surface based on WSN: preliminary results and its uncertainty." SPIE Asia-Pacific Remote Sensing 9260, no. : 92603P.
The development of efficient and systematic groundbased spatial sampling strategies is critical for the validation of medium-resolution satellite-derived leaf area index (LAI) products, particularly over heterogeneous land surfaces. In this paper, a new sampling strategy based on high-resolution vegetation index prior knowledge (SSVIP) is proposed to generate accurate LAI reference maps over heterogeneous areas. To capture the variability across a site, the SSVIP is designed to 1) stratify the nonhomogeneous area into zones with minimum within-class variance; 2) assign the number of samples to each zone using Neyman optimal allocation; and 3) determine the spatial distribution of samples with a nearest neighbor index. The efficiency of the proposed method was examined using different vegetation types and pixel heterogeneities. The results indicate that the SSVIP approach can properly divide a heterogeneous area into different vegetation cover zones. Whereas the LAI reference maps generated by SSVIP attain the target accuracy of 0.1 LAI units in cropland and broadleaf forest sites, the current sampling strategy based on vegetation type has a root mean square error (RMSE) of 0.14 for the same number of samples. SSVIP was compared with the current sampling strategy at 24 VALERI sites, and the results suggested that samples selected by SSVIP were more representative in the feature space and geographical space, which further indicated the reasonable validation over heterogeneous land surfaces.
Yelu Zeng; Jing Li; Qinhuo Liu; Longhui Li; Baodong Xu; Gaofei Yin; Jingjing Peng. A Sampling Strategy for Remotely Sensed LAI Product Validation Over Heterogeneous Land Surfaces. IEEE Journal of Selected Topics in Applied Earth Observations and Remote Sensing 2014, 7, 3128 -3142.
AMA StyleYelu Zeng, Jing Li, Qinhuo Liu, Longhui Li, Baodong Xu, Gaofei Yin, Jingjing Peng. A Sampling Strategy for Remotely Sensed LAI Product Validation Over Heterogeneous Land Surfaces. IEEE Journal of Selected Topics in Applied Earth Observations and Remote Sensing. 2014; 7 (7):3128-3142.
Chicago/Turabian StyleYelu Zeng; Jing Li; Qinhuo Liu; Longhui Li; Baodong Xu; Gaofei Yin; Jingjing Peng. 2014. "A Sampling Strategy for Remotely Sensed LAI Product Validation Over Heterogeneous Land Surfaces." IEEE Journal of Selected Topics in Applied Earth Observations and Remote Sensing 7, no. 7: 3128-3142.
Land surface temperature (LST) is an important parameter that modulates land surface process. The combination of infrared temperature and microwave temperature is a trend in the research of LST. Thermal infrared temperature and microwave temperature have different physical significances and values. However, they are always treated as the same temperature nowadays in the research on the combination of infrared temperature and microwave temperature. In this study, the homogeneous canopy is the leaf-dominated crown layer ignoring the effect of branches. Two layers with different temperature, the canopy layer and the soil layer, are considered. MESCAM model based on matrix doubling method has been modified by getting rid of the effects of the main and secondary stems. The effect of multiple scattering at L and C band has been studied by comparing the results of taoomiga model with that of the modified MESCAM model. Tao-omiga model was adopted to compute the canopy brightness temperature at L band and a simple geometric-optical model basing on gap probabilities was used to compute the canopy brightness temperature at thermal infrared band in the same scene. The relationship and the difference between thermal infrared canopy surface physical temperature and L band canopy effective physical temperature with different soil moisture have been analyzed in three different situations of TC (the temperature of the foliage component) and TS (the temperature of the soil component). It is a base of further exploring the cooperative inversion combining thermal infrared remote sensing with passive microwave remote sensing.
Jing Liu; Qinhuo Liu; Hongzhang Ma; Le Yang; Jingjing Peng. Investigation of the difference between thermal infrared canopy temperature and microwave effective canopy temperature over homogeneous corn canopy. SPIE Remote Sensing 2012, 8531, 1 .
AMA StyleJing Liu, Qinhuo Liu, Hongzhang Ma, Le Yang, Jingjing Peng. Investigation of the difference between thermal infrared canopy temperature and microwave effective canopy temperature over homogeneous corn canopy. SPIE Remote Sensing. 2012; 8531 ():1.
Chicago/Turabian StyleJing Liu; Qinhuo Liu; Hongzhang Ma; Le Yang; Jingjing Peng. 2012. "Investigation of the difference between thermal infrared canopy temperature and microwave effective canopy temperature over homogeneous corn canopy." SPIE Remote Sensing 8531, no. : 1.
MicroRNA-1 (miR-1) has been demonstrated as a tumor-suppressive miRNA, which shows a down-regulated pattern in several human malignancies including hepatocellular carcinoma (HCC). However, the pathophysiologic roles of miR-1 and their mechanisms in HCC tumorigenesis are still not totally elucidated. Pre-miR-1 was cloned into pSuper plasmid to overexpress the miR-1 in hepatoma cells. Real-time PCR and Western blot were applied to detect miR-1, ET-1 mRNA and protein levels respectively. Dual luciferase reporter assay was conducted to investigate the binding site of miR-1 on 3′UTR of ET-1 mRNA. Proliferation of hepatoma cells was evaluated by MTT assay. We observed that over-expression of miR-1 by miRNA-expressing plasmid transfection in HepG2 and Hep3B cells significantly reduced the proliferation of these cells. To explore the mechanism, we examined the potential target genes of miR-1 by bioinformatics. A potent mitogen, Endothelin-1 (ET-1), attracted our attention. Elevated expression of ET-1 but reduced miR-1 level was detected both in human liver cancer tissues and in hepatoma cell lines using Western Blot and miRNA real-time PCR respectively. By the over-expression and inhibition of miR-1 in HepG2 and Hep3B, we confirmed that miR-1 negatively regulated ET-1 expression in hepatoma cells. A luciferase reporter assay showed that miR-1 regulation was established by pairing to a complementary binding site within the ET-1 3′UTR. Finally, attenuated proliferation of hepatoma cells by over-expression of miR-1 could be partially restored by exogenous ET-1 treatment. Our findings demonstrate that miR-1 could inhibit ET-1 expression to attenuate the proliferation of hepatoma cells.
Ng Li; Pengyuan Yang; Hua Li; Peng Cheng; Ling Zhang; Dong Wei; Xiaomei Su; Jingjing Peng; Hui Gao; Yong Tan; Zhenguo Zhao; Yan Li; Zhongchun Qi; Yaocheng Rui; Tao Zhang. MicroRNA-1 inhibits proliferation of hepatocarcinoma cells by targeting endothelin-1. Life Sciences 2012, 91, 440 -447.
AMA StyleNg Li, Pengyuan Yang, Hua Li, Peng Cheng, Ling Zhang, Dong Wei, Xiaomei Su, Jingjing Peng, Hui Gao, Yong Tan, Zhenguo Zhao, Yan Li, Zhongchun Qi, Yaocheng Rui, Tao Zhang. MicroRNA-1 inhibits proliferation of hepatocarcinoma cells by targeting endothelin-1. Life Sciences. 2012; 91 (11):440-447.
Chicago/Turabian StyleNg Li; Pengyuan Yang; Hua Li; Peng Cheng; Ling Zhang; Dong Wei; Xiaomei Su; Jingjing Peng; Hui Gao; Yong Tan; Zhenguo Zhao; Yan Li; Zhongchun Qi; Yaocheng Rui; Tao Zhang. 2012. "MicroRNA-1 inhibits proliferation of hepatocarcinoma cells by targeting endothelin-1." Life Sciences 91, no. 11: 440-447.
The continuous fine spectrums obtained by hyperspectral remote sensing provide broad accessibility to precisely estimate physiological and biochemical parameters of ground vegetation. Chlorophyll is responsible for absorbing sunlight, so the real-time and accurate monitoring of chlorophyll becomes an important research field of hyperspectral remote sensing in precision agriculture. By utilizing a spectral index which is sensitive to the chlorophyll content(Chl), this paper tried to calculate the Chl profiles of the arid region in Heihe River Basin based on hyperspectral remote sensing images acquired by Operational Modular Imaging Spectrometer (OMIS) in WATER campaign[1]. In addition, an Absorption Depth Index(ADI) was proposed as an effective indicator of the emissive chlorophyll fluorescence (ChlF) based on the spectral characteristics of Solar Fraunhofer lines, and the ChlF and ADI profiles at 760nm band of each experiment site were worked out. The inversion result of Chl and ChlF were in good conformity with the actual situation, which would serve as important materials for the real-time monitoring of crop growth in the Heihe river basin.
Jingjing Peng; Qiang Liu; Jiahong Li; Qinhuo Liu. Quantitative Analysis of Crops Chlorophyll in the Heihe River Basin by Hyperspectral Remote Sensing Image. Lecture Notes in Electrical Engineering 2012, 681 -689.
AMA StyleJingjing Peng, Qiang Liu, Jiahong Li, Qinhuo Liu. Quantitative Analysis of Crops Chlorophyll in the Heihe River Basin by Hyperspectral Remote Sensing Image. Lecture Notes in Electrical Engineering. 2012; ():681-689.
Chicago/Turabian StyleJingjing Peng; Qiang Liu; Jiahong Li; Qinhuo Liu. 2012. "Quantitative Analysis of Crops Chlorophyll in the Heihe River Basin by Hyperspectral Remote Sensing Image." Lecture Notes in Electrical Engineering , no. : 681-689.
Jing-Jing Peng; Qiang Liu; Qin-Huo Liu; Jia-Hong Li; Hong-Zhang Ma; Li Fang. Kernel-driven model fitting of multi-angle thermal infrared brightness temperature and its application. Journal of Infrared and Millimeter Waves 2011, 30, 361 -365.
AMA StyleJing-Jing Peng, Qiang Liu, Qin-Huo Liu, Jia-Hong Li, Hong-Zhang Ma, Li Fang. Kernel-driven model fitting of multi-angle thermal infrared brightness temperature and its application. Journal of Infrared and Millimeter Waves. 2011; 30 (4):361-365.
Chicago/Turabian StyleJing-Jing Peng; Qiang Liu; Qin-Huo Liu; Jia-Hong Li; Hong-Zhang Ma; Li Fang. 2011. "Kernel-driven model fitting of multi-angle thermal infrared brightness temperature and its application." Journal of Infrared and Millimeter Waves 30, no. 4: 361-365.