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An enhanced retrieval of the wet tropospheric correction for Sentinel-3 using dynamic inputs from ERA5

JOURNAL OF GEODESY 2022年第4期96卷 1-19页

作者： Vieira, Telmo Fernandes, M. Joana Lazaro, Clara Univ Porto Fac Ciencias P-4169007 Porto Portugal Ctr Interdisciplinar Invest Marinha & Ambiental C Matosinhos Portugal

Sentinel-3 (S3) satellites are equipped with microwave radiometers that perform brightness temperature (TB) measurements at 23.8 and 36.5 GHz to determine the wet tropospheric correction (WTC). The analysis of the two MWR-derived WTC present in S3 products, retrieved from three- and five-input neural network (NN) algorithms, suggest the need for their improvement. Focusing on the inputs and physical component, this paper aims at improving the WTC retrieval for open ocean, considering a suitable learning for S3 and a better accounting for the surface contribution to the WTC retrieval. Adopting a purely empirical approach, the learning database has been built using 1 year (2017) of valid S3A measurements, ERA5-derived WTC, and dynamic sea surface temperature (SST) from ERA5. The proposed approach is a similar NN with four inputs: TB at 23.8 and 36.5 GHz, altimeter backscattering coefficient and SST. Results show that the use of a dynamic SST, instead of static tables as currently adopted in S3, makes the fifth input (vertical temperature decrease) redundant. Comparisons with reference and independent WTC sources show that the WTC derived from this algorithm, when compared with those available in the S3 products, leads to a decrease in the RMS values of WTC differences, with respect to these independent WTC, by about 1 mm globally, that locally can reach almost 1 cm. This study proposes a new approach for the WTC of Sentinel-3 by considering a suitable set of dynamic inputs that better characterize the atmosphere, which is a significant enhancement over the current algorithms.

关键词： Brightness temperature Microwave radiometer retrieval algorithm Sentinel-3 Wet tropospheric correction

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First retrieval of absorbing aerosol height over dark target using TROPOMI oxygen B band: algorithm development and application for surface particulate matter estimates

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REMOTE SENSING OF ENVIRONMENT 2021年 265卷 112674-112674页

作者： Chen, Xi Wang, Jun Xu, Xiaoguang Zhou, Meng Zhang, Huanxin Garcia, Lorena Castro Colarco, Peter R. Janz, Scott J. Yorks, John McGill, Matthew Reid, Jeffrey S. de Graaf, Martin Kondragunta, Shobha Univ Iowa Dept Chem & Biochem Engn Iowa City IA 52242 USA Univ Iowa Ctr Global & Reg Environm Res Iowa City IA 52242 USA Univ Iowa Iowa Technol Inst Iowa City IA 52242 USA Univ Iowa Interdisciplinary Grad Program Geoinformat Iowa City IA 52242 USA Univ Maryland Baltimore Cty Joint Ctr Earth Syst Technol Baltimore MD 21250 USA NASA Goddard Space Flight Ctr Code 916 Greenbelt MD 20771 USA US Naval Res Lab Marine Meteorol Div Monterey CA 93943 USA Royal Netherlands Meteorol Inst KNMI De Bilt Netherlands NOAA Ctr Satellite Applicat & Res NESDIS College Pk MD 20740 USA

Constraint of the vertical distribution of aerosol particles is crucial for the study of aerosol plume structure, aerosol radiative effects, and ultimately monitoring surface air pollution. We developed an algorithm to retrieve the aerosol optical central height (AOCH) of absorbing aerosols by using, for the first time, the oxygen (O-2) A and B absorption band measurements from the TROPOspheric Monitoring Instrument (TROPOMI) over dark targets. For the retrieval, narrow band radiance at seven channels ranging from ultraviolet (UV) to shortwave infrared (SWIR) are convolved from TROPOMI hyperspectral measurements. Subsequently, cloudy pixels are screened out by using the slope of spectral reflectance, while aerosol types (dust and smoke) are classified by the wavelength dependence of aerosol path radiance in conjunction with UV aerosol index. Surface reflectance over land is derived from the MODIS surface bi-directional reflectance climatology, and over water from the GOME-2 surface Lambert-equivalent reflectivity (LER) database. The aerosol optical depth (AOD) and AOCH are retrieved through an approach of look-up-table accounting for AERONET-based dust and smoke optical properties. For multiple smoke and dust plume events around the world, our retrieved AOCH values agree with space-borne lidar CALIOP counterparts, with a mean bias of <0.15 km and a correlation coefficient of 0.85-0.87. Due in part to adding the O-2 B band, our retrieval represents an aerosol extinction peak height better than the TROPOMI operational Level 2 aerosol layer height retrieved from only the O-2 A band. The latter shows 0.5-2 km low bias, especially over land. Finally, the high potential of AOCH for improving surface PM2.5 estimates is also illustrated with a case study in which the high bias of surface PM2.5 in MERRA-2 data is corrected after being scaled by the retrieved AOCH.

关键词： Aerosol optical central height TROPOMI PM2.5 retrieval algorithm O-2 absorption band

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A Hybrid Particle Swarm Optimization-Tuning algorithm for the Prediction of Nanoparticle Morphology from Microscopic images

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AEROSOL AND AIR QUALITY RESEARCH 2023年第4期23卷 1-19页

作者： Singh, Abhishek Thajudeen, Thaseem Indian Inst Technol Goa Sch Mech Sci Veling 403401 Goa India

Aggregated nanoparticle structures are quite ubiquitous in aerosol and colloidal science, specifically in nanoparticle synthesis systems such as combustion processes where coagulation results in the formation of fractal-like structures. In addition to their size, morphology of the particles also plays a key role in defining various physicochemical properties. Electron microscopy based images are the most commonly used tools in visualizing these aggregates, and prediction of the 3-dimensional structures from the microscopic images is quite complex. Typically, 2-dimensional features from the images are compared to available structures in a database or regression equations are used to predict 3-dimensional morphological parameters including fractal dimension and pre -exponential factor. In this study, we propose a combination of evolutionary algorithm and forward tuning model to predict the best fit 3-dimensional structures of aggregates from their projection images. 2-dimensional features from a projection image are compared to the candidate projections generated using FracVAL code and optimized using Particle Swarm Optimization to obtain the 3-dimensional structure of the aggregate. Various 3-dimensional properties including hydrodynamic diameter and mobility diameter of the retrieved structures are then compared with the properties of the aggregate used to form the candidate projection image, to test the suitability of the algorithm. Results show that the hybrid algorithm can closely predict the 3-dimensional structures from the projection images with less than 10% difference in the predicted 3-dimensional properties including mobility diameter and radius of gyration.

关键词： Fractal aggregates retrieval algorithm Morphological analysis Particle swarm optimization

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Ground return signal simulation and retrieval algorithm of spaceborne integrated path DIAL for CO₂ measurements 14

Ground return signal simulation and retrieval algorithm of s...

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Conference on Lidar Remote Sensing for Environmental Monitoring XIV

作者： Liu, Bing-Yi Wang, Jun-Yang Liu, Zhi-Shen Ocean Univ China Ocean Remote Sensing Inst Qingdao 266003 Peoples R China

ISBN: (纸本)9781628413298

Spaceborne integrated path differential absorption (IPDA) lidar is an active-detection system which is able to perform global CO2 measurement with high accuracy of 1ppmv at day and night over ground and clouds. To evaluate the detection performance of the system, simulation of the ground return signal and retrieval algorithm for CO2 concentration are presented in this paper. Ground return signals of spaceborne IPDA lidar under various ground surface reflectivity and atmospheric aerosol optical depths are simulated using given system parameters, standard atmosphere profiles and HITRAN database, which can be used as reference for determining system parameters. The simulated signals are further applied to the research on retrieval algorithm for CO2 concentration. The column-weighted dry air mixing ratio of CO2 denoted by XCO2 is obtained. As the deviations of XCO2 between the initial values for simulation and the results from retrieval algorithm are within the expected error ranges, it is proved that the simulation and retrieval algorithm are reliable.

关键词： spaceborne lidar DIAL IPDA carbon dioxide simulation retrieval algorithm

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Sea Surface Temperature retrieval From the FY-3D MWRI Measurements

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IEEE TRANSACTIONS ON GEOSCIENCE AND REMOTE SENSING 2024年 62卷 1页

作者： Li, Zi-Chong Jiang, Geng-Ming Fudan Univ Sch Informat Sci & Technol Key Lab Informat Sci Electromagnet Waves Minist Educ Shanghai 200433 Peoples R China Shanghai Qi Zhi Inst Shanghai 200232 Peoples R China

Sea surface temperature (SST) is a key climate variable, which affects the behavior of the Earth's atmosphere. In this article, a method coupled with microwave sea surface emissivities (SSEs) is developed to retrieve SST from the intercalibrated measurements acquired by the microwave radiation imager (MWRI) on Fengyun 3D (FY-3D) satellite. First, the spatiotemporal matching samples over sea surfaces in 0.25 $<^>{\circ }\,\,\times0.25<^>{\circ }$ between FY-3D MWRI measurements and the fifth generation of European center for medium-range weather forecast (ECMWF) atmospheric reanalysis (ERA5) data in January, April, July, and October 2020 are collected and used to determine the unknown coefficients of the SST retrieval algorithm. To improve the accuracy, besides grouping the samples by sea surface wind speed and SST, pseudo-SSEs are introduced into the SST retrieval algorithm. The root-mean-square errors (RMSEs) of the SST retrieval algorithm in the three steps are 1.18, 0.73, and 0.68 K, respectively. Then, the SSTs in 2020 between 60 degrees S and 60 degrees N are retrieved from the FY-3D MWRI measurements without precipitation and heavy clouds. Finally, the SSTs retrieved in this work are validated with the GMI SST and the iQuam in situ data. The errors of the retrieved SSTs in the three steps are 0.19 +/- 1.23, 0.17 +/- 1.15, and 0.01 +/- 1.15 K against the GMI SST, respectively, while they are 0.48 +/- 1.24, 0.37 +/- 1.13, and 0.12 +/- 1.10 K against the iQuam in situ data, respectively. The errors of both the retrieval algorithm and the derived SSTs in this work are obviously reduced after introducing the pseudo-SSEs into the algorithm, which proves that the SST retrieval algorithm developed in this work is valid and accurate.

关键词： Fengyun 3D (FY-3D) microwave radiation imager (MWRI) measurements microwave sea surface emissivity (SSE) retrieval algorithm retrieval and validation sea surface temperature (SST)

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COMBINING THE 50-60 GHZ AND 118 GHZ PASSIVE MICROWAVE MEASUREMENTS FOR SURFACE PRESSURE retrieval OVER OCEANS

COMBINING THE 50-60 GHZ AND 118 GHZ PASSIVE MICROWAVE MEASUR...

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IEEE International Geoscience and Remote Sensing Symposium (IGARSS)

作者： Zhang, Zijin Dong, Xiaolong Chinese Acad Sci Natl Space Sci Ctr CAS Key Lab Microwave Remote Sensing Beijing 100190 Peoples R China Univ Chinese Acad Sci Beijing 100049 Peoples R China

ISBN: (数字)9781665427920

ISBN: (纸本)9781665427920

Previous studies used 50-60 GHz or 118 GHz passive microwave measurements separately for surface pressure retrieval. To improve the retrieval accuracy, a joint retrieval method is proposed in this study to use the 50-60 GHz and 118 GHz passive microwave measurements simultaneously for surface pressure retrieval over oceans. Based on information content analysis and footprint matching, collocated passive observations of the two bands are obtained, and then are used to establish back-propagation neural network retrieval models. Using the 50-60 GHz passive observations of Microwave Temperature Sounder-II (MWTS-II) onboard the Fengyun-3D (FY-3D) satellite and the 118.75 GHz observations of the Microwave Humidity and Temperature Sounder (MWHTS) onboard the FY-3D satellite, joint retrieval experiments are completed. Experimental results show that when using the 50-60 GHz and 118.75 GHz oxygen absorption band together for surface pressure measurements, more surface pressure information and better retrieval accuracy can be obtained than using them separately.

关键词： sea surface atmospheric pressure Fengyun-3D satellite passive microwave retrieval algorithm

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Mapping Freezing and Thawing Surface State Periods With the CYGNSS Based F/T Seasonal Threshold algorithm

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IEEE JOURNAL OF SELECTED TOPICS IN APPLIED EARTH OBSERVATIONS AND REMOTE SENSING 2022年 15卷 9943-9952页

作者： Carreno-Luengo, Hugo Ruf, Christopher S. S. Univ Michigan Coll Engn Dept Climate & Space Sci & Engn Ann Arbor MI 48109 USA

Freeze/Thaw (F/T) surface state detection and imaging has been demonstrated as a capability of NASA's Cyclone Global Navigation Satellite System mission. The objective of the research presented here is the application of an existing F/T retrieval algorithm to multiple target areas over several years in order to demonstrate the ability to provide long term trending of F/T behavior. Metrics are developed and evaluated to characterize F/T trends related to global warming. They include the annual fraction of time spent frozen and thawed as a function of location and year, and the earliest fall freeze and earliest spring thaw as a function of location and year. The results demonstrate the capability of Global Navigation Satellite Systems Reflectometry to provide long term trending of F/T behavior relevant to studies of climate change.

关键词： CH4 climate change CYGNSS freeze/thaw GNSS-R retrieval algorithm

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Constraining China's land carbon sink from emerging satellite CO2 observations: Progress and challenges

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GLOBAL CHANGE BIOLOGY 2022年第23期28卷 6838-6846页

作者： Wang, Yilong Tian, Xiangjun Chevallier, Frederic Johnson, Matthew S. Philip, Sajeev Baker, David F. Schuh, Andrew E. Deng, Feng Zhang, Xingying Zhang, Lu Zhu, Dan Wang, Xuhui Chinese Acad Sci Inst Tibetan Plateau Res State Key Lab Tibetan Plateau Earth Syst Resource Beijing Peoples R China Univ Chinese Acad Sci Beijing Peoples R China Univ Paris Saclay Lab Sci Climat & Environm LSCE IPSL CEA CNRS UVSQ Gif Sur Yvette France NASA Earth Sci Div Ames Res Ctr Moffett Field CA 94035 USA Indian Inst Technol Delhi Ctr Atmospher Sci New Delhi India Colorado State Univ CIRA Ft Collins CO 80523 USA Univ Toronto Dept Phys Toronto ON Canada China Meteorol Adm CMA Key Lab Radiometr Calibrat & Validat Environm Sat Natl Satellite Meteorol Ctr Natl Ctr Space Weather Beijing Peoples R China China Meteorol Adm CMA Innovat Ctr FengYun Meteorol Satellite FYSIC Beijing Peoples R China Peking Univ Coll Urban & Environm Sci Sino French Inst Earth Syst Sci Beijing Peoples R China

Land carbon sink is a vital component for the achievement of China's ambitious carbon neutrality goal, but its magnitude is poorly known. Atmospheric observations and inverse models are valuable tools to constrain the China's land carbon sink. Space-based CO2 measurements from satellites form an emerging data stream for application of such atmospheric inversions. Here, we reviewed the satellite missions that is dedicated to the monitoring of CO2, and the recent progresses on the inversion of China's land carbon sink using satellite CO2 measurements. We summarized the limitations and challenges in current space platforms, retrieval algorithms, and the inverse modeling. It is shown that there are large uncertainties of contemporary satellite-based estimates of China's land carbon sink. We discussed future opportunities of continuous improvements in three aspects to better constrain China's land carbon sink with space-based CO2 measurements.

关键词： atmospheric inversion China's land carbon sink retrieval algorithm satellite XCO2

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ASSESSMENT OF THE NASA SMAP SOIL MOISTURE PRODUCT OVER A SEMI-ARID AGRICULTURAL REGION IN MEXICO

ASSESSMENT OF THE NASA SMAP SOIL MOISTURE PRODUCT OVER A SEM...

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IEEE International Geoscience and Remote Sensing Symposium (IGARSS)

作者： Monsivais-Huertero, Alejandro Zempoaltecatl-Ramirez, Enrique Huerta-Batiz, Hector Ernesto Constantino-Recillas, Daniel Enrique Cotero-Manzo, Roberto Hernandez-Sanchez, Juan Carlos Quiroz-Ibarra, Jose Emilio Gonzalez-Ordiano, Jorge Angel Garcia-Sanchez, Abisay Rodriguez-Ortiz, Gerardo Florencio-Da Silva, Rodrigo Sauce-Rangel, Victor Manuel Jimenez-Escalona, Jose Carlos Inst Politecn Nacl ESIME Ticoman Mexico City 07320 DF Mexico Univ Iberoamer Inst Invest Aplicada & Tecnol INIAT Mexico City 01219 DF Mexico Univ Iberoamer Dept Estudios Ingn Innovac DEII Mexico City DF Mexico Inst Tecnol Valle Oaxaca Xoxocotlan 71230 Mexico

ISBN: (纸本)9798350320107

The National Aeronautics and Space Administration (NASA) Soil Moisture Active Passive (SMAP) satellite aims at estimating surface soil moisture at global scales. In order to validate the soil moisture retrieval algorithms, they need to be tested over different conditions worldwide. In response to this need, the Terrestrial Hydrology Experiment 2021 and 2022 in Mexico (THEXMEX-21 and -22) was conducted in Central Valleys, Oaxaca, Mexico over a twelve-month period. Ground crews collected soil moisture values, crop description, and biomass samples in support of these campaigns. The objective of these field experiments was to create a soil moisture network over a semi-arid agricultural area in Mexico and compare the SMAP soil moisture estimates with soil moisture measurements. The comparison between in-situ values and SMAP retrievals of soil moisture demonstrated that absolute soil moisture values can be delivered by satellite observations. SMAP soil moisture estimates followed the general trend observed during the field experiment.

关键词： Soil moisture retrieval algorithm agricultural area NASA SMAP

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PERFORMANCE ANALYSES OF PASSIVE MICROWAVE ATMOSPHERIC SOUNDING APPROACHES THAT USE HYPER-SPECTRAL-SAMPLING AND/OR MULTI-ANGLE-SAMPLING: METHODS, SIMULATION EXAMPLES, AND PITFALLS

PERFORMANCE ANALYSES OF PASSIVE MICROWAVE ATMOSPHERIC SOUNDI...

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IEEE International Geoscience and Remote Sensing Symposium (IGARSS)

作者： Blackwell, W. J. Milstein, A. Lincoln Lab 244 Wood St Lexington MA 02421 USA

ISBN: (纸本)9798350320107

In this paper, the key models, assumptions, and statistical characterizations/uncertainties are examined to better understand how to evaluate hyper-spectral sampling (HSS) and "multi-angle-sampling (MAS) systems and interpret results that are commonly presented in the contemporary literature. The analysis presented is based on a set of thousands of representative, global atmospheric profiles over a variety of surfaces. These profiles are used with a line-by-line radiative transfer model to calculate the at-sensor radiance for a variety of viewing angles, spectral response functions, channelization schemes, and noise assumptions. A neural-network-based retrieval scheme [Blackwell, 2005] similar to one that is used for AIRS/AMSU on Aqua and for TROPICS near-real-time processing is used to retrieve the profiles. Errors are characterized by bias, RMS uncertainty, averaging kernel width, and retrieved profile error correlation width for a variety of sensor configurations to explore HSS and MAS performance. Neural network jacobians [Blackwell, 2012] facilitate the direct calculation of these metrics in some cases.

关键词： hyperspectral microwave sounder temperature profile moisture profile retrieval algorithm

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