Pub Date : 2024-07-08DOI: 10.5194/angeo-42-313-2024
Theogene Ndacyayisenga, Jean Uwamahoro, Jean Claude Uwamahoro, Daniel Izuikedinachi Okoh, Kantepalli Sasikumar Raja, Akeem Babatunde Rabiu, Christian Kwisanga, Christian Monstein
Abstract. Type II solar radio bursts are signatures of the coronal shocks and, therefore, particle acceleration events in the solar atmosphere and interplanetary space. Type II bursts can serve as a proxy to provide early warnings of incoming solar storm disturbances, such as geomagnetic storms and radiation storms, which may further lead to ionospheric effects. In this article, we report the first observation of 32 type II bursts by measuring various plasma parameters that occurred between May 2021 and December 2022 in solar cycle 25. We further evaluated their accompanying space weather events in terms of ionospheric total electron content (TEC) enhancement using the rate of TEC index (ROTI). In this study, we find that at heliocentric distance ∼1–2 R⊙, the shock and the Alfvén speeds are in the range 504–1282 and 368–826 km−1, respectively. The Alfvén Mach number is of the order of 1.2≤MA≤1.8 at the above-mentioned heliocentric distance. In addition, the measured magnetic field strength is consistent with the earlier reports and follows a single power law B(r)=6.07r-3.96G. Based on the current analysis, it is found that 19 out of 32 type II bursts are associated with immediate space weather events in terms of radio blackouts and polar cap absorption events, making them strong indications of space weather disruption. The ROTI enhancements, which indicate ionospheric irregularities, strongly correlate with GOES X-ray flares, which are associated with the type II radio bursts recorded. The diurnal variability in ROTI is proportional to the strength of the associated flare class, and the corresponding longitudinal variation is attributed to the difference in longitude. This article demonstrates that since type II bursts are connected to space weather hazards, understanding various physical parameters of type II bursts helps to predict and forecast the space weather.
摘要第二类太阳射电暴是日冕冲击的特征，因此也是太阳大气层和行星际空间的粒子加速事件。II型射电暴可以作为一种替代物，为即将到来的太阳风暴扰动（如地磁暴和辐射风暴）提供预警，这些扰动可能会进一步导致电离层效应。在这篇文章中，我们通过测量太阳周期 25 中 2021 年 5 月至 2022 年 12 月期间发生的各种等离子体参数，首次报告了对 32 个 II 型爆发的观测结果。我们还利用 TEC 指数（ROTI）从电离层总电子含量（TEC）增强的角度进一步评估了与之伴随的空间天气事件。在这项研究中，我们发现在日心距离∼1-2 R⊙处，冲击速度和阿尔弗韦恩速度的范围分别为504-1282和368-826 km-1。在上述日心距离下，阿尔弗芬马赫数为 1.2≤MA≤1.8。此外，测得的磁场强度与之前的报告一致，遵循单幂律 B(r)=6.07r-3.96G 。根据目前的分析，发现 32 个 II 型爆发中有 19 个与无线电停电和极盖吸收事件等直接空间天气事件有关，是空间天气破坏的强烈迹象。表明电离层不规则的 ROTI 增强与 GOES X 射线耀斑密切相关，而 GOES X 射线耀斑与所记录的 II 型射电暴有关。ROTI 的昼夜变化与相关耀斑类别的强度成正比，相应的纵向变化归因于经度差异。这篇文章表明，由于 II 型爆发与空间气象灾害有关，了解 II 型爆发的各种物理参数有助于预测和预报空间气象。
{"title":"Low-frequency solar radio type II bursts and their association with space weather events during the ascending phase of solar cycle 25","authors":"Theogene Ndacyayisenga, Jean Uwamahoro, Jean Claude Uwamahoro, Daniel Izuikedinachi Okoh, Kantepalli Sasikumar Raja, Akeem Babatunde Rabiu, Christian Kwisanga, Christian Monstein","doi":"10.5194/angeo-42-313-2024","DOIUrl":"https://doi.org/10.5194/angeo-42-313-2024","url":null,"abstract":"Abstract. Type II solar radio bursts are signatures of the coronal shocks and, therefore, particle acceleration events in the solar atmosphere and interplanetary space. Type II bursts can serve as a proxy to provide early warnings of incoming solar storm disturbances, such as geomagnetic storms and radiation storms, which may further lead to ionospheric effects. In this article, we report the first observation of 32 type II bursts by measuring various plasma parameters that occurred between May 2021 and December 2022 in solar cycle 25. We further evaluated their accompanying space weather events in terms of ionospheric total electron content (TEC) enhancement using the rate of TEC index (ROTI). In this study, we find that at heliocentric distance ∼1–2 R⊙, the shock and the Alfvén speeds are in the range 504–1282 and 368–826 km−1, respectively. The Alfvén Mach number is of the order of 1.2≤MA≤1.8 at the above-mentioned heliocentric distance. In addition, the measured magnetic field strength is consistent with the earlier reports and follows a single power law B(r)=6.07r-3.96G. Based on the current analysis, it is found that 19 out of 32 type II bursts are associated with immediate space weather events in terms of radio blackouts and polar cap absorption events, making them strong indications of space weather disruption. The ROTI enhancements, which indicate ionospheric irregularities, strongly correlate with GOES X-ray flares, which are associated with the type II radio bursts recorded. The diurnal variability in ROTI is proportional to the strength of the associated flare class, and the corresponding longitudinal variation is attributed to the difference in longitude. This article demonstrates that since type II bursts are connected to space weather hazards, understanding various physical parameters of type II bursts helps to predict and forecast the space weather.","PeriodicalId":50777,"journal":{"name":"Annales Geophysicae","volume":"26 1","pages":""},"PeriodicalIF":1.9,"publicationDate":"2024-07-08","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"141569910","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":4,"RegionCategory":"地球科学","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
Pub Date : 2024-07-04DOI: 10.5194/egusphere-2024-1921
Somaiyeh Sabri, Stefaan Poedts
Abstract. In this research, the EUropean Heliosphere FORecasting Information Asset (EUHFORIA) is used as a mathematical model to examine how coronal mass ejections (CMEs) move through a solar wind flow that is not consistent in all areas, taking into account three dimensions and changes over time. Magnetohydrodynamic (MHD) simulations were conducted to analyze the propagation patterns of two specific CMEs that occurred on June 21 and 25, 2015. The EUHFORIA simulations for the inner region of the heliosphere involve incorporating conditions related to CMEs and the solar wind at the boundaries. Comparative examination using data from the WIND and OMNI spacecrafts reveals that the EUHFORIA model offers a moderately precise depiction. The study highlights that interactions of CMEs play a significant role in determining their impact on Earth, highlighting that their initial speeds, while similar, are less influential. Besides, the EUHFORIA numerical model align with the findings of the GFZ German research center, this implies that EUHFORIA has also the capability to compute and potentially forecast the impact of CMEs on the Earth.
{"title":"The investigation of June 21 and 25, 2015 CMEs using EUHFORIA","authors":"Somaiyeh Sabri, Stefaan Poedts","doi":"10.5194/egusphere-2024-1921","DOIUrl":"https://doi.org/10.5194/egusphere-2024-1921","url":null,"abstract":"<strong>Abstract.</strong> In this research, the EUropean Heliosphere FORecasting Information Asset (EUHFORIA) is used as a mathematical model to examine how coronal mass ejections (CMEs) move through a solar wind flow that is not consistent in all areas, taking into account three dimensions and changes over time. Magnetohydrodynamic (MHD) simulations were conducted to analyze the propagation patterns of two specific CMEs that occurred on June 21 and 25, 2015. The EUHFORIA simulations for the inner region of the heliosphere involve incorporating conditions related to CMEs and the solar wind at the boundaries. Comparative examination using data from the WIND and OMNI spacecrafts reveals that the EUHFORIA model offers a moderately precise depiction. The study highlights that interactions of CMEs play a significant role in determining their impact on Earth, highlighting that their initial speeds, while similar, are less influential. Besides, the EUHFORIA numerical model align with the findings of the GFZ German research center, this implies that EUHFORIA has also the capability to compute and potentially forecast the impact of CMEs on the Earth.","PeriodicalId":50777,"journal":{"name":"Annales Geophysicae","volume":"46 1","pages":""},"PeriodicalIF":1.9,"publicationDate":"2024-07-04","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"141552422","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":4,"RegionCategory":"地球科学","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
Pub Date : 2024-07-01DOI: 10.5194/angeo-42-301-2024
Rezy Pradipta, Pei-Chen Lai
Abstract. A major explosion that released a significant amount of energy into the atmosphere occurred in Beirut on 4 August 2020. The energy released may have reached the upper atmosphere and generated some traveling ionospheric disturbances (TIDs), which can affect radio wave propagation. In this study, we used data from the Defense Meteorological Satellite Program (DMSP) and ground-based ionosondes in the Mediterranean region to investigate the ionospheric response to this historic explosion event. Our DMSP data analysis revealed a noticeable increase in the ionospheric electron density near the Beirut area following the explosion, accompanied by some wavelike disturbances. Some characteristic TID signatures were also identified in the shape of ionogram traces at several locations in the Mediterranean. This event occurred during a period of relatively quiet geomagnetic conditions, making the observed TIDs likely to have originated from the Beirut explosion, not from other sources such as auroral activities. These observational findings demonstrate that TIDs from the Beirut explosion were able to propagate over longer distances, beyond the immediate areas of Lebanon and Israel–Palestine, reaching the Mediterranean and eastern Europe.
摘要2020 年 8 月 4 日在贝鲁特发生了一次大爆炸，向大气层释放了大量能量。释放的能量可能已经到达高层大气，并产生了一些行进电离层扰动（TID），这些扰动可能会影响无线电波的传播。在本研究中，我们利用国防气象卫星计划（DMSP）和地中海地区地基电离层探测仪的数据来研究电离层对这一历史性爆炸事件的响应。我们的 DMSP 数据分析显示，爆炸后贝鲁特地区附近的电离层电子密度明显增加，并伴有一些波状扰动。在地中海几个地点的电离图痕迹中还发现了一些特征性的 TID 信号。这一事件发生在地磁条件相对平静的时期，因此观测到的 TID 很可能来自贝鲁特爆炸，而不是极光活动等其他来源。这些观测结果表明，贝鲁特爆炸产生的热电离层能够传播到更远的地方，超越黎巴嫩和以色列-巴勒斯坦附近地区，到达地中海和东欧。
{"title":"Observations of ionospheric disturbances associated with the 2020 Beirut explosion by Defense Meteorological Satellite Program and ground-based ionosondes","authors":"Rezy Pradipta, Pei-Chen Lai","doi":"10.5194/angeo-42-301-2024","DOIUrl":"https://doi.org/10.5194/angeo-42-301-2024","url":null,"abstract":"Abstract. A major explosion that released a significant amount of energy into the atmosphere occurred in Beirut on 4 August 2020. The energy released may have reached the upper atmosphere and generated some traveling ionospheric disturbances (TIDs), which can affect radio wave propagation. In this study, we used data from the Defense Meteorological Satellite Program (DMSP) and ground-based ionosondes in the Mediterranean region to investigate the ionospheric response to this historic explosion event. Our DMSP data analysis revealed a noticeable increase in the ionospheric electron density near the Beirut area following the explosion, accompanied by some wavelike disturbances. Some characteristic TID signatures were also identified in the shape of ionogram traces at several locations in the Mediterranean. This event occurred during a period of relatively quiet geomagnetic conditions, making the observed TIDs likely to have originated from the Beirut explosion, not from other sources such as auroral activities. These observational findings demonstrate that TIDs from the Beirut explosion were able to propagate over longer distances, beyond the immediate areas of Lebanon and Israel–Palestine, reaching the Mediterranean and eastern Europe.","PeriodicalId":50777,"journal":{"name":"Annales Geophysicae","volume":"9 1","pages":""},"PeriodicalIF":1.9,"publicationDate":"2024-07-01","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"141511936","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":4,"RegionCategory":"地球科学","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
Pub Date : 2024-06-26DOI: 10.5194/angeo-42-285-2024
Yanlin Li, Tai-Yin Huang, Julio Urbina, Fabio Vargas, Wuhu Feng
Abstract. This study examines the relationship between the concentration of atmospheric sodium and its meteoric input function (MIF). We use the measurements from the Colorado State University (CSU) and the Andes Lidar Observatory (ALO) lidar instruments with a new numerical model that includes sodium chemistry in the mesosphere and lower-thermosphere (MLT) region. The model is based on the continuity equation to treat all sodium-bearing species and runs at a high temporal resolution. The model simulation employs data assimilation to compare the MIF inferred from the meteor radiant distribution and the MIF derived from the new sodium chemistry model. The simulation captures the seasonal variability in the sodium number density compared with lidar observations over the CSU site. However, there were discrepancies for the ALO site, which is close to the South Atlantic Anomaly (SAA) region, indicating that it is challenging for the model to capture the observed sodium over the ALO. The CSU site had significantly more lidar observations (27 930 h) than the ALO site (1872 h). The simulation revealed that the uptake of the sodium species on meteoric smoke particles was a critical factor in determining the sodium concentration in the MLT, with the sodium removal rate by uptake found to be approximately 3 times that of the NaHCO3 dimerization. Overall, the study's findings provide valuable information on the correlation between the MIF and the sodium concentration in the MLT region, contributing to a better understanding of the complex dynamics of this region. This knowledge can inform future research and guide the development of more accurate models to enhance our comprehension of the MLT region's behavior.
{"title":"On the relationship between the mesospheric sodium layer and the meteoric input function","authors":"Yanlin Li, Tai-Yin Huang, Julio Urbina, Fabio Vargas, Wuhu Feng","doi":"10.5194/angeo-42-285-2024","DOIUrl":"https://doi.org/10.5194/angeo-42-285-2024","url":null,"abstract":"Abstract. This study examines the relationship between the concentration of atmospheric sodium and its meteoric input function (MIF). We use the measurements from the Colorado State University (CSU) and the Andes Lidar Observatory (ALO) lidar instruments with a new numerical model that includes sodium chemistry in the mesosphere and lower-thermosphere (MLT) region. The model is based on the continuity equation to treat all sodium-bearing species and runs at a high temporal resolution. The model simulation employs data assimilation to compare the MIF inferred from the meteor radiant distribution and the MIF derived from the new sodium chemistry model. The simulation captures the seasonal variability in the sodium number density compared with lidar observations over the CSU site. However, there were discrepancies for the ALO site, which is close to the South Atlantic Anomaly (SAA) region, indicating that it is challenging for the model to capture the observed sodium over the ALO. The CSU site had significantly more lidar observations (27 930 h) than the ALO site (1872 h). The simulation revealed that the uptake of the sodium species on meteoric smoke particles was a critical factor in determining the sodium concentration in the MLT, with the sodium removal rate by uptake found to be approximately 3 times that of the NaHCO3 dimerization. Overall, the study's findings provide valuable information on the correlation between the MIF and the sodium concentration in the MLT region, contributing to a better understanding of the complex dynamics of this region. This knowledge can inform future research and guide the development of more accurate models to enhance our comprehension of the MLT region's behavior.","PeriodicalId":50777,"journal":{"name":"Annales Geophysicae","volume":"44 1","pages":""},"PeriodicalIF":1.9,"publicationDate":"2024-06-26","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"141511879","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":4,"RegionCategory":"地球科学","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
Paul Prikryl, David R. Themens, Jaroslav Chum, Shibaji Chakraborty, Robert G. Gillies, James M. Weygand
Abstract. Traveling ionospheric disturbances (TIDs) are observed by the Super Dual Auroral Radar Network (SuperDARN), the Poker Flat Incoherent Scatter Radar (PFISR), the multipoint and multifrequency continuous Doppler sounders, and the GNSS total electron content (TEC) mapping technique. PFISR measures electron density altitude profiles, from which TIDs are obtained by a filtering method to remove background densities. SuperDARN observes the ionospheric convection at high latitudes and TIDs modulating the ground scatter power. The Doppler sounders at mid latitudes can determine TID propagation velocities and azimuths. The aim of this study is to attribute the observed TIDs to atmospheric gravity waves generated in the lower thermosphere at high latitudes, or gravity waves generated by mid-latitude tropospheric weather systems. The solar wind-magnetosphere-ionosphere-thermosphere coupling modulates the dayside ionospheric convection and currents that generate gravity waves driving equatorward propagating medium to large scale TIDs. The horizontal equivalent ionospheric currents are estimated from the ground-based magnetometer data using an inversion technique. At high latitudes, TIDs observed in the detrended TEC maps are dominated by equatorward TIDs pointing to auroral sources. At mid to low latitudes, the azimuths of TIDs vary, indicating sources in the troposphere. The cases of eastward to southeastward propagating TIDs that are observed in the detrended TEC maps and by the HF Doppler sounders in Czechia are attributed to gravity waves that were likely generated by geostrophic adjustment processes and shear instability in the intensifying low-pressure systems.
摘要。通过超级双极光雷达网、扑克牌平相干散射雷达、多点和多频连续多普勒探空仪以及全球导航卫星系统电子总含量（TEC）绘图技术观测电离层旅行扰动。PFISR 测量电子密度高度剖面，通过滤波方法去除背景密度，从中获得 TID。SuperDARN 观测高纬度电离层对流和调制地面散射功率的 TID。中纬度的多普勒探测仪可以确定 TID 的传播速度和方位角。本研究的目的是将观测到的 TID 归因于高纬度低热层产生的大气重力波或中纬度对流层天气系统产生的重力波。太阳风-磁层-电离层-热大气层耦合调节日侧电离层对流和电流，产生重力波，推动赤道向外传播中尺度到大尺度的热电离层波动。水平等效电离层电流是利用反演技术从地基磁强计数据中估算出来的。在高纬度地区，在去趋势 TEC 图中观测到的 TID 主要是指向极光源的赤道向 TID。在中低纬度，TID 的方位角各不相同，表明其来源于对流层。捷克的高频多普勒探空仪和经过去趋势处理的 TEC 地图中观测到的向东向东南传播的 TID，是由重力波引起的，而重力波很可能是由地心调整过程和不断加强的低压系统中的切变不稳定性产生的。
{"title":"Observations of traveling ionospheric disturbances driven by gravity waves from sources in the upper and lower atmosphere","authors":"Paul Prikryl, David R. Themens, Jaroslav Chum, Shibaji Chakraborty, Robert G. Gillies, James M. Weygand","doi":"10.5194/angeo-2024-6","DOIUrl":"https://doi.org/10.5194/angeo-2024-6","url":null,"abstract":"<strong>Abstract.</strong> Traveling ionospheric disturbances (TIDs) are observed by the Super Dual Auroral Radar Network (SuperDARN), the Poker Flat Incoherent Scatter Radar (PFISR), the multipoint and multifrequency continuous Doppler sounders, and the GNSS total electron content (TEC) mapping technique. PFISR measures electron density altitude profiles, from which TIDs are obtained by a filtering method to remove background densities. SuperDARN observes the ionospheric convection at high latitudes and TIDs modulating the ground scatter power. The Doppler sounders at mid latitudes can determine TID propagation velocities and azimuths. The aim of this study is to attribute the observed TIDs to atmospheric gravity waves generated in the lower thermosphere at high latitudes, or gravity waves generated by mid-latitude tropospheric weather systems. The solar wind-magnetosphere-ionosphere-thermosphere coupling modulates the dayside ionospheric convection and currents that generate gravity waves driving equatorward propagating medium to large scale TIDs. The horizontal equivalent ionospheric currents are estimated from the ground-based magnetometer data using an inversion technique. At high latitudes, TIDs observed in the detrended TEC maps are dominated by equatorward TIDs pointing to auroral sources. At mid to low latitudes, the azimuths of TIDs vary, indicating sources in the troposphere. The cases of eastward to southeastward propagating TIDs that are observed in the detrended TEC maps and by the HF Doppler sounders in Czechia are attributed to gravity waves that were likely generated by geostrophic adjustment processes and shear instability in the intensifying low-pressure systems.","PeriodicalId":50777,"journal":{"name":"Annales Geophysicae","volume":"208 1","pages":""},"PeriodicalIF":1.9,"publicationDate":"2024-06-17","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"141511880","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":4,"RegionCategory":"地球科学","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
Tuomas Häkkilä, Maxime Grandin, Markus Battarbee, Monika E. Szeląg, Markku Alho, Leo Kotipalo, Niilo Kalakoski, Pekka T. Verronen, Minna Palmroth
Abstract. Modelling the distribution of odd nitrogen (NOx) in the polar middle and upper atmosphere has proven to be a complex task. Firstly, its production by energetic electron precipitation is highly variable on hourly time scales. Secondly, there are uncertainties in the measurement-based but simplified electron flux data sets that are currently used in atmosphere and climate models. The altitude distribution of NOx is strongly affected by atmospheric dynamics also on monthly time scales, particularly in the polar winter periods when the isolated air inside the polar vortex descends from lower thermosphere to mesosphere and stratosphere. Recent comparisons between measurements and simulations have revealed strong differences in the NOx distribution, with questions remaining about the representation of both production and transport in models. Here we present for the first time a novel approach, where the electron atmospheric forcing in the auroral energy range (50 eV–50 keV) is derived from a magnetospheric hybrid-kinetic simulation with a detailed description of energy range and resolution, and spatial and diurnal distribution. These electron data are used as input in a global whole atmosphere model to study the impact on polar NOx and ozone. We will show that the magnetospheric electron data provides a realistic representation of the forcing which leads to considerable impact in the lower thermosphere, mesosphere and stratosphere. We find that during the polar winter the simulated auroral electron precipitation increases the polar NOx concentrations up to 200 %, 50 %, and 7 % in the lower thermosphere, mesosphere, and upper stratosphere, respectively, when compared to no auroral electron forcing in the atmospheric model. These results demonstrate the potential of combining magnetospheric and atmospheric simulations for detailed studies of solar wind – atmosphere coupling.
{"title":"Atmospheric odd nitrogen response to electron forcing from a 6D magnetospheric hybrid-kinetic simulation","authors":"Tuomas Häkkilä, Maxime Grandin, Markus Battarbee, Monika E. Szeląg, Markku Alho, Leo Kotipalo, Niilo Kalakoski, Pekka T. Verronen, Minna Palmroth","doi":"10.5194/angeo-2024-7","DOIUrl":"https://doi.org/10.5194/angeo-2024-7","url":null,"abstract":"<strong>Abstract.</strong> Modelling the distribution of odd nitrogen (NO<sub>x</sub>) in the polar middle and upper atmosphere has proven to be a complex task. Firstly, its production by energetic electron precipitation is highly variable on hourly time scales. Secondly, there are uncertainties in the measurement-based but simplified electron flux data sets that are currently used in atmosphere and climate models. The altitude distribution of NO<sub>x</sub> is strongly affected by atmospheric dynamics also on monthly time scales, particularly in the polar winter periods when the isolated air inside the polar vortex descends from lower thermosphere to mesosphere and stratosphere. Recent comparisons between measurements and simulations have revealed strong differences in the NO<sub>x</sub> distribution, with questions remaining about the representation of both production and transport in models. Here we present for the first time a novel approach, where the electron atmospheric forcing in the auroral energy range (50 eV–50 keV) is derived from a magnetospheric hybrid-kinetic simulation with a detailed description of energy range and resolution, and spatial and diurnal distribution. These electron data are used as input in a global whole atmosphere model to study the impact on polar NO<sub>x</sub> and ozone. We will show that the magnetospheric electron data provides a realistic representation of the forcing which leads to considerable impact in the lower thermosphere, mesosphere and stratosphere. We find that during the polar winter the simulated auroral electron precipitation increases the polar NO<sub>x</sub> concentrations up to 200 %, 50 %, and 7 % in the lower thermosphere, mesosphere, and upper stratosphere, respectively, when compared to no auroral electron forcing in the atmospheric model. These results demonstrate the potential of combining magnetospheric and atmospheric simulations for detailed studies of solar wind – atmosphere coupling.","PeriodicalId":50777,"journal":{"name":"Annales Geophysicae","volume":"44 1","pages":""},"PeriodicalIF":1.9,"publicationDate":"2024-06-12","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"141511881","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":4,"RegionCategory":"地球科学","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
Pub Date : 2024-06-04DOI: 10.5194/angeo-42-213-2024
Tinna L. Gunnarsdottir, Ingrid Mann, Wuhu Feng, Devin R. Huyghebaert, Ingemar Haeggstroem, Yasunobu Ogawa, Norihito Saito, Satonori Nozawa, Takuya D. Kawahara
Abstract. Meteoric ablation in the Earth's atmosphere produces particles of nanometer size and larger. These particles can become charged and influence the charge balance in the D region (60–90 km) and the incoherent scatter observed with radar from there. Radar studies have shown that, if enough dust particles are charged, they can influence the received radar spectrum below 100 km, provided the electron density is sufficiently high (>109 m3). Here, we study an observation made with the EISCAT VHF radar on 9 January 2014 during strong particle precipitation so that incoherent scatter was observed down to almost 60 km altitude. We found that the measured spectra were too narrow in comparison to the calculated spectra. Adjusting the collision frequency provided a better fit in the frequency range of ± 10–30 Hz. However, this did not lead to the best fit in all cases, especially not for the central part of the spectra in the narrow frequency range of ±10 Hz. By including a negatively charged dust component, we obtained a better fit for spectra observed at altitudes of 75–85 km, indicating that dust influences the incoherent-scatter spectrum at D-region altitudes. The observations at lower altitudes were limited by the small number of free electrons, and observations at higher altitudes were limited by the height resolution of the observations. Inferred dust number densities range from a few particles up to 104 cm−3, and average sizes range from approximately 0.6 to 1 nm. We find an acceptable agreement with the dust profiles calculated with the WACCM-CARMA (Whole Atmosphere Community Climate Model-Community Aerosol Radiation Model for Atmospheres) model. However, these do not include charging, which is also based on models.
{"title":"Influence of meteoric smoke particles on the incoherent scatter measured with EISCAT VHF","authors":"Tinna L. Gunnarsdottir, Ingrid Mann, Wuhu Feng, Devin R. Huyghebaert, Ingemar Haeggstroem, Yasunobu Ogawa, Norihito Saito, Satonori Nozawa, Takuya D. Kawahara","doi":"10.5194/angeo-42-213-2024","DOIUrl":"https://doi.org/10.5194/angeo-42-213-2024","url":null,"abstract":"Abstract. Meteoric ablation in the Earth's atmosphere produces particles of nanometer size and larger. These particles can become charged and influence the charge balance in the D region (60–90 km) and the incoherent scatter observed with radar from there. Radar studies have shown that, if enough dust particles are charged, they can influence the received radar spectrum below 100 km, provided the electron density is sufficiently high (>109 m3). Here, we study an observation made with the EISCAT VHF radar on 9 January 2014 during strong particle precipitation so that incoherent scatter was observed down to almost 60 km altitude. We found that the measured spectra were too narrow in comparison to the calculated spectra. Adjusting the collision frequency provided a better fit in the frequency range of ± 10–30 Hz. However, this did not lead to the best fit in all cases, especially not for the central part of the spectra in the narrow frequency range of ±10 Hz. By including a negatively charged dust component, we obtained a better fit for spectra observed at altitudes of 75–85 km, indicating that dust influences the incoherent-scatter spectrum at D-region altitudes. The observations at lower altitudes were limited by the small number of free electrons, and observations at higher altitudes were limited by the height resolution of the observations. Inferred dust number densities range from a few particles up to 104 cm−3, and average sizes range from approximately 0.6 to 1 nm. We find an acceptable agreement with the dust profiles calculated with the WACCM-CARMA (Whole Atmosphere Community Climate Model-Community Aerosol Radiation Model for Atmospheres) model. However, these do not include charging, which is also based on models.","PeriodicalId":50777,"journal":{"name":"Annales Geophysicae","volume":"2013 1","pages":""},"PeriodicalIF":1.9,"publicationDate":"2024-06-04","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"141257065","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":4,"RegionCategory":"地球科学","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
Pub Date : 2024-06-04DOI: 10.5194/angeo-42-229-2024
Spencer Mark Hatch, Heikki Vanhamäki, Karl Magnus Laundal, Jone Peter Reistad, Johnathan K. Burchill, Levan Lomidze, David J. Knudsen, Michael Madelaire, Habtamu Tesfaw
Abstract. Ionospheric electrodynamics is a problem of mechanical stress balance mediated by electromagnetic forces. Joule heating (the total rate of frictional heating of thermospheric gases and ionospheric plasma) and ionospheric Hall and Pedersen conductances comprise three of the most basic descriptors of this problem. More than half a century after identification of their central role in ionospheric electrodynamics, several important questions about these quantities, including the degree to which they exhibit hemispheric symmetry under reversal of the sign of dipole tilt and the sign of the y component of the interplanetary magnetic field (so-called “mirror symmetry”), remain unanswered. While global estimates of these key parameters can be obtained by combining existing empirical models, one often encounters some frustrating sources of uncertainty: the measurements from which such models are derived, usually magnetic field and electric field or ion drift measurements, are typically measured separately and do not necessarily align. The models to be combined moreover often use different input parameters, different assumptions about hemispheric symmetry, and/or different coordinate systems. We eliminate these sources of uncertainty in model predictions of electromagnetic work J⋅E (in general not equal to Joule heating ηJ2) and ionospheric conductances by combining two new empirical models of the high-latitude ionospheric electric potential and ionospheric currents that are derived in a mutually consistent fashion: these models do not assume any form of symmetry between the two hemispheres; are based on Apex magnetic coordinates (denoted Apex), spherical harmonics, and the same model input parameters; and are derived exclusively from convection and magnetic field measurements made by the Swarm and CHAMP satellites. The model source code is open source and publicly available. Comparison of high-latitude distributions of electromagnetic work in each hemisphere as functions of dipole tilt and interplanetary magnetic field clock angle indicates that the typical assumption of mirror symmetry is largely justified. Model predictions of ionospheric Hall and Pedersen conductances exhibit a degree of symmetry, but clearly asymmetric responses to dipole tilt and solar wind driving conditions are also identified. The distinction between electromagnetic work and Joule heating allows us to identify where and under what conditions the assumption that the neutral wind corotates with the Earth is not likely to be physically consistent with predicted Hall and Pedersen conductances.
{"title":"Does high-latitude ionospheric electrodynamics exhibit hemispheric mirror symmetry?","authors":"Spencer Mark Hatch, Heikki Vanhamäki, Karl Magnus Laundal, Jone Peter Reistad, Johnathan K. Burchill, Levan Lomidze, David J. Knudsen, Michael Madelaire, Habtamu Tesfaw","doi":"10.5194/angeo-42-229-2024","DOIUrl":"https://doi.org/10.5194/angeo-42-229-2024","url":null,"abstract":"Abstract. Ionospheric electrodynamics is a problem of mechanical stress balance mediated by electromagnetic forces. Joule heating (the total rate of frictional heating of thermospheric gases and ionospheric plasma) and ionospheric Hall and Pedersen conductances comprise three of the most basic descriptors of this problem. More than half a century after identification of their central role in ionospheric electrodynamics, several important questions about these quantities, including the degree to which they exhibit hemispheric symmetry under reversal of the sign of dipole tilt and the sign of the y component of the interplanetary magnetic field (so-called “mirror symmetry”), remain unanswered. While global estimates of these key parameters can be obtained by combining existing empirical models, one often encounters some frustrating sources of uncertainty: the measurements from which such models are derived, usually magnetic field and electric field or ion drift measurements, are typically measured separately and do not necessarily align. The models to be combined moreover often use different input parameters, different assumptions about hemispheric symmetry, and/or different coordinate systems. We eliminate these sources of uncertainty in model predictions of electromagnetic work J⋅E (in general not equal to Joule heating ηJ2) and ionospheric conductances by combining two new empirical models of the high-latitude ionospheric electric potential and ionospheric currents that are derived in a mutually consistent fashion: these models do not assume any form of symmetry between the two hemispheres; are based on Apex magnetic coordinates (denoted Apex), spherical harmonics, and the same model input parameters; and are derived exclusively from convection and magnetic field measurements made by the Swarm and CHAMP satellites. The model source code is open source and publicly available. Comparison of high-latitude distributions of electromagnetic work in each hemisphere as functions of dipole tilt and interplanetary magnetic field clock angle indicates that the typical assumption of mirror symmetry is largely justified. Model predictions of ionospheric Hall and Pedersen conductances exhibit a degree of symmetry, but clearly asymmetric responses to dipole tilt and solar wind driving conditions are also identified. The distinction between electromagnetic work and Joule heating allows us to identify where and under what conditions the assumption that the neutral wind corotates with the Earth is not likely to be physically consistent with predicted Hall and Pedersen conductances.","PeriodicalId":50777,"journal":{"name":"Annales Geophysicae","volume":"27 1","pages":""},"PeriodicalIF":1.9,"publicationDate":"2024-06-04","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"141257027","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":4,"RegionCategory":"地球科学","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
Abstract. EISCAT_3D is a project to build a multi-site phased-array incoherent scatter radar system in northern Fenno-Scandinavia. We demonstrate via numerical simulation how useful monochromatic images taken by a multi-point imager network are for auroral research in the EISCAT_3D project. We apply the generalized aurora computed tomography (G-ACT) method to modelled observational data from real instruments, such as the Auroral Large Imaging System (ALIS) and the EISCAT_3D radar. G-ACT is a method for reconstructing the three-dimensional (3D) distribution of auroral emissions and ionospheric electron density (corresponding to the horizontal two-dimensional (2D) distribution of energy spectra of precipitating electrons) from multi-instrument data. It is assumed that the EISCAT_3D radar scans an area of 0.8° in geographic latitude and 3° in longitude at an altitude of 130 km with 10 × 10 beams from the radar core site at Skibotn (69.35° N, 20.37° E). Two neighboring discrete arcs are assumed to appear in the observation region of the EISCAT_3D radar. The reconstruction results from G-ACT are compared with those from the normal ACT as well as the ionospheric electron density from the radar. It is found that G-ACT can interpolate the ionospheric electron density at a much higher spatial resolution than that observed by the EISCAT_3D radar. Furthermore, the multiple arcs reconstructed by G-ACT are more precise than those by ACT. In particular, underestimation of the ionospheric electron density and precipitating electrons' energy fluxes inside the arcs is significantly improved by G-ACT including the EISCAT_3D data. Even when the ACT reconstruction is difficult due to the unsuitable locations of the imager sites relative to the discrete arcs and/or a small number of available images, G-ACT allows us to obtain better reconstruction results.
{"title":"Application of generalized aurora computed tomography to the EISCAT_3D project","authors":"Yoshimasa Tanaka, Yasunobu Ogawa, Akira Kadokura, Takehiko Aso, Björn Gustavsson, Urban Brändström, Tima Sergienko, Genta Ueno, Satoko Saita","doi":"10.5194/angeo-42-179-2024","DOIUrl":"https://doi.org/10.5194/angeo-42-179-2024","url":null,"abstract":"Abstract. EISCAT_3D is a project to build a multi-site phased-array incoherent scatter radar system in northern Fenno-Scandinavia. We demonstrate via numerical simulation how useful monochromatic images taken by a multi-point imager network are for auroral research in the EISCAT_3D project. We apply the generalized aurora computed tomography (G-ACT) method to modelled observational data from real instruments, such as the Auroral Large Imaging System (ALIS) and the EISCAT_3D radar. G-ACT is a method for reconstructing the three-dimensional (3D) distribution of auroral emissions and ionospheric electron density (corresponding to the horizontal two-dimensional (2D) distribution of energy spectra of precipitating electrons) from multi-instrument data. It is assumed that the EISCAT_3D radar scans an area of 0.8° in geographic latitude and 3° in longitude at an altitude of 130 km with 10 × 10 beams from the radar core site at Skibotn (69.35° N, 20.37° E). Two neighboring discrete arcs are assumed to appear in the observation region of the EISCAT_3D radar. The reconstruction results from G-ACT are compared with those from the normal ACT as well as the ionospheric electron density from the radar. It is found that G-ACT can interpolate the ionospheric electron density at a much higher spatial resolution than that observed by the EISCAT_3D radar. Furthermore, the multiple arcs reconstructed by G-ACT are more precise than those by ACT. In particular, underestimation of the ionospheric electron density and precipitating electrons' energy fluxes inside the arcs is significantly improved by G-ACT including the EISCAT_3D data. Even when the ACT reconstruction is difficult due to the unsuitable locations of the imager sites relative to the discrete arcs and/or a small number of available images, G-ACT allows us to obtain better reconstruction results.","PeriodicalId":50777,"journal":{"name":"Annales Geophysicae","volume":"68 1","pages":""},"PeriodicalIF":1.9,"publicationDate":"2024-05-29","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"141189724","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":4,"RegionCategory":"地球科学","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
Pub Date : 2024-05-29DOI: 10.5194/angeo-42-191-2024
Samuel Kočiščák, Andreas Kvammen, Ingrid Mann, Nicole Meyer-Vernet, David Píša, Jan Souček, Audun Theodorsen, Jakub Vaverka, Arnaud Zaslavsky
Abstract. Solar Orbiter is equipped with electrical antennas performing fast measurements of the surrounding electric field. The antennas register high-velocity dust impacts through the electrical signatures of impact ionization. Although the basic principle of the detection has been known for decades, the understanding of the underlying process is not complete, due to the unique mechanical and electrical design of each spacecraft and the variability of the process. We present a study of electrical signatures of dust impacts on Solar Orbiter's body, as measured with the Radio and Plasma Waves electrical suite. A large proportion of the signatures present double-peak electrical waveforms in addition to the fast pre-spike due to electron motion, which are systematically observed for the first time. We believe this is due to Solar Orbiter's unique antenna design and a high temporal resolution of the measurements. The double peaks are explained as being due to two distinct processes. Qualitative and quantitative features of both peaks are described. The process for producing the primary peak has been studied extensively before, and the process for producing the secondary peak has been proposed before (Pantellini et al., 2012a) for Solar Terrestrial Relations Observatory (STEREO), although the corresponding delay of 100–300 µs between the primary and the secondary peak has not been observed until now. Based on this study, we conclude that the primary peak's amplitude is the better measure of the impact-produced charge, for which we find a typical value of around 8 pC. Therefore, the primary peak should be used to derive the impact-generated charge rather than the maximum. The observed asymmetry between the primary peaks measured with individual antennas is quantitatively explained as electrostatic induction. A relationship between the amplitude of the primary and the secondary peak is found to be non-linear, and the relation is partially explained with a model for electrical interaction through the antennas' photoelectron sheath.
{"title":"Impact ionization double peaks analyzed in high temporal resolution on Solar Orbiter","authors":"Samuel Kočiščák, Andreas Kvammen, Ingrid Mann, Nicole Meyer-Vernet, David Píša, Jan Souček, Audun Theodorsen, Jakub Vaverka, Arnaud Zaslavsky","doi":"10.5194/angeo-42-191-2024","DOIUrl":"https://doi.org/10.5194/angeo-42-191-2024","url":null,"abstract":"Abstract. Solar Orbiter is equipped with electrical antennas performing fast measurements of the surrounding electric field. The antennas register high-velocity dust impacts through the electrical signatures of impact ionization. Although the basic principle of the detection has been known for decades, the understanding of the underlying process is not complete, due to the unique mechanical and electrical design of each spacecraft and the variability of the process. We present a study of electrical signatures of dust impacts on Solar Orbiter's body, as measured with the Radio and Plasma Waves electrical suite. A large proportion of the signatures present double-peak electrical waveforms in addition to the fast pre-spike due to electron motion, which are systematically observed for the first time. We believe this is due to Solar Orbiter's unique antenna design and a high temporal resolution of the measurements. The double peaks are explained as being due to two distinct processes. Qualitative and quantitative features of both peaks are described. The process for producing the primary peak has been studied extensively before, and the process for producing the secondary peak has been proposed before (Pantellini et al., 2012a) for Solar Terrestrial Relations Observatory (STEREO), although the corresponding delay of 100–300 µs between the primary and the secondary peak has not been observed until now. Based on this study, we conclude that the primary peak's amplitude is the better measure of the impact-produced charge, for which we find a typical value of around 8 pC. Therefore, the primary peak should be used to derive the impact-generated charge rather than the maximum. The observed asymmetry between the primary peaks measured with individual antennas is quantitatively explained as electrostatic induction. A relationship between the amplitude of the primary and the secondary peak is found to be non-linear, and the relation is partially explained with a model for electrical interaction through the antennas' photoelectron sheath.","PeriodicalId":50777,"journal":{"name":"Annales Geophysicae","volume":"36 1","pages":""},"PeriodicalIF":1.9,"publicationDate":"2024-05-29","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"141189727","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":4,"RegionCategory":"地球科学","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
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