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190 results on '"Hou, Weizhen"'

2. Global haze aerosol distribution: a direct view by Geofen-5 satellite with 3.3 km spatial resolution

Author

Li, Zhengqiang, Xie, Yisong, Hou, Weizhen, Xu, Hua, Li, Kaitao, Li, Li, and Zhang, Yang

Subjects
Physics - Atmospheric and Oceanic Physics
Abstract

The Directional Polarimetric Camera (DPC) is the first Chinese multi-angle polarized earth observation satellite sensor, which has been launched onboard the GaoFen-5 Satellite in Chinese High-resolution Earth Observation Program. GaoFen-5 runs in a sun-synchronous orbit with the 2-days revisiting period. DPC employed a charge coupled device detection unit, and can realize spatial resolution of 3.3 km under a swath width of 1850 km. Moreover, DPC has 3 polarized channels together with 5 non-polarized bands, and is able to obtain at least 9 viewing angles by continuously capturing series images over the same target on orbit. Based on the Directional Polarization Camera (DPC) onboard GF-5 satellite, the first global high-resolution (3.3 km) map of fine-mode aerosol optical depth (AODf) over land has been obtained together by Aerospace Information Institute, Chinese Academy of Sciences, Anhui Institute of Optics and Fine Mechanics, Chinese Academy of Sciences (the manufacturer of DPC sensor) and other institutes. This AODf remote sensing observation dataset has the highest spatial resolution in the world. It can reflect the spatial information of major air pollutants (PM2.5, etc.) and provide critical basic products for "decryption" of global haze distribution., Comment: 15 pages, 5 figures

Published
2019

3. Study on the spectral reconstruction of typical surface types based on spectral library and principal component analysis

Author

Hou, Weizhen, Mao, Yilan, Xu, Chi, Li, Zhengqiang, Li, Donghui, Ma, Yan, and Xu, Hua

Subjects
Electrical Engineering and Systems Science - Image and Video Processing
Abstract

To meet the demanding of spectral reconstruction in the visible and near-infrared wavelength, the spectral reconstruction method for typical surface types is discussed based on the USGS /ASTER spectral library and principal component analysis (PCA). A new spectral reconstructed model is proposed by the information of several typical bands instead of all of the wavelength bands, and a linear combination spectral reconstruction model is also discussed. By selecting 4 typical spectral datasets including green vegetation, bare soil, rangeland and concrete in the spectral range of 400-900 nm, the PCA results show that 6 principal components could characterized the spectral dataset, and the relative reconstructed errors are smaller than 2%. If only 6-7 selected typical bands are employed to spectral reconstruction for all the surface reflectance in 400-900 nm, except that the reconstructed error of green vegetation is about 3.3%, the relative errors of other 3 datasets are all smaller than 1.6%. The correlation coefficients of those 4 datasets are all larger than 0.99, which can effectively satisfy the needs of spectral reconstruction. In addition, based on the spectral library and the linear combination model of 4 common used bands of satellite remote sensing such as 490, 555, 670 and 865 nm, the reconstructed errors are smaller than 8.5% in high reflectance region and smaller than 1.5% in low reflectance region respectively, which basically meet the needs of spectral reconstruction. This study can provide a reference value for the surface reflectance processing and spectral reconstruction in satellite remote sensing research., Comment: 10 pages, 7 figures

Published
2019
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9. Polarimetric remote sensing of atmospheric aerosols: Instruments, methodologies, results, and perspectives

Author

Dubovik, Oleg, Li, Zhengqiang, Mishchenko, Michael I., Tanré, Didier, Karol, Yana, Bojkov, Bojan, Cairns, Brian, Diner, David J., Espinosa, W. Reed, Goloub, Philippe, Gu, Xingfa, Hasekamp, Otto, Hong, Jin, Hou, Weizhen, Knobelspiesse, Kirk D., Landgraf, Jochen, Li, Li, Litvinov, Pavel, Liu, Yi, Lopatin, Anton, Marbach, Thierry, Maring, Hal, Martins, Vanderlei, Meijer, Yasjka, Milinevsky, Gennadi, Mukai, Sonoyo, Parol, Frederic, Qiao, Yanli, Remer, Lorraine, Rietjens, Jeroen, Sano, Itaru, Stammes, Piet, Stamnes, Snorre, Sun, Xiaobing, Tabary, Pierre, Travis, Larry D., Waquet, Fabien, Xu, Feng, Yan, Changxiang, and Yin, Dekui

Published
2019
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10. Radiometric Calibration of the Near-Infrared Bands of GF-5-02/DPC for Water Vapor Retrieval.

Author

Xie, Yanqing, Zhu, Qingyu, Zhu, Sifeng, Hou, Weizhen, Zhang, Liguo, Lei, Xuefeng, Zhang, Miaomiao, Li, Yunduan, Liu, Zhenhai, Wen, Yuan, and Li, Zhengqiang

Subjects
WATER vapor, PRECIPITABLE water, ARTIFICIAL satellite launching, AUTOMATED storage retrieval systems, OPTICAL sensors, CALIBRATION
Abstract

The GaoFen (GF)-5-02 satellite is one of the new generations of hyperspectral observation satellites launched by China in 2021. The directional polarimetric camera (DPC) is an optical sensor onboard the GF-5-02 satellite. The precipitable water vapor (PWV) is a key detection parameter of DPC. However, the existing PWV data developed using DPC data have significant errors due to the lack of the timely calibration of the two bands (865, 910 nm) of DPC used for PWV retrieval. In order to acquire DPC PWV data with smaller errors, a calibration method is developed for these two bands. The method consists of two parts: (1) calibrate the 865 nm band of the DPC using the cross-calibration method, (2) calibrate the 910 nm band of the DPC according to the calibrated 865 nm band of the DPC. This method effectively addresses the issue of the absence of a calibration method for the water vapor absorption band (910 nm) of the DPC. Regardless of whether AERONET PWV data or SuomiNET PWV data are used as the reference data, the accuracy of the DPC PWV data developed using calibrated DPC data is significantly superior to that of the DPC PWV data retrieved using data before recalibration. This means that the calibration method for the NIR bands of the DPC can effectively enhance the quality of DPC PWV data. [ABSTRACT FROM AUTHOR]

Published
2024
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15. High-accuracy FY-3A/MERSI precipitable water vapour (PWV) data over the continental United States.

Author

Xie, Yanqing, Hu, Zhongzheng, Hou, Weizhen, Zhang, Miaomiao, Wang, Zijun, Zhang, Liguo, Wen, Yuan, Zhou, Aiming, Yuan, Muye, Chang, Yuan, and Li, Zhengqiang

Subjects
WATER vapor, PRECIPITABLE water, STANDARD deviations, OUTLIER detection, PHOTOTHERMAL effect
Abstract

Water vapour is an important atmospheric gas with a direct impact on climate and weather. Given the significant variations of water vapour distribution in the tridimensional and temporal space, it is of great significance to use remote sensing data to monitor it on a large scale. One of the main missions of the Medium Resolution Spectral Imager (MERSI) onboard FengYun (FY)-3A satellite is to monitor the distribution of precipitable water vapour (PWV). However, the official MERSI PWV data is not widely used due to the limitation of its accuracy. The primary objective of this study is to develop FY-3A/MERSI PWV data with higher accuracy. The study area of this paper is the continental United States (125°W–65°W, 25°–50°N), and the selected period is the year 2010. Three PWV retrieval models for three near-infrared (NIR) channels (0.905, 0.940 and 0.980 μm) of MERSI are constructed based on the matching results between MERSI data and SuomiNET PWV data. Compared with the existing semi-empirical PWV retrieval algorithms, the algorithm developed in this work has two main changes: (1) MERSI PWV retrieval models are constructed using data after removing outliers rather than all data. (2) The algorithm can identify abnormal retrieval results. The validation results based on PWV data derived from Aerosol Robotic NETwork (AERONET) indicate that these two changes both contribute positively to enhancing the accuracy of MERSI PWV data. The root mean square errors (RMSE) of MERSI PWV data developed using the three channels at 0.905, 0.940 and 0.980 μm are 0.28 cm, 0.22 cm and 0.24 cm, respectively. The relative errors (RE) of these PWV data are 0.14, 0.10 and 0.12, respectively. In comparison to the official MERSI PWV data, the RMSE of MERSI PWV data retrieved in this study is reduced by at least 44%, and RE is reduced by at least 42%. [ABSTRACT FROM AUTHOR]

Published
2024
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16. Quantifying the effects of the microphysical properties of black carbon on the determination of brown carbon using measurements at multiple wavelengths.

Author

Luo, Jie, Li, Dan, Wang, Yuanyuan, Sun, Dandan, Hou, Weizhen, Ren, Jinghe, Wu, Hailing, Zhou, Peng, and Qiu, Jibing

Subjects
CARBON-black, WAVELENGTH measurement, CHEMICAL models, RADIATIVE forcing, LIGHT absorption
Abstract

Methods based on the absorption Ångström exponent (AAE) are widely used to estimate the absorption by brown carbon (BrC), and the estimated absorption by BrC can be significantly different from 0, even for pure black carbon (BC). However, few studies have systematically quantified the effects of BC microphysical properties. Moreover, the conditions under which AAE-based methods are applicable are still unclear. In this work, we used BC models partially coated with non-absorbing materials to calculate the total absorption. Since the total absorption is entirely due to BC, the estimated BrC absorption should be 0 if the retrieval methods are accurate. Thus, the ratio of the estimated BrC absorption to BC absorption (ABS BrC) should be the proportion of the BC absorption that is incorrectly attributed to BrC. The results show that a BC AAE of 1 can generally provide reasonable estimates for freshly emitted BC, since ABS BrC is generally in the range of -4.8 % to 2.7 % during that period. However, when BC aerosols are aged, ABS BrC can sometimes reach about 38.7 %. The wavelength dependence of the AAE (WDA) method does not necessarily improve the estimates; sometimes a negative ABSBrC of about -40.8 % is found for partially coated BC. By combining simulations of a global chemical transport model, this work also quantified the effects of BC microphysical properties on BrC global aerosol absorption optical depth (AAOD) estimates. The AAE = 1 method sometimes leads to a misassigned global mean AAOD of about - 0.43– 0.46×10-3 if the BC aerosols have a complex morphology. The WDA method does not necessarily improve the estimates. In our cases, the WDA methods based on spherical models could lead to a global-mean misassigned AAOD range of about -0.87 – 0.04×10-3. At the regional scale, the AAE = 1 method sometimes leads to a distributed AAOD of about -7.3 to 5.7×10-3 in some specific regions. Mie-theory-based WDA methods lead to an estimated AAOD error of about -22×10-3 in some regions (e.g., East Asia). This work also showed that the misattributed BrC absorption would lead to substantial uncertainties in the estimation of the global direct radiative forcing (DRF) of absorbing aerosols from different sources. [ABSTRACT FROM AUTHOR]

Published
2024
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17. Data Comparison and Cross-Calibration between Level 1 Products of DPC and POSP Onboard the Chinese GaoFen-5(02) Satellite

Author

Lei, Xuefeng, primary, Liu, Zhenhai, additional, Tao, Fei, additional, Dong, Hao, additional, Hou, Weizhen, additional, Xiang, Guangfeng, additional, Qie, Lili, additional, Meng, Binghuan, additional, Li, Congfei, additional, Chen, Feinan, additional, Xie, Yanqing, additional, Zhang, Miaomiao, additional, Fan, Lanlan, additional, Cheng, Liangxiao, additional, and Hong, Jin, additional

Published
2023
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19. Quantifying the effects of the microphysical properties of black carbon on the determination of brown carbon using measurements at multiple wavelengths

Author

Luo, Jie, Li, Dan, Wang, Yuanyuan, Sun, Dandan, Hou, Weizhen, Ren, Jinghe, Wu, Hailing, Zhou, Peng, and Qiu, Jibing

Abstract

The absorption Ångström exponent (AAE)-based methods are widely used to estimate brown carbon (BrC) absorption, and the estimated BrC absorption can be significantly different from 0 even for pure black carbon (BC). However, few studies have systematically quantified the effects of BC microphysical properties. Moreover, it is still unclear under which conditions the AAE-based method is applicable. In this work, we used BC models partially coated with non-absorbing materials to calculate the total absorption. Since the total absorption is entirely from BC, the estimated BrC absorption should be 0 if the retrieval methods are accurate. Thus, the estimated BrC absorption (ABSBrC) should be the absorption from BC that is incorrectly attributed to BrC. The results show that a BC AAE of 1 can generally provide reasonable estimates for freshly emitted BC, since at this time ABSBrC is generally in the range of -3 % to 4.5 %. However, when BC aerosols are aged, ABSBrC of about 35 % could be observed. The WDA method does not necessarily improve the estimates, sometimes a negative ABSBrC of -40 % can be found for partially coated BC. By combining simulations of a global chemical transport model, this work also quantified the effects of BC microphysical properties on BrC global optical absorption aerosol depth (AAOD) estimates. The AAE = 1 method could sometimes lead to a misassigned global mean AAOD of about -0.4 – 0.5 × 10-3 if BC aerosols have a complex morphology, leading to a global mean direct radiation factor (DRF) of about -0.068 ± 0.0172 to +0.085 ± 0.0215 W/m2 from BC, which is incorrectly assigned to BrC. The WDA method does not necessarily improve the estimates. In our cases, the WDA methods based on the spherical models can lead to a range of about -0.9 – 0.05 × 10-3 of misassigned AAOD, which could lead to a global mean DRF error range of -0.153 ± 0.0387 to +0.0085 ± 0.0022 W/m2. At the regional scale, the AAE = 1 method in East Asia sometimes leads to a distributed AAOD of over 3 × 10-3, resulting in a BC DRF of about +0.51 ± 0.129 W/m2, which is incorrectly attributed to BrC. Mie theory-based WDA methods would lead to an estimated AAOD error of more than 6 × 10-3 in some regions (e.g., East Asia), resulting in an estimated misattributed DRF of +1.0 ± 0.258 W/m2.

Published
2023

20. 高分二号全色卫星影像大气校正

Author

Zheng Yang, 郑杨, primary, Li Zhengqiang, 李正强, additional, Wang Siheng, 王思恒, additional, Ma Yan, 马䶮, additional, Li Kaitao, 李凯涛, additional, Zhang Yuhuan, 张玉环, additional, Liu Zhenhai, 刘振海, additional, Yang Leiku, 杨磊库, additional, Hou Weizhen, 侯伟真, additional, Gu Haoran, 顾浩然, additional, Li Yinna, 李殷娜, additional, Yao Qian, 姚前, additional, and He Zhuo, 何卓, additional

Published
2023
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21. Performance of the Semi-Empirical Precipitable Water Vapor Retrieval Algorithm Developed for Polarized Scanning Atmospheric Corrector (PSAC) in the Presence of Sensor Decay

Author

Xie, Yanqing, primary, Zhang, Miaomiao, additional, Wang, Zijun, additional, Wen, Yuan, additional, Zhang, Liguo, additional, Li, Yunduan, additional, Hou, Weizhen, additional, Liu, Zhenhai, additional, Hong, Jin, additional, Lei, Xuefeng, additional, Hu, Zhongzheng, additional, and Li, Zhengqiang, additional

Published
2023
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22. 基于星载偏振交火模式的气溶胶层高被动遥感成像反演信息量分析

Author

Gu Haoran, 顾浩然, primary, Li Zhengqiang, 李正强, additional, Hou Weizhen, 侯伟真, additional, Liu Zhenhai, 刘振海, additional, Qie Lili, 伽丽丽, additional, Li Yinna, 李殷娜, additional, Zheng Yang, 郑杨, additional, Shi Zheng, 史正, additional, Xu Hua, 许华, additional, Hong Jin, 洪津, additional, Ma Jinji, 麻金继, additional, and Chen Zhenting, 陈震霆, additional

Published
2023
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24. Predicting Time Series Using Incremental Langrangian Support Vector Regression

Author

Duan, Hua, Hou, Weizhen, He, Guoping, Zeng, Qingtian, Hutchison, David, editor, Kanade, Takeo, editor, Kittler, Josef, editor, Kleinberg, Jon M., editor, Mattern, Friedemann, editor, Mitchell, John C., editor, Naor, Moni, editor, Nierstrasz, Oscar, editor, Rangan, C. Pandu, editor, Steffen, Bernhard, editor, Sudan, Madhu, editor, Terzopoulos, Demetri, editor, Tygar, Doug, editor, Vardi, Moshe Y., editor, Weikum, Gerhard, editor, Liu, Derong, editor, Fei, Shumin, editor, Hou, Zengguang, editor, Zhang, Huaguang, editor, and Sun, Changyin, editor

Published
2007
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25. Polarimetric Remote Sensing of Atmospheric Aerosols: Instruments, Methodologies, Results, and Perspectives

Author

Dubovik, Oleg, Li, Zhengqiang, Mishchenko, Michael I, Tanre, Didier, Karol, Yana, Bojkov, Bojan, Cairns, Brian, Diner, David J, Espinosa, W. Reed, Goloub, Philippe, Gu, Xingfa, Hasekamp, Otto, Hong, Jin, Hou, Weizhen, Knobelspiesse, Kirk D, Landgraf, Jochen, Litvinov, Pavel, Liu, Yi, Lopatin, Anton, Marbach, Thierry, Maring, Hal, Martins, Vanderlei, Meijer, Yasjka, Milinevsky, Gennadi, Mukai, Sonoyo, Parol, Frederic, Qiao, Yanli, Remer, Lorraine, Rietjens, Jeroen, Sano, Itaru, Stammes, Piet, Stamnes, Snorre A, Sun, Xiaobing, Tabary, Pierre, Travis, Larry D, Waquet, Fabien, Xu, Feng, Yan, Changxiang, and Yin, Dekui

Subjects
Earth Resources And Remote Sensing, Instrumentation And Photography
Abstract

Polarimetry is one of the most promising types of remote sensing for improved characterization of atmospheric aerosol. Indeed, aerosol particles constitute a highly variable atmospheric component characterized by a large number of parameters describing particle sizes, morphologies (including shape and internal structure), absorption and scattering properties, amounts, horizontal and vertical distribution, etc. Reliable monitoring of all these parameters is very challenging, and therefore the aerosol effects on climate and environment are considered to be among the most uncertain factors in climate and environmental research. In this regard, observations that provide both the angular distribution of the scattered atmospheric radiation as well as its polarization state at multiple wavelengths covering the UV–SWIR spectral range carry substantial implicit information on the atmospheric composition. Therefore, high expectations in improving aerosol characterization are associated with detailed passive photopolarimetric observations. The critical need to use space-borne polarimetry for global accurate monitoring of detailed aerosol properties was first articulated in the late 1980s and early 1990s. By now, several orbital instruments have already provided polarization observations from space, and a number of advanced missions are scheduled for launch in the coming years by international and national space agencies. The first and most extensive record of polarimetric imagery was provided by POLDER-I, POLDER-II, and POLDER/PARASOL multi-angle multi-spectral polarization sensors. Polarimetric observations with the POLDER-like design intended for collecting extensive multi-angular multi-spectral measurements will be provided by several instruments, such as the MAI/TG-2, CAPI/TanSat, and DPC/GF-5 sensors recently launched by the Chinese Space Agency. Instruments such as the 3MI/MetOp-SG, MAIA, SpexOne and HARP2 on PACE, POSP, SMAC, PCF, DPC–Lidar, ScanPol and MSIP/Aerosol-UA, MAP/Copernicus CO2 Monitoring, etc. are planned to be launched by different space agencies in the coming decade. The concepts of these future instruments, their technical designs, and the accompanying algorithm development have been tested intensively and analyzed using diverse airborne prototypes. Certain polarimetric capabilities have also been implemented in such satellite sensors as GOME-2/MetOp and SGLI/GCOM-C.

Published
2018
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30. 高分二号全色卫星影像大气校正

Author

郑杨 Zheng Yang, 李正强 Li Zhengqiang, 王思恒 Wang Siheng, 马䶮 Ma Yan, 李凯涛 Li Kaitao, 张玉环 Zhang Yuhuan, 刘振海 Liu Zhenhai, 杨磊库 Yang Leiku, 侯伟真 Hou Weizhen, 顾浩然 Gu Haoran, 李殷娜 Li Yinna, 姚前 Yao Qian, and 何卓 He Zhuo

Subjects
Atomic and Molecular Physics, and Optics, Electronic, Optical and Magnetic Materials
Published
2023
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32. Columnar Water Vapor Retrieval by Using Data from the Polarized Scanning Atmospheric Corrector (PSAC) Onboard HJ-2 A/B Satellites

Author

Xie, Yanqing, primary, Hou, Weizhen, additional, Li, Zhengqiang, additional, Zhu, Sifeng, additional, Liu, Zhenhai, additional, Hong, Jin, additional, Ma, Yan, additional, Fan, Cheng, additional, Guang, Jie, additional, Yang, Benyong, additional, Lei, Xuefeng, additional, Huang, Honglian, additional, Sun, Xiaobing, additional, Liu, Xiao, additional, Zhang, Ying, additional, Song, Maoxin, additional, Zou, Peng, additional, and Qiao, Yanli, additional

Published
2022
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34. In-Orbit Test of the Polarized Scanning Atmospheric Corrector (PSAC) Onboard Chinese Environmental Protection and Disaster Monitoring Satellite Constellation HJ-2 A/B

Author

Li, Zhengqiang, primary, Xie, Yanqing, additional, Hou, Weizhen, additional, Liu, Zhenhai, additional, Bai, Zhaoguang, additional, Hong, Jin, additional, Ma, Yan, additional, Huang, Honglian, additional, Lei, Xuefeng, additional, Sun, Xiaobing, additional, Liu, Xiao, additional, Yang, Benyong, additional, Qiao, Yanli, additional, Zhu, Jun, additional, Cong, Qiang, additional, Zheng, Yang, additional, Song, Maoxin, additional, Zou, Peng, additional, Hu, Zhongzheng, additional, Lin, Jun, additional, and Fan, Lanlan, additional

Published
2022
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36. Preliminary On-Orbit Performance Test of the First Polarimetric Synchronization Monitoring Atmospheric Corrector (SMAC) On-Board High-Spatial Resolution Satellite Gao Fen Duo Mo (GFDM)

Author

Li, Zhengqiang, primary, Hou, Weizhen, additional, Qiu, Zhenwei, additional, Ge, Bangyu, additional, Xie, Yanqing, additional, Hong, Jin, additional, Ma, Yan, additional, Peng, Zongren, additional, Fang, Wei, additional, Zhang, Dongying, additional, Sun, Xiaobing, additional, Qiao, Yanli, additional, Yu, Jing, additional, Yang, Wentao, additional, Lin, Jun, additional, and Hu, Zhongzheng, additional

Published
2022
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