The recently deployed Transition Region Explorer(TREx)-RGB(red-green-blue)all-sky imager(ASI)is designed to capture“true color”images of the aurora and airglow.Because the 557.7 nm green line is usually the brightes...The recently deployed Transition Region Explorer(TREx)-RGB(red-green-blue)all-sky imager(ASI)is designed to capture“true color”images of the aurora and airglow.Because the 557.7 nm green line is usually the brightest emission line in visible auroras,the green channel of a TREx-RGB camera is usually dominated by the 557.7 nm emission.Under this rationale,the TREx mission does not include a specific 557.7 nm imager and is designed to use the RGB green-channel data as a proxy for the 557.7 nm aurora.In this study,we present an initial effort to establish the conversion ratio or formula linking the RGB green-channel data to the absolute intensity of 557.7 nm auroras,which is crucial for quantitative uses of the RGB data.We illustrate two approaches:(1)through a comparison with the collocated measurement of green-line auroras from the TREx spectrograph,and(2)through a comparison with the modeled green-line intensity according to realistic electron precipitation flux measurements from low-Earth-orbit satellites,with the aid of an auroral transport model.We demonstrate the procedures and provide initial results for the TREx-RGB ASIs at the Rabbit Lake and Lucky Lake stations.The RGB response is found to be nonlinear.Empirical conversion ratios or formulas between RGB green-channel data and the green-line auroral intensity are given and can be applied immediately by TREx-RGB data users.The methodology established in this study will also be applicable to the upcoming SMILE ASI mission,which will adopt a similar RGB camera system in its deployment.展开更多
Using high temporal resolution optical data obtained from three-wavelength all-sky imagers at Chinese Yellow River Station in the Arctic, together with the EISCAT Svalbard radar （ESR） and SuperDARN radars, we invest...Using high temporal resolution optical data obtained from three-wavelength all-sky imagers at Chinese Yellow River Station in the Arctic, together with the EISCAT Svalbard radar （ESR） and SuperDARN radars, we investigated the dayside pole- ward moving auroral forms （PMAFs） and the associated plasma features in the polar ionosphere under difibrent interplanetary magnetic field （1MF） conditions, between 0900 and 1010 UT on 22 December 2003. Simultaneous optical and ESR observations revealed that all PMAFs were clearly associated with pulsed particle precipitations. During northward IMF, particles can precipi- tate into lower altitudes and reach the ionospheric E-region, and there is a reverse convection cell associated with these PMAFs. This cell is one of the typical signatures of the dayside high-latitude （lobe） reconnection in the polar ionosphere. These results indicate that the PMAFs were associated with the high-latitude reconnection. During southward IMF, the PMAFs show larger lati- tudinal motion, indicating a longer mean lifetime, and the associated ionospheric features indicate that the PMAFs were generated by the dayside low-latitude reconnection.展开更多
Preliminary analyses of low and high resolution data are presented from the polar plasma waves measured on board INTERBALL 2 satellite in three frequency bands: ELF(5 1000 Hz),VLF(1 20 kHz)and LF(20 260 kHz). The ...Preliminary analyses of low and high resolution data are presented from the polar plasma waves measured on board INTERBALL 2 satellite in three frequency bands: ELF(5 1000 Hz),VLF(1 20 kHz)and LF(20 260 kHz). The propagation and polarization characteristics of the Auroral Kilometric Radiation (AKR) emission are estimated and studied. The obtained result shows that R X and L O modes of AKR emission just above source regions are found. The propagation characteristics are also determined: wave normal directions weakly oblique or quasi parallel to the earth magnetic field direction.展开更多
The Super Dual Auroral Radar Network （SuperDARN） is a network of HF coherent scatter radars. At the end of 2012 there were 31 operational radars of which 22 were in the northern hemisphere and 9 in the southern hemi...The Super Dual Auroral Radar Network （SuperDARN） is a network of HF coherent scatter radars. At the end of 2012 there were 31 operational radars of which 22 were in the northern hemisphere and 9 in the southern hemisphere. The radars are operated by 17 different research groups from 11 different countries. In this paper we give an overview of the network and its development over the last twenty years, concentrating on the nature of the collaboration. We describe the data parameters that are available, radar operational modes, and the structure of the SuperDARN collaboration. A brief, ＂light touch＂ review is also given of the science achieved with the network. Finally we give a brief look to future science directions.展开更多
基金jointly funded by the Canada Foundation for Innovationthe Alberta Economic Development and Trade organization+1 种基金the University of Calgarysupported by the Canadian Space Agency。
文摘The recently deployed Transition Region Explorer(TREx)-RGB(red-green-blue)all-sky imager(ASI)is designed to capture“true color”images of the aurora and airglow.Because the 557.7 nm green line is usually the brightest emission line in visible auroras,the green channel of a TREx-RGB camera is usually dominated by the 557.7 nm emission.Under this rationale,the TREx mission does not include a specific 557.7 nm imager and is designed to use the RGB green-channel data as a proxy for the 557.7 nm aurora.In this study,we present an initial effort to establish the conversion ratio or formula linking the RGB green-channel data to the absolute intensity of 557.7 nm auroras,which is crucial for quantitative uses of the RGB data.We illustrate two approaches:(1)through a comparison with the collocated measurement of green-line auroras from the TREx spectrograph,and(2)through a comparison with the modeled green-line intensity according to realistic electron precipitation flux measurements from low-Earth-orbit satellites,with the aid of an auroral transport model.We demonstrate the procedures and provide initial results for the TREx-RGB ASIs at the Rabbit Lake and Lucky Lake stations.The RGB response is found to be nonlinear.Empirical conversion ratios or formulas between RGB green-channel data and the green-line auroral intensity are given and can be applied immediately by TREx-RGB data users.The methodology established in this study will also be applicable to the upcoming SMILE ASI mission,which will adopt a similar RGB camera system in its deployment.
基金supported by the National Natural Science Foundation of China (Grant nos. 40974083, 41031064, 41104091,41104090, 41274149 and 41274164)the Ocean Public Welfare Scientific Research Project of China (Grant no. 201005017)+1 种基金the Polar Strategic Research Foundation of China (Grant nos. 20100202, 20100203 and 20120304)the Polar Environment Comprehensive Investigation & Assessment Programs(Grant no. CHINARE 2012-02-03)
文摘Using high temporal resolution optical data obtained from three-wavelength all-sky imagers at Chinese Yellow River Station in the Arctic, together with the EISCAT Svalbard radar （ESR） and SuperDARN radars, we investigated the dayside pole- ward moving auroral forms （PMAFs） and the associated plasma features in the polar ionosphere under difibrent interplanetary magnetic field （1MF） conditions, between 0900 and 1010 UT on 22 December 2003. Simultaneous optical and ESR observations revealed that all PMAFs were clearly associated with pulsed particle precipitations. During northward IMF, particles can precipi- tate into lower altitudes and reach the ionospheric E-region, and there is a reverse convection cell associated with these PMAFs. This cell is one of the typical signatures of the dayside high-latitude （lobe） reconnection in the polar ionosphere. These results indicate that the PMAFs were associated with the high-latitude reconnection. During southward IMF, the PMAFs show larger lati- tudinal motion, indicating a longer mean lifetime, and the associated ionospheric features indicate that the PMAFs were generated by the dayside low-latitude reconnection.
文摘Preliminary analyses of low and high resolution data are presented from the polar plasma waves measured on board INTERBALL 2 satellite in three frequency bands: ELF(5 1000 Hz),VLF(1 20 kHz)and LF(20 260 kHz). The propagation and polarization characteristics of the Auroral Kilometric Radiation (AKR) emission are estimated and studied. The obtained result shows that R X and L O modes of AKR emission just above source regions are found. The propagation characteristics are also determined: wave normal directions weakly oblique or quasi parallel to the earth magnetic field direction.
基金Super DARN is a collection of radars funded by national scientific funding agencies of Australia,Canada,China,Finland,France,Italy,Japan,the Russian Federation,South Africa,United Kingdom and United States of America
文摘The Super Dual Auroral Radar Network （SuperDARN） is a network of HF coherent scatter radars. At the end of 2012 there were 31 operational radars of which 22 were in the northern hemisphere and 9 in the southern hemisphere. The radars are operated by 17 different research groups from 11 different countries. In this paper we give an overview of the network and its development over the last twenty years, concentrating on the nature of the collaboration. We describe the data parameters that are available, radar operational modes, and the structure of the SuperDARN collaboration. A brief, ＂light touch＂ review is also given of the science achieved with the network. Finally we give a brief look to future science directions.
