Annales Geophysicae最新文献

{"title":"Analysis of in situ measurements of electron, ion and neutral temperatures in the lower thermosphere–ionosphere","authors":"Panagiotis Pirnaris, Theodoros Sarris","doi":"10.5194/angeo-41-339-2023","DOIUrl":"https://doi.org/10.5194/angeo-41-339-2023","url":null,"abstract":"Abstract. Simultaneous knowledge of the temperatures of electrons, ions and neutrals is key to the understanding and quantification of energy transfer processes in planetary atmospheres. However, whereas electron and ion temperature measurements are routinely obtained from ground-based incoherent scatter radars, simultaneous measurements of electron, ion and neutral temperature measurements can only be made in situ. For the Earth's lower thermosphere–ionosphere, the only available comprehensive in situ dataset of electron, ion and neutral temperatures to date is that of the Atmosphere Explorers C, D and E and the Dynamics Explorer 2 missions. In this study we first perform a cross-comparison of all co-temporal and co-spatial measurements between in situ electron and ion temperature measurements from the above in situ spacecraft missions with corresponding measurements from the Arecibo, Millstone Hill and Saint-Santin incoherent scatter radars, during times of overflights of these spacecraft over the radar fields of view. This expands upon a previous study that only considered data from the Atmosphere Explorer C. The results indicate good agreement between satellite and ground-based radar measurements. Subsequently, out of the above datasets, all instances where ion temperatures appear to be lower than neutral temperatures are identified and are studied statistically. Whereas current understanding indicates that ion temperatures are generally expected to be higher than neutral temperatures in the lower thermosphere–ionosphere, a non-negligible number of events is found where this does not hold true. The distribution of all such cases in altitude, latitude and longitude is presented and discussed. Potential causes leading to neutral temperatures being higher than ion temperatures are outlined, including both instrumental effects or measurement errors and physical causes. Whereas a conclusive case cannot be made based on the present analysis, it is speculated from the results presented herein that not all cases can be attributed to instrument effects or measurement errors. This can have significant implications for the current understanding that the energy of the ions is expected to be higher than that of the neutrals and points to the need for additional simultaneous in situ measurements in the lower thermosphere–ionosphere (LTI).","PeriodicalId":50777,"journal":{"name":"Annales Geophysicae","volume":null,"pages":null},"PeriodicalIF":0.0,"publicationDate":"2023-09-11","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"135980676","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}

{"title":"Velocity of magnetic holes in the solar wind from Cluster multipoint measurements","authors":"H. Trollvik, T. Karlsson, S. Raptis","doi":"10.5194/angeo-41-327-2023","DOIUrl":"https://doi.org/10.5194/angeo-41-327-2023","url":null,"abstract":"Abstract. We present the first statistical study on the velocity of magnetic holes (MHs) in the solar wind. Magnetic holes are localized depressions of the magnetic field, often divided into two classes: rotational and linear MHs. We have conducted a timing analysis of observations of MHs from the Cluster mission in the first quarter of 2005. In total, 69 events were used; out of these, there were 40 linear and 29 rotational MHs, where the limit of magnetic field rotation was set to 50∘. The resulting median velocity was 7.4 ± 45 and 25 ± 42 km s−1 for linear and rotational MHs, respectively. For both classes, around 70 % of the events had a velocity in the solar wind frame that was lower than the Alfvén velocity. Therefore, we conclude that within the observational uncertainties, both linear and rotational MHs are convected with the solar wind.\u0000","PeriodicalId":50777,"journal":{"name":"Annales Geophysicae","volume":null,"pages":null},"PeriodicalIF":1.9,"publicationDate":"2023-08-21","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"88464656","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}

{"title":"Comparison of radiation belt electron fluxes simultaneously measured with PROBA-V/EPT and RBSP/MagEIS instruments","authors":"A. Winant, V. Pierrard, E. Botek","doi":"10.5194/angeo-41-313-2023","DOIUrl":"https://doi.org/10.5194/angeo-41-313-2023","url":null,"abstract":"Abstract. Relativistic radiation belt electron observations from the Energetic Particle Telescope (EPT) on board the PROBA-V (Project for On-Board Autonomy and Vegetation) satellite are compared to those performed by the Magnetic Electron Ion Spectrometer (MagEIS) on board the Van Allen Probes formerly known as the Radiation Belt Storm Probes (RBSP). Despite their very different orbits, both instruments are able to measure fluxes of electrons trapped on a given magnetic shell. In the outer belt, the comparison of high- and low-altitude fluxes is performed during the first 3 months of 2014, featuring the most intense storms of the year. In the inner belt, measurements from the two instruments are compared only at conjunction, when the satellites are physically close to each other. Due to the low number of conjunctions, the whole period of mutual operation of both instruments is used (i.e., May 2013–October 2019). The comparisons show that flux variations appear simultaneously on both spacecraft, but the fluxes observed by the EPT are almost always lower than for MagEIS, as expected from their different orbits. In addition, this difference in flux intensity increases with electron energy. During geomagnetic storms, it is also shown that dropout events (i.e., sudden depletion of electrons) in the outer belt are more pronounced at low altitudes than near the geomagnetic Equator. The effect of the equatorial pitch angle value of electrons is investigated in the outer belt. Despite the difference in flux intensity observed by the two instruments, especially at high energies, a linear relationship with a linear correlation higher than 0.7 was found. The correlation is at its maximum when low-pitch-angle electrons near the Equator are considered.\u0000","PeriodicalId":50777,"journal":{"name":"Annales Geophysicae","volume":null,"pages":null},"PeriodicalIF":1.9,"publicationDate":"2023-08-17","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"91062228","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}

{"title":"Electron radiation belt safety indices based on the SafeSpace modelling pipeline and dedicated to the internal charging risk","authors":"N. Dahmen, A. Brunet, S. Bourdarie, C. Katsavrias, G. Bernoux, Stefanos Doulfis, A. Nasi, I. Sandberg, C. Papadimitriou, Jesus Oliveros Fernandez, I. Daglis","doi":"10.5194/angeo-41-301-2023","DOIUrl":"https://doi.org/10.5194/angeo-41-301-2023","url":null,"abstract":"Abstract. In this paper, we present the SafeSpace prototype for a safety warning system, dedicated to the electron radiation-belt-induced internal charging hazard aboard spacecraft. The space weather tool relies on a synergy of physical models associated in a chain that covers the whole Sun–interplanetary-space–Earth's inner magnetosphere medium. With the propagation of uncertainties along the modelling pipeline, the safety prototype provides a global nowcast and forecast (within a 4 d lead time) of the electron radiation belt dynamic as well as tailored indicators for space industry operators. They are meant to inform the users about the severity of the electron space environment via a three-coloured alarm system, which sorts the index intensity according to a representative historical distribution of in situ data. The system was tested during the challenging 2015 St Patrick's Day storm in order to assess its performance. It showed overall good nowcasting and forecasting capabilities due to its broad physics-driven pipeline.\u0000","PeriodicalId":50777,"journal":{"name":"Annales Geophysicae","volume":null,"pages":null},"PeriodicalIF":1.9,"publicationDate":"2023-08-04","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"78219218","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}

{"title":"Greenhouse gas effects on the solar cycle response of water vapour and noctilucent clouds","authors":"Ashique Vellalassery, G. Baumgarten, M. Grygalashvyly, F. Lübken","doi":"10.5194/angeo-41-289-2023","DOIUrl":"https://doi.org/10.5194/angeo-41-289-2023","url":null,"abstract":"Abstract. The responses of water vapour (H2O) and noctilucent clouds (NLCs) to the\u0000solar cycle are studied using the Leibniz Institute for Middle Atmosphere\u0000(LIMA) model and the Mesospheric Ice Microphysics And tranSport (MIMAS)\u0000model. NLCs are sensitive to the solar cycle because their formation depends\u0000on background temperature and the H2O concentration. The solar cycle\u0000affects the H2O concentration in the upper mesosphere mainly in two\u0000ways: directly through the photolysis and, at the time and place of NLC\u0000formation, indirectly through temperature changes. We found that H2O\u0000concentration correlates positively with the temperature changes due to the\u0000solar cycle at altitudes above about 82 km, where NLCs form. The photolysis\u0000effect leads to an anti-correlation of H2O concentration and solar\u0000Lyman-α radiation, which gets even more pronounced at altitudes\u0000below ∼ 83 km when NLCs are present. We studied the H2O\u0000response to Lyman-α variability for the period 1992 to 2018,\u0000including the two most recent solar cycles. The amplitude of Lyman-α\u0000variation decreased by about 40 % in the period 2005 to 2018 compared to\u0000the preceding solar cycle, resulting in a lower H2O response in the\u0000late period. We investigated the effect of increasing greenhouse gases\u0000(GHGs) on the H2O response throughout the solar cycle by performing\u0000model runs with and without increases in carbon dioxide (CO2) and\u0000methane (CH4). The increase of methane and carbon dioxide amplifies the\u0000response of water vapour to the solar variability. Applying the geometry of\u0000satellite observations, we find a missing response when averaging over\u0000altitudes of 80 to 85 km, where H2O has a positive response and a negative\u0000response (depending on altitude), which largely cancel each other out. One main finding\u0000is that, during NLCs, the solar cycle response of H2O strongly depends on\u0000altitude.\u0000","PeriodicalId":50777,"journal":{"name":"Annales Geophysicae","volume":null,"pages":null},"PeriodicalIF":1.9,"publicationDate":"2023-07-24","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"86013293","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}

{"title":"On mechanisms for HF pump-enhanced optical emissions at 557.7 and 630.0 nm from atomic oxygen in the high-latitude F-region ionosphere","authors":"Thomas B. Leyser, Tima Sergienko, Urban Brändström, Björn Gustavsson, Michael T. Rietveld","doi":"10.5194/angeo-2023-21","DOIUrl":"https://doi.org/10.5194/angeo-2023-21","url":null,"abstract":"<strong>Abstract.</strong> The EISCAT Heating facility was used to transmit powerful high frequency (HF) electromagnetic waves into the F-region ionosphere to enhance optical emissions at 557.7 and 630.0 nm from atomic oxygen. The emissions were imaged by three stations of the Auroral Large Imaging System in northern Sweden and the EISCAT UHF incoherent scatter radar was used to obtain plasma parameter values. The ratio of the 557.7 to 630.0 nm column emission rates changed from <em>I</em>₅₅₇₇/<em>I</em>₆₃₀₀ ≈ 0.2 for the HF pump frequency <em>f</em>₀ = 6.200 MHz ≈ 4.6 <em>f</em>_e to <em>I</em>₅₅₇₇/<em>I</em>₆₃₀₀ ≈ 0.5 when <em>f</em>₀ = 5.423 MHz <img alt=\"\" height=\"13\" src=\"data:image/png;base64,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","PeriodicalId":50777,"journal":{"name":"Annales Geophysicae","volume":null,"pages":null},"PeriodicalIF":1.9,"publicationDate":"2023-07-20","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"138541803","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}

{"title":"Characteristic Analysis of the Differences between TEC Values in GIM Grids","authors":"Qisheng Wang, Jiaru Zhu","doi":"10.5194/angeo-2023-25","DOIUrl":"https://doi.org/10.5194/angeo-2023-25","url":null,"abstract":"<strong>Abstract.</strong> Using total electron content (TEC) from global ionosphere map (GIM) for ionospheric delay correction is a common method of eliminating ionospheric errors in satellite navigation and positioning. On this basis, the TEC of puncture point can be obtained by GIM grid TEC interpolation. However, in terms of grid, only few studies have analyzed the TEC value size characteristics of its four grid points, that is, the TEC difference characteristics among them. In view of this, by utilizing the GIM data from high solar activity years (2014) and low solar activity years (2021) provided by CODE, this paper proposes the grid TEC difference to analyze TEC variation characteristics within the grid, which is conducive to exploring and analyzing the variation characteristics of the ionosphere TEC in the single-station area. The results show that the TEC difference size within GIM grid is mainly related to the activity of ionosphere. The value is larger in high solar activity years and generally small in low solar activity years, and the value of high latitude area is always smaller than that of low latitude area. Specifically, in high solar activity years, most of the GIM grid TEC internal differences are within 4TECu in high and mid latitude regions, while only 78.17 % in low latitude regions; the grid TEC differences at 2-hour intervals are more scattered, and larger values occur in low latitude regions. In low solar activity years, the TEC difference values within GIM grid are mostly less than 2TECu, and most of them in the high and middle latitudes are within 1TECu. The GIM grid TEC difference values within 1-hour intervals are mostly less than 4TECu, and most of them in the high and middle latitudes are within 2TECu. The main finding of this analysis is that the grid TEC differences are small for most GIM grids, especially in the mid-high latitudes of low solar years. This means that relevant extraction methods and processes can be simplified when TEC within these GIM grids is needed.","PeriodicalId":50777,"journal":{"name":"Annales Geophysicae","volume":null,"pages":null},"PeriodicalIF":1.9,"publicationDate":"2023-07-19","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"138541759","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}

{"title":"Comparison of meteor radar and TIDI winds in the Brazilian equatorial region","authors":"Ana Roberta Paulino, Delis Otildes Rodrigues, Igo Paulino, Lourivaldo Mota Lima, Ricardo Arlen Buriti, Paulo Prado Batista, Aaron Ridley, Chen Wu","doi":"10.5194/angeo-2023-23","DOIUrl":"https://doi.org/10.5194/angeo-2023-23","url":null,"abstract":"<strong>Abstract.</strong> Using data collected from a meteor radar deployed at São João do Cariri (7.4°, 36.5° S) and the TIMED Doppler Interferometer (TIDI) on board the Thermosphere-Ionosphere-Mesosphere Energetics and Dynamics (TIMED) satellite for 2006, comparisons of the horizontal winds (meridional and zonal components) were made in order to evaluate these techniques for scientific investigation and pointed out advantages of each instrument. A grid of ± 5 degrees of latitude and longitude centered at São João do Cariri was used to calculate the mean winds from the TIDI, which have a resolution of 2.5 km altitude starting from 82.5 km up to 102 km altitude. Otherwise, the meteor radar computes the winds for 7 layers of 4 km thickness overlapping 0.5 km above and below, which produces layers spaced by 3 km from 81 to 99 km altitude. When almost simultaneous measurements were compared, substantial discrepancies were observed in the vertical wind profiles. It happened because the meteor radar uses one hour bin size to estimate the wind from the echoes detected in the whole sky. While the TIDI measures instantaneous winds from the airglow emissions. In contrast, when the longer period of observation was taken into account, the meteor radar daily winds, averaged within a time interval of one month, were smoothed and showed more clearly the characteristics of the propagation of tides. The responses of the horizontal wind to the intraseasonal, semiannual and annual oscillations were satisfactory for the both techniques.","PeriodicalId":50777,"journal":{"name":"Annales Geophysicae","volume":null,"pages":null},"PeriodicalIF":1.9,"publicationDate":"2023-07-18","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"138541777","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}

{"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-2023-20","DOIUrl":"https://doi.org/10.5194/angeo-2023-20","url":null,"abstract":"<strong>Abstract.</strong> 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) Lidar and the Andes Lidar Observatory (ALO) 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 and the MIF derived from the new sodium chemistry model. The simulation captures the seasonal variability of sodium number density compared with lidar observations over CSU site. However, there were discrepancies for the ALO site, which is close to the South Atlantic Anomaly (SAA) region, indicating it is challenging for the model to capture the observed sodium over ALO. The CSU site had significantly more lidar observations (27,930 hours) than the ALO sites (1872 hours). The simulation revealed that the uptake of the sodium species on meteoric smoke particles was a critical factor in determining the sodium concentration in MLT, with the sodium removal rate by uptake found to be approximately three times that of the NaHCO₃ dimerization. Overall, the study's findings provide valuable information on the correlation between MIF and sodium concentration in the MLT region, contributing to a better understanding of the complex dynamics in 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":null,"pages":null},"PeriodicalIF":1.9,"publicationDate":"2023-07-17","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"138541760","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}

{"title":"Fluid models capturing Farley–Buneman instabilities","authors":"E. Rojas, K. Burns, D. Hysell","doi":"10.5194/angeo-41-281-2023","DOIUrl":"https://doi.org/10.5194/angeo-41-281-2023","url":null,"abstract":"Abstract. It is generally accepted that modeling Farley–Buneman instabilities requires resolving ion Landau damping to reproduce experimentally observed features. Particle-in-cell (PIC) simulations have been able to reproduce most of these but at a computational cost that severely affects their scalability. This limitation hinders the study of non-local phenomena that require three dimensions or coupling with larger-scale processes. We argue that a form of the five-moment fluid system can recreate several qualitative aspects of Farley–Buneman dynamics such as density and phase speed saturation, wave turning, and heating. Unexpectedly, these features are still reproduced even without using artificial viscosity to capture Landau damping. Comparing the proposed fluid models and a PIC implementation shows good qualitative agreement.\u0000","PeriodicalId":50777,"journal":{"name":"Annales Geophysicae","volume":null,"pages":null},"PeriodicalIF":1.9,"publicationDate":"2023-07-13","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"78936351","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}