Utilizing observations by the Sounding of the Atmosphere using Broadband Emission Radiometry(SABER)instrument,we quantitatively assessed the dawn-dusk asymmetry in temperature disturbances within the high-latitude mes...Utilizing observations by the Sounding of the Atmosphere using Broadband Emission Radiometry(SABER)instrument,we quantitatively assessed the dawn-dusk asymmetry in temperature disturbances within the high-latitude mesosphere and lower thermosphere(MLT)during the main phase of geomagnetic storms in this study.An analysis of five geomagnetic superstorm events indicated that during the main phase,negative temperature disturbances were more prevalent on the dawn side than on the dusk side in the high-latitude MLT region.Results of a statistical analysis of 54 geomagnetic storm events also revealed a notable disparity in temperature disturbances between the dawn and dusk sides.At high latitudes,38.2%of the observational points on the dawn side exhibited negative temperature disturbances(less than−5 K),whereas on the dusk side,this percentage was only 29.5%.In contrast,at mid-latitudes,these proportions were 34.1%and 36.5%,respectively,showing no significant difference.We also conducted a statistical analysis of temperature disturbances at different altitudes,which revealed an increase in the proportion of warming disturbances with altitude.Conversely,the proportion of cooling disturbances initially rose with altitude,reaching a peak around 105 km,and subsequently decreased.These temperature disturbance differences could be explained by the day-night asymmetry in vertical wind disturbances during storm conditions.展开更多
Accurate knowledge of mesospheric winds and waves is essential for studying the dynamics and climate in the mesosphere and lower thermosphere(MLT)region.In this study,we conduct a comparative analysis of the mesospher...Accurate knowledge of mesospheric winds and waves is essential for studying the dynamics and climate in the mesosphere and lower thermosphere(MLT)region.In this study,we conduct a comparative analysis of the mesosphere tidal results obtained from two adjacent meteor radars at low latitudes in Kunming,China,from November 2013 to December 2014.These two radars operate at different frequencies of 37.5 MHz and 53.1 MHz,respectively.However,overall good agreement is observed between the two radars in terms of horizontal winds and tide observations.The results show that the dominant tidal waves of the zonal and meridional winds are diurnal and semidiurnal tides.Moreover,we conduct an exhaustive statistical analysis to compare the tidal amplitudes and vertical wavelengths recorded by the dual radar systems,which reveals a high degree of alignment in tidal dynamics.The investigation includes variances and covariances of tidal amplitudes,which demonstrate remarkable consistency across measurements from both radars.This finding highlights clear uniformity in the mesospheric tidal patterns observed at low latitudes by the two neighboring meteor radars.Results of the comparative analysis specifically underscore the significant correlation in vertical wavelength measurements,validating the robustness of radar observations for tidal research.展开更多
本文通过中层大气高空冰探测器(Aeronomy of Ice in the Mesosphere,AIM)卫星的仪器载荷——用于云成像和粒子实验的探测器(Cloud Imaging and Particle Size,CIPS)和用于冰晶实验的太阳掩星探测器(Solar Occultation for Ice Experimen...本文通过中层大气高空冰探测器(Aeronomy of Ice in the Mesosphere,AIM)卫星的仪器载荷——用于云成像和粒子实验的探测器(Cloud Imaging and Particle Size,CIPS)和用于冰晶实验的太阳掩星探测器(Solar Occultation for Ice Experiment,SOFIE)在2007—2014年间南、北半球的观测数据,分析了2007—2014年间夜光云的反照率、冰水含量(ice water content,IWC)、每日发生率及中层顶温度在南、北半球的变化趋势,讨论了夜光云发生位置和年变化,并且对夜光云反照率、中层顶温度和IWC的相关性进行了分析。结果表明:南、北半球夜光云主要发生在80°~85°纬度范围内,与南半球相比,北半球夜光云反照率持续时间更长、年波动更小、IWC更高且每日发生率更高,而南半球90°W~150°W位置的反照率总是较低;南、北半球夜光云反照率和IWC均与中层顶温度之间存在负相关关系,但反照率和冰水含量相关性表现不明显。本文的研究结果为夜光云作为中间层大气变化的敏感指标提供了量化依据;同时,南、北半球夜光云的差异特性有助于改进气候模型,对理解长期气候变化中的半球不对称响应具有参考意义。展开更多
Polar mesosphere summer echoes(PMSEs)are very strong radar echoes in the polar mesopause in local summer.Here we present the frequency dependence of the volume reflectivity and the effect of energetic particle precipi...Polar mesosphere summer echoes(PMSEs)are very strong radar echoes in the polar mesopause in local summer.Here we present the frequency dependence of the volume reflectivity and the effect of energetic particle precipitation on modulated PMSEs by using PMSEs observations carried out by European Incoherent SCATter(EISCAT)heating equipment simultaneously with very high frequency(VHF)radar and ultra high frequency(UHF)radar on 12 July 2007.According to the experimental observations,the PMSEs occurrence rate at VHF was much higher than that at UHF,and the altitude of the PMSEs maximum observed at VHF was higher than that at UHF.Overlapping regions were observed by VHF radar between high energetic particle precipitation and the PMSEs.In addition,highfrequency heating had a very limited impact on PMSEs when the UHF electron density was enhanced because of energetic particle precipitation.In addition,an updated qualitative method was used to study the relationship between volume reflectivity and frequency.The volume reflectivity was found to be inversely proportional to the fourth power of radar frequency.The theoretical and experimental results provide a definitive data foundation for further analysis and investigation of the physical mechanism of PMSEs.展开更多
Polar mesosphere summer echoes （PMSE） are very strong radar echoes from alti- tudes close to the polar summer mesopause. The data from sounding rocket campaigns indicate that the radar signal to noise ratio （SNR）,...Polar mesosphere summer echoes （PMSE） are very strong radar echoes from alti- tudes close to the polar summer mesopause. The data from sounding rocket campaigns indicate that the radar signal to noise ratio （SNR）, electron density and dust charge density of polar meso- sphere in summer show obvious layered structure. In this paper the theory of wave propagation in layered media is used to study the reflectance and SNR at each layer in polar mesosphere. The calculated SNR using theory of dusty plasma is found in good agreement with the experimental result, which may imply that the intensity of the radar echoes reflected by the layered structure in polar mesosphere where polar mesosphere summer echoes used to occur can interpret partially the phenomenon of PMSE. In other words, reflection may play an important role in the occurrence of PMSE.展开更多
The European Incoherent Scatter Scientific Association(EISCAT) Very High Frequency(224 MHz) Radar has been used to investigate the aspect sensitivity of polar mesosphere summer echoes(PMSE) in the period 13–15 July 2...The European Incoherent Scatter Scientific Association(EISCAT) Very High Frequency(224 MHz) Radar has been used to investigate the aspect sensitivity of polar mesosphere summer echoes(PMSE) in the period 13–15 July 2010. The aspect sensitivity of PMSE using this radar and at such a high frequency has not been previously reported. Data concerning the aspect sensitivity of PMSE were collected by traversing the antenna beam from the zenith direction, and comparing the received power. Surprisingly, as the intensity received by the oblique beam was often larger than that of the vertical beam, suggesting the presence of tilted dusty plasma layers as a potential cause, a theoretical model was developed to confirm the existence of these layers and their formation process. The experimental results and theoretical model presented help elucidate the structural properties of the possible generation mechanism of strong radar echoes in the polar summer mesosphere region.展开更多
In this work,for the first time,we have analyzed and compared the responses of polar mesosphere winter echoes(PMWE)and their summer counterpart,polar mesosphere summer echoes(PMSE),to high-frequency(HF)heating in term...In this work,for the first time,we have analyzed and compared the responses of polar mesosphere winter echoes(PMWE)and their summer counterpart,polar mesosphere summer echoes(PMSE),to high-frequency(HF)heating in terms of modulated characteristics(i.e.,backscatter intensity reduction,recovery,and overshoot).Both PMWE and PMSE observations were from the same site(Tromsφ,Norway;69.6°N,19.2°E)and radar(EISCAT[European Incoherent Scatter Scientific Association]very high frequency,224 MHz).The heating patterns of both PMWE and PMSE were found to be similar;however,PMSE was more greatly affected by HF heating.Polar mesosphere summer echoes showed recovery and overshoot more frequently than did PMWE.In addition,the mean recovery and overshoot of PMSE were greater than those of PMWE.The associated electron temperature enhancement was estimated for both PMWE and PMSE and showed that,compared with PMWE,the electron temperature enhancement was more significant in PMSE.The strong heating effects on PMSE may be due to the considerable increase in electron temperature.展开更多
Radar echoes intensity of polar mesosphere summer echoes（PMSE） is greatly affected by the temperature of dusty plasma and the frequency of electromagnetic wave about the radar.In this paper,a new method is developed...Radar echoes intensity of polar mesosphere summer echoes（PMSE） is greatly affected by the temperature of dusty plasma and the frequency of electromagnetic wave about the radar.In this paper,a new method is developed to explain the active experiment results of PMSE.The theory of wave propagation in a layered media is used to study the propagation characteristics of an electromagnetic wave at different electron temperatures.The simulation results show that the variation tendency of the reflected power fraction almost agrees with the results observed by radar in the European Incoherent Scatter Scientific Association（EISCAT）.The radar echoes intensity of PMSE greatly decreases with the increase of the radio frequency and the enhancement of the electron temperature.展开更多
This paper deals with the dielectric permittivity of dusty plasma in the earth’s mesosphere.We give expressions for the complex dielectric permittivity of dusty plasma,taking into account the effects of the dust char...This paper deals with the dielectric permittivity of dusty plasma in the earth’s mesosphere.We give expressions for the complex dielectric permittivity of dusty plasma,taking into account the effects of the dust charging process and magnetic field.We discuss the dielectric permittivity of dusty plasma in several cases,such as high frequency approximation,parallel propagation in MF/HF band,and effects of plasma movement.Finally,the expressions are employed to study the phenomenon of radar echoes from the polar summer mesosphere.We report that dielectric permittivity caused by the dust charging process gives a radar cross section proportional to ω–4 and produces a number density of charged dust that agrees with measurements of mesopheric radar echoes.展开更多
An investigation of the influence of the relief of a planet on the global circulation of the Earth’s atmosphere is an important problem. Beyond doubt, mountains affect the global circulation of the troposphere, howev...An investigation of the influence of the relief of a planet on the global circulation of the Earth’s atmosphere is an important problem. Beyond doubt, mountains affect the global circulation of the troposphere, however, their influence on the global circulation of the stratosphere and mesosphere is not evident. In the present study, to investigate the influence of the relief of a planet on the global circulation of the Earth’s stratosphere and mesosphere, the non-hydrostatic mathematical model, developed earlier in the Polar Geophysical Institute, is utilized. Calculations were made for two distinct cases. The relief of the planet was taken into account for the first case. Unlike, the Earth’s surface was assumed to be smooth for the second case. Simulations were performed for the winter period in the northern hemisphere (January). Simulation results, obtained for both considered cases, are qualitatively similar at the levels of stratosphere and mesosphere, however, some noticeable distinctions exist. The horizontal domains exist, where the simulated horizontal and vertical components of the neutral wind velocity, obtained for two considered cases, differ noticeably at the levels of the stratosphere and mesosphere. Some of these horizontal domains are not connected with positions of mountains at the Earth’s surface. On the contrary, some of these horizontal domains are situated above mountains.展开更多
基金the National Key R&D Program of China(Grant No.2022YFF0503702)the National Natural Science Foundation of China(Grant Nos.42004132,42074195 and 42074183)+1 种基金the open funding of the Ministry of Natural Resources Key Laboratory for Polar Science(Grant No.KP202104)the China Geological Survey(Grant No.ZD20220145).
文摘Utilizing observations by the Sounding of the Atmosphere using Broadband Emission Radiometry(SABER)instrument,we quantitatively assessed the dawn-dusk asymmetry in temperature disturbances within the high-latitude mesosphere and lower thermosphere(MLT)during the main phase of geomagnetic storms in this study.An analysis of five geomagnetic superstorm events indicated that during the main phase,negative temperature disturbances were more prevalent on the dawn side than on the dusk side in the high-latitude MLT region.Results of a statistical analysis of 54 geomagnetic storm events also revealed a notable disparity in temperature disturbances between the dawn and dusk sides.At high latitudes,38.2%of the observational points on the dawn side exhibited negative temperature disturbances(less than−5 K),whereas on the dusk side,this percentage was only 29.5%.In contrast,at mid-latitudes,these proportions were 34.1%and 36.5%,respectively,showing no significant difference.We also conducted a statistical analysis of temperature disturbances at different altitudes,which revealed an increase in the proportion of warming disturbances with altitude.Conversely,the proportion of cooling disturbances initially rose with altitude,reaching a peak around 105 km,and subsequently decreased.These temperature disturbance differences could be explained by the day-night asymmetry in vertical wind disturbances during storm conditions.
基金supported by the National Natural Science Foundation of China (Grant Nos. 42125402 and 42174183)the National Key Technologies R&D Program of China (Grant No.2022YFF0503703)+2 种基金the B-type Strategic Priority Program of the Chinese Academy of Sciences (Grant No. XDB41000000)the foundation of the National Key Laboratory of Electromagnetic Environment and the Fundamental Research Funds for the Central Universitiesthe Chinese Meridian Project
文摘Accurate knowledge of mesospheric winds and waves is essential for studying the dynamics and climate in the mesosphere and lower thermosphere(MLT)region.In this study,we conduct a comparative analysis of the mesosphere tidal results obtained from two adjacent meteor radars at low latitudes in Kunming,China,from November 2013 to December 2014.These two radars operate at different frequencies of 37.5 MHz and 53.1 MHz,respectively.However,overall good agreement is observed between the two radars in terms of horizontal winds and tide observations.The results show that the dominant tidal waves of the zonal and meridional winds are diurnal and semidiurnal tides.Moreover,we conduct an exhaustive statistical analysis to compare the tidal amplitudes and vertical wavelengths recorded by the dual radar systems,which reveals a high degree of alignment in tidal dynamics.The investigation includes variances and covariances of tidal amplitudes,which demonstrate remarkable consistency across measurements from both radars.This finding highlights clear uniformity in the mesospheric tidal patterns observed at low latitudes by the two neighboring meteor radars.Results of the comparative analysis specifically underscore the significant correlation in vertical wavelength measurements,validating the robustness of radar observations for tidal research.
文摘本文通过中层大气高空冰探测器(Aeronomy of Ice in the Mesosphere,AIM)卫星的仪器载荷——用于云成像和粒子实验的探测器(Cloud Imaging and Particle Size,CIPS)和用于冰晶实验的太阳掩星探测器(Solar Occultation for Ice Experiment,SOFIE)在2007—2014年间南、北半球的观测数据,分析了2007—2014年间夜光云的反照率、冰水含量(ice water content,IWC)、每日发生率及中层顶温度在南、北半球的变化趋势,讨论了夜光云发生位置和年变化,并且对夜光云反照率、中层顶温度和IWC的相关性进行了分析。结果表明:南、北半球夜光云主要发生在80°~85°纬度范围内,与南半球相比,北半球夜光云反照率持续时间更长、年波动更小、IWC更高且每日发生率更高,而南半球90°W~150°W位置的反照率总是较低;南、北半球夜光云反照率和IWC均与中层顶温度之间存在负相关关系,但反照率和冰水含量相关性表现不明显。本文的研究结果为夜光云作为中间层大气变化的敏感指标提供了量化依据;同时,南、北半球夜光云的差异特性有助于改进气候模型,对理解长期气候变化中的半球不对称响应具有参考意义。
基金This research was funded by the Sichuan Science and Technology Program(no.2019YJ0188)the National Natural Science Foundation of China(nos.61671116,61771096,11905026)+2 种基金the National Key Research and Development Program of China(no.2019YFA0210202)Fundamental Research Funds for the Central Universities(nos.ZYGX2019Z006,ZYGX2019J012)We are grateful to the EISCAT Scientific Association for providing the PMSE experimental data(http://portal.eiscat.se/schedule/schedule.cgi).The EISCAT Scientific Association is supported by China(China Research Institute of Radio Wave Propagation),Finland(Suomen Akatemia of Finland),Japan(the National Institute of Polar Research of Japan and Institute for Space-Earth Environmental Research at Nagoya University),Norway(Norges Forskningsråd of Norway),Sweden(the Swedish Research Council),and the UK(the Natural Environment Research Council).We also acknowledge the China Scholarship Council.
文摘Polar mesosphere summer echoes(PMSEs)are very strong radar echoes in the polar mesopause in local summer.Here we present the frequency dependence of the volume reflectivity and the effect of energetic particle precipitation on modulated PMSEs by using PMSEs observations carried out by European Incoherent SCATter(EISCAT)heating equipment simultaneously with very high frequency(VHF)radar and ultra high frequency(UHF)radar on 12 July 2007.According to the experimental observations,the PMSEs occurrence rate at VHF was much higher than that at UHF,and the altitude of the PMSEs maximum observed at VHF was higher than that at UHF.Overlapping regions were observed by VHF radar between high energetic particle precipitation and the PMSEs.In addition,highfrequency heating had a very limited impact on PMSEs when the UHF electron density was enhanced because of energetic particle precipitation.In addition,an updated qualitative method was used to study the relationship between volume reflectivity and frequency.The volume reflectivity was found to be inversely proportional to the fourth power of radar frequency.The theoretical and experimental results provide a definitive data foundation for further analysis and investigation of the physical mechanism of PMSEs.
基金supported by National Natural Science Foundation of China (Nos.40831062, 60971034)the Scientific Research Starting Foundation of University of Electronic Science and Technology of China (No.Y02002010401066)
文摘Polar mesosphere summer echoes （PMSE） are very strong radar echoes from alti- tudes close to the polar summer mesopause. The data from sounding rocket campaigns indicate that the radar signal to noise ratio （SNR）, electron density and dust charge density of polar meso- sphere in summer show obvious layered structure. In this paper the theory of wave propagation in layered media is used to study the reflectance and SNR at each layer in polar mesosphere. The calculated SNR using theory of dusty plasma is found in good agreement with the experimental result, which may imply that the intensity of the radar echoes reflected by the layered structure in polar mesosphere where polar mesosphere summer echoes used to occur can interpret partially the phenomenon of PMSE. In other words, reflection may play an important role in the occurrence of PMSE.
基金supported by CRIRP (China)NIPR (Japan)+3 种基金NFR (Sweden)PPARC (UK)RCN (Norway)SA (Finland)
文摘The European Incoherent Scatter Scientific Association(EISCAT) Very High Frequency(224 MHz) Radar has been used to investigate the aspect sensitivity of polar mesosphere summer echoes(PMSE) in the period 13–15 July 2010. The aspect sensitivity of PMSE using this radar and at such a high frequency has not been previously reported. Data concerning the aspect sensitivity of PMSE were collected by traversing the antenna beam from the zenith direction, and comparing the received power. Surprisingly, as the intensity received by the oblique beam was often larger than that of the vertical beam, suggesting the presence of tilted dusty plasma layers as a potential cause, a theoretical model was developed to confirm the existence of these layers and their formation process. The experimental results and theoretical model presented help elucidate the structural properties of the possible generation mechanism of strong radar echoes in the polar summer mesosphere region.
基金supported by the National Natural Science Foundation of China(No.62271113,62201529)the National Key Laboratory of Electromagnetic Environment(No.202102010)the Natural Science Foundation of Sichuan Province(No.2022NSFSC1848).
文摘In this work,for the first time,we have analyzed and compared the responses of polar mesosphere winter echoes(PMWE)and their summer counterpart,polar mesosphere summer echoes(PMSE),to high-frequency(HF)heating in terms of modulated characteristics(i.e.,backscatter intensity reduction,recovery,and overshoot).Both PMWE and PMSE observations were from the same site(Tromsφ,Norway;69.6°N,19.2°E)and radar(EISCAT[European Incoherent Scatter Scientific Association]very high frequency,224 MHz).The heating patterns of both PMWE and PMSE were found to be similar;however,PMSE was more greatly affected by HF heating.Polar mesosphere summer echoes showed recovery and overshoot more frequently than did PMWE.In addition,the mean recovery and overshoot of PMSE were greater than those of PMWE.The associated electron temperature enhancement was estimated for both PMWE and PMSE and showed that,compared with PMWE,the electron temperature enhancement was more significant in PMSE.The strong heating effects on PMSE may be due to the considerable increase in electron temperature.
基金supported by National Natural Science Foundation of China(Nos.41104097 and 41304119)by the National Key Laboratoryof Electromagnetic Environment,China Research Institute of Radiowave Propagation(CRIRP)
文摘Radar echoes intensity of polar mesosphere summer echoes（PMSE） is greatly affected by the temperature of dusty plasma and the frequency of electromagnetic wave about the radar.In this paper,a new method is developed to explain the active experiment results of PMSE.The theory of wave propagation in a layered media is used to study the propagation characteristics of an electromagnetic wave at different electron temperatures.The simulation results show that the variation tendency of the reflected power fraction almost agrees with the results observed by radar in the European Incoherent Scatter Scientific Association（EISCAT）.The radar echoes intensity of PMSE greatly decreases with the increase of the radio frequency and the enhancement of the electron temperature.
基金the National Natural Science Foundation of China(NSFC)with grant No.61601419.
文摘This paper deals with the dielectric permittivity of dusty plasma in the earth’s mesosphere.We give expressions for the complex dielectric permittivity of dusty plasma,taking into account the effects of the dust charging process and magnetic field.We discuss the dielectric permittivity of dusty plasma in several cases,such as high frequency approximation,parallel propagation in MF/HF band,and effects of plasma movement.Finally,the expressions are employed to study the phenomenon of radar echoes from the polar summer mesosphere.We report that dielectric permittivity caused by the dust charging process gives a radar cross section proportional to ω–4 and produces a number density of charged dust that agrees with measurements of mesopheric radar echoes.
文摘An investigation of the influence of the relief of a planet on the global circulation of the Earth’s atmosphere is an important problem. Beyond doubt, mountains affect the global circulation of the troposphere, however, their influence on the global circulation of the stratosphere and mesosphere is not evident. In the present study, to investigate the influence of the relief of a planet on the global circulation of the Earth’s stratosphere and mesosphere, the non-hydrostatic mathematical model, developed earlier in the Polar Geophysical Institute, is utilized. Calculations were made for two distinct cases. The relief of the planet was taken into account for the first case. Unlike, the Earth’s surface was assumed to be smooth for the second case. Simulations were performed for the winter period in the northern hemisphere (January). Simulation results, obtained for both considered cases, are qualitatively similar at the levels of stratosphere and mesosphere, however, some noticeable distinctions exist. The horizontal domains exist, where the simulated horizontal and vertical components of the neutral wind velocity, obtained for two considered cases, differ noticeably at the levels of the stratosphere and mesosphere. Some of these horizontal domains are not connected with positions of mountains at the Earth’s surface. On the contrary, some of these horizontal domains are situated above mountains.
