Annales Geophysicae最新文献

{"title":"A comparison of Jason-2 plasmasphere electron content measurements with ground-based measurements","authors":"Andrew J. Mazzella Jr., E. Yizengaw","doi":"10.5194/angeo-41-269-2023","DOIUrl":"https://doi.org/10.5194/angeo-41-269-2023","url":null,"abstract":"Abstract. Previous studies utilizing the Global Positioning System\u0000(GPS) receivers aboard Jason satellites have performed measurements of\u0000plasmasphere electron content (PEC) by determining the total electron\u0000content (TEC) above these satellites, which are at altitudes of about 1340 km. This study uses similar methods to determine PEC for the Jason-2\u0000receiver for 24 July 2011. These PEC values are compared to previous\u0000determinations of PEC from a chain of ground-based GPS receivers in Africa\u0000using the SCORPION method, with a nominal ionosphere–plasmasphere boundary\u0000at 1000 km. The Jason-2 PECs with elevations greater than 60∘\u0000were converted to equivalent vertical PEC and compared to SCORPION vertical\u0000PEC determinations. In addition, slant (off-vertical) PECs from Jason-2\u0000were compared to a small set of nearly co-aligned ground-based slant PECs.\u0000The latter comparison avoids any conversion of Jason-2 slant PEC to\u0000equivalent vertical PEC, and it can be considered a more representative\u0000comparison. The mean difference between the vertical PEC (ground-based\u0000minus Jason-2 measurements) values is 0.82 ± 0.28 TEC units (1 TEC unit=1016 electrons m−2). Similarly, the mean difference\u0000between slant PEC values is 0.168 ± 0.924 TEC units. The Jason-2 slant\u0000PEC comparison method may provide a reliable determination for the\u0000plasmasphere baseline value for the ground-based receivers, especially if\u0000the ground stations are confined to only midlatitude or low-latitude\u0000regions, which can be affected by a non-negligible PEC baseline.\u0000","PeriodicalId":50777,"journal":{"name":"Annales Geophysicae","volume":null,"pages":null},"PeriodicalIF":1.9,"publicationDate":"2023-06-20","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"90199886","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":"Concerning the detection of electromagnetic knot structures in space plasmas using the wave telescope technique","authors":"S. Toepfer, K. Glassmeier, U. Motschmann","doi":"10.5194/angeo-41-253-2023","DOIUrl":"https://doi.org/10.5194/angeo-41-253-2023","url":null,"abstract":"Abstract. The wave telescope technique is broadly established in the analysis of spacecraft data and serves as a bridge between local measurements and the global picture of spatial structures. The technique is originally based on plane waves and has been extended to spherical waves, phase-shifted waves and planetary magnetic field representation. The goal of the present study is the extension of the wave telescope technique using electromagnetic knot structures as a basis. As the knots are an exact solution of Maxwell's equations they open the door for a new modeling and interpretation of magnetospheric structures, such as plasmoids.\u0000","PeriodicalId":50777,"journal":{"name":"Annales Geophysicae","volume":null,"pages":null},"PeriodicalIF":1.9,"publicationDate":"2023-05-31","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"76573884","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":"Statistical distribution of mirror-mode-like structures in the magnetosheaths of unmagnetised planets – Part 1: Mars as observed by the MAVEN spacecraft","authors":"C. Simon Wedlund, M. Volwerk, C. Mazelle, S. Rojas Mata, G. Stenberg Wieser, Y. Futaana, J. Halekas, D. Rojas-Castillo, C. Bertucci, J. Espley","doi":"10.5194/angeo-41-225-2023","DOIUrl":"https://doi.org/10.5194/angeo-41-225-2023","url":null,"abstract":"Abstract. In this series of papers, we present statistical maps of mirror-mode-like (MM) structures in the magnetosheaths of Mars and Venus and calculate the probability of detecting them in spacecraft data. We aim to study and compare them with the same tools and a similar payload at both planets. We consider their dependence on extreme ultraviolet (EUV) solar flux levels (high and low) and, specific to Mars, on Mars Year (MY) as well as atmospheric seasons (four solar longitudes Ls).\u0000We first use magnetic-field-only criteria to detect these structures and present ways to mitigate ambiguities in their nature. In line with many previous studies at Earth, this technique has the advantage of using one instrument (a magnetometer) with good time resolution, facilitating comparisons between planetary and cometary environments. Applied to the magnetometer data of the Mars Atmosphere and Volatile EvolutioN (MAVEN) spacecraft from November 2014 to February 2021 (MY32–MY35), we detect events closely resembling MMs lasting in total more than 170 000 s, corresponding to about 0.1 % of MAVEN's total time spent in the Martian plasma environment. We calculate MM-like occurrences normalised to the spacecraft's residence time during the course of the mission. Detection probabilities are about 1 % at most for any given controlling parameter. In general, MM-like structures appear in two main regions: one behind the shock and the other close to the induced magnetospheric boundary, as expected from theory. Detection probabilities are higher on average in low-solar-EUV conditions, whereas high-solar-EUV conditions see an increase in detections within the magnetospheric tail. We tentatively link the former tendency to two combining effects: the favouring of ion cyclotron waves the closer to perihelion due to plasma beta effects and, possibly, the non-gyrotropy of pickup ion distributions. This study is the first of two on the magnetosheaths of Mars and Venus.\u0000","PeriodicalId":50777,"journal":{"name":"Annales Geophysicae","volume":null,"pages":null},"PeriodicalIF":1.9,"publicationDate":"2023-05-31","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"73378136","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":"Effects of the terdiurnal tide on the sporadic E (Es) layer development at low latitudes over the Brazilian sector","authors":"P. A. Fontes, M. Muella, L. Resende, V. Andrioli, P. Fagundes, V. G. Pillat, P. Batista, A. J. Carrasco","doi":"10.5194/angeo-41-209-2023","DOIUrl":"https://doi.org/10.5194/angeo-41-209-2023","url":null,"abstract":"Abstract. Sporadic E (Es) layers are patches of high ionization observed at\u0000around 100–140 km height in the E region. Their formation at low latitudes\u0000is primarily associated with the diurnal and semidiurnal components of the\u0000tidal winds via the ion convergence driven by the wind shear mechanism.\u0000However, recent studies have shown the influence of other tidal modes, such\u0000as the terdiurnal tide. Therefore, this work investigates the effect of\u0000terdiurnal tide-like oscillations on the occurrence and formation of the Es layers\u0000observed over Palmas (10.17∘ S, 48.33∘ W; dip lat.\u0000−7.31∘), a low-latitude station in Brazil. The analysis was\u0000conducted from December 2008 to November 2009 by using data collected from\u0000CADI (Canadian Advanced Digital Ionosonde). Additionally, the E\u0000Region Ionospheric Model (MIRE) was used to simulate the terdiurnal tidal\u0000component in the Es layer development. The results show modulations of 8 h\u0000periods on the occurrence rates of the Es layers during all seasonal periods.\u0000In general, we see three well-defined peaks in a superimposed summation of\u0000the Es layer types per hour in summer and autumn. We also observed that the\u0000amplitude modulation of the terdiurnal tide on the Es occurrence rates\u0000minimizes in December in comparison to the other months of the summer\u0000season. Other relevant aspects of the observations, with complementary\u0000statistical and periodogram analysis, are highlighted and discussed.\u0000","PeriodicalId":50777,"journal":{"name":"Annales Geophysicae","volume":null,"pages":null},"PeriodicalIF":1.9,"publicationDate":"2023-04-21","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"83328846","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":"Identifying gravity waves launched by the Hunga Tonga–Hunga Ha′apai volcanic eruption in mesosphere/lower-thermosphere winds derived from CONDOR and the Nordic Meteor Radar Cluster","authors":"G. Stober, A. Liu, A. Kozlovsky, Z. Qiao, Witali Krochin, Guochun Shi, J. Kero, M. Tsutsumi, N. Gulbrandsen, S. Nozawa, M. Lester, Kathrin Baumgarten, E. Belova, N. Mitchell","doi":"10.5194/angeo-41-197-2023","DOIUrl":"https://doi.org/10.5194/angeo-41-197-2023","url":null,"abstract":"Abstract. The Hunga Tonga–Hunga Ha′apai volcano eruption was a unique event that caused many atmospheric phenomena around the globe. In this study, we investigate the atmospheric gravity waves in the mesosphere/lower-thermosphere (MLT) launched by the volcanic explosion in the Pacific, leveraging multistatic meteor radar observations from the Chilean Observation Network De Meteor Radars (CONDOR) and the Nordic Meteor Radar Cluster in Fennoscandia. MLT winds are computed using a recently developed 3DVAR+DIV algorithm. We found eastward- and westward-traveling gravity waves in the CONDOR zonal and meridional wind measurements, which arrived 12 and 48 h after the eruption, and we found one in the Nordic Meteor Radar Cluster that arrived 27.5 h after the volcanic detonation. We obtained observed phase speeds for the eastward great circle path at both locations of about 250 m s−1, and they were 170–150 m s−1 for the opposite propagation direction. The intrinsic phase speed was estimated to be 200–212 m s−1. Furthermore, we identified a potential lamb wave signature in the MLT winds using 5 min resolved 3DVAR+DIV retrievals.\u0000","PeriodicalId":50777,"journal":{"name":"Annales Geophysicae","volume":null,"pages":null},"PeriodicalIF":1.9,"publicationDate":"2023-04-18","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"80712334","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":"Effects of the super-powerful tropospheric western Pacific phenomenon of September–October 2018 on the ionosphere over China: results from oblique sounding","authors":"L. Chernogor, K. Garmash, Q. Guo, V. Rozumenko, Yu. Zheng","doi":"10.5194/angeo-41-173-2023","DOIUrl":"https://doi.org/10.5194/angeo-41-173-2023","url":null,"abstract":"Abstract. Doppler measurements at oblique propagation paths from\u0000the city of Harbin, the People's Republic of China (PRC), to 10 high-frequency (HF) radio\u0000broadcast stations in the PRC, Japan, Mongolia, and the Republic of Korea\u0000captured the response in the ionosphere to the activity of the super typhoon, Typhoon Kong-rey,\u0000from 30 September to 6 October 2018. The Harbin Engineering University\u0000coherent software-defined radio system generates the database containing\u0000the complex amplitudes of the radio signals that have been acquired along 14 propagation\u0000paths since 2018. The complex amplitudes are used for calculating the\u0000temporal dependences of the Doppler spectra and signal amplitudes, and the\u0000Doppler spectra are used to plot the Doppler shift as a function of time,\u0000fD(t), for all rays. The scientific objectives of this study are to\u0000reveal the possible perturbations caused by the activity of Typhoon Kong-rey\u0000and to estimate the magnitudes of wave parameters of the ionospheric plasma\u0000and radio signals. The amplitudes, fDa, of the Doppler shift variations\u0000were observed to noticeably increase (factor of ∼2–3) on 1–2 and 5–6 October 2018, while the 20–120 min periods, T, of the Doppler\u0000shift variations suggest that the wavelike disturbances in the ionosphere\u0000are caused by atmospheric gravity waves. The periods and amplitudes of\u0000quasi-sinusoidal variations in the Doppler shift, which have been determined\u0000for all propagation paths, may be used to estimate the amplitudes, δNa, of quasi-sinusoidal variations in the electron density. Thus,\u0000T≈20 min and fDa≈0.1 Hz yield δNa≈0.4 %, whereas T≈30 min and\u0000fDa≈0.2 Hz give δNa≈1.2 %. If\u0000T≈60 min and fDa≈0.5 Hz, then δNa≈6 %. The periods T are found to change within the\u000015–120 min limits, and the Doppler shift amplitudes, fDa, show\u0000variability within the 0.05–0.4 Hz limits.\u0000","PeriodicalId":50777,"journal":{"name":"Annales Geophysicae","volume":null,"pages":null},"PeriodicalIF":1.9,"publicationDate":"2023-04-17","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"85949738","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":"Ionosonde and GPS total electron content observations during the 26 December 2019 annular solar eclipse over Indonesia","authors":"Jiyo Harjosuwito, A. Husin, V. Dear, J. Muhamad, Agri Faturahman, Afrizal Bahar, A. Syetiawan, R. Pradipta","doi":"10.5194/angeo-41-147-2023","DOIUrl":"https://doi.org/10.5194/angeo-41-147-2023","url":null,"abstract":"Abstract. We report the investigation of the ionospheric response to the passage of an annular solar eclipse over Southeast Asia on 26 December 2019 using multiple sets of observations. Two ionosondes (one at Kototabang and another at Pontianak) were used to measure dynamical changes in the ionospheric layer during the event. A network of ground-based GPS receiver stations in Indonesia was used to derive the distribution of total electron content (TEC) over the region. In addition, extreme ultraviolet (EUV) images of the Sun from the Atmospheric Imaging Assembly (AIA) instrument on board the Solar Dynamics Observatory (SDO) satellite were also analyzed to determine possible impacts of solar-active regions on the changes that occurred in the ionosphere during the eclipse. We found −1.62 and −1.90 MHz reductions (24.0 % and 27.5 % relative reduction) in foF2 during the solar eclipse over Kototabang and Pontianak, respectively. The respective TEC reductions over Kototabang and Pontianak during the eclipse were −4.34 and −5.45 TECU (24.9 % and 27.9 % relative reduction). Data from both ionosondes indicate a consistent 34–36 min delay between maximum eclipse and minimum foF2. The corresponding time delays for eclipse-related TEC reduction at these two locations were 40 and 16 min, respectively. The ionospheric F layer was found to descend with a speed of 9–19 m s−1 during the first half of the eclipse period. We also found an apparent rise in the ionospheric F-layer height near the end of the solar eclipse period, equivalent to a vertical drift velocity of 44–47 m s−1. The GPS TEC data mapping along a set of cross-sectional cuts indicates that the greatest TEC reduction actually occurred to the north of the solar-eclipse path, opposite of the direction from which the lunar shadow fell. As the central path of the solar eclipse was located just to the north of the southern equatorial ionization anomaly (EIA) crest, it is suspected that such a peculiar TEC reduction pattern was caused by plasma flow associated with the equatorial fountain effect. Net perturbations of TEC were also computed and analyzed, which revealed the presence of some wavelike fluctuations associated with the solar-eclipse event. Some of the observed TEC perturbation patterns that propagated with a velocity matching the lunar shadow may be explained in terms of nonuniform EUV illumination that arose as various active regions on the Sun went obstructed and unobstructed during the eclipse. The remaining wavelike features are likely to be traveling ionospheric disturbances (TIDs) generated by the passage of the solar eclipse on top of other diurnal factors.\u0000","PeriodicalId":50777,"journal":{"name":"Annales Geophysicae","volume":null,"pages":null},"PeriodicalIF":1.9,"publicationDate":"2023-04-13","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"81399023","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":"Effect of intermittent structures on the spectral index of the magnetic field in the slow solar wind","authors":"Xin Wang, Xuanhao Fan, Yuxin Wang, Honghong Wu, Lei Zhang","doi":"10.5194/angeo-41-129-2023","DOIUrl":"https://doi.org/10.5194/angeo-41-129-2023","url":null,"abstract":"Abstract. Intermittent structures are ubiquitous in the solar wind turbulence,\u0000and they can significantly affect the power spectral index (which reflects the cascading process of\u0000the turbulence) of\u0000magnetic field fluctuations. However, to date, an analytical relationship between the intermittency level and the magnetic spectral index has not been shown. Here, we\u0000present the continuous variation in the magnetic spectral index in\u0000the inertial range as a function of the intermittency level. Using the measurements from the Wind spacecraft, we find 42 272\u0000intervals with different levels of intermittency and with a\u0000duration of 5–6 min from 46 slow-wind streams between 2005 and\u00002013. Among them, each of the intermittent intervals is composed of\u0000one dominant intermittent structure and background turbulent\u0000fluctuations. For each interval, a magnetic spectral index αB is\u0000determined for the Fourier spectrum of the magnetic field fluctuations\u0000in the inertial range between 0.01 and 0.3 Hz. A parameter\u0000Imax, which corresponds to the maximum of the trace of the partial\u0000variance increments of the intermittent structure, is introduced as\u0000an indicator of the intermittency level. Our statistical result\u0000shows that, as Imax increases from 0 to 20, the magnetic\u0000spectrum becomes gradually steeper and the magnetic spectral index αB\u0000decreases from −1.63 to −2.01. Accordingly, for the first time, an empirical\u0000relation is established between αB and Imax: αB=0.4exp⁡(-Imax/5)-2.02. The\u0000result will help us to uncover more details about the contributions of\u0000the intermittent structures to the magnetic power spectra and, furthermore, about\u0000the physical nature of the energy cascade taking place in the solar\u0000wind. It will also help to improve turbulence theories that contain intermittent structures.\u0000","PeriodicalId":50777,"journal":{"name":"Annales Geophysicae","volume":null,"pages":null},"PeriodicalIF":1.9,"publicationDate":"2023-03-28","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"74131336","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":"Morphological evolution and spatial profile changes of poleward moving auroral forms","authors":"A. Goertz, N. Partamies, D. Whiter, L. Baddeley","doi":"10.5194/angeo-41-115-2023","DOIUrl":"https://doi.org/10.5194/angeo-41-115-2023","url":null,"abstract":"Abstract. We investigated the morphology of poleward moving auroral forms (PMAFs)\u0000qualitatively by visual inspection of all-sky camera (ASC) images\u0000and quantitatively using the arciness index. The PMAFs in this study\u0000were initially identified with a meridian scanning photometer (MSP) located\u0000at the Kjell Henriksen Observatory (KHO), Svalbard, and analyzed using\u0000ASC images taken by cameras at the KHO and in Ny-Ålesund, Svalbard. We\u0000present a detailed six-step evolution of PMAF morphology in two dimensions.\u0000This evolution includes (1) an equatorward expansion of the auroral\u0000oval and an intensification of auroral brightness at the open–closed\u0000boundary (OCB), (2) the appearance of an arc-like structure in the oval,\u0000(3) poleward and possible west/eastward propagation,\u0000(4) azimuthal expansion events, (5) re-brightening of the PMAF and\u0000eventual (6) fading away. This is the first work dedicated to the\u0000morphological evolution of PMAFs and it includes more detailed discussion\u0000and novel aspects, such as the observation of initial merging of 557.7 nm\u0000auroral patches to form a PMAF. Moreover, the morphology of PMAFs\u0000is quantified using the arciness index, which is a number describing\u0000how arc-like auroral forms appear in ASC images. This allows an unbiased\u0000statistical investigation of auroral morphology. We present the results\u0000of a superposed epoch analysis of arciness in relation to PMAF occurrence.\u0000This analysis uncovered that arciness increases suddenly during the\u0000onset of a PMAF event and decreases over the PMAF lifetime to return\u0000to its baseline value once the event has concluded. This behavior\u0000may be understood based on changes in the morphology of PMAFs and\u0000validates our understanding of PMAF morphology. Furthermore, our findings\u0000relating to arciness may enable automatic identification of PMAFs,\u0000which has been found to be notoriously difficult.\u0000","PeriodicalId":50777,"journal":{"name":"Annales Geophysicae","volume":null,"pages":null},"PeriodicalIF":1.9,"publicationDate":"2023-03-21","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"89479708","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":"Modulation of polar mesospheric summer echoes (PMSEs) with high-frequency heating during low solar illumination","authors":"Tinna L. Gunnarsdottir, A. Poggenpohl, I. Mann, A. Mahmoudian, P. Dalin, Ingemar Haeggstroem, M. Rietveld","doi":"10.5194/angeo-41-93-2023","DOIUrl":"https://doi.org/10.5194/angeo-41-93-2023","url":null,"abstract":"Abstract. Polar mesospheric summer echo (PMSE) formation is linked to charged dust/ice particles in the mesosphere. We investigate the modulation of PMSEs with radio waves based on measurements with EISCAT VHF radar and EISCAT heating facility during low solar illumination. The measurements were made in August 2018 and 2020 around 20:02 UT. Heating was operated in cycles with intervals of 48 s on and 168 s off.\u0000More than half of the observed heating cycles show a PMSE modulation with a decrease in PMSE when the heater is on and an increase when it is switched off again. The PMSE often increases beyond its initial strength.\u0000Less than half of the observed modulations have such an overshoot.\u0000The overshoots are small or nonexistent at strong PMSE, and they are not observed when the ionosphere is influenced by particle precipitation.\u0000We observe instances of very large overshoots at weak PMSE. PMSE modulation varies strongly from one cycle to the next, being highly variable on spatial scales smaller than a kilometer and timescales shorter than the timescales assumed for the variation in dust parameters. Average curves over several heating cycles are similar to the overshoot curves predicted by theory and observed previously. Some of the individual curves show stronger overshoots than reported in previous studies, and they exceed the values predicted by theory. A possible explanation is that the dust-charging conditions are different either because of the reduced solar illumination around midnight or because of long-term changes in ice particles in the mesosphere. We conclude that it is not possible to reliably derive the dust-charging parameters from the observed PMSE modulations.\u0000","PeriodicalId":50777,"journal":{"name":"Annales Geophysicae","volume":null,"pages":null},"PeriodicalIF":1.9,"publicationDate":"2023-02-14","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"77997995","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}