The geophysical model function （GMF） describes the relationship between a backscattering and a sea surface wind, and enables a wind vector retrieval from backscattering measurements. It is clear that the GMF plays a...The geophysical model function （GMF） describes the relationship between a backscattering and a sea surface wind, and enables a wind vector retrieval from backscattering measurements. It is clear that the GMF plays an important role in an ocean wind vector retrieval. The performance of the existing Ku-band model function QSCAT-1 is considered to be effective at low and moderate wind speed ranges. However, in the conditions of higher wind speeds, the existing algorithms diverge alarmingly, owing to the lack of in situ data required for developing the GMF for the high wind conditions, the QSCAT-1 appears to overestimate the a0, which results in underestimating the wind speeds. Several match-up QuikSCAT and special sensor microwave/imager （SSM/I） wind speed measurements of the typhoons occurring in the west Pacific Ocean are analyzed. The results show that the SSM/I wind exhibits better agreement with the ＂best track＂ analysis wind speed than the QuikSCAT wind retrieved using QSCAT-1. On the basis of this evaluation, a correction of the QSCAT-1 model function for wind speed above 16 m/s is proposed, which uses the collocated SSM/I and QuikSCAT measurements as a training set, and a neural network approach as a multiple nonlinear regression technologytechnology.In order to validate the revised GMF for high winds, the modified GMF was applied to the QuikSCAT observations of Hurricane IOKE. The wind estimated by the QuikSCAT for Typhoon IOKE in 2006 was improved with the maximum wind speed reaching 55 m/s. An error analysis was performed using the wind fields from the Holland model as the surface truth. The results show an improved agreement with the Holland model wind when compared with the wind estimated using the QSCAT-1. However, large bias still existed, indicating that the effects of rain must be considered for further improvement.展开更多
This paper presents the TDS-1 GNSS reflectometry wind Geophysical Model Function(GMF)response to GPS block types.The observables were extracted from Delay Doppler Maps(DDMs)after taking the receiver antenna gains effe...This paper presents the TDS-1 GNSS reflectometry wind Geophysical Model Function(GMF)response to GPS block types.The observables were extracted from Delay Doppler Maps(DDMs)after taking the receiver antenna gains effects and GNSS-R geometry effects into account.Since the DDM is affected by GPS EffectiveIsotropic Radiated Power(EIRP),we first investigate the sensitivity of observables to the GPS block.Additionally,the observables at high SNRs are more sensitive to wind speed,but the spatial coverage at high signal to noise ratios(SNRs)is lower,while DDMs at low SNRs have the opposite characteristics.To balance the accuracy and spatial coverage,the DDM datasets are divided into two parts:high SNR(>0 dB)and low SNR(>−10 dB and≤0 dB)to develop wind GMF.Then,the influences of GPS block on wind speed retrieval both at high and low SNR is analyzed.Results show that the block types have impacts on wind GMF and the use of a prior GPS block can contribute to a better wind speed retrieval both at high and low SNR.Compared with ASCAT,the Root Mean Square Error(RMSE)value of wind speed retrieval at high and low SNR are 2.19 m/s and 3.13 m/s,respectively,when all TDS data are processed without distinguishing GPS block types.However,if the TDS data are separately processed and used to develop wind GMF through different blocks,both the accuracy and correlation coefficient can be improved to some extent.Finally,the influence of significant height of the swell(Hs)on SNR observables is analyzed,and it is demonstrated that there is no obvious linear or nonlinear relationship between them.展开更多
The State Key Laboratory of Numerical Modelling for Atmospheric Science and Geophysical Fluid Dynamics (LASG) was established in 1985. It was considered an Excellent Opening Laboratory in the national assessment organ...The State Key Laboratory of Numerical Modelling for Atmospheric Science and Geophysical Fluid Dynamics (LASG) was established in 1985. It was considered an Excellent Opening Laboratory in the national assessment organized by the former State Science and Technology Committee (now the Ministry of Science and Technology) in 1988. Because of this, LASG was upgraded to a State Key Laboratory in 1989. It won the honor of "Excellent展开更多
The State Key Laboratory of Numerical Modeling for Atmospheric Science and Geophysical Fluid Dynamics (LASG) was set up as early as in 1985. It has been appraised as an Excellent State Key Lab in each of the three nat...The State Key Laboratory of Numerical Modeling for Atmospheric Science and Geophysical Fluid Dynamics (LASG) was set up as early as in 1985. It has been appraised as an Excellent State Key Lab in each of the three national assessments organized by State Economic Planning Commission, National Natural Science Foundation (NSFC) and the Ministry of Science and Technology (MOST) in 1991, 1996 and 2000, respectively.展开更多
The successful launch of the Cyclone Global Navigation Satellite System(CYGNSS)has opened an unprecedented opportunity for rapid observation of Wind Speed(WS)across vast oceanic regions.However,considerable debate per...The successful launch of the Cyclone Global Navigation Satellite System(CYGNSS)has opened an unprecedented opportunity for rapid observation of Wind Speed(WS)across vast oceanic regions.However,considerable debate persists over the choice of input feature parameters for WS retrieval models based on CYGNSS data,and enhancing the accuracy of WS retrieval is a focal point of current research.To address the aforementioned problems,this study establishes a comprehensive CYGNSS wind speed retrieval feature parameter set through an in-depth analysis of CYGNSS data,thereby providing a reference and basis for selecting input features for WS retrieval models.Through this analysis,we identified three crucial observational features:the normalized bistatic radar cross section,leading edge slope,and signal-to-noise ratio.Using these features,we developed a WS retrieval model based on the geophysical model function for CYGNSS data.Furthermore,acknowledging the intrinsic interconnection between wind and wave dynamics,we incorporate significant wave height into the WS retrieval model to further improve the WS retrieval accuracy.Comparative assessments with datasets from the European Centre for Medium-Range Weather Forecasts,the Chinese-French Oceanography Satellite Scatterometer,and buoy WS data underscore the high accuracy of our model,demonstrating its utility as a valuable tool for research in ocean dynamics and marine environmental prediction.展开更多
The China Seismo-Electromagnetic Satellite(CSES-01)launched on February 2,2018,has been steadily operating in orbit for more than six years,exceeding its designed five-year lifespan expectation.The evaluation results ...The China Seismo-Electromagnetic Satellite(CSES-01)launched on February 2,2018,has been steadily operating in orbit for more than six years,exceeding its designed five-year lifespan expectation.The evaluation results suggest that the satellite platform and the majority of payloads are performing well,and still providing reliable measurements.This report briefly introduces the representative scientific results obtained from CSES-01's fiveyear observations.The first result is the long-term global geophysical field data accumulated for the first time,including the global geomagnetic field,the electromagnetic field and waves in a broad frequency band,the in-situ and profile ionospheric plasma parameters,and the energetic particles.The second result is that a series of data processing and validation methods were obtained,and some of the methods are unique worldwide.The third result is that the geomagnetic field,lithospheric magnetic field,and ionospheric electron density 3D models were built based on CSES-01's data.The fourth result is that statistical features of seismic-ionospheric disturbances were revealed and the direct observational evidence for the electromagnetic wave propagation models in the lithosphere-atmosphere-ionosphere was also confirmed.The fifth result is the physical processing of the space weather events was clearly described,showing CSES-01's good capability of monitoring space weather conditions.展开更多
Episodes of tectonic activities since Archaean time in one of the oldest craton,the eastern Yilgarn Craton of Western Australia,have left a complex pattern in the architectural settings.Insights of the crustal scale a...Episodes of tectonic activities since Archaean time in one of the oldest craton,the eastern Yilgarn Craton of Western Australia,have left a complex pattern in the architectural settings.Insights of the crustal scale architectural settings of the Craton have been made through geophysical data modelling and imaging using high resolution aeromagnetic and Bouguer gravity data.The advanced technique of image processing using pseudocolour composition,hill-shading and the multiple data layers compilation in the hue,saturation and intensity(HSI)space has been used for image based analysis of potential field data.Geophysical methods of anomaly enhancement technique along with the imaging technique are used to delineate several regional and as well as local structures.Multiscale analysis in geophysical data processing with the application of varying upward continuation levels,and also anomaly enhancement techniques using spatial derivatives are used delineating major shear zones and regional scale structures.A suitable data based interpretation of basement architecture of the study area is given.展开更多
To retrieve wind field from SAR images, the development for surface wind field retrieval from SAR images based on the improvement of new inversion model is present. Geophysical Model Functions （GMFs） have been widel...To retrieve wind field from SAR images, the development for surface wind field retrieval from SAR images based on the improvement of new inversion model is present. Geophysical Model Functions （GMFs） have been widely applied for wind field retrieval from SAR images. Among them CMOD4 has a good performance under low and moderate wind conditions. Although CMOD5 is developed recently with a more fundamental basis, it has ambiguity of wind speed and a shape gradient of normalized radar cross section under low wind speed condition. This study proposes a method of wind field retrieval from SAR image by com-bining CMOD5 and CMOD4 Five VV-polarisation RADARSAT2 SAR images are implemented for validation and the retrieval re-suits by a combination method （CMOD5 and CMOD4） together with CMOD4 GMF are compared with QuikSCAT wind data. The root-mean-square error （RMSE） of wind speed is 0.75 m s-1 with correlation coefficient 0.84 using the combination method and the RMSE of wind speed is 1.01 m s-1 with correlation coefficient 0.72 using CMOD4 GMF alone for those cases. The proposed method can be applied to SAR image for avoiding the internal defect in CMOD5 under low wind speed condition.展开更多
The advances in satellite navigation and positioning technology and the worldwide establishment of continuoustracking stations have greatly promoted the development and application of the high-precision Global Navigat...The advances in satellite navigation and positioning technology and the worldwide establishment of continuoustracking stations have greatly promoted the development and application of the high-precision Global Navigation Satellite System(GNSS).GAMIT/GLOBK,as a popular high-precision GNSS data-processing software,has been widely used in monitoring crustal deformation,tsunami,iceberg,etc.Based on the basic observations and various geophysical models processed by GAMIT/GLOBK,we analyze the influence of the correction of applied geophysical models,and describe the techniques of parameter estimation and accuracy assessment.In addition,taking the present crustal movement in the Chinese mainland and the MW7.8 earthquake in Nepal as examples,we discuss the applications of GAMIT/GLOBK in crustal deformation monitoring and its future prospect.展开更多
基金The National Natural Science Foundation of China under contract No.41106152the National Science and Technology Support Program under contract No.2013BAD13B01+3 种基金the National High Technology Research and Development Program(863 Program)of China under contract No.2013AA09A505the International Science and Technology Cooperation Program of China under contract No.2011DFA22260the National High Technology Industrialization Project under contract No.[2012]2083the Marine Public Projects of China under contract Nos 201105032,201305032 and 201105002-07
文摘The geophysical model function （GMF） describes the relationship between a backscattering and a sea surface wind, and enables a wind vector retrieval from backscattering measurements. It is clear that the GMF plays an important role in an ocean wind vector retrieval. The performance of the existing Ku-band model function QSCAT-1 is considered to be effective at low and moderate wind speed ranges. However, in the conditions of higher wind speeds, the existing algorithms diverge alarmingly, owing to the lack of in situ data required for developing the GMF for the high wind conditions, the QSCAT-1 appears to overestimate the a0, which results in underestimating the wind speeds. Several match-up QuikSCAT and special sensor microwave/imager （SSM/I） wind speed measurements of the typhoons occurring in the west Pacific Ocean are analyzed. The results show that the SSM/I wind exhibits better agreement with the ＂best track＂ analysis wind speed than the QuikSCAT wind retrieved using QSCAT-1. On the basis of this evaluation, a correction of the QSCAT-1 model function for wind speed above 16 m/s is proposed, which uses the collocated SSM/I and QuikSCAT measurements as a training set, and a neural network approach as a multiple nonlinear regression technologytechnology.In order to validate the revised GMF for high winds, the modified GMF was applied to the QuikSCAT observations of Hurricane IOKE. The wind estimated by the QuikSCAT for Typhoon IOKE in 2006 was improved with the maximum wind speed reaching 55 m/s. An error analysis was performed using the wind fields from the Holland model as the surface truth. The results show an improved agreement with the Holland model wind when compared with the wind estimated using the QSCAT-1. However, large bias still existed, indicating that the effects of rain must be considered for further improvement.
基金supported by the Funds for Creative Research Groups of China[Grant no.41721003]the National Natural Science Foundation of China[Grant nos.41825009 and 41774034].
文摘This paper presents the TDS-1 GNSS reflectometry wind Geophysical Model Function(GMF)response to GPS block types.The observables were extracted from Delay Doppler Maps(DDMs)after taking the receiver antenna gains effects and GNSS-R geometry effects into account.Since the DDM is affected by GPS EffectiveIsotropic Radiated Power(EIRP),we first investigate the sensitivity of observables to the GPS block.Additionally,the observables at high SNRs are more sensitive to wind speed,but the spatial coverage at high signal to noise ratios(SNRs)is lower,while DDMs at low SNRs have the opposite characteristics.To balance the accuracy and spatial coverage,the DDM datasets are divided into two parts:high SNR(>0 dB)and low SNR(>−10 dB and≤0 dB)to develop wind GMF.Then,the influences of GPS block on wind speed retrieval both at high and low SNR is analyzed.Results show that the block types have impacts on wind GMF and the use of a prior GPS block can contribute to a better wind speed retrieval both at high and low SNR.Compared with ASCAT,the Root Mean Square Error(RMSE)value of wind speed retrieval at high and low SNR are 2.19 m/s and 3.13 m/s,respectively,when all TDS data are processed without distinguishing GPS block types.However,if the TDS data are separately processed and used to develop wind GMF through different blocks,both the accuracy and correlation coefficient can be improved to some extent.Finally,the influence of significant height of the swell(Hs)on SNR observables is analyzed,and it is demonstrated that there is no obvious linear or nonlinear relationship between them.
文摘The State Key Laboratory of Numerical Modelling for Atmospheric Science and Geophysical Fluid Dynamics (LASG) was established in 1985. It was considered an Excellent Opening Laboratory in the national assessment organized by the former State Science and Technology Committee (now the Ministry of Science and Technology) in 1988. Because of this, LASG was upgraded to a State Key Laboratory in 1989. It won the honor of "Excellent
文摘The State Key Laboratory of Numerical Modeling for Atmospheric Science and Geophysical Fluid Dynamics (LASG) was set up as early as in 1985. It has been appraised as an Excellent State Key Lab in each of the three national assessments organized by State Economic Planning Commission, National Natural Science Foundation (NSFC) and the Ministry of Science and Technology (MOST) in 1991, 1996 and 2000, respectively.
基金The Fund of Key Laboratory of Space Ocean Remote Sensing and Application,Ministry of Natural Resources under contract No.2023CFO016the National Natural Science Foundation of China under contract No.61931025the Key Program of Joint Fund of the National Natural Science Foundation of China and Shandong Province under contract No.U22A20586.
文摘The successful launch of the Cyclone Global Navigation Satellite System(CYGNSS)has opened an unprecedented opportunity for rapid observation of Wind Speed(WS)across vast oceanic regions.However,considerable debate persists over the choice of input feature parameters for WS retrieval models based on CYGNSS data,and enhancing the accuracy of WS retrieval is a focal point of current research.To address the aforementioned problems,this study establishes a comprehensive CYGNSS wind speed retrieval feature parameter set through an in-depth analysis of CYGNSS data,thereby providing a reference and basis for selecting input features for WS retrieval models.Through this analysis,we identified three crucial observational features:the normalized bistatic radar cross section,leading edge slope,and signal-to-noise ratio.Using these features,we developed a WS retrieval model based on the geophysical model function for CYGNSS data.Furthermore,acknowledging the intrinsic interconnection between wind and wave dynamics,we incorporate significant wave height into the WS retrieval model to further improve the WS retrieval accuracy.Comparative assessments with datasets from the European Centre for Medium-Range Weather Forecasts,the Chinese-French Oceanography Satellite Scatterometer,and buoy WS data underscore the high accuracy of our model,demonstrating its utility as a valuable tool for research in ocean dynamics and marine environmental prediction.
基金a project funded by the China National Space Administration(CNSA)China Earthquake Administration(CEA)+3 种基金supported by the National Key Research and Development Program of China 2023YFE0117300the National Natural Science Foundation of China Grant 4187417the APSCO Earthquake Research Project PhaseⅡ,and the Dragon 5 cooperation 2020–2024(ID.59236)the CSES02 project。
文摘The China Seismo-Electromagnetic Satellite(CSES-01)launched on February 2,2018,has been steadily operating in orbit for more than six years,exceeding its designed five-year lifespan expectation.The evaluation results suggest that the satellite platform and the majority of payloads are performing well,and still providing reliable measurements.This report briefly introduces the representative scientific results obtained from CSES-01's fiveyear observations.The first result is the long-term global geophysical field data accumulated for the first time,including the global geomagnetic field,the electromagnetic field and waves in a broad frequency band,the in-situ and profile ionospheric plasma parameters,and the energetic particles.The second result is that a series of data processing and validation methods were obtained,and some of the methods are unique worldwide.The third result is that the geomagnetic field,lithospheric magnetic field,and ionospheric electron density 3D models were built based on CSES-01's data.The fourth result is that statistical features of seismic-ionospheric disturbances were revealed and the direct observational evidence for the electromagnetic wave propagation models in the lithosphere-atmosphere-ionosphere was also confirmed.The fifth result is the physical processing of the space weather events was clearly described,showing CSES-01's good capability of monitoring space weather conditions.
基金supported by Spaceage Geoconsulting,a research oriented consulting firm.
文摘Episodes of tectonic activities since Archaean time in one of the oldest craton,the eastern Yilgarn Craton of Western Australia,have left a complex pattern in the architectural settings.Insights of the crustal scale architectural settings of the Craton have been made through geophysical data modelling and imaging using high resolution aeromagnetic and Bouguer gravity data.The advanced technique of image processing using pseudocolour composition,hill-shading and the multiple data layers compilation in the hue,saturation and intensity(HSI)space has been used for image based analysis of potential field data.Geophysical methods of anomaly enhancement technique along with the imaging technique are used to delineate several regional and as well as local structures.Multiscale analysis in geophysical data processing with the application of varying upward continuation levels,and also anomaly enhancement techniques using spatial derivatives are used delineating major shear zones and regional scale structures.A suitable data based interpretation of basement architecture of the study area is given.
基金supported by the National Natural Science Foundation of China (Nos.41376010 and 40830959)the Start-up Foundation of Zhejiang Ocean University (No.21105011913)
文摘To retrieve wind field from SAR images, the development for surface wind field retrieval from SAR images based on the improvement of new inversion model is present. Geophysical Model Functions （GMFs） have been widely applied for wind field retrieval from SAR images. Among them CMOD4 has a good performance under low and moderate wind conditions. Although CMOD5 is developed recently with a more fundamental basis, it has ambiguity of wind speed and a shape gradient of normalized radar cross section under low wind speed condition. This study proposes a method of wind field retrieval from SAR image by com-bining CMOD5 and CMOD4 Five VV-polarisation RADARSAT2 SAR images are implemented for validation and the retrieval re-suits by a combination method （CMOD5 and CMOD4） together with CMOD4 GMF are compared with QuikSCAT wind data. The root-mean-square error （RMSE） of wind speed is 0.75 m s-1 with correlation coefficient 0.84 using the combination method and the RMSE of wind speed is 1.01 m s-1 with correlation coefficient 0.72 using CMOD4 GMF alone for those cases. The proposed method can be applied to SAR image for avoiding the internal defect in CMOD5 under low wind speed condition.
基金This work is supported by the Beijing Natural Science Foundation,China(8204077)Grants from the National Natural Science Foundation of China(42004010).
文摘The advances in satellite navigation and positioning technology and the worldwide establishment of continuoustracking stations have greatly promoted the development and application of the high-precision Global Navigation Satellite System(GNSS).GAMIT/GLOBK,as a popular high-precision GNSS data-processing software,has been widely used in monitoring crustal deformation,tsunami,iceberg,etc.Based on the basic observations and various geophysical models processed by GAMIT/GLOBK,we analyze the influence of the correction of applied geophysical models,and describe the techniques of parameter estimation and accuracy assessment.In addition,taking the present crustal movement in the Chinese mainland and the MW7.8 earthquake in Nepal as examples,we discuss the applications of GAMIT/GLOBK in crustal deformation monitoring and its future prospect.
