Firstly,the relationship between the accuracy of low altitude aerial photogrammetry and the field angle of camera is made by a quantitative analysis from the theory.The conclusion that the low altitude photogrammetry ...Firstly,the relationship between the accuracy of low altitude aerial photogrammetry and the field angle of camera is made by a quantitative analysis from the theory.The conclusion that the low altitude photogrammetry should use wide-angle camera as much as possible is done.Then,the limitation of the single lens camera to expand field angle and the combined wide-angle camera existing on the market not suitable for light load of low altitude UAV(Unmanned Aerial Vehicle)due to excessive weight are pointed out.The characteristics of combined wide-angle low altitude light camera with self-calibration and self-stabilization developed by the author are described,especially the principle of self-calibration for the combination of static error and dynamic error.Based on the practice of large scale mapping,a technical procedure in aerial photography by taking with wide-angle camera and large overlap simultaneously for improving the accuracy of low altitude photogrammetry is proposed.The typical engineering produced data is used to verity the above theoretical analysis.A technical route for increasing accuracy of low altitude photogrammetry with combined wide-angle camera is expounded.展开更多
Millimeter-wave cloud radar(MMCR)provides the capability of detecting the features of micro particles inside clouds and describing the internal microphysical structure of the clouds.Therefore,MMCR has been widely appl...Millimeter-wave cloud radar(MMCR)provides the capability of detecting the features of micro particles inside clouds and describing the internal microphysical structure of the clouds.Therefore,MMCR has been widely applied in cloud observations.However,due to the influence of non-meteorological factors such as insects,the cloud observations are often contaminated by non-meteorological echoes in the clear air,known as clear-air echoes.It is of great significance to automatically identify the clear-air echoes in order to extract effective meteorological information from the complex weather background.The characteristics of clear-air echoes are studied here by combining data from four devices:an MMCR,a laser-ceilometer,an L-band radiosonde,and an all-sky camera.In addition,a new algorithm,which includes feature extraction,feature selection,and classification,is proposed to achieve the automatic identification of clear-air echoes.The results show that the recognition algorithm is fairly satisfied in both simple and complex weather conditions.The recognition accuracy can reach up to 95.86%for the simple cases when cloud echoes and clear-air echoes are separate,and 88.38%for the complicated cases when low cloud echoes and clear-air echoes are mixed.展开更多
In this paper we use a correlation analysis technique of random pattern to calculation of shift velocity of auroral image. The velocity thus obtained is a kind of apparent 'average' velocity of whole image. in...In this paper we use a correlation analysis technique of random pattern to calculation of shift velocity of auroral image. The velocity thus obtained is a kind of apparent 'average' velocity of whole image. instead of the velocity of some certain points or parts in the auroral pattern. The technique is used to an example of aurora australis recorded at Zhongshang Station of Antarctica in 1997. The typical velocity of the auroral pattern for the studied cases is about 3 km/s.展开更多
Substorm processes have been studied in detail,and it is well known that interplanetary(IP)shock encountering the terrestrial magnetosphere causes global responses.However,how IP shock compression to the magnetosphere...Substorm processes have been studied in detail,and it is well known that interplanetary(IP)shock encountering the terrestrial magnetosphere causes global responses.However,how IP shock compression to the magnetosphere affects the development of an ongoing substorm remains uninvestigated.Herein,the simultaneous satellite and ground-based auroral evolutions associated with an IP shock impact on the magnetopause during an ongoing substorm on May 7th,2005,were examined.The IMAGE satellite over the Southern Hemisphere captured the global development substorm,which was initiated at 17:38:47 UT.The poleward branch of the nightside auroral oval was fortuitously monitored by an all-sky camera at the Zhongshan Station(-74.5°magnetic latitude,ZHO)in Antarctica.The satellite imager observed continuous brightening and broadening of the nightside auroral oval after the IP shock arrival.The simultaneous ground-based optical aurora measurement displayed the intensification and expansion of a preexisting auroral surge poleward of the aurora oval.The geomagnetic field variations and the instantly increased PC indices indicated an elevated merging rate and enhanced the convection-related DP-2 currents.Therefore,this IP shock transient impact did not significantly change the ongoing development of the substorm,although it meets the magnetospheric precondition hypothesis.展开更多
文摘Firstly,the relationship between the accuracy of low altitude aerial photogrammetry and the field angle of camera is made by a quantitative analysis from the theory.The conclusion that the low altitude photogrammetry should use wide-angle camera as much as possible is done.Then,the limitation of the single lens camera to expand field angle and the combined wide-angle camera existing on the market not suitable for light load of low altitude UAV(Unmanned Aerial Vehicle)due to excessive weight are pointed out.The characteristics of combined wide-angle low altitude light camera with self-calibration and self-stabilization developed by the author are described,especially the principle of self-calibration for the combination of static error and dynamic error.Based on the practice of large scale mapping,a technical procedure in aerial photography by taking with wide-angle camera and large overlap simultaneously for improving the accuracy of low altitude photogrammetry is proposed.The typical engineering produced data is used to verity the above theoretical analysis.A technical route for increasing accuracy of low altitude photogrammetry with combined wide-angle camera is expounded.
基金supported by the National Key R&D Program of China(Grant No.2018YFC1506605)Sichuan Provincial Department of Education Scientific research projects(Grant No.16ZB0211)Chengdu University of Information Technology research and development projects(Grant No.CRF201705)。
文摘Millimeter-wave cloud radar(MMCR)provides the capability of detecting the features of micro particles inside clouds and describing the internal microphysical structure of the clouds.Therefore,MMCR has been widely applied in cloud observations.However,due to the influence of non-meteorological factors such as insects,the cloud observations are often contaminated by non-meteorological echoes in the clear air,known as clear-air echoes.It is of great significance to automatically identify the clear-air echoes in order to extract effective meteorological information from the complex weather background.The characteristics of clear-air echoes are studied here by combining data from four devices:an MMCR,a laser-ceilometer,an L-band radiosonde,and an all-sky camera.In addition,a new algorithm,which includes feature extraction,feature selection,and classification,is proposed to achieve the automatic identification of clear-air echoes.The results show that the recognition algorithm is fairly satisfied in both simple and complex weather conditions.The recognition accuracy can reach up to 95.86%for the simple cases when cloud echoes and clear-air echoes are separate,and 88.38%for the complicated cases when low cloud echoes and clear-air echoes are mixed.
文摘In this paper we use a correlation analysis technique of random pattern to calculation of shift velocity of auroral image. The velocity thus obtained is a kind of apparent 'average' velocity of whole image. instead of the velocity of some certain points or parts in the auroral pattern. The technique is used to an example of aurora australis recorded at Zhongshang Station of Antarctica in 1997. The typical velocity of the auroral pattern for the studied cases is about 3 km/s.
基金supported by the National Key R&D Program of China(Grant No.2021YFE0106400)the National Scientific Foundation of China(Grant Nos.42120104003,41974185 and 42130210)+3 种基金Shanghai Science and Technology Innovation Action Plan(Grant Nos.21DZ1206100 and 22ZR1481200)SOA Key Laboratory for Polar Science(Grant No.KP201703)Chinese Meridian ProjectMNR Innovative Youth Talents Program(Grant No.12110600000018003921)。
文摘Substorm processes have been studied in detail,and it is well known that interplanetary(IP)shock encountering the terrestrial magnetosphere causes global responses.However,how IP shock compression to the magnetosphere affects the development of an ongoing substorm remains uninvestigated.Herein,the simultaneous satellite and ground-based auroral evolutions associated with an IP shock impact on the magnetopause during an ongoing substorm on May 7th,2005,were examined.The IMAGE satellite over the Southern Hemisphere captured the global development substorm,which was initiated at 17:38:47 UT.The poleward branch of the nightside auroral oval was fortuitously monitored by an all-sky camera at the Zhongshan Station(-74.5°magnetic latitude,ZHO)in Antarctica.The satellite imager observed continuous brightening and broadening of the nightside auroral oval after the IP shock arrival.The simultaneous ground-based optical aurora measurement displayed the intensification and expansion of a preexisting auroral surge poleward of the aurora oval.The geomagnetic field variations and the instantly increased PC indices indicated an elevated merging rate and enhanced the convection-related DP-2 currents.Therefore,this IP shock transient impact did not significantly change the ongoing development of the substorm,although it meets the magnetospheric precondition hypothesis.
