Fuke (19.5°N, 109.1°E) meteor radar is the first radar of the low latitudes of China, which is used to detect the wind in the meso- sphere and lower thermosphere. In this paper, by using the wind data near t...Fuke (19.5°N, 109.1°E) meteor radar is the first radar of the low latitudes of China, which is used to detect the wind in the meso- sphere and lower thermosphere. In this paper, by using the wind data near three months (1 February-20 April, 2009), we first present the variation of the atmospheric diurnal tide, semidiurnal tide and mean wind in the height range 80-100 km over the low latitudes of China. The results from our analysis are summarized below. During spring months, there are quite strong tides in the mesopause region of Fuke. The diurnal tidal amplitude is significantly larger than the amplitude of semidiurnal tide, and the maximum amplitude (about 100 m/s) of diurnal tide appear in the meridional wind. The vertical phases of both diurnal tide and semidiurnal tide propagate downward. In addition, the observed tides are compared with the linear tide model (Global Scale Wave Model, GSWM02), and the results show that Fuke diurnal tide agrees well with the model, but there are many differences between Fuke semidiurnal tide and the results from model.展开更多
The Wuhan meteor radar is the first all-sky meteor radar in China. The circulation near the mesopause from February to September 2002 is studied based on the data obtained by the Wuhan meteor radar. The zonal wind is ...The Wuhan meteor radar is the first all-sky meteor radar in China. The circulation near the mesopause from February to September 2002 is studied based on the data obtained by the Wuhan meteor radar. The zonal wind is usually eastward in winter from 80 to 100 km. The mean zonal wind become westward from March to early of May, when the winter circulation reverses to the summer circulation. But at the meteor heights, the zonal circulation usually becomes eastward after the middle of May. The meridional circulation is always equatorward. The peaks of the meridional wind move downward with the height, and the peak value reaches its maximum of 21 ms-1 in July. Having made a comparison between monthly mean wind and HWM93 model wind, the value of southward wind, the maximal value of eastward wind as well as the reversal height of zonal wind are found to be quite different from each other.展开更多
All-sky meteor radars are primarily used for meteor observations. This paper reports the first observations of ionospheric Eregion field-aligned irregularities(FAIs) from a conventional all-sky meteor radar located at...All-sky meteor radars are primarily used for meteor observations. This paper reports the first observations of ionospheric Eregion field-aligned irregularities(FAIs) from a conventional all-sky meteor radar located at Wuhan(31°N, 114°E) for the period of March–June 2018. E-region FAI echoes evident in range-time intensity(RTI) maps show quasiperiodic striations with positive and negative slopes, which are consistent with multiple FAI structures moving across the wide beam of the meteor radar. A statistical analysis shows that out of a total of 111 d, there are 73 d with E-region FAI echoes detected by the meteor radar. The FAI events correspond well with the presence of sporadic-E layers which provide the necessary plasma density gradient for the development of gradient drift instability producing FAIs. The results demonstrate the capability of conventional meteor radars to make simultaneous routine observations of meteors and ionospheric E-region FAIs through incorporating RTI and spectral analysis into the online realtime data processing. Meteor radar observations could potentially address the limitations of ionospheric radars, which cannot provide simultaneous measurements of neutral winds and irregularity structures, and thereby contribute to better understanding of the dynamical processes producing E-region irregularities.展开更多
Since 2002, we have been observing the mesosphere and lower thermosphere （MLT） region over King Sejong Station （KSS; 62.22°S, 58.78°W）, Antarctica, using various instruments such as the Spectral Airglow ...Since 2002, we have been observing the mesosphere and lower thermosphere （MLT） region over King Sejong Station （KSS; 62.22°S, 58.78°W）, Antarctica, using various instruments such as the Spectral Airglow Temperature Imager （SATI）, All Sky Camera （ASC） and VHF meteor radar. The meteor radar, installed in March 2007, continuously measures neutral winds in the alti- tude region 70-110 km and neutral temperature near the mesopause 24 h.d-1, regardless of weather conditions. In this study, we present results of an analysis of the neutral wind data for gravity wave activity over the tip of the Antarctic Peninsula, where such activity is known to be very high. Also presented is temperature estimation from measurement of the decay times of meteor trails, which is compared with other temperature measurements from SATI and the Sounding of the Atmosphere using Broadband Emis- sion Radiometry （SABER） instrument onboard the Thermosphere Ionosphere Mesosphere Energy and Dynamics （TIMED） satel- lite.展开更多
为了分析阵列布局对流星雷达到达角(direction of arrival,DOA)估计性能的影响,本文以阵列信号空间谱和克拉美-罗界(Cramer-Rao bound,CRB)作为评估指标,对流星雷达的三种天线阵型即十字阵型、T阵型和L阵型进行了DOA估计性能比较分析,...为了分析阵列布局对流星雷达到达角(direction of arrival,DOA)估计性能的影响,本文以阵列信号空间谱和克拉美-罗界(Cramer-Rao bound,CRB)作为评估指标,对流星雷达的三种天线阵型即十字阵型、T阵型和L阵型进行了DOA估计性能比较分析,并对比了十字阵型调整天线元间距后与传统方式的性能差异.研究结果表明:三种阵型中,T阵型在精确度和稳定性上均优于其他两种阵型,L阵型在某些方向的DOA中性能最优,但在其他方向上表现较差;改变天线间距会使得某个方向的DOA估计精度提高,但以降低其他方向的DOA精度为代价.展开更多
The Nippon/Norway Svalbard Meteor Radar(NSMR), has been in operation since March 2001. While primarily thought of as an instrument for examining mean wind, tidal and gravity wave neutral atmosphere dynamics in the upp...The Nippon/Norway Svalbard Meteor Radar(NSMR), has been in operation since March 2001. While primarily thought of as an instrument for examining mean wind, tidal and gravity wave neutral atmosphere dynamics in the upper mesosphere region, it is also possible to investigate spatial and temporal structure of temperature and windshear. Here, the radar itself is described followed by a presentation of these derived parameters.展开更多
基金supported by the National Natural Science Foundation of China (Grant Nos. 40621003 40804037 and 40621003)+1 种基金National Basic Research Program of China (Grant No. 2006CB806306) Specialized Research Fund for State Key Laboratories
文摘Fuke (19.5°N, 109.1°E) meteor radar is the first radar of the low latitudes of China, which is used to detect the wind in the meso- sphere and lower thermosphere. In this paper, by using the wind data near three months (1 February-20 April, 2009), we first present the variation of the atmospheric diurnal tide, semidiurnal tide and mean wind in the height range 80-100 km over the low latitudes of China. The results from our analysis are summarized below. During spring months, there are quite strong tides in the mesopause region of Fuke. The diurnal tidal amplitude is significantly larger than the amplitude of semidiurnal tide, and the maximum amplitude (about 100 m/s) of diurnal tide appear in the meridional wind. The vertical phases of both diurnal tide and semidiurnal tide propagate downward. In addition, the observed tides are compared with the linear tide model (Global Scale Wave Model, GSWM02), and the results show that Fuke diurnal tide agrees well with the model, but there are many differences between Fuke semidiurnal tide and the results from model.
基金supported by the National Natura1 Science Foundations of China(Grant Nos.40174048 and 40134020)
文摘The Wuhan meteor radar is the first all-sky meteor radar in China. The circulation near the mesopause from February to September 2002 is studied based on the data obtained by the Wuhan meteor radar. The zonal wind is usually eastward in winter from 80 to 100 km. The mean zonal wind become westward from March to early of May, when the winter circulation reverses to the summer circulation. But at the meteor heights, the zonal circulation usually becomes eastward after the middle of May. The meridional circulation is always equatorward. The peaks of the meridional wind move downward with the height, and the peak value reaches its maximum of 21 ms-1 in July. Having made a comparison between monthly mean wind and HWM93 model wind, the value of southward wind, the maximal value of eastward wind as well as the reversal height of zonal wind are found to be quite different from each other.
基金supported by the National Natural Science Foundation of China(Grant Nos.41727803,41574149,41621063)
文摘All-sky meteor radars are primarily used for meteor observations. This paper reports the first observations of ionospheric Eregion field-aligned irregularities(FAIs) from a conventional all-sky meteor radar located at Wuhan(31°N, 114°E) for the period of March–June 2018. E-region FAI echoes evident in range-time intensity(RTI) maps show quasiperiodic striations with positive and negative slopes, which are consistent with multiple FAI structures moving across the wide beam of the meteor radar. A statistical analysis shows that out of a total of 111 d, there are 73 d with E-region FAI echoes detected by the meteor radar. The FAI events correspond well with the presence of sporadic-E layers which provide the necessary plasma density gradient for the development of gradient drift instability producing FAIs. The results demonstrate the capability of conventional meteor radars to make simultaneous routine observations of meteors and ionospheric E-region FAIs through incorporating RTI and spectral analysis into the online realtime data processing. Meteor radar observations could potentially address the limitations of ionospheric radars, which cannot provide simultaneous measurements of neutral winds and irregularity structures, and thereby contribute to better understanding of the dynamical processes producing E-region irregularities.
基金financially supported by research funds(Grant nos.PE13010 and PP12320)from the Korea Polar Research Institute
文摘Since 2002, we have been observing the mesosphere and lower thermosphere （MLT） region over King Sejong Station （KSS; 62.22°S, 58.78°W）, Antarctica, using various instruments such as the Spectral Airglow Temperature Imager （SATI）, All Sky Camera （ASC） and VHF meteor radar. The meteor radar, installed in March 2007, continuously measures neutral winds in the alti- tude region 70-110 km and neutral temperature near the mesopause 24 h.d-1, regardless of weather conditions. In this study, we present results of an analysis of the neutral wind data for gravity wave activity over the tip of the Antarctic Peninsula, where such activity is known to be very high. Also presented is temperature estimation from measurement of the decay times of meteor trails, which is compared with other temperature measurements from SATI and the Sounding of the Atmosphere using Broadband Emis- sion Radiometry （SABER） instrument onboard the Thermosphere Ionosphere Mesosphere Energy and Dynamics （TIMED） satel- lite.
文摘为了分析阵列布局对流星雷达到达角(direction of arrival,DOA)估计性能的影响,本文以阵列信号空间谱和克拉美-罗界(Cramer-Rao bound,CRB)作为评估指标,对流星雷达的三种天线阵型即十字阵型、T阵型和L阵型进行了DOA估计性能比较分析,并对比了十字阵型调整天线元间距后与传统方式的性能差异.研究结果表明:三种阵型中,T阵型在精确度和稳定性上均优于其他两种阵型,L阵型在某些方向的DOA中性能最优,但在其他方向上表现较差;改变天线间距会使得某个方向的DOA估计精度提高,但以降低其他方向的DOA精度为代价.
文摘The Nippon/Norway Svalbard Meteor Radar(NSMR), has been in operation since March 2001. While primarily thought of as an instrument for examining mean wind, tidal and gravity wave neutral atmosphere dynamics in the upper mesosphere region, it is also possible to investigate spatial and temporal structure of temperature and windshear. Here, the radar itself is described followed by a presentation of these derived parameters.
